MCG > MCU frame error

[Mascotte]

Hi,

Experience problems on the set up listed below and will try to explain in my best English:

European Tandberg 880 via IP to local Tandberg MCU 16-16 via PRI to Polycom MCG-100 via PRI to Avaya PBX via BRI to New York Polycom Viewstation

(a long chain for a point to point call ... )

Sometimes New York video freeze or goes black, audio will continue as normal. According to service provider their MCG is showing 'frame errors' and 'Europe is causing this'.

(Political awareness: corp. standard is Polycom, European install base is Tandberg so Europe is the exception and to blame)

VP @ NY is 'helping me' troubleshooting and did sent over an outdated Polycom Viewstation to hook up for next scheduled conferences. I do not like to hook up this unit because I've the feeling that we did not do 'basic troubleshooting' and will end up having the same problems.

I did trace my MCU during test calls but no issues found. Also I've tried to reproduce the problem but no luck.


My questions:

> any problems known with ISDN channels provided by an Avaya PBX ?
> Does frame errors indicate ISDN network problems ?
> are there any compatibility issues between Tandberg MCU and Polycom MCG ?
> Can I detect which software version the far end is using or is that blocked by the third party MCG ?

hints and tips would be helpful

thanks

[ChuckF]

You will have a tough battle with this many links and this many players. I would start troubleshooting each link first. I'm pretty confident it is not the 880 or the Tberg MCU. Possibly the LD provider between the Tberg MCU and the MGC, but not the Tandberg equipment. My gut is telling me that the Viewstation going thru the Avaya would be the issue, but will need some more questions answered first.

1. Does the MGC have Transcoding or Continuous Presence invoked?
2. What version s/w on MGC and Viewstation?

Basic troubleshooting steps - check each segment first -
1. What happens when VS connects to MGC only (without Tbergs in call)?
2. Try having the VS call the Tandberg MCU directly (bypass mgc). According to network description, you should be able to test this.
3. What happens when Tberg MCU connects to others?

Answers to your questions:
1. Yes - there are 'known' issues with this configuration, typically a incorrect configuration on the Avaya. But if this was the case, VS would not be able to connect to anyone else. Otherwise, no known issues. Assuming that the Avaya is pulling its timing from the carrier.
2. Frame errors do indicate ISDN Network problems - typically with timing mismatch or clock slips.
3. There are some compatibility issues, but none that would cause this issue. Typically issues would be H.239 or H.264, but I do not think those are playing a role in this problem.
4. You cannot detect which s/w version in this scenario. You will have to ask that question.

And sending that Polycom VS over for testing will not provide anything useful IMO.

My 2 cents.