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New Member

Calls over intercluster trunk fail from certain hour


We have an h323 intercluster trunk between a 4.2(3) cluster - Belgium - and a 6.1 cluster - USA.

Since last week we suddenly experience calls failing between certain times.      During the day, there is no problem... calls are setup ok, voice quality is ok.

Starting 17h30 no call can come through from the 6.1 to the 4.2(3) ... this lasts till 7u30 in the morning.   Calls from the 4.2(3) towards the 6.1 keep working.

In the tracing we get the message ' h323hostcall > 59283 [RST] Seq=1 Win=0 Len=0 '   where for calls that do go though we get an [ACK] followed by callProceeding.

Does anyone have an idea what this could be ?     I couldn't find any scheduled tasks ... no SQL jobs ... no timeschedules in CCM that start at 17h30 .



Maybe worth noting : We recently changes firewalls from CheckPoint to Cisco ASA about the same time this started.

Cisco Employee

Re: Calls over intercluster trunk fail from certain hour

I wouldn't look at CUCM but at my underlying network instead.

I once had a case where phones would unregister at certain time, it turned out during that time a huge backup process from another department was eating the whole BW.

Have you asked in your company if some process is running at that time that could use the BW???

Probably not yours, but someone is doing it and without noticing it, is causing you trouble.

Have you checked your WAN at that time??



If this helps, please rate



if this helps, please rate
New Member

Re: Calls over intercluster trunk fail from certain hour

thanks for the reply...

We have a PRTG system that monitors the bandwidth... there is definitly enough bandwidth available

The strangest thing is that it starts at 5:30 pm to 12:00 am.  Like clockwork... calls that are in progress have no problems, new calls at 5:30:01 get a reset command.