Reuse of Citrix Session ID



We have Windows 2000 Server with SP3 (3 servers) configured in a Citrix Farm
(Citrix MF XP1.0 FR3).

Each time a new user is connected to the Citrix farm, server issues a
session ID. These session IDs are incremental for each new connection, and
are not reused after the user has disconnected. The only way to force it to
reuse, is to restart the server!

You may ask 'so what?' but this has an impact on the third party printing
application - it simply won't work once the session ID count reaches 1000.

We contacted Citrix and they advised that Microsoft has a hotfix for it but
not publicly available for download. We could not find the relevant article
on the web either.

Any clues please?

Vera Noest [MVP]

I'm not aware of such a hotfix, and to me it sounds unlikely that
there is one. Incremental session numbering is by design, and it
is really the 3th party application that should be fixed, not the
I would call Citrix again and ask them for the KB article number
that describes the hotfix.
Note that W2K SP4 contained many printer fixes. It is possible
that some of those never made it as a separate hotfix.
Have you considered installing SP4?

One other thought: if the problem with the 3th party application
is caused by the fact that the printer name becomes 1 character
too long when you reach session 1000, you might be able to
workaround this issue by shortening the local name of the printer.

This is the only relevant information that I can find:

INFO: Working with Long Printer Names;en-us;240082


Thanks for your response.
We have installed the SP4 on all 3 servers last week. Shall wait and see...

Also, as I mentioned restart is the only means we are using as a workaround
for the time being.


Is there any maximum session number, and what happens when it is
Does TerminalServices behave identically to Citrix in this issue? I
seem to have notices some differences.

With thanks


Vera Noest [MVP]

Haven't seen this documented, but since the listener session has
session number 65536, that should be the limit.
Session numbering starts at zero again after a reboot of the
server, maybe it does this as well when you reach the session
number limit.



Thanks for the information. Is there any way I can check this, and what
happens when the limit it reached? Is this number likely to change in
the future, such as in 64-bit Windows?

And does the Citrix session ID exactly mirror the Terminal Services
session ID? I noticed with some tests that I made that while Terminal
Services always seemed to increment my Session ID, Citrix sessions
often reused previous session numbers.

With thnaks


Vera Noest [MVP]

rdp session numbers are independent of ica session numbers.
With Citrix you can have several connections to the same farm, to
different published application, in one session.
Such a setup would mean running several rdp connections.

May I ask why do you want to know these details?
I get the feeling that you are trying to rely on session numbering
being consistent, in an application or some other setup.
If that's what you are trying to do, I would forget it.


Thanks for the answer, and the questions.

I have checked our design here, and what really interests me is the
Terminal Service Session number. If that is bounded by 65536, I have
all the information I need. The consistency is over a period over a
second, so I imagine it will not change over that time frame.

With thanks again

Vera Noest [MVP]

OK, that sounds reasonable.
I was afraid that you relied on the session number to connect to
redirected printers from within your application, or some other
client resource, or for licensing reasons. Some applications try to
do that, and that just doesn't work.
But within a time frame of a second, things should be consistent

Note that the 65536 boundary is only *my best guess*. I have never
seen an upper boundary documented (never searched for this info
either), but the standard rdp listener session (which is a
"template" session to start a new user session) has always number
65536 on a Windows 2003 server. So that's why I guess that a user
session number cannot get higher than that.

Vera Noest
MCSE, CCEA, Microsoft MVP - Terminal Server
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