Presentation Server 4.0 Virtual IP

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Feature Assessment Page 1 Date Created: May 26, 2005 Feature Assessment - Presentation Server 4.0 Virtual IP Date Updated: June 6, 2005

Presentation Server 4.0 Virtual IP

Overview of Feature

Virtual IP enables a unique IP address from a designated range to be assigned to each ICA connection. By enabling this feature, additional applications can utilize Citrix Presentation Server 4.0.

Because the IP address of the Presentation Server is passed to end databases by default, this feature enables back-end databases that require distinct IP addresses to see each ICA connection as unique because a secondary virtual IP address is assigned. These virtual IP Addresses are bound to the Presentation Server NIC and can be readily observed via IPCONFIG, as well as the user connection information within the Presentation Server Console.

The impact of virtual IP can best be illustrated by the two tables below. This illustration shows a Presentation Server environment which accesses a database server:

Without Virtual IP Configured

Behind the

scenes… Without Virtual IP configured, each session would not be distinguished by the back-end database since the IP address of the Presentation Server would be used for communications with the application. For many applications, this is acceptable.

With Virtual IP Configured

Behind the

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An alternative to virtual IP is to have the IP address of the client device passed to the Presentation Server and back-end database. Registry modifications are necessary to invoke this type of IP addressing. Please see Page 249 of the Presentation Server 4.0 Administrator’s Guide.

Impact to Architectural Designs

Virtual IP allows ICA connections to obtain and pass unique IP addresses. Scenarios may arise where unique IP addresses are required to access and operate applications appropriately. Prime examples of this are back-end databases like CRM and CTI. Virtual IP configurations require a detailed configuration and interaction with the network administrator. Key items to configure are:

• IP Range. Ensure that the IP range exists on the same subnet as the Presentation Server. This is because it is not possible to traverse subnets.

• Server(s) in the farm. Each ICA connection to the designated server(s) gets assigned a virtual IP from the range, so there must be enough IP addresses allotted for every ICA connection. If multiple servers are allotted addresses from a range, the number of IP addresses is divided by the number of servers.

• Application. Only the designated applications actually use the virtual IP.

Virtual IP configuration is designated within the farm properties. In most cases, virtual IP processes will be designated rather than virtual IP loopback.

• Use virtual IP if the application: o Uses Windows sockets and o Requires a unique IP address or o Uses a specified TCP port number

• Use virtual loopback if the application:

o Uses the loopback address 127.0.0.1 and o Uses a specified TCP port number .

Virtual IP Configuration

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Considerations

IP Address Ranges. Presentation Server administrators, in conjunction with network administrators, must ensure that a sufficient number of valid IP addresses are available within that same subnet as the Presentation Servers when configuring virtual IP. Duplicate IP addresses cannot coexist within the same environment.

For example, if 50 Presentation Servers exist in a Class C network and 10 IP addresses are reserved for router interfaces and other network devices that would mean the following IP addresses are available:

Class C network: 256 addresses, of which the first address is used to identify the network and the last address is the broadcast address

Total number of addresses available: 254

-50 (servers)

-10 (reserved)

194 IP addresses available in subnet

The processes used within the virtual IP range are also designated via the “Virtual IP Processes” panel by clicking the respective “Add Process” button and following the configuration wizard. In most cases, virtual IP processes will be used. This is illustrated by the upper panel of the screenshot to the left.

Similarly, “Virtual Loopback Processes” can be configured via the lower panel by clicking the respective “Add Process” button and following the configuration wizard. Only these designated processes will use virtual IP addresses.

The specific processes designated in the “Virtual Loopback Processes,” (see screenshot above), require additional configuration. These configurations are made via the “Virtual Loopback Configuration” node of the farm properties.

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Based on an environment with 1,000 concurrent users, there will only be 194 IP addresses available to support virtual IP addressing, which is insufficient. Options are:

• Implement IP address pass-through from client device if this provides controlled, unique IP addresses

• Create a load managed group based on only the application(s) that require virtual IP addressing and designate only those servers in virtual IP addressing (up to 194 addresses in this case)

• Have the Presentation Server farm span subnets; however, the virtual IP address range assigned to each Presentation Server must be on the same subnet as the Presentation Server.

IP Address Assignments. Specific virtual IP addresses cannot be assigned to specific users; each ICA connection is allocated a virtual IP address based on availability. If a specific IP address is required, passing the IP address of the client may be a better option if uniqueness can be assured.

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Notice

The information in this publication is subject to change without notice.

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