From: Gregg N 

I have two services running on Windows XP. One of them acts as a COM server
and the other as a client of this server. The client issues a periodic call
to the server (say once per second) that ordinarilly completes almost
immediately (it is just an "are you still responding" status
check).

I have been trying to diagnose a problem that occurs when the ethernet
cable is removed from the machine. Since the client and server are on the
same machine, both executing under the SYSTEM account, I would not expect
this to have any effect. What happens is that the client seems to block on
the call to the server at time T0, and finally returns at time T1,
typically several (5-10) seconds later. When I trace the server, I see that
the call does not even arrive until a few miliseconds before T1, at which
point it executes it normally.

           +---SS----------+
client     |               |
call  -----+               +------

                          +-+
server                    | |
response             -----+ +------

           || |<-- 2ms

The delay is causing the client to time out and determine that the server
is no longer healthy.

The only thing the network interface is used for is communicating with a
domain controller, but as I said, both services are running under the local
system account. I find it is more likely to happen if I have a remote
destkop session open to the server (through this network interface) at the
time. Does remote desktop server do nasty things to RPC when it loses its
network interface?

Could someone explain what is likely happening, or at least suggest an
approach to diagnose this? I posted this message to
microsoft.public.win32.programmer.ole, but there has been no response, and
that group seems relatively inactive. Is there a better place to ask this
question?

Thanks,

Gregg

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