Title of Invention

METHOD AND SYSTEM FOR PROVIDING A HIERARCHY OF APPLIANCES TO MORE EFFICIENT ACCESS RESOURCES ACROSS A PLURALITY OF BRANCH OFFICES

Abstract Systems and methods are disclosed for providing a hierarchy of appliances to more efficiently access resources across a plurality of branch offices. A method comprises the steps of: establishing, by a first aggregator appliance, connections with a first plurality of branch office appliances; establishing, by a second aggregator appliance, connections with a second plurality of branch office appliances, the first plurality of branch office appliances not having information identifying the second plurality of branch office appliances; receiving, by the first aggregator appliance, from a first branch office appliance a request from a client for access to a resource; identifying, by the first aggregator appliance via the second aggregator appliance, a second branch office appliance from the second plurality of branch office appliances to service the request; transmitting, by the first aggregator appliance, to the first branch office appliance information identifying the second branch office appliance; and establishing, by the first branch office appliance, a connection with the second branch office appliance. Corresponding systems are also described.
Full Text SYSTEMS AND METHODS FOR
HIERARCHICAL GLOBAL LOAD BALANCING
Field of the Invention
The present invention generally relates to data communication networks. In
particular, the present invention relates to systems and methods for providing aggregator
appliances for global and hierarchical load balancing of branch offices.
Background of the Invention
A corporate or enterprise network may service many branch offices. Each branch
office may have its own network, servers and resources. An appliance may be deployed at a
branch office to provide gateway services locally to the client or servers located at the branch
office. In the corporate-wide network, branch office appliances may be deployed at each of
the branch offices. Many resources, such as servers, applications, data files may be deployed
across these branch offices. Additionally, a branch office may have under utilized resources
and available computing time.
At any of the branch offices there may be resources that could be available or useful
to access by users or computing devices at other branch offices. For example, a client of a
first branch office may want to access a resource, such as an application, on a server at a
second branch office. In some cases, the client of the first branch office is not aware of the
existence or availability of resources at the second branch office. In other cases, resources at
branch offices lay idle as they are not easily available to users across the corporate network.
This results in inefficient use of the corporate network and deployed resource. In order to
avail a client of a branch office access to resources from another branch office, an
administrator may need to manually and specifically configure the gateway or branch office
appliance to know of the other appliances in the network. With resources deployed across

many branch offices, each of the branch office appliances may need to be manually
configured to know of the other branch office appliances. This leads to significant amount of
time and costs in configuring and maintaining multiple branch office appliances or gateway.
It would, therefore, be desirable to provide systems and methods to reduce branch
office configuration while load-balancing resources globally across the enterprise and branch
offices.
Brief Summary of the Invention
The present invention is directed towards an aggregator appliance that provides
aggregation and load-balancing of branch office appliances in a hierarchical fashion and a
manner that reduces configuration of the branch office appliance. Any of the branch office
appliances may be configured to know of or identify a single aggregator appliance 400. For
example, a first branch office appliance may be configured to identify and connect to the first
aggregator appliance. The first branch office appliance may not be configured to have any
information and therefore may not know of the second aggregator appliance or any branch
office appliances connected to the second aggregator appliance. In this manner, the
configuration of branch office appliance is reduced. Even though the configuration is
reduced, a branch office appliance servicing a request may access any of the other appliances
known to an aggregator appliance. Since the aggregator appliances share information on
branch office appliance, a first aggregator appliance can identify to a first branch office
appliance information identifying any of the branch office appliances connected via any of
the aggregator appliances. In this way, resource requests can be load balanced globally
across all branch offices and branch office appliances.
In one aspect, the present invention is related to a method for providing a hierarchy of
appliances to more efficiently access resources across a plurality of branch offices. The
method includes the steps of: establishing, by a first aggregator appliance, connections with a

first plurality of branch office appliances, and establishing, by a second aggregator appliance,
connections with a second plurality of branch office appliances. The first plurality of branch
office appliances may not have information identifying the second plurality of branch office
appliances. The second plurality of branch office appliances may also not have information
identifying the first plurality of branch office appliances. The method includes receiving, by
the first aggregator appliance, from a first branch office appliance of the first plurality of
branch office a request from a client for access to a resource. The first aggregator appliance
identifies via the second aggregator appliance a second branch office appliance from the
second plurality of branch office appliances to service the request. The first aggregator
appliance transmits to one of the client or a first branch office appliance information
identifying the second branch office appliance. The method includes the client establishing a
connection with the second branch office appliance.
In one embodiment, the method includes transmitting, by the first branch office
appliance, information identifying the second branch office appliance to the client.
In another embodiment, the method includes establishes, by the client via the first branch
office appliance, a second connection via the second branch office appliance with a server.
In some embodiments, the method includes establishing, by the first aggregator appliance,
communications with the second aggregator appliance, in one embodiment, the first
aggregator appliance communicates information about the first plurality of branch office
appliances to the second aggregator appliance. In another embodiments, the second
aggregator appliance communicates information about the second plurality of branch office
appliances to the first aggregator appliance.
In another embodiment, the method includes determining, by the first aggregator
appliance, information on performance or operational characteristics for each of the first
plurality of branch office appliances. In some embodiments, the method includes
determining, by the second aggregator appliance, performance or operational characteristics

of each of the second plurality of branch office appliances. In one embodiment, the method
includes selecting, by the first or second aggregator appliance, the second branch office
appliance based on one of the performance or operational characteristics.
In yet another embodiment, the method includes by the first office branch office
appliance or the second branch office appliance, communications between the client and the
server. The method may include accelerating using one or more of the following techniques:
1) compression, 2) TCP connection pooling, 3)TCP connection multiplexing, 4) TCP
buffering, and 5) caching. In some embodiments, the first aggregator appliance or the second
aggregator appliance is deployed at a data center. In another embodiment, the client is
deployed at the first branch office.
In another aspect, the present invention is related to a system for providing a
hierarchy of appliances to more efficiently access resources across a plurality of branch
offices, the system comprises a first aggregator appliance and a second aggregator appliance.
The first aggregator appliance establishes connections with a first plurality of branch office
appliances. The second aggregator appliance establishes connections with a second plurality
of branch office appliances. The first plurality of branch office appliances may not have
information identifying the second plurality of branch office appliances. The second plurality
of branch office appliances may also not have information identifying the first plurality of
branch office appliances. The system also includes a first branch office appliance of the first
plurality of branch offices transmitting to the first aggregator appliance a request from a
client for access to a resource. The first aggregator appliance identifies via the second
aggregator appliance a second branch office appliance from the second plurality of branch
office appliances to service the request and transmits to the first branch office appliance
information identifying the second branch office appliance. The system also includes the
client establishing a connection with the second branch office appliance.

In one embodiment, the first branch office appliance transmits information identifying
the second branch office appliance to the client. In another embodiment, the client
establishes via the first branch office appliance a second connection via the second branch
office appliance with a server. In some embodiments, the first aggregator appliamce
establishes communications with the second aggregator appliance. In one embodiment, the
first aggregator appliance communicates information about the first plurality of branch office
appliances to the second aggregator appliance. In yet another embodiment, the second
aggregator appliance communicates information about the second plurality of branch office
appliances to the first aggregator appliance. In some embodiments, the first or second
aggregator appliance determines information on performance or operational charactersitics
for each of the first plurality of branch office appliances. In another embodiment of the
system, the first aggregator appliance selects the second branch office appliance based on one
of the performance or operational characteristics.
In some embodiments, the first office branch office appliance or the second branch
office appliance accelerates communications between the client and a server. The
acceleration techniques may include one or more of the following: 1) compression, 2) TCP
connection pooling, 3)TCP connection multiplexing, 4) TCP buffering, and 5) caching.
In other embodiments, the first aggregator appliance or the second aggregator appliance is
deployed at a data center. In one embodiment, the client is deployed at the first branch office.
The details of various embodiments of the invention are set forth in the accompanying
drawings and the description below.
Brief Description of the Figures
The foregoing and other objects, aspects, features, and advantages of the invention
will become more apparent and better understood by referring to the following description
taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment for a client
to access a server via an appliance;
FIG. IB is a block diagram of an embodiment of an environment for delivering a
computing environment from a server to a client via an appliance;
FIGs. 1C and ID are block diagrams of embodiments of a computing device;
FIG. 2A is a block diagram of an embodiment of an appliance for processing
communications between a client and a server;
FIG. 2B is a block diagram of another embodiment of an appliance for optimizing,
accelerating, load-balancing and routing communications between a client and a server;
FIG. 3 is a block diagram of an embodiment of a client for communicating with a
server via the appliance;
FIG. 4A is a block diagram of an embodiment of aggregator appliances to access
resources across branch offices;
FIG. 4B is a block diagram of another embodiment of a deployment of aggregator
appliances to load balance a plurality of branch offices; and
FIG. 5 is a flow diagram of steps of an embodiment of a method for practicing
hierarchical load balancing with aggregator appliances to access resources across branch
offices.
The features and advantages of the present invention will become more apparent from
the detailed description set forth below when taken in conjunction with the drawings, in
which like reference characters identify corresponding elements throughout. In the drawings,
like reference numbers generally indicate identical, functionally similar, and/or structurally
similar elements.

Detailed Description of the Invention
A. Network and Computing Environment
Prior to discussing the specifics of embodiments of the systems and methods of an
appliance and/or client, it may be helpful to discuss the network and computing environments
in which such embodiments may be deployed. Referring now to Figure 1 A, an embodiment
of a network environment is depicted. In brief overview, the network environment comprises
one or more clients 102a-102n (also generally referred to as local machine(s) 102, or client(s)
102) in communication with one or more servers 106a-106n (also generally referred to as
server(s) 106, or remote machine(s) 106) via one or more networks 104, 104' (generally
referred to as network 104). In some embodiments, a client 102 communicates with a server
106 via an appliance 200.
Although FIG. 1A shows a network 104 and a network 104' between the clients 102
and the servers 106, the clients 102 and the servers 106 may be on the same network 104.
The networks 104 and 104' can be the same type of network or different types of networks.
The network 104 and/or the network 104' can be a local-area network (LAN), such as a
company Intranet, a metropolitan area network (MAN), or a wide area network (WAN), such
as the Internet or the World Wide Web. In one embodiment, network 104' may be a private
network and network 104 may be a public network. In some embodiments, network 104 may
be a private network and network 104' a public network. In another embodiment, networks
104 and 104' may both be private networks. In some embodiments, clients 102 may be
located at a branch office of a corporate enterprise communicating via a WAN connection
over the network 104 to the servers 106 located at a corporate data center.
The network 104 and/or 104' be any type and/or form of network and may include
any of the following: a point to point network, a broadcast network, a wide area network, a
local area network, a telecommunications network, a data communication network, a
computer network, an ATM (Asynchronous Transfer Mode) network, a SONET

(Synchronous Optical Network) network, a SDH (Synchronous Digital Hierarchy) network, a
wireless network and a wireline network. In some embodiments, the network 104 may
comprise a wireless link, such as an infrared channel or satellite band. The topology of the
network 104 and/or 104' may be a bus, star, or ring network topology. The network 104
and/or 104' and network topology may be of any such network or network topology as
known to those ordinarily skilled in the art capable of supporting the operations described
herein.
As shown in FIG. 1 A, the appliance 200, which also may be referred to as an interface
unit 200 or gateway 200, is shown between the networks 104 and 104'. In some
embodiments, the appliance 200 may be located on network 104. For example, a branch
office of a corporate enterprise may deploy an appliance 200 at the branch office. In other
embodiments, the appliance 200 may be located on network 104'. For example, an appliance
200 may be located at a corporate data center. In yet another embodiment, a plurality of
appliances 200 may be deployed on network 104. In some embodiments, a plurality of
appliances 200 may be deployed on network 104'. In one embodiment, a first appliance 200
communicates with a second appliance 200'. In other embodiments, the appliance 200 could
be a part of any client 102 or server 106 on the same or different network 104,104' as the
client 102. One or more appliances 200 may be located at any point in the network or
network communications path between a client 102 and a server 106.
In one embodiment, the system may include multiple, logically-grouped servers 106.
In these embodiments, the logical group of servers may be referred to as a server farm 38. In
some of these embodiments, the serves 106 may be geographically dispersed. In some cases,
a farm 38 may be administered as a single entity. In other embodiments, the server farm 38
comprises a plurality of server farms 38. In one embodiment, the server farm executes one or
more applications on behalf of one or more clients 102.

The servers 106 within each farm 38 can be heterogeneous. One or moire of the
servers 106 can operate according to one type of operating system platform (e.g., WINDOWS
NT, manufactured by Microsoft Corp. of Redmond, Washington), while one or more of the
other servers 106 can operate on according to another type of operating system platform (e.g.,
Unix or Linux). The servers 106 of each farm 38 do not need to be physically proximate to
another server 106 in the same farm 38. Thus, the group of servers 106 logically grouped as
a farm 38 may be interconnected using a wide-area network (WAN) connection or medium-
area network (MAN) connection. For example, a farm 38 may include servers 106 physically
located in different continents or different regions of a continent, countiy, state, city, campus,
or room. Data transmission speeds between servers 106 in the farm 38 can be increased if the
servers 106 are connected using a local-area network (LAN) connection or some form of
direct connection.
Servers 106 may be referred to as a file server, application server, web server, proxy
server, or gateway server. In some embodiments, a server 106 may have the capacity to
function as either an application server or as a master application server. In one embodiment,
a server 106 may include an Active Directory. The clients 102 may also be referred to as
client nodes or endpoints. In some embodiments, a client 102 has the capacity to function as
both a client node seeking access to applications on a server and as an application server
providing access to hosted applications for other clients 102a-102n.
In some embodiments, a client 102 communicates with a server 106. In one
embodiment, the client 102 communicates directly with one of the servers 106 in a farm 38.
In another embodiment, the client 102 executes a program neighborhood application to
communicate with a server 106 in a farm 38. In still another embodiment, the server 106
provides the functionality of a master node. In some embodiments, the client 102
communicates with the server 106 in the farm 38 through a network 104. Over the network
104, the client 102 can, for example, request execution of various applications hosted by the

servers 106a-106n in the farm 38 and receive output of the results of the application
execution for display. In some embodiments, only the master node provides the functionality
required to identify and provide address information associated with a server 106' hosting a
requested application.
In one embodiment, the server 106 provides functionality of a web server. In another
embodiment, the server 106a receives requests from the client 102, forwards the requests to a
second server 106b and responds to the request by the client 102 with a response to the
request from the server 106b. Tn still another embodiment, the server 106 acquires an
enumeration of applications available to the client 102 and address information associated
with a server 106 hosting an application identified by the enumeration of applications. In yet
another embodiment, the server 106 presents the response to the request to the client 102
using a web interface. In one embodiment, the client 102 communicates directly with the
server 106 to access the identified application. In another embodiment, the client 102
receives application output data, such as display data, generated by an execution of the
identified application on the server 106.
Referring now to FIG. IB, a network environment for delivering and/or operating a
computing environment on a client 102 is depicted. In some embodiments, a server 106
includes an application delivery system 190 for delivering a computing environment or an
application and/or data file to one or more clients 102. In brief overview, a client 10 is in
communication with a server 106 via network 104, 104' and appliance 200. For example, the
client 102 may reside in a remote office of a company, e.g., a branch office, and the server
106 may reside at a corporate data center. The client 102 comprises a client agent 120, and a
computing environment 15. The computing environment 15 may execute or operate an
application that accesses, processes or uses a data file. The computing environment 15,
application and/or data file may be delivered via the appliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of a computing
environment 15, or any portion thereof, to a client 102. In one embodiment, the appliance
200 accelerates the delivery of the computing environment 15 by the application delivery
system 190. For example, the embodiments described herein may be used to accelerate
delivery of a streaming application and data file processable by the application from a central
corporate data center to a remote user location, such as a branch office of the company. In
another embodiment, the appliance 200 accelerates transport layer traffic between a client
102 and a server 106. The appliance 200 may provide acceleration techniques for
accelerating any transport layer payload from a server 106 to a client 102, such as: 1)
transport layer connection pooling, 2) transport layer connection multiplexing, 3) transport
control protocol buffering, 4) compression and 5) caching. In some embodiments, the
appliance 200 provides load balancing of servers 106 in responding to requests from clients
102. In other embodiments, the appliance 200 acts as a proxy or access server to provide
access to the one or more servers 106. In another embodiment, the appliance 200 provides a
secure virtual private network connection from a first network 104 of the client 102 to the
second network 104' of the server 106, such as an SSL VPN connection. It yet other
embodiments, the appliance 200 provides application firewall security, control and
management of the connection and communications between a client 102 and a server 106.
In some embodiments, the application delivery management system 190 provides
application delivery techniques to deliver a computing environment to a desktop of a user,
remote or otherwise, based on a plurality of execution methods and based on any
authentication and authorization policies applied via a policy engine 195. With these
techniques, a remote user may obtain a computing environment and access to server stored
applications and data files from any network connected device 100. In one embodiment, the
application delivery system 190 may reside or execute on a server 106. In another
embodiment, the application delivery system 190 may reside or execute on a plurality of

servers 106a-106n. In some embodiments, the application delivery system 190 may execute
in a server farm 38. In one embodiment, the server 106 executing the application delivery
system 190 may also store or provide the application and data file. In another embodiment, a
first set of one or more servers 106 may execute the application delivery system 190, and a
different server 106n may store or provide the application and data file. In some
embodiments, each of the application delivery system 190, the application, and data file may
reside or be located on different servers. In yet another embodiment, any portion of the
application delivery system 190 may reside, execute or be stored on or distributed to the
appliance 200, or a plurality of appliances.
The client 102 may include a computing environment 15 for executing an application
that uses or processes a data file. The client 102 via networks 104, 104' and appliance 200
may request an application and data file from the server 106. In one embodiment, the
appliance 200 may forward a request from the client 102 to the server 106. For example, the
client 102 may not have the application and data file stored or accessible locally. In response
to the request, the application delivery system 190 and/or server 106 may deliver the
application and data file to the client 102. For example, in one embodiment, the server 106
may transmit the application as an application stream to operate in computing environment
15 on client 102.
In some embodiments, the application delivery system 190 comprises any portion of
the Citrix Access Suite™ by Citrix Systems, Inc., such as the MetaFrame or Citrix
Presentation Server™ and/or any of the Microsoft® Windows Terminal Services
manufactured by the Microsoft Corporation. In one embodiment, the application delivery
system 190 may deliver one or more applications to clients 102 or users via a remote-display
protocol or otherwise via remote-based or server-based computing. In another embodiment,
the application delivery system 190 may deliver one or more applications to clients or users
via steaming of the application.

In one embodiment, the application delivery system 190 includes a policy engine 195
for controlling and managing the access to, selection of application execution methods and
the delivery of applications. In some embodiments, the policy engine 195 determines the one
or more applications a user or client 102 may access. In another embodiment, the policy
engine 195 determines how the application should be delivered to the user or client 102, e.g.,
the method of execution. In some embodiments, the application delivery system 190
provides a plurality of delivery techniques from which to select a method of application
execution, such as a server-based computing, streaming or delivering the application locally
to the client 120 for local execution.
In one embodiment, a client 102 requests execution of an application program and the
application delivery system 190 comprising a server 106 selects a method of executing the
application program. In some embodiments, the server 106 receives credentials from the
client 102. In another embodiment, the server 106 receives a request for an enumeration of
available applications from the client 102. In one embodiment, in response to the request or
receipt of credentials, the application delivery system 190 enumerates a plurality of
application programs available to the client 102. The application delivery system 190
receives a request to execute an enumerated application. The application delivery system 190
selects one of a predetermined number of methods for executing the enumerated application,
for example, responsive to a policy of a policy engine. The application delivery system 190
may select a method of execution of the application enabling the client 102 to receive
application-output data generated by execution of the application program on a server 106.
The application delivery system 190 may select a method of execution of the application
enabling the local machine 10 to execute the application program locally after retrieving a
plurality of application files comprising the application. In yet another embodiment, the
application delivery system 190 may select a method of execution of the application to stream
the application via the network 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application, which can be
any type and/or form of software, program, or executable instructions such as any type and/or
form of web browser, web-based client, client-server application, a thin-client computing
client, an ActiveX control, or a Java applet, or any other type and/or form of executable
instructions capable of executing on client 102. In some embodiments, the application may
be a server-based or a remote-based application executed on behalf of the client 102 on a
server 106. In one embodiments the server 106 may display output to the client 102 using
any thin-client or remote-display protocol, such as the Independent Computing Architecture
(ICA) protocol manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Florida or the
Remote Desktop Protocol (RDP) manufactured by the Microsoft Corporation of Redmond,
Washington. The application can use any type of protocol and it can be, for exa.mple, an
HTTP client, an FTP client, an Oscar client, or a Telnet client. In other embodiments, the
application comprises any type of software related to VoIP communications, such as a soft IP
telephone. In further embodiments, the application comprises any application related to real-
time data communications, such as applications for streaming video and/or audio.
In some embodiments, the server 106 or a server farm 38 may be running one or more
applications, such as an application providing a thin-client computing or remote display
presentation application. In one embodiment, the server 106 or server farm 38 executes as an
application, any portion of the Citrix Access Suite™ by Citrix Systems, Inc., such as the
MetaFrame or Citrix Presentation Server™, and/or any of the Microsoft® Windows Terminal
Services manufactured by the Microsoft Corporation. In one embodiment, the application is
an ICA client, developed by Citrix Systems, Inc. of Fort Lauderdale, Florida. In other
embodiments, the application includes a Remote Desktop (RDP) client, developed by
Microsoft Corporation of Redmond, Washington. Also, the server 106 may run an
application, which for example, may be an application server providing email services such
as Microsoft Exchange manufactured by the Microsoft Corporation of Redmond,

Washington, a web or Internet server, or a desktop sharing server, or a collaboration server.
In some embodiments, any of the applications may comprise any type of hosted service or
products, such as GoToMeeting™ provided by Citrix Online Division, Inc. of Santa Barbara,
California, WebEx™ provided by WebEx, Inc. of Santa Clara, California, or Microsoft
Office Live Meeting provided by Microsoft Corporation of Redmond, Washington.
The client 102, server 106, and appliance 200 may be deployed as and/or executed on
any type and form of computing device, such as a computer, network device or appliance
capable of communicating on any type and form of network and performing the operations
described herein. FIGs. IC and ID depict block diagrams of a computing device 100 useful
for practicing an embodiment of the client 102, server 106 or appliance 200. As shown in
FIGs. IC and ID, each computing device 100 includes a central processing unit 101, and a
main memory unit 122. As shown in FIG. IC, a computing device 100 may include a visual
display device 124, a keyboard 126 and/or a pointing device 127, such as a mouse. Each
computing device 100 may also include additional optional elements, such as one or more
input/output devices 130a-130b (generally referred to using reference numeral 130), and a
cache memory 140 in communication with the central processing unit 101.
The central processing unit 101 is any logic circuitry that responds to and processes
instructions fetched from the main memory unit 122. In many embodiments, the central
processing unit is provided by a microprocessor unit, such as: those manufactured by Intel
Corporation of Mountain View, California; those manufactured by Motorola Corporation of
Schaumburg, Illinois; those manufactured by Transmeta Corporation of Santa Clara,
California; the RS/6000 processor, those manufactured by International Business Machines
of White Plains, New York; or those manufactured by Advanced Micro Devices of
Sunnyvale, California. The computing device 100 may be based on any of these processors,
or any other processor capable of operating as described herein.

Mam memory unit 122 may be one or more memory chips capable of storing data and
allowing any storage location to be directly accessed by the microprocessor 101, such as
Static random access memory (SRAM), Burst SRAM or SynchBurst SRAM (BSRAM),
Dynamic random access memory (DRAM), Fast Page Mode DRAM (FPM DRAM),
Enhanced DRAM (EDRAM), Extended Data Output RAM (EDO RAM), Extended Data
Output DRAM (EDO DRAM), Burst Extended Data Output DRAM (BEDO DRAM),
Enhanced DRAM (EDRAM), synchronous DRAM (SDRAM), JEDEC SRAM, PC100
SDRAM, Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM),
SyncLink DRAM (SLDRAM), Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM
(FRAM). The main memory 122 may be based on any of the above described memory chips,
or any other available memory chips capable of operating as described herein. In the
embodiment shown in FIG. 1C, the processor 101 communicates with main memory 122 via
a system bus 150 (described in more detail below). FIG. 1C depicts an embodiment of a
computing device 100 in which the processor communicates directly with main memory 122
via a memory port 103. For example, in FIG. ID the main memory 122 may be DRDRAM.
FIG. ID depicts an embodiment in which the main processor 101 communicates
directly with cache memory 140 via a secondary bus, sometimes referred to as a backside
bus. In other embodiments, the main processor 101 communicates with cache memory 140
using the system bus 150. Cache memory 140 typically has a faster response time than main
memory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In the embodiment
shown in FIG. 1C, the processor 101 communicates with various I/O devices 130 via a local
system bus 150. Various busses may be used to connect the central processing unit 101 to
any of the I/O devices 130, including a VESA VL bus, an ISA bus, an EISA bus, a
MicroChannel Architecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or a
NuBus. For embodiments in which the I/O device is a video display 124, the processor 101
may use an Advanced Graphics Port (AGP) to communicate with the display 124. FIG. ID

depicts an embodiment of a computer 100 in which the main processor 101 communicates
directly with I/O device 130 via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1D also
depicts an embodiment in which local busses and direct communication are mixed: the
processor 101 communicates with I/O device 130 using a local interconnect bus while
communicating with I/O device 130 directly.
The computing device 100 may support any suitable installation device 116, such as a
floppy disk drive for receiving floppy disks such as 3.5-inch, 5.25-inch disks or ZIP disks, a
CD-ROM drive, a CD-R/RW drive, a DVD-ROM drive, tape drives of various formats, USB
device, hard-drive or any other device suitable for installing software and programs such as
any client agent 120, or portion thereof. The computing device 100 may further comprise a
storage device 128, such as one or more hard disk drives or redundant arrays of independent
disks, for storing an operating system and other related software, and for storing application
software programs such as any program related to the client agent 120. Optionally, any of the
installation devices 116 could also be used as the storage device 128. Additionally, the
operating system and the software can be run from a bootable medium, for example, a
bootable CD, such as KNOPPIX®, a bootable CD for GNU/Linux that is available as a
GNU/Linux distribution from knoppix.net.
Furthermore, the computing device 100 may include a network interface 118 to
interface to a Local Area Network (LAN), Wide Area Network (WAN) or the Internet
through a variety of connections including, but not limited to, standard telephone lines, LAN
or WAN links (e.g., 802.11, Tl, T3, 56kb, X.25), broadband connections (e.g., ISDN, Frame
Relay, ATM), wireless connections, or some combination of any or all of the above. The
network interface 118 may comprise a built-in network adapter, network interface card,
PCMCIA network card, card bus network adapter, wireless network adapter, USB network
adapter, modem or any other device suitable for interfacing the computing device 100 to any
type of network capable of communication and performing the operations described herein.

A wide variety of I/O devices 130a-130n may be present in the computing device 100. Input
devices include keyboards, mice, trackpads, trackballs, microphones, and drawing tablets.
Output devices include video displays, speakers, inkjet printers, laser printers, and dye-
sublimation printers. The I/O devices 130 may be controlled by an I/O controller 123 as
shown in FIG. 1C. The I/O controller may control one or more I/O devices such as a
keyboard 126 and a pointing device 127, e.g., a mouse or optical pen. Furthermore, an I/O
device may also provide storage 128 and/or an installation medium 116 for the computing
device 100. In still other embodiments, the computing device 100 may provide USB
connections to receive handheld USB storage devices such as the USB Flash Drive line of
devices manufactured by Twintech Industry, Inc. of Los Alamitos, California.
In some embodiments, the computing device 100 may comprise or be connected to
multiple display devices 124a-124n, which each may be of the same or different type and/or
form. As such, any of the I/O devices 130a-130n and/or the I/O controller 123 may comprise
any type and/or form of suitable hardware, software, or combination of hardware and
software to support, enable or provide for the connection and use of multiple display devices
124a-124n by the computing device 100. For example, the computing device 100 may
include any type and/or form of video adapter, video card, driver, and/or library to interface,
communicate, connect or otherwise use the display devices 124a-124n. In one embodiment, a
video adapter may comprise multiple connectors to interface to multiple display devices
124a-124n. In other embodiments, the computing device 100 may include multiple video
adapters, with each video adapter connected to one or more of the display devices 124a-124n.
In some embodiments, any portion of the operating system of the computing device 100 may
be configured for using multiple displays 124a-124n. In other embodiments, one or more of
the display devices 124a-124n may be provided by one or more other computing devices,
such as computing devices 100a and 100b connected to the computing device 100, for
example, via a network. These embodiments may include any type of software designed and

constructed to use another computer's display device as a second display device 124a for the
computing device 100. One ordinarily skilled in the art will recognize and appreciate the
various ways and embodiments that a computing device 100 may be configured to have
multiple display devices 124a-124n.
In further embodiments, an I/O device 130 may be a bridge 170 between the system
bus 150 and an external communication bus, such as a USB bus, an Apple Desktop Bus, an
RS-232 serial connection, a SCSI bus, a Fire Wire bus, a FireWire 800 bus, an Ethernet bus,
an AppleTalk bus, a Gigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus,
a Super HIPPI bus, a SerialPius bus, a SCI/LAMP bus, a FibreChannei bus, or a Serial
Attached small computer system interface bus.
A computing device 100 of the sort depicted in FIGs. 1C and ID typically operate
under the control of operating systems, which control scheduling of tasks and access to
system resources. The computing device 100 can be running any operating system such as
any of the versions of the Microsoft® Windows operating systems, the different releases of
the Unix and Linux operating systems, any version of the Mac OS® for Macintosh
computers, any embedded operating system, any real-time operating system, any open source
operating system, any proprietary operating system, any operating systems for mobile
computing devices, or any other operating system capable of running on the computing
device and performing the operations described herein. Typical operating systems include:
WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT 3.51,
WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which are manufactured by
Microsoft Corporation of Redmond, Washington; MacOS, manufactured by Apple Computer
of Cupertino, California; OS/2, manufactured by International Business Machines of
Armonk, New York; and Linux, a freely-available operating system distributed by Caldera
Corp. of Salt Lake City, Utah, or any type and/or form of a Unix operating system, among
others.

In other embodiments, the computing device 100 may have different processors,
operating systems, and input devices consistent with the device. For example, in one
embodiment the computer 100 is a Treo 180, 270, 1060, 600 or 650 smart phone
manufactured by Palm, Inc. In this embodiment, the Treo smart phone is operated under the
control of the PalmOS operating system and includes a stylus input device as well as a five-
way navigator device. Moreover, the computing device 100 can be any workstation, desktop
computer, laptop or notebook computer, server, handheld computer, mobile telephone, any
other computer, or other form of computing or telecommunications device that is capable of
communication and that has sufficient processor power and memory capacity to perform the
operations described herein.
B. Appliance Architecture
FIG. 2A illustrates an example embodiment of the appliance 200. The architecture of
the appliance 200 in FIG. 2A is provided by way of illustration only and is not intended to be
limiting. As shown in FIG. 2, appliance 200 comprises a hardware layer 206 and a software
layer divided into a user space 202 and a kernel space 204.
Hardware layer 206 provides the hardware elements upon which programs and
services within kernel space 204 and user space 202 are executed. Hardware layer 206 also
provides the structures and elements which allow programs and services within kernel space
204 and user space 202 to communicate data both internally and externally with respect to
appliance 200. As shown in FIG. 2, the hardware layer 206 includes a processing unit 262
for executing software programs and services, a memory 264 for storing software and data,
network ports 266 for transmitting and receiving data over a network, and an encryption
processor 260 for performing functions related to Secure Sockets Layer processing of data
transmitted and received over the network. In some embodiments, the central processing unit
262 may perform the functions of the encryption processor 260 in a single processor.

Additionally, the hardware layer 206 may comprise multiple processors for each of the
processing unit 262 and the encryption processor 260. The processor 262 may include any of
the processors 101 described above in connection with FIGs. 1C and ID. In some
embodiments, the central processing unit 262 may perform the functions of the encryption
processor 260 in a single processor. Additionally, the hardware layer 206 may comprise
multiple processors for each of the processing unit 262 and the encryption processor 260. For
example, in one embodiment, the appliance 200 comprises a first processor 262 and a second
processor 262'. In other embodiments, the processor 262 or 262' comprises a multi-core
processor.
Although the hardware layer 206 of appliance 200 is generally illustrated with an
encryption processor 260, processor 260 may be a processor for performing functions related
to any encryption protocol, such as the Secure Socket Layer (SSL) or Transport Layer
Security (TLS) protocol. In some embodiments, the processor 260 may be a general purpose
processor (GPP), and in further embodiments, may be have executable instructions for
performing processing of any security related protocol.
Although the hardware layer 206 of appliance 200 is illustrated with certain elements
in FIG. 2, the hardware portions or components of appliance 200 may comprise any type and
form of elements, hardware or software, of a computing device, such as the computing device
100 illustrated and discussed herein in conjunction with FIGs. 1C and ID. In some
embodiments, the appliance 200 may comprise a server, gateway, router, switch, bridge or
other type of computing or network device, and have any hardware and/or software elements
associated therewith.
The operating system of appliance 200 allocates, manages, or otherwise segregates
the available system memory into kernel space 204 and user space 204. In example software
architecture 200, the operating system may be any type and/or form of Unix operating system
although the invention is not so limited. As such, the appliance 200 can be running any

operating system such as any of the versions of the Microsoft® Windows operating systems,
the different releases of the Unix and Linux operating systems, any version of the Mac OS®
for Macintosh computers, any embedded operating system, any network operating system,
any real-time operating system, any open source operating system, any proprietary operating
system, any operating systems for mobile computing devices or network devices, or any other
operating system capable of running on the appliance 200 and performing the operations
described herein.
The kernel space 204 is reserved for running the kernel 230, including any device
drivers, kernel extensions or other kernel related software. As known to those skilled in the
art, the kernel 230 is the core of the operating system, and provides access, control, and
management of resources and hardware-related elements of the application 104. In
accordance with an embodiment of the appliance 200, the kernel space 204 also includes a
number of network services or processes working in conjunction with a cache manager 232.
sometimes also referred to as the integrated cache, the benefits of which are described in
detail further herein. Additionally, the embodiment of the kernel 230 will depend on the
embodiment of the operating system installed, configured, or otherwise used by the device
200.
In one embodiment, the device 200 comprises one network stack 267, such as a
TCP/IP based stack, for communicating with the client 102 and/or the server 106. In one
embodiment, the network stack 267 is used to communicate with a first network, such as
network 108, and a second network 110. In some embodiments, the device 200 terminates a
first transport layer connection, such as a TCP connection of a client 102, and establishes a
second transport layer connection to a server 106 for use by the client 102, e.g., the second
transport layer connection is terminated at the appliance 200 and the server 106. The first
and second transport layer connections may be established via a single network stack 267. In
other embodiments, the device 200 may comprise multiple network stacks, for example 267

and 267', and the first transport layer connection may be established or terminated at one
network stack 267, and the second transport layer connection on the second network stack
267'. For example, one network stack may be for receiving and transmitting network packet
on a first network, and another network stack for receiving and transmitting network packets
on a second network. Tn one embodiment, the network stack 267 comprises a buffer 243 for
queuing one or more network packets for transmission by the appliance 200.
As shown in FIG. 2, the kernel space 204 includes the cache manager 232, a high-
speed layer 2-7 integrated packet engine 240, an encryption engine 234, a policy engine 236
and multi-protocol compression logic 238. Running these components or processes 232,
240, 234, 236 and 238 in kernel space 204 or kernel mode instead of the user space 202
improves the performance of each of these components, alone and in combination. Kernel
operation means that these components or processes 232, 240, 234, 236 and 238 run in the
core address space of the operating system of the device 200. For example, running the
encryption engine 234 in kernel mode improves encryption performance by moving
encryption and decryption operations to the kernel, thereby reducing the number of
transitions between the memory space or a kernel thread in kernel mode and the memory
space or a thread in user mode. For example, data obtained in kernel mode may not need to
be passed or copied to a process or thread running in user mode, such as from a kernel level
data structure to a user level data structure. In another aspect, the number of context switches
between kernel mode and user mode are also reduced. Additionally, synchronization of and
communications between any of the components or processes 232, 240, 235, 236 and 238 can
be performed more efficiently in the kernel space 204.
In some embodiments, any portion of the components 232, 240, 234, 236 and 238
may run or operate in the kernel space 204, while other portions of these components 232,
240, 234, 236 and 238 may run or operate in user space 202. In one embodiment, the
appliance 200 uses a kernel-level data structure providing access to any portion of one or

more network packets, for example, a network packet comprising a request from a client 102
or a response from a server 106. In some embodiments, the kernel-level data structure may
be obtained by the packet engine 240 via a transport layer driver interface or filter to the
network stack 267. The kernel-level data structure may comprise any interface and/or data
accessible via the kernel space 204 related to the network stack 267, network traffic or
packets received or transmitted by the network stack 267. In other embodiments, the kernel-
level data structure maybe used by any of the components or processes 232, 240, 234, 236
and 238 to perform the desired operation of the component or process. In one embodiment, a
component 232, 240, 234, 236 and 238 is running in kernel mode 204 when using the kernel-
level data structure, while in another embodiment, the component 232, 240, 234, 236 and 238
is running in user mode when using the kernel-level data structure. In some embodiments,
the kernel-level data structure may be copied or passed to a second kernel-level data
structure, or any desired user-level data structure.
The cache manager 232 may comprise software, hardware or any combination of
software and hardware to provide cache access, control and management of any type and
form of content, such as objects or dynamically generated objects served by the originating
servers 106. The data, objects or content processed and stored by the cache manager 232
may comprise data in any format, such as a markup language, or communicated via any
protocol. In some embodiments, the cache manager 232 duplicates original data stored
elsewhere or data previously computed, generated or transmitted, in which the original data
may require longer access time to fetch, compute or otherwise obtain relative to reading a
cache memory element. Once the data is stored in the cache memory element, future use can
be made by accessing the cached copy rather than refetching or recomputing the original
data, thereby reducing the access time. In some embodiments, the cache memory element nat
comprise a data object in memory 264 of device 200. In other embodiments, the cache
memory element may comprise memory having a faster access time than memory 264. In

another embodiment, the cache memory element may comrpise any type and form of storage
element of the device 200, such as a portion of a hard disk. Tn some embodiments, the
processing unit 262 may provide cache memory for use by the cache manager 232. In yet
further embodiments, the cache manager 232 may use any portion and combination of
memory, storage, or the processing unit for caching data, objects, and other content.
Furthermore, the cache manager 232 includes any logic, functions, rules, or
operations to perform any embodiments of the techniques of the appliance 200 described
herein. For example, the cache manager 232 includes logic or functionality to invalidate
objects based on the expiration of an invalidation time period or upon receipt of an
invalidation command from a client 102 or server 106. In some embodiments, the cache
manager 232 may operate as a program, service, process or task executing in the kernel space
204, and in other embodiments, in the user space 202. In one embodiment, a first portion of
the cache manager 232 executes in the user space 202 while a second portion executes in the
kernel space 204. In some embodiments, the cache manager 232 can comprise any type of
general purpose processor (GPP), or any other type of integrated circuit, such as a Field
Programmable Gate Array (FPGA), Programmable Logic Device (PLD), or Application
Specific Integrated Circuit (ASIC).
The policy engine 236 may include, for example, an intelligent statistical engine or
other programmable application(s). In one embodiment, the policy engine 236 provides a
configuration mechanism to allow a user to identifying, specify, define or configure a caching
policy. Policy engine 236, in some embodiments, also has access to memory to support data
structures such as lookup tables or hash tables to enable user-selected caching policy
decisions. In other embodiments, the policy engine 236 may comprise any logic, rules,
functions or operations to determine and provide access, control and management of objects,
data or content being cached by the appliance 200 in addition to access, control and
management of security, network traffic, network access, compression or any other function

or operation performed by the appliance 200. Further examples of specific caching policies
are further described herein.
The encryption engine 234 comprises any logic, business rules, functions or
operations for handling the processing of any security related protocol, such as SSL or TLS,
or any function related thereto. For example, the encryption engine 234 encrypts and
decrypts network packets, or any portion thereof, communicated via the appliance 200. The
encryption engine 234 may also setup or establish SSL or TLS connections on behalf of the
client 102a-102n, server 106a-106n, or appliance 200. As such, the encryption engine 234
provides offloading and acceleration of SSL processing. In one embodiment, the encryption
engine 234 uses a tunneling protocol to provide a virtual private network between a client
102a-102n and a server 106a-106n. In some embodiments, the encryption engine 234 is in
communication with the Encryption processor 260. In other embodiments, the encryption
engine 234 comprises executable instructions running on the Encryption processor 260.
The multi-protocol compression engine 238 comprises any logic, business rules,
function or operations for compressing one or more protocols of a network packet, such as
any of the protocols used by the network stack 267 of the device 200. In one embodiment,
multi-protocol compression engine 238 compresses bi-directionally between clients 102a-
102n and servers 106a-106n any TCP/IP based protocol, including Messaging Application
Programming Interface (MAPI) (email), File Transfer Protocol (FTP), HyperText Transfer
Protocol (HTTP), Common Internet File System (CIFS) protocol (file transfer), Independent
Computing Architecture (ICA) protocol, Remote Desktop Protocol (RDP), Wireless
Application Protocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol. In
other embodiments, multi-protocol compression engine 238 provides compression of
Hypertext Markup Language (HTML) based protocols and in some embodiments, provides
compression of any markup languages, such as the Extensible Markup Language (XML). In
one embodiment, the multi-protocol compression engine 238 provides compression of any

high-performance protocol, such as any protocol designed for appliance 200 to appliance 200
communications. In another embodiment, the multi-protocol compression engine 238
compresses any pay load of or any communication using a modified transport control
protocol, such as Transaction TCP (T/TCP), TCP with selection acknowledgements (TCP-
SACK), TCP with large windows (TCP-LW), a congestion prediction protocol such as the
TCP-Vegas protocol, and a TCP spoofing protocol.
As such, the multi-protocol compression engine 238 accelerates performance for users
accessing applications via desktop clients, e.g., Microsoft Outlook and non-Web thin clients,
such as any client launched by popular enterprise applications like Oracle, SAP and Siebel,
and even mobile clients, such as the Pocket PC. In some embodiments, the multi-protocol
compression engine 238 by executing in the kernel mode 204 and integrating with packet
processing engine 240 accessing the network stack 267 is able to compress any of the
protocols canned by the TCP/IP protocol, such as any application layer protocol.
High speed layer 2-7 integrated packet engine 240, also generally referred to as a
packet processing engine or packet engine, is responsible for managing the kernel-level
processing of packets received and transmitted by appliance 200 via network ports 266. The
high speed layer 2-7 integrated packet engine 240 may comprise a buffer for queuing one or
more network packets during processing, such as for receipt of a network packet or
transmission of a network packer. Additionally, the high speed layer 2-7 integrated packet
engine 240 is in communication with one or more network stacks 267 to send and receive
network packets via network ports 266. The high speed layer 2-7 integrated packet engine
240 works in conjunction with encryption engine 234, cache manager 232, policy engine 236
and multi-protocol compression logic 238. In particular, encryption engine 234 is configured
to perform SSL processing of packets, policy engine 236 is configured to perform functions
related to traffic management such as request-level content switching and request-level cache

redirection, and multi-protocol compression logic 238 is configured to perform functions
related to compression and decompression of data.
The high speed layer 2-7 integrated packet engine 240 includes a packet processing
timer 242. In one embodiment, the packet processing timer 242 provides one or more time
intervals to trigger the processing of incoming, i.e., received, or outgoing, i.e., transmitted,
network packets. In some embodiments, the high speed layer 2-7 integrated packet engine
240 processes network packets responsive to the timer 242. The packet processing timer 242
provides any type and form of signal to the packet engine 240 to notify, trigger, or
communicate a time related event, interval or occurrence. In many embodiments, the packet
processing timer 242 operates in the order of milliseconds, such as for example 100ms, 50ms
or 25ms. For example, in some embodiments, the packet processing timer 242 provides time
intervals or otherwise causes a network packet to be processed by the high speed layer 2-7
integrated packet engine 240 at a 10 ms time interval, while in other embodiments, at a 5 ms
time interval, and still yet in further embodiments, as short as a 3, 2, or 1 ms time interval.
The high speed layer 2-7 integrated packet engine 240 may be interfaced, integrated or in
communication with the encryption engine 234, cache manager 232, policy engine 236 and
multi-protocol compression engine 238 during operation. As such, any of the logic,
functions, or operations of the encryption engine 234, cache manager 232, policy engine 236
and multi-protocol compression logic 238 may be performed responsive to the packet
processing timer 242 and/or the packet engine 240. Therefore, any of the logic, functions, or
operations of the encryption engine 234, cache manager 232, policy engine 236 and multi-
protocol compression logic 238 may be performed at the granularity of time intervals
provided via the packet processing timer 242, for example, at a time interval of less than or
equal to 10ms. For example, in one embodiment, the cache manager 232 may perform
invalidation of any cached objects responsive to the high speed layer 2-7 integrated packet
engine 240 and/or the packet processing timer 242. In another embodiment, the expiry or

invalidation time of a cached object can be set to the same order of granularity as the time
interval of the packet processing timer 242, such as at every 10 ms.
In contrast to kernel space 204, user space 202 is the memory area or portion of the
operating system used by user mode applications or programs otherwise running in user
mode. A user mode application may not access kernel space 204 directly and uses service
calls in order to access kernel services. As shown in FIG. 2, user space 202 of appliance 200
includes a graphical user interface (GUI) 210, a command line interface (CLI) 212, shell
services 214, health monitoring program 216, and daemon services 218. GUI 210 and CLI
212 provide a means by which a system administrator or other user can interact with and
control the operation of appliance 200, such as via the operating system of the appliance 200
and either is user space 202 or kernel space 204. The GUI 210 may be any type and form of
graphical user interface and may be presented via text, graphical or otherwise, by any type of
program or application, such as a browser. The CLI 212 may be any type and form of
command line or text-based interface, such as a command line provided by the operating
system. For example, the CLI 212 may comprise a shell, which is a tool to enable users to
interact with the operating system. In some embodiments, the CLI 212 may be provided via a
bash, csh, tcsh, or ksh type shell. The shell services 214 comprises the programs, services,
tasks, processes or executable instructions to support interaction with the appliance 200 or
operating system by a user via the GUI 210 and/or CLI 212.
Health monitoring program 216 is used to monitor, check, report and ensure that
network systems are functioning properly and that users are receiving requested content over
a network. Health monitoring program 216 comprises one or more programs, services, tasks,
processes or executable instructions to provide logic, rules, functions or operations for
monitoring any activity of the appliance 200. In some embodiments, the health, monitoring
program 216 intercepts and inspects any network traffic passed via the appliance 200. In
other embodiments, the health monitoring program 216 interfaces by any suitable means

and/or mechanisms with one or more of the following: the encryption engine 234, cache
manager 232, policy engine 236, multi-protocol compression logic 238, packet engine 240,
daemon services 218, and shell services 214. As such, the health monitoring program 216
may call any application programming interface (API) to determine a state, status, or health
of any portion of the appliance 200. For example, the health monitoring program 216 may
ping or send a status inquiry on a periodic basis to check if a program, process, service or task
is active and currently running. In another example, the health monitoring program 216 may
check any status, error or history logs provided by any program, process, service or task to
determine any condition, status or error with any portion of the appliance 200.
Daemon services 218 are programs that run continuously or in the background and
handle periodic service requests received by appliance 200. In some embodiments, a daemon
service may forward the requests to other programs or processes, such as another daemon
service 218 as appropriate. As known to those skilled in the art, a daemon service 218 may
run unattended to perform continuous or periodic system wide functions, such as network
control, or to perform any desired task. In some embodiments, one or more daemon services
218 run in the user space 202, while in other embodiments, one or more daemon services 218
run in the kernel space.
Referring now to FIG. 2B, another embodiment of the appliance 200 is depicted. In
brief overview, the appliance 200 provides one or more of the following services,
functionality or operations: SSL VPN connectivity 280, switching/load balancing 284,
Domain Name Service resolution 286, acceleration 288 and an application firewall 290 for
communications between one or more clients 102 and one or more servers 106. In one
embodiment, the appliance 200 comprises any of the network devices manufactured by Citrix
Systems, Inc. of Ft. Lauderdale Florida, referred to as Citrix NetScaler devices. Each of the
servers 106 may provide one or more network related services 270a-270n (referred to as
services 270). For example, a server 106 may provide an http service 270. The appliance

200 comprises one or more virtual servers or virtual internet protocol servers, referred to as a
vServer, VIP server, or just VIP 275a-275n (also referred herein as vServer 275). The
vServer 275 receives, intercepts or otherwise processes communications between a client 102
and a server 106 in accordance with the configuration and operations of the appliance 200.
The vServer 275 may comprise software, hardware or any combination of software
and hardware. The vServer 275 may comprise any type and form of program, service, task,
process or executable instructions operating in user mode 202, kernel mode 204 or any
combination thereof in the appliance 200. The vServer 275 includes any logic, functions,
rules, or operations to perform any embodiments of the techniques described herein, such as
SSL VPN 280, switching/load balancing 284, Domain Name Service resolution 286,
acceleration 288 and an application firewall 290. In some embodiments, the vServer 275
establishes a connection to a service 270 of a server 106. The service 275 may comprise any
program, application, process, task or set of executable instructions capable of connecting to
and communicating to the appliance 200, client 102 or vServer 275. For example, the service
275 may comprise a web server, http server, ftp, email or database server. In some
embodiments, the service 270 is a daemon process or network driver for listening, receiving
and/or sending communications for an application, such as email, database or an enterprise
application. In some embodiments, the service 270 may communicate on a specific IP
address, or IP address and port.
In some embodiments, the vServer 275 applies one or more policies of the policy
engine 236 to network communications between the client 102 and server 106. In one
embodiment, the policies are associated with a VServer 275. In another embodiment, the
policies are based on a user, or a group of users. In yet another embodiment, a policy is
global and applies to one or more vServers 275a-275n, and any user or group of users
communicating via the appliance 200. In some embodiments, the policies of the policy
engine have conditions upon which the policy is applied based on any content of the

communication, such as internet protocol address, port, protocol type, header or fields in a
packet, or the context of the communication, such as user, group of the user, vServer 275,
transport layer connection, and/or identification or attributes of the client 102 or server 106.
In other embodiments, the appliance 200 communicates or interfaces with the policy
engine 236 to determine authentication and/or authorization of a remote user or a remote
client 102 to access the computing environment 15, application, and/or data file from a server
106. In another embodiment, the appliance 200 communicates or interfaces with the policy
engine 236 to determine authentication and/or authorization of a remote user or a remote
client 102 to have the application delivery system 190 deliver one or more of the computing
environment 15, application, and/or data file. In yet another embodiment, the appliance 200
establishes a VPN or SSL VPN connection based on the policy engine's 236 authentication
and/or authorization of a remote user or a remote client 103 In one embodiment, the
appliance 102 controls the flow of network traffic and communication sessions based on
policies of the policy engine 236. For example, the appliance 200 may control the access to
a computing environment 15, application or data file based on the policy engine 236.
In some embodiments, the vServer 275 establishes a transport layer connection, such
as a TCP or UDP connection with a client 102 via the client agent 120. In one embodiment,
the vServer 275 listens for and receives communications from the client 102. In other
embodiments, the vServer 275 establishes a transport layer connection, such as a TCP or
UDP connection with a client server 106. In one embodiment, the vServer 275 establishes
the transport layer connection to an internet protocol address and port of a server 270 running
on the server 106. In another embodiment, the vServer 275 associates a first transport layer
connection to a client 102 with a second transport layer connection to the server 106. In
some embodiments, a vServer 275 establishes a pool of tranport layer connections to a server
106 and multiplexes client requests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280
between a client 102 and a server 106. For example, a client 102 on a first network 102
requests to establish a connection to a server 106 on a second network 104'. In some
embodiments, the second network 104' is not routable from the first network 104. In other
embodiments, the client 102 is on a public network 104 and the server 106 is on a private
network 104', such as a corporate network. In one embodiment, the client agent 120
intercepts communications of the client 102 on the first network 104, encrypts the
communications, and transmits the communications via a first transport layer connection to
the appliance 200. The appliance 200 associates the first transport layer connection on the
first network 104 to a second transport layer connection to the server 106 on the second
network 104. The appliance 200 receives the intercepted communication from the client
agent 102, decrypts the communications, and transmits the communication to the server 106
on the second network 104 via the second transport layer connection. The second transport
layer connection may be a pooled transport layer connection. As such, the appliance 200
provides an end-to-end secure transport layer connection for the client 102 between the two
networks 104, 104'.
In one embodiment, the appliance 200 hosts an intranet internet protocol or intranetIP
282 address of the client 102 on the virtual private network 104. The client 102 has a local
network identifier, such as an internet protocol (IP) address and/or host name on the first
network 104. When connected to the second network 104' via the appliance 200, the
appliance 200 establishes, assigns or otherwise provides an IntranetIP, which is network
identifier, such as IP address and/or host name, for the client 102 on the second network 104'.
The appliance 200 listens for and receives on the second or private network 104' for any
communications directed towards the client 102 using the client's established IntranetIP 282.
In one embodiment, the appliance 200 acts as or on behalf of the client 102 on the second
private network 104. For example, in another embodiment, a vServer 275 listens for and

responds to communications to the IntranetIP 282 of the client 102. In some embodiments, if
a computing device 100 on the second network 104' transmits a request, the appliance 200
processes the request as if it were the client 102. For example, the appliance 200 may
respond to a ping to the client's IntranetIP 282. In another example, the appliance may
establish a connection, such as a TCP or UDP connection, with computing device 100 on the
second network 104 requesting a connection with the client's IntranetIP 282.
In some embodiments, the appliance 200 provides one or more of the following
acceleration techniques 288 to communications between the client 102 and server 106: 1)
compression; 2) decompression; 3) Transmission Control Protocol pooling; 4) Transmission
Control Protocol multiplexing; 5) Transmission Control Protocol buffering; and 6) caching.
In one embodiment, the appliance 200 relieves servers 106 of much of the processing load
caused by repeatedly opening and closing transport layers connections to clients 102 by
opening one or more transport layer connections with each server 106 and maintaining these
connections to allow repeated data accesses by clients via the Internet. This technique is
referred to herein as "connection pooling".
In some embodiments, in order to seamlessly splice communications from a client
102 to a server 106 via a pooled transport layer connection, the appliance 200 translates or
multiplexes communications by modifying sequence number and acknowledgment numbers
at the transport layer protocol level. This is referred to as "connection multiplexing". In some
embodiments, no application layer protocol interaction is required. For example, in the case
of an in-bound packet (that is, a packet received from a client 102), the source network
address of the packet is changed to that of an output port of appliance 200, and the destination
network address is changed to that of the intended server. In the case of an outbound packet
(that is, one received from a server 106), the source network address is changed from that of
the server 106 to that of an output port of appliance 200 and the destination address is
changed from that of appliance 200 to that of the requesting client 102. The sequence

numbers and acknowledgment numbers of the packet are also translated to sequence numbers
and acknowledgement expected by the client 102 on the appliance's 200 transport layer
connection to the client 102. In some embodiments, the packet checksum of the transport
layer protocol is recalculated to account for these translations.
In another embodiment, the appliance 200 provides switching or load-balancing
functionality 284 for communications between the client 102 and server 106. In some
embodiments, the appliance 200 distributes traffic and directs client requests to a server 106
based on layer 4 or application-layer request data. In one embodiment, although the network
layer or layer 2 of the network packet identifies a destination server 106, the appliance 200
determines the server 106 to distribute the network packet by application information and
data carried as payload of the transport layer packet. In one embodiment, the health
monitoring programs 216 of the appliance 200 monitor the health of servers to determine the
server 106 for which to distribute a client's request. In some embodiments, if the appliance
200 detects a server 106 is not available or has a load over a predetermined threshold, the
appliance 200 can direct or distribute client requests to another server 106.
In some embodiments, the appliance 200 acts as a Domain Name Service (DNS)
resolver or otherwise provides resolution of a DNS request from clients 102. In some
embodiments, the appliance intercepts' a DNS request transmitted by the client 102. In one
embodiment, the appliance 200 responds to a client's DNS request with an IP address of or
hosted by the appliance 200. In this embodiment, the client 102 transmits network
communication for the domain name to the appliance 200. In another embodiment, the
appliance 200 responds to a client's DNS request with an IP address of or hosted by a second
appliance 200'. In some embodiments, the appliance 200 responds to a client's DNS request
with an IP address of a server 106 determined by the appliance 200.
In yet another embodiment, the appliance 200 provides application firewall
functionality 290 for communications between the client 102 and server 106. In one

embodiment, the policy engine 236 provides rules for detecting and blocking illegitimate
requests. In some embodiments, the application firewall 290 protects against denial of
service (DoS) attacks. In other embodiments, the appliance inspects the content of intercepted
requests to identify and block application-based attacks. In some embodiments, the
rules/policy engine 236 comprises one or more application firewall or security control
policies for providing protections against various classes and types of web or Internet based
vulnerabilities, such as one or more of the following: 1) buffer overflow, 2) CGI-BIN
parameter manipulation, 3) form/hidden field manipulation, 4) forceful browsing, 5) cookie
or session poisoning, 6) broken access control list (ACLs) or weak passwords, 7) cross-site
scripting (XSS), 8) command injection, 9) SQL injection, 10) error triggering sensitive
information leak, 11) insecure use of cryptography, 12) server misconfiguration, 13) back
doors and debug options, 14) website defacement, 15) platform or operating systems
vulnerabilities, and 16) zero-day exploits. In an embodiment, the application firewall 290
provides HTML form field protection in the form of inspecting or analyzing the network
communication for one or more of the following: 1) required fields are returned, 2) no added
field allowed, 3) read-only and hidden field enforcement, 4) drop-down list and radio button
field conformance, and 5) form-field max-length enforcement. In some embodiments, the
application firewall 290 ensures cookies are not modified. In other embodiments, the
application firewall 290 protects against forceful browsing by enforcing legal URLs.
In still yet other embodiments, the application firewall 290 protects any confidential
information contained in the network communication. The application firewall 290 may
inspect or analyze any network communication in accordance with the rules or polices of the
engine 236 to identify any confidential information in any field of the network packet. In
some embodiments, the application firewall 290 identifies in the network communication one
or more occurrences of a credit card number, password, social security number, name, patient
code, contact information, and age. The encoded portion of the network communication may

comprise these occurrences or the confidential information. Based on these occurrences, in
one embodiment, the application firewall 290 may take a policy action on the network
communication, such as prevent transmission of the network communication. In another
embodiment, the application firewall 290 may rewrite, remove or otherwise mask such
identified occurrence or confidential information.
C. Client Agent
Referring now to FIG. 3, an embodiment of the client agent 120 is depicted. The
client 102 includes a client agent 120 for establishing and exchanging communications with
the appliance 200 and/or server 106 via a network 104. In brief overview, the client 102
operates on computing device 100 having an operating system with a kernel mode 302 and a
user mode 303, and a network stack 310 with one or more layers 310a-310b. The client 102
may have installed and/or execute one or more applications. In some embodiments, one or
more applications may communicate via the network stack 310 to a network 104. One of the
applications, such as a web browser, may also include a first program 322. For example, the
first program 322 may be used in some embodiments to install and/or execute the client agent
120, or any portion thereof. The client agent 120 includes an interception mechanism, or
interceptor 350, for intercepting network communications from the network stack 310 from
the one or more applications.
The network stack 310 of the client 102 may comprise any type and form of software,
or hardware, or any combinations thereof, for providing connectivity to and communications
with a network. In one embodiment, the network stack 310 comprises a software
implementation for a network protocol suite. The network stack 310 may comprise one or
more network layers, such as any networks layers of the Open Systems Interconnection (OSI)
communications model as those skilled in the art recognize and appreciate. As such, the

network stack 310 may comprise any type and form of protocols for any of the following
layers of the OS1 model: 1) physical link layer, 2) data link layer, 3) network layer, 4)
transport layer, 5) session layer, 6) presentation layer, and 7) application layer. In one
embodiment, the network stack 310 may comprise a transport control protocol (TCP) over the
network layer protocol of the internet protocol (TP), generally referred to as TCP/IP. In some
embodiments, the TCP/IP protocol may be carried over the Ethernet protocol, which may
comprise any of the family of IEEE wide-area-network (WAN) or local-area-network (LAN)
protocols, such as those protocols covered by the IEEE 802.3. In some embodiments, the
network stack 310 comprises any type and form of a wireless protocol, such as IEEE 802.11
and/or mobile internet protocol.
In view of a TCP/IP based network, any TCP/IP based protocol may be used,
including Messaging Application Programming Interface (MAPI) (email), File Transfer
Protocol (FTP), HyperText Transfer Protocol (HTTP), Common Internet File System (CIFS)
protocol (file transfer), Independent Computing Architecture (ICA) protocol, Remote
Desktop Protocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol, and
Voice Over IP (VoIP) protocol. In another embodiment, the network stack 310 comprises
any type and form of transport control protocol, such as a modified transport control protocol,
for example a Transaction TCP (T/TCP), TCP with selection acknowledgements (TCP-
SACK), TCP with large windows (TCP-LW), a congestion prediction protocol such as the
TCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments, any type and
form of user datagram protocol (UDP), such as UDP over IP, may be used by the network
stack 310, such as for voice communications or real-time data communications.
Furthermore, the network stack 310 may include one or more network drivers
supporting the one or more layers, such as a TCP driver or a network layer driver. The
network drivers may be included as part of the operating system of the computing device 100
or as part of any network interface cards or other network access components of the

computing device 100. In some embodiments, any of the network drivers of the network
stack 310 may be customized, modified or adapted to provide a custom or modified portion
of the network stack 310 in support of any of the techniques described herein. In other
embodiments, the acceleration program 120 is designed and constructed to operate with or
work in conjunction with the network stack 310 installed or otherwise provided by the
operating system of the client 102.
The network stack 310 comprises any type and form of interfaces for receiving,
obtaining, providing or otherwise accessing any information and data related to network
communications of the client 102. In one embodiment, an interface to the network stack 310
comprises an application programming interface (API). The interface may also comprise any
function call, hooking or filtering mechanism, event or call back mechanism, or any type of
interfacing technique. The network stack 310 via the interface may receive or provide any
type and form of data structure, such as an object, related to functionality or operation of the
network stack 310. For example, the data structure may comprise information and data
related to a network packet or one or more network packets. In some embodiments, the data
structure comprises a portion of the network packet processed at a protocol layer of the
network stack 310, such as a network packet of the transport layer. In some embodiments,
the data structure 325 comprises a kernel-level data structure, while in other embodiments,
the data structure 325 comprises a user-mode data structure. A kernel-level data structure
may comprise a data structure obtained or related to a portion of the network stack 310
operating in kernel-mode 302, or a network driver or other software running in kernel-mode
302, or any data structure obtained or received by a service, process, task, thread or other
executable instructions running or operating in kernel-mode of the operating system.
Additionally, some portions of the network stack 310 may execute or operate in
kernel-mode 302, for example, the data link or network layer, while other portions execute or
operate in user-mode 303, such as an application layer of the network stack 310. For

example, a first portion 310a of the network stack may provide user-mode access to the
network stack 310 to an application while a second portion 310a of the network stack 310
provides access to a network. In some embodiments, a first portion 310a of the network stack
may comprise one or more upper layers of the network stack 310, such as any of layers 5-7.
In other embodiments, a second portion 31 Ob of the network stack 310 comprises one or
more lower layers, such as any of layers 1-4. Each of the first portion 310a and second
portion 310b of the network stack 310 may comprise any portion of the network stack 310, at
any one or more network layers, in user-mode 203, kernel-mode, 202, or combinations
thereof, or at any portion of a network layer or interface point to a network layer or any
portion of or interface point to the user-mode 203 and kernel-mode 203. .
The interceptor 350 may comprise software, hardware, or any combination of
software and hardware. In one embodiment, the interceptor 350 intercept a network
communication at any point in the network stack 310, and redirects or transmits the network
communication to a destination desired, managed or controlled by the mterceptor 350 or
client agent 120. For example, the interceptor 350 may intercept a network communication
of a network stack 310 of a first network and transmit the network communication to the
appliance 200 for transmission on a second network 104. In some embodiments, the
interceptor 350 comprises any type interceptor 350 comprises a driver, such as a network
driver constructed and designed to interface and work with the network stack 310. In some
embodiments, the client agent 120 and/or interceptor 350 operates at one or more layers of
the network stack 310, such as at the transport layer. In one embodiment, the interceptor 350
comprises a filter driver, hooking mechanism, or any form and type of suitable network
driver interface that interfaces to the transport layer of the network stack, such as via the
transport driver interface (TDI). In some embodiments, the interceptor 350 interfaces to a
first protocol layer, such as the transport layer and another protocol layer, such as any layer
above the transport protocol layer, for example, an application protocol layer. In one

embodiment, the interceptor 350 may comprise a driver complying with the Network Driver
Interface Specification (NDIS), or a NDIS driver. In another embodiment, the interceptor
350 may comprise a min-filter or a mini-port driver. In one embodiment, the interceptor 350,
or portion thereof, operates in kernel-mode 202. In another embodiment, the interceptor 350,
or portion thereof, operates in user-mode 203. In some embodiments, a portion of the
interceptor 350 operates in kernel-mode 202 while another portion of the interceptor 350
operates in user-mode 203. In other embodiments, the client agent 120 operates in user-mode
203 but interfaces via the interceptor 350 to a kernel-mode driver, process, service, task or
portion of the operating system, such as to obtain a kernel-level data structure 225. In further
embodiments, the interceptor 350 is a user-mode application or program, such as application.
In one embodiment, the interceptor 350 intercepts any transport layer connection
requests. In these embodiments, the interceptor 350 execute transport layer application
programming interface (API) calls to set the destination information, such as destination IP
address and/or port to a desired location for the location. In this manner, the interceptor 350
intercepts and redirects the transport layer connection to a IP address and port controlled or
managed by the interceptor 350 or client agent 120. In one embodiment, the interceptor 350
sets the destination information for the connection to a local IP address and port of the client
102 on which the client agent 120 is listening. For example, the client agent 120 may
comprise a proxy service listening on a local IP address and port for redirected transport layer
communications. In some embodiments, the client agent 120 then communicates the
redirected transport layer communication to the appliance 200.
In some embodiments, the interceptor 350 intercepts a Domain Name Service (DNS)
request. In one embodiment, the client agent 120 and/or interceptor 350 resolves the DNS
request. In another embodiment, the interceptor transmits the intercepted DNS request to the
appliance 200 for DNS resolution. In one embodiment, the appliance 200 resolves the DNS

request and communicates the DNS response to the client agent 120. In some embodiments,
the appliance 200 resolves the DNS request via another appliance 200' or a DNS server 106.
In yet another embodiment, the client agent 120 may comprise two agents 120 and
120'. In one embodiment, a first agent 120 may comprise an interceptor 350 operating at the
network layer of the network stack 310. In some embodiments, the first agent 120 intercepts
network layer requests such as Internet Control Message Protocol (ICMP) requests (e.g., ping
and traceroute). In other embodiments, the second agent 120' may operate at the transport
layer and intercept transport layer communications. In some embodiments, the first agent
120 intercepts communications at one layer of the network stack 210 and interfaces with or
communicates the intercepted communication to the second agent 120'.
The client agent 120 and/or interceptor 350 may operate at or interface with a protocol
layer in a manner transparent to any other protocol layer of the network stack 310. For
example, in one embodiment, the interceptor 350 operates or interfaces with the transport
layer of the network stack 310 transparently to any protocol layer below the transport layer,
such as the network layer, and any protocol layer above the transport layer, such as the
session, presentation or application layer protocols. This allows the other protocol layers of
the network stack 310 to operate as desired and without modification for using the interceptor
350. As such, the client agent 120 and/or interceptor 350 can interface with the transport
layer to secure, optimize, accelerate, route or load-balance any communications provided via
any protocol carried by the transport layer, such as any application layer protocol over
TCP/IP.
Furthermore, the client agent 120 and/or interceptor may operate at or interface with
the network stack 310 in a manner transparent to any application, a user of the client 102, and
any other computing device, such as a server, in communications with the client 102. The
client agent 120 and/or interceptor 350 may be installed and/or executed on the client 102 in a
manner without modification of an application. In some embodiments, the user of the client

102 or a computing device in communications with the client 102 are not aware of the
existence, execution or operation of the client agent 120 and/or interceptor 350. As such, in
some embodiments, the client agent 120 and/or interceptor 350 is installed, executed, and/or
operated transparently to an application, user of the client 102, another computing device,
such as a server, or any of the protocol layers above and/or below the protocol layer
interfaced to by the interceptor 350.
The client agent 120 includes an acceleration program 302, a streaming client 306,
and/or a collection agent 304. In one embodiment, the client agent 120 comprises an
Independent Computing Architecture (ICA) client, or any portion thereof, developed by
Citrix Systems, Inc. of Fort Lauderdale, Florida, and is also referred to as an ICA client. In
some embodiments, the client 120 comprises an application streaming client 306 for
streaming an application from a server 106 to a client 102. In some embodiments, the client
agent 120 comprises an acceleration program 302 for accelerating communications between
client 102 and server 106. In another embodiment, the client agent 120 includes a collection
agent 304 for performing end-point detection/scanning and collecting end-point information
for the appliance 200 and/or server 106.
In some embodiments, the acceleration program 302 comprises a client-side
acceleration program for performing one or more acceleration techniques to accelerate,
enhance or otherwise improve a client's communications with and/or access to a server 106,
such as accessing an application provided by a server 106. The logic, functions, and/or
operations of the executable instructions of the acceleration program 302 may perform one or
more of the following acceleration techniques: 1) multi-protocol compression, 2) transport
control protocol pooling, 3) transport control protocol multiplexing, 4) transport control
protocol buffering, and 5) caching via a cache manager. Additionally, the acceleration
program 302 may perform encryption and/or decryption of any communications received
and/or transmitted by the client 102. In some embodiments, the acceleration program 302

performs one or more of the acceleration techniques in an integrated manner or fashion.
Additionally, the acceleration program 302 can perform compression on any of the protocols,
or multiple-protocols, carried as a payload of a network packet of the transport layer protocol.
The streaming client 306 comprises an application, program, process, service, task or
executable instructions for receiving and executing a streamed application from a server 106.
A server 106 may stream one or more application data files to the streaming client 306 for
playing, executing or otherwise causing to be executed the application on the client 102. In
some embodiments, the server 106 transmits a set of compressed or packaged application
data files to the streaming client 306. In some embodiments, the plurality of application files
are compressed and stored on a file server within an archive file such as a CAB, ZIP, SIT,
TAR, JAR or other archive. In one embodiment, the server 106 decompresses, unpackages or
unarchives the application files and transmits the files to the client 102. In another
embodiment, the client 102 decompresses, unpackages or unarchives the application files.
The streaming client 306 dynamically installs the application, or portion thereof, and executes
the application. In one embodiment, the streaming client 306 may be an executable program.
In some embodiments, the streaming client 306 may be able to launch another executable
program.
The collection agent 304 comprises an application, program, process, service, task or
executable instructions for identifying, obtaining and/or collecting information about the
client 102. In some embodiments, the appliance 200 transmits the collection agent 304 to the
client 102 or client agent 120. The collection agent 304 may be configured according to one
or more policies of the policy engine 236 of the appliance. In other embodiments, the
collection agent 304 transmits collected information on the client 102 to the appliance 200.
In one embodiment, the policy engine 236 of the appliance 200 uses the collected information
to determine and provide access, authentication and authorization control of the client's
connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-point detection and
scanning mechanism, which identifies and determines one or more attributes or
characteristics of the client. For example, the collection agent 304 may identify and
determine any one or more of the following client-side attributes: 1) the operating system
an/or a version of an operating system, 2) a service pack of the operating system, 3) a running
service, 4) a running process, and 5) a file. The collection agent 304 may also identify and
determine the presence or versions of any one or more of the following on the client: 1)
antivirus software, 2) personal firewall software, 3) anti-spam software, and 4) internet
security software. The policy engine 236 may have one or more policies based on any one or
more of the attributes or characteristics of the client or client-side attributes.
In some embodiments and still referring to FIG. 3, a first program 322 may be used to
install and/or execute the client agent 120, or portion thereof, such as the interceptor 350,
automatically, silently, transparently, or otherwise. In one embodiment, the first program 322
comprises a plugin component, such an ActiveX control or Java control or script that is
loaded into and executed by an application. For example, the first program comprises an
ActiveX control loaded and run by a web browser application, such as in the memory space
or context of the application. In another embodiment, the first program 322 comprises a set
of executable instructions loaded into and run by the application, such as a browser. In one
embodiment, the first program 322 comprises a designed and constructed program to install
the client agent 120. In some embodiments, the first program 322 obtains, downloads, or
receives the client agent 120 via the network from another computing device. In another
embodiment, the first program 322 is an installer program or a plug and play manager for
installing programs, such as network drivers, on the operating system of the client 102.
D. Hierarchical Global Load Balancing

Referring now to FIG. 4A, an embodiment of a hierarchy of aggregator appliances
400A-400B (also referred herein as aggregator appliance 400) for load balancing resources
across branch offices is depicted. In brief overview, a first aggregator appliance 400A is
connected to a first set of branch office appliances 200A-200N (also referred herein as branch
office appliance 200) providing services to branch offices 405A-405N. A second aggregator
appliance 400B is connected to a second set of branch office appliances 200A'-200N'
providing services to branch offices 405A'-405N'. The first aggregator appliance 405A and
the second aggregator appliance 400B establish connections with each other to communicate
information 410A, 410A' and 410B, 410B' on performance and operational characteristics of
respective branch office appliances. With this information 410, 420, either of the aggregator
appliances 400A-400N can perform load balancing/switching 284 to select a branch office
appliance 200 from the first set of branch office appliances 200A-200N or the second set of
branch office appliances 200A'-200N' to service requests to access resources from a client
102.
Any of the branch office appliances 200A-200N or 200A'-200N' may be configured
to know of or identify a single aggregator appliance 400. For example, a first branch office
appliance 200A may be configured to identify and connect to the first aggregator appliance
400A. The first branch office appliance 200A may not be configured to have any information
and therefore may not know of the second aggregator appliance 400B or any branch office
appliances 200A'-200N' connected to the second aggregator appliance 400EJ. In this manner,
the configuration of branch office appliance 200 is reduced. Even though the configuration is
reduced, a branch office appliance servicing a request may access any of the other appliances
200A-200N' known to an aggregator appliance 400. Since the aggregator appliances 400A-
400B share information on branch office appliance 200A-200N', a first aggregator appliance
200 can identify to a first branch office appliance 200 information identifying any of the

branch office appliances 200A-200N' connected via any of the aggregator appliances 400A-
400B.
In some embodiments, the branch office appliances 200 provide any of the
functionality, operations and services of an appliance 200 described in conjunction with
FIGs. 2A and 2B. The branch office appliances 200A'-200N' provide acceleration 288, load
balancing/switching 284, SSL VPN 280 and/or application firewall services 290 to any of the
computing devices and users of its respective branch office 405AM05N'. The branch office
appliances 200A-200N provide acceleration 288, load balancing 284, switching, SSL VPN
280 and/or application firewall services 290 to any of the computing devices and users of its
respective branch office 405A-405N. In one embodiment, each of the branch office
appliances 200A'-200N' provide the same functionality, operations and service. In other
embodiments, each of the branch office appliance 200 may provide different functionality,
operations or services than another branch office appliance. For example, a first branch
office appliance 200A may provide for SSL VPN 280 and acceleration 288, and a second
branch office appliance 200A' may provide load balancing/switching 284 with SSL VPN
280. A third branch office appliance 200N may provide only SSL VPN 280 and a fourth
branch office appliance 200N, acceleration 288. Further to the example, a fifth branch office
appliance 200B may provide acceleration 288 while a sixth branch office appliance 200C
provides application firewall 290 functionality.
Although branch office appliances 200 are generally described as an appliance 200 in
a branch office 405, the branch office appliance 200 may be an appliance 200 deployed at
any location in a network 104, 105'. For example, a branch office appliance 200 may be
deployed at a data center. In another example, a branch office appliance 200 may be
deployed on a subnet or network segment of a corporate LAN 104. In another embodiment, a
branch office appliance 200A may be deployed on a first corporate LAN and a second branch
office appliance 200B' on a second corporate LAN. In some embodiments, a branch office

appliance 200 may be deployed on the same network 104, 104' as an aggregator appliance
400. So, although the appliance 200 is described in FTG. 4A as a branch office appliance
200, it is not limited to operations only at a branch office 405.
The aggregator appliance 400 comprises software, hardware or any combination of
software and hardware. Tn one embodiment, the aggregator appliance 400 comprises logic,
functions or operations, such as via the aggregator 450, to determine, collect and aggregates
information 410 about one or more branch office appliances 200. For example, the
information 410 may comprise information on the status, load or performance of a branch
office appliance 200. In one embodiment, the aggregator 450 comprises an application,
process, service, task or set of executable instructions. The aggregator 450 comprises any
type, form and combination of data structures, objects, files and/or databases for receiving
and storing information 410 about any of the branch office appliances 200. In some
embodiments, the aggregator 450 stores the information 410 in an organized or arranged
manner associated with or identified by a name or identifier of the branch office appliance
200. For example, the information 410 may be indexed via an identifier of the appliance
200. In some embodiments, the aggregator 450 stores or associates temporal data with the
information 410, such as time of recording or time related to an event.
In one embodiment, the aggregator appliance 400 and/or aggregator 450 receive
information 410 from the branch office appliance via a connection. In some embodiments,
the aggregator appliance 400 and a branch office appliance 200 establish or communicate via
a transport layer connection, such as a TCP or UDP connection. Tn other embodiments, the
aggregator appliance 400 and branch office appliance 200 maintain a connection. In other
embodiments, the aggregator appliance 400 and branch office appliance 200 establish a
connection on an as needed basis, e.g., connect and reconnect when they need to
communicate.

In some embodiments, the aggregator appliance 400 establishes a connection or
communicates with a predetermined number of branch office appliances 200. In other
embodiments, the aggregator appliance 400 collects and aggregates information on a
predetermined number of branch office appliances 200. In one embodiment, the
predetermined number of branch offices is 31. In another embodiments, the predetermined
number of branch offices is 32. In yet other embodiments, the predetermined number of
branch offices is 16,48, 60, 96, 128 or 256. In a further embodiment, the predetermined
number of branch offices is 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200 or 250. The
number of branch offices an aggregator appliance 400 may connect to or collect information
from may depend on the operational or performance characteristics of the networks 104,
104', the appliance 200, the branch offices 405, and branch office networks 104 along with
the applications, data, and resource usage of the users across branch offices. In some
embodiments, the predetermined number of branch office appliance 200 may not be set or
configured, or otherwise limited only by the memory, capacity and performance of the
aggregator appliance 400.
In another embodiment, the aggregator appliance 400 requests information 410 from
each of the branch office appliance 200 it is connected to. In some embodiments, the
aggregator appliance 400 requests information upon establishment of the connection to the
branch office appliance 200. In another embodiment, the aggregator appliance 400 requests
information 410 from the branch office appliance 200 on a predetermined frequency, such as
every 1 sec, or 1 msec. For example, the aggregator appliance 400 may poll each of its
branch office appliances 200A-200N every 1 sec for information 410. In some embodiments,
the aggregator appliance 400 requests information 410 from the branch office appliance 200
over a predetermined time period, such as every 1 sec for an hour. In yet another
embodiment, the aggregator appliance 400 requests information 410 from a branch office

appliance 200 upon an event, such as receiving a request from a client 102, or receiving a
DNS request.
The information 410 may comprise any type and form of data, statistics, status or
information related to or associated with the operational and/or performance characteristics of
the branch office appliance 200, the network 104 of the branch office appliance 200, and/or
any connection to the branch office appliance 200, such as via a client 102, server 106 or the
aggregator appliance 400. In some embodiments, the information 410 comprises operational
and/or performance data on any client 102 and/or server 106 connected to the branch office
appliance 200. In one embodiment, the branch office appliance 200 determines operational
and/or performance information about any client 102 or server 106 it is connected to or
servicing, and creates information 410 on these clients 102 and/or server 106. In this
embodiment, the branch office appliance 200 may provide this information 410 to the
aggregator appliance 400.
In some embodiments, the operational and/or performance characteristic information
410 includes information on any of the following for a branch office appliance 200, client
102 or server: 1) load; 2) numbers and types of connections, 3) resource usage, 4) resource
availability, 5) number of requests outstanding, 6) number of requests transmitted, 7) number
of clients servicing, 8) response time information, including average and historical response
times, 9) errors, status, performance or bandwidth of a connection, and 10) number of
sessions, and states or status thereof. In another embodiment, the information 410 includes
information on any IP or network layer information of the appliance 200, or the connections
of the appliance 200, or of the clients and/or servers serviced by the appliance 200. For
example, the information 410 may include a routing table of the appliance 2 OOfor performing
network address translation, such as for an SSL VPN connection.
Each of the aggregator appliances 400A-400B may share or otherwise communicate
the aggregated information 410 with the other aggregator appliance. The first aggregator

appliance 400A establishes a connection, such as a TCP or UDP transport layer connection
with the second aggregator appliance 400B. In one embodiment, the second aggregator
appliance 400B uses this connection. In another embodiment, the second aggregator
appliance 400B establishes a connection, such as a TCP or UDP transport layer connection,
to the first aggregator appliance 400A. In one embodiment, the aggregator appliances 400A-
400B may establish a connection or communication channel with each other upon bootup or
startup. In other embodiments, the aggregator appliances 400A-400B may establish
connections upon a configuration change or event. In another embodiment, the aggregator
appliances 400A-400B may send out a broadcast on the network 104 to determine the
existence or availability of another aggregator appliance 400.
In one embodiment, the first aggregator appliance 400A transmits its information
410A to the second aggregator appliance 400B. The second aggregator appliance 400B
stores the received information 410A as information 410A' as illustrated in FIG. 4A. In
some embodiments, information 410A' is aggregated or combined with information 410A.
In other embodiments, mformation 410A' is associated with information 410A. In another
embodiment, the second aggregator appliance 400B transmits its information 410B to the
first aggregator appliance 400A. The first aggregator appliance 400A stores the received
information 410B as information 4i0B> as illustrated m FiG. 4A. In some embodiments,
information 410B' is aggregated or combined with information 410B. In other embodiments,
information 410B' is associated with information 410B. The first and second aggregator
appliances 400A-400B may exchange or provide information 410A and 410B once, or on a
predetermined frequency, such as every 1 msec or 1 sec. In some embodiments, the first and
second aggregator appliances 400A-400B use a request/reply messaging mechanism or
protocol to transmit information 410A-410B to each other. In other embodiments, the first
and second aggregator appliances 400A-400B have a custom or proprietary exchange

protocol for exchanging information 410A-410B about branch office appliances 200A-
200N'.
By exchanging information 410A-410B, each of the first aggregator appliance 400A
and second aggregator appliance 400B have information 410A and 41 OB on both the first set
of one or more branch office appliances 200A-200N and the second set of one or more
branch office appliances 200A'-200N'. Although the first aggregator appliance 400A is
collecting, aggregating and monitoring information 410A about the branch office appliances
200A-200N, the first aggregator appliance 400A obtains information 410B about the branch
office appliances 200A'-200N' collected, aggregated and monitored by the second aggregator
appliance 400B. Likewise, although the second aggregator appliance 400B is collecting,
aggregating and monitoring information 410B about the branch office appliances 200A'-
200N', the second aggregator appliance 400B obtains information 410A about the branch
office appliances 200A-200N collected, aggregated and monitored by the first aggregator
appliance 400A.
With the aggregator appliances 400A-400B, a first branch office appliance 200A, in
one embodiment, need only know the identity or internet protocol information of the first
aggregator appliance 400A, but obtains the identify other branch office appliances 200A'-
200N' via the aggregator appliance 400A. For example, upon receiving a request from a
client for a resource, the first branch office appliance 200A may forward the request to the
aggregator appliance 400a. In response, the aggregator appliance 400A may transmit the
identity of a branch office appliance 200A'-200N' monitored by aggregator appliance 400B
in order to service the request. In some embodiments, this simplifies the configuration of
each or any of the branch office appliances 200, yet, at the same time, allows any branch
office appliance 200A-200N to access the services of or connect to a resource via another
branch office appliance 200A'-200N'. In this way, clients can access resources across any of
the branch offices 405A-405N via any of the branch office appliances 200A-200N' using the

information 410A-410B collected via the aggregator appliances 400A-400B. In other
embodiments, a client 102 can connect directly to any of the aggregators 400A-400N and get
load balanced to any of the branch office appliances 200.
The aggregator appliances 400A-400B comprises load-balancing/switching 284
functionality, operations and/or logic for determining and providing load-balancing services
to any of the branch office appliances 200, clients 102 of the branch offices 405, or servers
106 accessed via the branch offices 405 or branch office appliances 200. Using the
information 410A and 410B', in one embodiment, the first aggregator appliance 400A can
determine a branch office appliance 200 from any of the branch office appliances 200A-
200N' to service a request from a client 102. Using the information 410A' and 410B, in
another embodiment, the first second appliance 400B can determine a branch office appliance
200 from any of the branch office appliances 200A-200N' to service a request from a client
102. Additionally, the aggregator appliances 400A-400N can use information 410A, 4ION
to determine a resource, such as server 106, access via a branch office appliance 200 to
service a request. In this manner and in some embodiments, the aggregator appliances 400A-
440N provide load-balancing and switching information for the aggregation of all resources
and branch office appliances 200A-200N across all the branch office 405A-405N'.
The aggregator appliance 400, in some embodiments, comprises any of the
functionality, operations or services of a branch office appliance 200. For example, in
addition to the load balancing 284 and aggregation operations of the aggregator appliance
400 described herein, the aggregator appliance may perform acceleration, SSL VPN or
application firewall functionality. The first aggregator appliance 400A and the second
aggregator appliance 400B may be deployed on the same network 104 and/or different
networks 104, 104'. In some embodiments, additional aggregator appliances 400 may be
deployed to scale up to service a plurality of branch offices 405 and branch office appliances
200.

Referring now to FIG. 4B, another embodiment of a deployment of multiple
aggregator appliances is depicted. In brief overview, a plurality of aggregator appliances
400A, 400B and 400N are deployed to provide aggregation and/or load-balancing services to
a plurality of branch offices: branch offices 1-31 405A-405N, branch offices 32-63 405A'-
405N, and branch offices 64-N 405A"-405N". The first aggregator appliance 400A is
connected to and obtains information 410 on a first set of one or more branch office
appliances 405A-405N. The second aggregator appliance 400B is connected to and obtains
information 410 on a second set of one or more branch office appliances 405A'-405N'. The
third aggregator appliance 400N is connected to and obtains information 410 on a third set of
one or more branch office appliances 405A"-405N".
Each of the aggregator appliances 400A-400N can exchange information 410 with
each other to identify, learn about and obtain information 410 on other branch office
appliances 200A-220N, 200A'-200N' and 200A"-200N"". In one embodiment, the first
aggregator appliance 400A establishes a connection with the second aggregator appliance
400B and third aggregator appliance 400N. In another embodiment, the second aggregator
appliance 400B establishes a connection with the first aggregator appliance 400A and third
aggregator appliance 400N. In yet another embodiment, the third aggregator appliance 400N
establishes a connection with the second aggregator appliance 400B and first aggregator
appliance 400A. Through any of these connections, the aggregator appliances 400 can ask,
receive, transmit, or otherwise obtain information 410 on a set of one or more branch office
appliances 200 to which it may not be currently connected.
In some embodiments, each of the aggregator appliances 400 may be connected to,
obtain and monitor information 410 on a number of branch office appliances 200 different
than another aggregator appliance 400. For example, the first aggregator appliance 400A
may monitor and obtain information 410 on 2,3, 4, 5 or 10 appliances 200 while the second
aggregator appliance 200 monitors and obtains information 410 on 20, 30 or 31 appliances

200. Further to the example, the third aggregator appliance 400C may monitor and obtain
information 410 on a single branch office appliance 200 or any number of branch office
appliances 200. Although the deployment illustrated in FIG. 4B depicts three aggregator
appliances 400A-400N servicing three sets of multiple branch offices, any number of
aggregator appliances 400 may be deployed to service any number of branch offices 405.
In one embodiment, an aggregator appliance, such as aggregator appliance 400N',
depicted with dotted connected lines in FIG. 4B may be used as a master aggregator node or
appliance 400. For example, in some embodiments, the master aggregator appliance 400N'
may not collect information 410 from branch office appliances 200 directly, but instead
aggregates the information 410 from the other aggregator appliances 400A-400N that
collected such information. In some embodiments, the master aggregator appliance 400N
acts as a backup service to any of the other aggregator appliances 400. For example, in one
case, if an aggregator appliance 400A went down or was rebooted, upon startup the
aggregator appliance 400A can obtain the latest saved information 410 from the master
aggregator appliance 400N'. In other embodiments, each of the aggregator appliance 400A-
400N establish a connection with the master aggregator appliance 400N' to provide or update
the information 410 on the master aggregator appliance 400N' and/or to also obtain
information 410 from the other appliances 400 it may not yet have.
With the deployment architecture illustrated in FIG. 4B, in some embodiments, any
number of aggregator appliances 400 can be deployed to scale load-balancing and
aggregation services to any number of branch offices 405. As the number of branch offices
405 and/or branch office appliances 200 increases, the configuration of a branch office
appliance 200 remains relatively simple in that it needs only to be configured to know of an
existing aggregator appliance 400A or a newly deployed aggregator appliance 400N.
Through the aggregation and exchanging of information 410 among the aggregation

appliances 200, any client or branch office appliance 200 can access resources across any of
the branch offices 405.
Referring now to FIG. 5, steps of an embodiment of a method 500 for practicing
aggregations and load-balancing via the aggregation appliances 400 is depicted. In brief
overview, at step 505, a first aggregator appliance 405A establishes connections with and
obtains information 410A on a first plurality of branch office appliances 200A-200N. At
step 510, a second aggregator appliance 410A establishes connections with and obtains
information 410B a second plurality of branch offices 200A'-200N'. One or more of the first
set of branch office appliances 200A-200N may not have any information or be configured
to identify any of the second set of branch office appliances 200A'-200N'. At step 515, the
first and second aggregator appliances 400A-400B establish a connection or communication
between each other. At step 520, the first and second aggregator appliances 400A-400N
exchange identification, operational and performance information 410 about the first and
. second set of branch office appliances 200. At step 525, a first aggregator appliance 400A
receives a request from a client 102 to access a resource. For example, a first branch office
appliance 200A may transmit the request to the first aggregator appliance 400A, such a for
client 102a depicted in FIG. 4A. In another example, a client 102 may transmit the request to
an aggregator appliance 400A, such as clients 102b and 102n as illustrated in FIG. 4A. At
step 530, the first aggregator appliance selects via information 410 received from the second
aggregator appliance 400B a second branch office appliance 200A' from the second set of
branch office appliances 200A'-200N' to service the request. At step 540, the first
aggregator appliance 200 transmits the information on the selected second branch office
appliance 200A' to the client 102, directly or via a first branch office appliance 200A
servicing the client 102. At step 545, the client 102 establishes a connection with the second
branch office appliance 200A', directly or via the first branch office appliance 200A.

In further detail, at step 505, a first aggregator appliance 200A establishes any type
and form of connection to one or more branch office appliances 200A-200N. Tn one
embodiment, the first aggregator appliance 200A established a transport layer connection,
such as TCP or UDP, to the branch office appliances 200A-200N. In one embodiment, any
of the branch office appliances 200A-200N requests the connection to the aggregator
appliance 400A. In another embodiment, the aggregator appliance 400A requests the
connection to any of the branch office appliance 200A-200N. In some embodiments, any of
the branch office appliances 200A-200N may have a transport layer connection to one or
more clients 102, such as with a client agent 120. In another embodiment, any of the branch
office appliances 200A-200N may have a transport layer connection to one or more servers
106, such as with a service 270.
The first aggregator appliance 400 A may obtain information 410 about any of the first
set of branch office appliances 200A-200N via any of its connections to these appliances. In
one embodiment, the first aggregator appliance 400A obtains information 410 from a branch
office appliance 200 upon establishment of the connection. In another embodiment, the first
aggregator appliance 400A obtains information 410 from a branch office appliance 200 upon
a predetermined frequency, such as polling every 1 msec or 1 sec. In some embodiments,,
the first aggregator appliance 400A obtains information 410 from a branch office appliance
200 via a request/reply mechanism. In yet another embodiment, a branch office appliance
200 transmits the information 410 to the aggregator appliance 400A upon startup or on a
predetermined frequency, such as pushing the information to the aggregator 400 every 1 msec
or 1 sec.
Likewise to step 505, at step 510, the second aggregator appliance 400B establishes a
connection, such as a transport layer connection, to a second set of one or more branch
offices appliances 200A'-200N'. The second set of branch office appliances 200A'-200N'
may have transport layer connections to one or more clients 102 and/or servers 106. The

second aggregator appliance 400B may obtain information 410 about any of the second set of
branch office appliances 200A'-200N' via any of its connections to these appliances. The
second aggregator appliance 400B may receive, request or obtain information 410 at any time
or frequency.
Although the first aggregator appliance 400A has information 410A on the first set of
branch office appliances 200A-200N and the second aggregator appliance 400B has
information 410B on the second set of branch office appliances 200A'-200N', the first
aggregator appliance 400A may not know the identification of or have information on any of
the second set of branch office appliances 200A'-200N\ Likewise, the second aggregator
appliance 400B may not know the identification or have information on any of the firs set of
branch office appliances 200A-200N. In some embodiments, a first branch office appliance
200 A of the first set of branch office appliances 200A-200N does not know the identification
of or have information on any of the second set of branch office appliances 200A'-200N'. In
other embodiments, a second branch office appliance 200A' of the second set of branch
office appliances 200A'-200N' does not know the identification of or have information on
any of the second set of branch office appliances 200A-200N.
At step 515, the first aggregator appliance 400A and the second aggregator appliance
400B establish communications, such as via a transport layer connection, for example, TCP
or UDP. In some embodiments, the first aggregator appliance 400A and second aggregator
appliance 400B establish one connection between each other for communications. In other
embodiments, the first aggregator appliance 400A establishes a connection with the second
aggregator appliance 400B, and the second aggregator appliance 400B establishes a
connection with the first aggregator appliance 400A.
At step 520, the aggregator appliances 400A and 400B may exchange information
410 on a periodic basis, such as a frequency of every 1 sec or 1 msec. In some embodiments,
an aggregator appliance 400A transmits information 410 to another aggregator appliance

400B upon receipt of such information 410 from a branch office appliance 200. In one
embodiment, the aggregator appliances 400A and 400B exchange or receive information 410
from a master aggregator appliance 400N'. By the exchange or receipt of information 410,
each aggregator appliance 400A-400B has information 410A, 410B on each of the sets of
branch office appliances. Although the first aggregator appliance 400A is connected to the
first set of branch office appliances 200A-200N, the first aggregator appliance 400A has also
obtained information 410B' on the second set of branch office appliances 200A'-200N'.
Likewise, although the second aggregator appliance 400B is connected to the second set of
branch office appliances 200A'-200N', the second aggregator appliance 400B has also
obtained information 410A' on the first set of branch office appliances 200'-200N. With
both sets of information 410A, 410B, an aggregator appliance 400 can make switching and
load-balancing decisions to access resources across all of the branch office appliances 200
and branch office 405.
At step 525, one of the aggregator appliances 400 received a request from a client to
access a resource. In one embodiment, the client 102 transmits the request to the aggregator
appliance 400. In another embodiment, a branch office appliance 200 transmits the request
on behalf of the client 102 to the aggregator appliance 400. In yet another embodiment,
another aggregator appliance 400B may transmit the request to the aggregator appliance
400A. In some embodiments, the request comprises a connect request, such as a TCP or
UDP connection request or a VPN request. In other embodiments, the request comprises a
session request, such as an SSL or TLS session or an application session such as to a hosted
service. In another embodiment, the request comprises a Domain Name Service (DNS)
request, such as to resolve a domain name. In one embodiment, the request comprises a
request to execute an application, such as via the application delivery system 500. In other
embodiments, the request comprises an authentication or authorization request. In yet

another embodiment, the request comprises a request to receive a portion of a computing
environment 15, such as an application, or portion thereof, or a data file.
At step 535, in response to receipt of the request, the aggregator appliance 400
determines, identifies and selects a branch office appliance 200 to service the request. The
aggregator appliance 400 uses any of the information 410A, 410B to determine a branch
office appliance 200 suitable to service the request. In one embodiment, the aggregator
appliance 400 uses the information 410 to determine, identify and select a server 106 access
or serviced by a branch office appliance 200. In some embodiments, the aggregator
appliance 400 analyzes or processes any of the operational and/or performance characteristics
of the information 410 to determine an appliance 200 suitable for the request. In other
embodiments, the aggregator appliance 400 may maintain persistence between a client 102
and a branch office appliance 200. For example, the aggregator appliance 400 may assign a
client 102 to a branch office appliance 200 that is currently servicing the client 102, recently
serviced the client 102 or has previously serviced the client 102.
In some embodiments, the first aggregator appliance 400A identifies and selects a
second branch office appliance 200A' from the second set of branch office appliances 200A'-
200N'. In one embodiment, the first aggregator appliance 400A identifies and selects a first
branch office appliance 200A from the first set of branch office appliances 200A-200N. In
other embodiments, the second aggregator appliance 400B identifies and selects a first branch
office appliance 200A from the first set of branch office appliances 200A-200N. In yet
another embodiment, the second aggregator appliance 400B identifies and selects a second
branch office appliance 200A' from the second set of branch office appliances 200A'-200N'.
At step 540, the aggregator appliance 400 in response to the client request, transmits
information about the selected branch office appliance 200 to the client 102 or the appliance
200 servicing the client 102. In one embodiment, the aggregator appliance 400 transmits the
identification or selection of the appliance 200 directly to the client 102, such as to client

agent 120. In another embodiment, the aggregator appliance 400 transmits the identification
or selection of the appliance 200 to the branch office appliance 2~. In some embodiments,
the aggregator appliance 400 identifies to the client 102 or branch office appliance the IP
address or domain name, or other IP layer information, of the selected branch office
appliance 200. In other embodiments, the aggregator appliance 400 identifies to the client
102 or branch office appliance 200 information to connect to the selected branch office
appliance 200.
At step 545, the client 102 establishes a connection with the branch office appliance
200 selected or identified by the aggregator appliance 400. In some embodiments, the client
102, such a via client agent 120, establishes a transport layer connection, for example, a TCP
or UDP with the selected branch office appliance 200. In other embodiments, the branch
office appliance 200 connected to the client 102 establishes a transport layer connection to
the selected branch office appliance, for example, on behalf of the client 102. In some
embodiments, the client 102 establishes an SSL VPN connection with the selected branch
office appliance 200. In some embodiments, the selected branch office appliance 200
provides or establishes connections to one or more servers 106. For example, the branch
office appliance 200 may have pooled transport layer connections to the servers 106 over
which client requests are multiplexed. In yet other embodiments, the selected branch office
appliance 200 may provide additional load-balancing/switching functionality 284 for the
client 102. In another embodiments, the selected branch office appliance 200 provides
acceleration or application firewall services to the client 102.
Although an embodiment of the method 500 is generally described above in
connection with a client 102 accessing the resource from a branch office 405 and/or branch
office appliance 200, the method 500 may be practiced with any client 102 accessing the
aggregator appliances 400 from any location. For example, as illustrated in FIG. 4A, clients
102b and 102n may access an aggregator appliance 400 without first accessing a branch

office appliance 200. In one embodiment, a client 102b or 102n may be on the Internet and
connect to an aggregator appliance 200. In other embodiments, the client 102 or 102n may
be on the same network 104, such as a LAN, as the aggregator appliance 400A-400N. The
aggregator appliance 400 can load-balance the client's request and direct the client 102b-
102n to a selected branch office appliance 200.
In view of the structure, functions and operations of the aggregator appliances
described herein, the aggregator appliances provide for reduced configuration of branch
office appliances while also providing a scalable, hierarchical deployment of branch office
appliances. By exchanging branch office appliance information among aggregator appliances
deployed in a hierarchical fashion, any of the aggregator appliances can make load-balancing
and switching decisions to access any of the branch office appliances, or any resources
provided via branch office appliances. Although a branch office appliance may be configured
to communicate with or know of an aggregator appliance, the branch office appliance may
learn of or obtain information of other branch office resources via the aggregation and load-
balancing techniques discussed herein. The aggregator appliances globally load-balance
resource requests of any client from any location across all branch offices and branch office
appliances.


We Claim:
1. A method for providing a hierarchy of appliances to more efficiently access resources
across a plurality of branch offices, the method comprising the steps of:
(a) establishing, by a first aggregator appliance, connections with a first plurality of
branch office appliances;
(b) establishing, by a second aggregator appliance, connections with a second
plurality of branch office appliances, the first plurality of branch office appliances not having
information identifying the second plurality of branch office appliances;
(c) receiving, by the first aggregator appliance, from a first branch office appliance of
the first plurality of branch offices a request from a client for access to a resource;
(d) identifying, by the first aggregator appliance via the second aggregator appliance,
a second branch office appliance from the second plurality of branch office appliances to
service the request;
(e) transmitting, by the first aggregator appliance, to the first branch office appliance
information identifying the second branch office appliance; and
(f) establishing, by the client, a connection with the second branch office appliance.

2. The method of claim 1, wherein step (e) further comprises transmitting, by the first
branch office appliance, information identifying the second branch office appliance to the
client.
3. The method of claim 1, comprising establishing, by the client via the first branch
office appliance, a second connection via the second branch office appliance with a server.
4. The method of claim 1, comprising establishing, by the first aggregator appliance,
communications with the second aggregator appliance.
5. The method of claim 3, comprising communicating, by the first aggregator appliance,
information about the first plurality of branch office appliances to the second aggregator
appliance.
6. The method of claim 3, comprising communicating, by the second aggregator
appliance, information about the second plurality of branch office appliances to the first
aggregator appliance.
7. The method of claim 1, determining, by the first aggregator appliance, information on
one of performance or operational characteristics for each of the first plurality of branch
office appliances.

8. The method of claim 1, determining, by the second aggregator appliance, one of
performance or operational characteristics of each of the second plurality of branch office
appliances.
9. The method of claim 7, wherein step (d) comprising selecting, by the first aggregator
appliance, the second branch office appliance based on one of the performance or operational
characteristics.
10. The method of claim 8, comprising accelerating, by one of the first office branch
office appliance or the second branch office appliance, communications between the client
and the server.
11. The method of claim 10, wherein accelerating comprises using one or more of the
following techniques:
compression;
TCP connection pooling;
TCP connection multiplexing;
TCP buffering; and
caching.
12. The method of claim 1, wherein one of the first aggregator appliance or the second
aggregator appliance is deployed at a data center.
13. The method of claim 1, wherein the client is deployed at the first branch office..
14. A system for providing a hierarchy of appliances to more efficiently access resources
across a plurality of branch offices, the system comprising:
a first aggregator appliance establishing connections with a first plurality of branch
office appliances;
a second aggregator appliance establishing connections with a second plurality of
branch office appliances, the first plurality of branch office appliances not having information
identifying the second plurality of branch office appliances;
a first branch office appliance of the first plurality of branch offices transmitting to the
first aggregator appliance a request from a client for access to a resource;
wherein the first aggregator appliance identifies via the second aggregator appliance,
a second branch office appliance from the second plurality of branch office appliances to
service the request, and transmitting to the first branch office appliance information
identifying the second branch office appliance; and

the client establishes a connection with the second branch office appliance.
15. The system of claim 14, wherein the first branch office appliance transmitting
information identifying the second branch office appliance to the client.
16. The system of claim 14, wherein the client establishes via the first branch office
appliance a second connection via the second branch office appliance with a server.
17. The system of claim 14, wherein the first aggregator appliance establishes
communications with the second aggregator appliance.
18. The system of claim 17, wherein the first aggregator appliance communicates
information about the first plurality of branch office appliances to the second aggregator
appliance.
19. The system of claim 14, wherein the second aggregator appliance communicates
information about the second plurality of branch office appliances to the first aggregator
appliance.
20. The system of claim 14, wherein the first aggregator appliance determines
information on one of performance or operational characteristics for each of the first plurality
of branch office appliances.
21. The system of claim 14, wherein the second aggregator appliance determines one of
performance or operational characteristics of each of the second plurality of branch office
appliances.
22. The system of claim 21, wherein the first aggregator appliance selects the second
branch office appliance based on one of the performance or operational characteristics.
23. The system of claim 14, wherein one of the first office branch office appliance or the
second branch office appliance accelerates communications between the client and a server.
24. The system of claim 23, wherein accelerating comprises using one or more of the
following techniques:
compression;
TCP connection pooling;
TCP connection multiplexing;
TCP buffering; and
caching.

25. The system of claim 14, wherein one of the first aggregator appliance or the second
aggregator appliance is deployed at a data center.
26. The system of claim 14, wherein the client is deployed at the first branch office.

Systems and methods are disclosed for providing a hierarchy of appliances to more efficiently access resources
across a plurality of branch offices. A method comprises the steps of: establishing, by a first aggregator appliance, connections with
a first plurality of branch office appliances; establishing, by a second aggregator appliance, connections with a second plurality of
branch office appliances, the first plurality of branch office appliances not having information identifying the second plurality of
branch office appliances; receiving, by the first aggregator appliance, from a first branch office appliance a request from a client
for access to a resource; identifying, by the first aggregator appliance via the second aggregator appliance, a second branch office
appliance from the second plurality of branch office appliances to service the request; transmitting, by the first aggregator appliance,
to the first branch office appliance information identifying the second branch office appliance; and establishing, by the first branch
office appliance, a connection with the second branch office appliance. Corresponding systems are also described.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=Z95Ecs/4E0mtDQq+jdQLBQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 279788
Indian Patent Application Number 728/KOLNP/2009
PG Journal Number 05/2017
Publication Date 03-Feb-2017
Grant Date 31-Jan-2017
Date of Filing 24-Feb-2009
Name of Patentee CITRIX SYSTEMS, INC.
Applicant Address 851 WEST CYPRESS CREEK ROAD, FORT LAUDERDALE, FL
Inventors:
# Inventor's Name Inventor's Address
1 SHETTY, ANIL C/O CITRIX SILICON VALLEY, 4988 GREAT AMERICA PARKWAY, SANTA CLARA, CA 95054
2 KAMATH, SANDEEP C/O CITRIX SILICON VALLEY, 4988 GREAT AMERICA PARKWAY, SANTA CLARA, CA 95054
3 SUGANTHI, JOSEPHINE C/O CITRIX SILICON VALLEY, 4988 GREAT AMERICA PARKWAY, SANTA CLARA, CA 95054
PCT International Classification Number H04L 29/08
PCT International Application Number PCT/US2007/075037
PCT International Filing date 2007-08-02
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/462,345 2006-08-03 U.S.A.