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NAM Probe considerations for Citrix server and Windows terminal services monitoring

In certain thin-client environments, the number of session mappings received by the NAM Probe per second can be very large. In such cases, the mappings are dropped from the input buffer before they can be handled by the NAM Probe.

Tracing this problem can be difficult because the only observable effect is an increased number of unmapped sessions, and unmapped sessions can have many other causes.


Knowing the expected number of mappings per second (new TCP sessions per second) can help you determine the number of NAM Probes required to monitor high-end environments.

A NAM Probe can handle approximately 300 mappings per second. The number of mappings generated by a single agent depends on the number of clients connecting to it and, on the back-end server traffic profile (the number of new TCP sessions per user per second).

To help identify appropriate mapping information, check the TCAM diagnostic log on the running agent. This log contains information about every mapping sent to the NAM Probe in the form of sees.proto messages. For more information, see Thin Client Analysis Module.

Compatibility notes

Citrix 7.x
In general, the NAM ICA decode and TCAM work with all Citrix 7.x releases, but you should be aware of the following limitations concerning NAM and Citrix 7.x:

  • TCAM reports a loopback address as the client IP address if the client comes through NetScaler.
  • The ICA decode does not report on Citrix Framehawk channels or on traffic that uses Citrix EDT transport (a Citrix protocol that enhances UDP) instead of TCP.