Using Mixed Mode for Interoperability with MetaFrame 1.8

Document ID: CTX485555
This solution pertains to:

• MetaFrame XP for Windows 2000
• MetaFrame XP for Microsoft NT Server 4.0, Terminal Server

Last modified: Wed Jun 13 15:09:27 2001

Features of Native Mode and Mixed Mode

This note describes how MetaFrame XP servers operate and communicate, and defines functional differences when the server farm is in native mode and mixed mode.

Native Mode

• The Program Neighborhood and ICA Browser services are disabled on all farm servers by default.
• MetaFrame XP servers do not share Program Neighborhood or ICA Browser information with MetaFrame 1.8 servers.
• Each MetaFrame XP server does not send Program Neighborhood information to every other server in the farm, which reduces network traffic.
• Network utilization is more efficient because ICA Browser traffic is no longer broadcast-based. The IMA service uses TCP/IP, while the ICA Browser service uses UDP.
• MetaFrame XP servers do not share dynamic information through the ICA Browser service. Instead, the IMA service notifies the data collectors of dynamic changes.
• MetaFrame XP connection licenses are not pooled with MetaFrame 1.8 servers.
• Published applications are not load balanced across both MetaFrame XP and MetaFrame 1.8 servers.

Mixed Mode

• The Program Neighborhood and ICA Browser services are enabled for every server in the farm.
• MetaFrame XP servers send Program Neighborhood information to MetaFrame 1.8 servers with the same farm name.
• MetaFrame XP servers with the same farm name as MetaFrame 1.8 servers appear to ICA Clients as the same application set.
• MetaFrame XP servers share ICA Browser information with MetaFrame 1.8 servers on the same subnet.
• Published applications in the same application set can be load balanced across MetaFrame XP and MetaFrame 1.8 servers that share the same farm name.
• Applications published using the CMC in MetaFrame XP prevents the publishing of an application with the same name using the MetaFrame 1.8 Published Application Manager.
• Every server running the Program Neighborhood service maintains a connection with every other server with the same farm name to share Program Neighborhood data. The formula to calculate the number of connections is N*(N-1)/2, where N is the number of servers in a farm.
• Program Neighborhood and ICA Browser communication is redundant and in addition to IMA communication.
• By default, MetaFrame XP servers win master ICA Browser elections over MetaFrame 1.8 servers on the same subnet.
• MetaFrame XP servers answer ICA Client UDP broadcasts.
• License pooling is available between MetaFrame XP servers and MetaFrame 1.8 servers on the same subnet.
• MetaFrame XP master ICA Browsers remove MetaFrame 1.8 ICA license gateways, but leave MetaFrame 1.8 ICA gateways intact
• UDP is unreliable and is usually not passed through firewalls.
• Load balancing algorithms for MetaFrame XP published applications are different than the load balancing algorithms for MetaFrame 1.8.

Native And Mixed Mode Details

IMA communication greatly improves the scalability and stability of server farms. Citrix recommends that MetaFrame XP farms operate in native mode. Enable mixed-mode operation only when MetaFrame XP servers must be integrated with an existing MetaFrame 1.8 farm.

TIP: Mixed mode is intended only as a temporary solution until all MetaFrame 1.8 servers are upgraded to MetaFrame XP.

MetaFrame XP servers operating in mixed mode generate more network traffic than MetaFrame XP servers operating in native mode. The ICA Browser and Program Neighborhood services that are started on MetaFrame XP servers, when operating in mixed mode, duplicate the MetaFrame XP IMA functionality to maintain compatibility with MetaFrame 1.8 servers. From a network utilization standpoint, ICA Browser and Program Neighborhood communications are not as efficient as IMA communication because of fundamental differences in design.

The two primary benefits of mixed mode, which are described in detail later, are:

• The ability to pool MetaFrame XP connection licenses with MetaFrame 1.8 user licenses
• The ability to integrate MetaFrame XP servers with an existing MetaFrame 1.8 farm

License Pooling With Existing MetaFrame 1.8 Servers

By enabling mixed mode on a MetaFrame XP server farm, organizations that have existing MetaFrame 1.8 user licenses can pool those licenses with mixed mode MetaFrame XP servers. In addition, mixed mode allows MetaFrame XP connection licenses to be pooled with MetaFrame 1.8 servers when those servers reside on the same subnets as MetaFrame XP servers in a mixed mode XP farm.

There are some caveats to this capability. By default, MetaFrame XP servers win master ICA Browser elections over MetaFrame 1.8 servers on the same subnet. MetaFrame XP servers acting as master ICA Browsers convert ICA license gateways to ICA gateways.

Also, in mixed mode, MetaFrame XP connection licenses are statically assigned to the subnets that contain MetaFrame XP servers from the same farm. This is different from native mode license pooling in which MetaFrame XP connection licenses are dynamically pooled across all subnets that contain servers from the same farm. The following example demonstrates this license pooling behavior.

Figure 7: License Pooling with MetaFrame 1.8

The diagram in Figure 7 shows six MetaFrame 1.8 servers and three MetaFrame XP servers on three different subnets. The six MetaFrame 1.8 servers existed in this configuration prior to the installation of the MetaFrame XP servers. MetaFrame 1.8 supports an ICA license gateway between two subnets only. In this scenario, an ICA license gateway is configured between subnets 1 and 3, with standard ICA gateways configured between subnets 1 and 2, and between subnets 2 and 3. The total number of possible pooled licenses on subnets 1 and 3 is 75 (45 licenses from subnet 1 plus 30 licenses from subnet 3). The total number of possible pooled licenses available on subnet 2 is 15. The MetaFrame XP servers are all members of the same farm and the farm contains 50 MetaFrame XP connection licenses.

If the MetaFrame XP farm is installed in native mode, no license pooling with MetaFrame 1.8 servers occurs. With the use of a license ICA gateway, the MetaFrame 1.8 servers have 75 possible pooled licenses shared among subnets 1 and 3, and 15 possible pooled licenses on subnet 2. The MetaFrame XP servers have a separate pool of 50 licenses. The MetaFrame XP licenses are dynamically pooled across the three subnets.

If the MetaFrame XP farm is installed in mixed mode, the ICA Browser and Program Neighborhood services are enabled and started on all three MetaFrame XP servers. Unless they are manually configured to never become the master ICA Browser, all three MetaFrame XP servers would win the master ICA Browser elections on their respective subnets. The existing MetaFrame 1.8 ICA license gateway is converted to a standard ICA gateway. The existing ICA gateways remain intact.

NOTE: In mixed mode, all MetaFrame XP licenses are evenly distributed to all subnets in the farm by default.

TIP: You can modify license distribution through Citrix Management Console. Use the Interoperability tab in the server farm’s Properties dialog box to change the number of MetaFrame XP licenses assigned to each subnet.

In a mixed mode MetaFrame XP farm, the MetaFrame 1.8 user licenses are not pooled across any of the three subnets, and the MetaFrame XP connection licenses are assigned equally to each subnet. By default, because there are three subnets, one third of the total MetaFrame XP connection licenses are assigned to each subnet. Because there are 50 MetaFrame XP connection licenses in this scenario, two subnets are assigned 17 connection licenses and the third subnet is assigned 16 connection licenses.

NOTE: The order of MetaFrame XP installations and committed licenses affects how MetaFrame XP evenly distributes its available licenses.

MetaFrame 1.8 user licenses and MetaFrame XP connection licenses are pooled on each subnet. The result is that subnet 1 has approximately 62 pooled licenses (45 MetaFrame 1.8 licenses and 17 MetaFrame XP licenses), subnet 2 has approximately 47 pooled licenses (30 MetaFrame 1.8 licenses and 17 MetaFrame XP licenses), and subnet 3 has the remaining 31 pooled licenses (15 MetaFrame 1.8 licenses and 16 MetaFrame XP licenses).

NOTE: If ICA license gateways existed prior to the MetaFrame XP installation, it can take up to 48 hours for licenses to be accurately reported due to cached information in the backup ICA Browsers.

Integrating MetaFrame XP Servers With an Existing MetaFrame 1.8 Farm

If you have an existing MetaFrame 1.8 farm (or farms), you probably want to integrate the new MetaFrame XP servers with existing MetaFrame 1.8 farms. For example, you want to publish applications on both MetaFrame XP and MetaFrame 1.8 servers that appear in the same application set for existing Program Neighborhood clients.

For MetaFrame XP servers to appear as if they are members of an existing MetaFrame 1.8 farm, the MetaFrame XP farm name must match the MetaFrame 1.8 farm name. Enter the MetaFrame XP farm name during installation of MetaFrame XP on the first server in a new server farm.

You must configure the MetaFrame XP farm for mixed-mode operation to integrate the MetaFrame XP farm with the MetaFrame 1.8 farm. MetaFrame XP farms and MetaFrame 1.8 farms that share the same farm name are separate farms that appear to Program Neighborhood clients as the same farm.

Manage MetaFrame 1.8 and MetaFrame XP farms with the same name using separate utilities. To create applications for the MetaFrame 1.8 farm, use the MetaFrame 1.8 Published Application Manager (Appcfg.exe). You cannot use Citrix Management Console to manage the MetaFrame 1.8 farm. You must use Citrix Management Console to manage the MetaFrame XP farm.

NOTE: The Published Application Manager and Citrix Server Administration tools are installed with MetaFrame XP. They are included only for use in managing MetaFrame 1.8 farms. Published Application Manager does not work with MetaFrame XP. Also, the Citrix Server Administration tool has limited functionality for MetaFrame XP.

WARNING: Published applications that are modified with the version of Published Application Manager that is installed with MetaFrame XP cannot later be modified with earlier versions of Published Application Manager (such as the version installed on MetaFrame 1.8 servers).

To load balance the same published application across MetaFrame XP servers and MetaFrame 1.8 servers, first publish the published application on the MetaFrame 1.8 servers using Published Application Manager (Appcfg.exe) and then on the MetaFrame XP servers using Citrix Management Console. The published application name must be identical between the MetaFrame 1.8 farm and the MetaFrame XP farm.

NOTE: MetaFrame XP uses a default load-balancing algorithm that differs from the MetaFrame 1.8 algorithm.

Recommendations

• If possible, configure MetaFrame XP servers to operate in native mode. Enable mixed mode only for the circumstances described above.

• Mixed-mode operation is a temporary solution to be used only until all MetaFrame 1.8 servers are upgraded to MetaFrame XP.

• As an alternative to mixed-mode operation, use NFuse to display published applications from both native mode MetaFrame XP farms and MetaFrame 1.8 farms to users. NFuse 1.51 ships with examples that describe how to programmatically consolidate results from multiple farms.

• MetaFrame XP interoperability is supported only with MetaFrame 1.8 servers.

• In mixed mode, use the qlicense command on a MetaFrame 1.8 server to display pooled licenses contributed by both MetaFrame XP and MetaFrame 1.8. For more information about qlicense, see the MetaFrame XP Administrator’s Guide.

• The Citrix Management Console and the clicense command do not report MetaFrame 1.8 licenses.

• Use the qserver command from both MetaFrame 1.8 and MetaFrame XP servers to display ICA Browser information when the MetaFrame XP servers are operating in mixed mode.