I just had a very interesting 3 days of troubleshooting videoconferencing calls that losses video or does not connect video when dialling trough an ISDN gateway to another ISDN gateway and connecting to a video systems DID.
Equipment on Client Site (Dialing from)
1. Cisco C20
2. Cisco C60
3. ISDN GW 3241
All codecs register to internal gatekeeper of ISDN GW 3241
Equipment of Site 1 that I dialed to
1. Cisco C20 - Software build TC 4.2.2
2. Cisco C40 - Software build TC 4.0.1
3. ISDN GW 3241 - Software build 2.0(1.51)P
4. VCS Control - Software build 7.1
All codecs and ISDN GW register to VCS Control with an E164/DID and 8 prefix for video dialling out.
Equipment of Site 2 that I dialed to
1. MXE 8510 Media 2 Blade - With Meeting room and ISDN DID - Software Unknown
2. MXE 8321 ISDN GW Blade - Software Unknown
3. VCS Control -Software Unknown
All blades registered with VCS Control
Equipment of Site 3 that I dialed to
1. 3rd party ISDN GW - Unknown
2. Polycom HDX - Software Unknown
3. Cisco EX 90 - Software Unknown
4. Cisco C20 - Software Unknown
All systems register with a gatekeeper and has an DID assigned to them.
When placing ISDN calls to any of the above sites DID from -
Equipment on Client Site (Dialing from)
1. Cisco C20 - Software Build TC 5.1
2. Cisco C60 - Software Build TC 5.1
3. ISDN GW 3241 - Software Build 2.1 (1.49)P
The call connects and the audio is stable, but one of the following happens:
* Call connects with two way video and after a couple of minutes the video drops one way or both ways.
* Call connects with only one way video.
* Call connects with no video
Step 1: Ruled out network by connecting different codec's directly to ISDN GW - Still experienced the same result
Step 2: Ruled out the ISDN GW by replacing it with the same model and software build - Still experienced the same result
Step 3: Not ruled out yet, but used a different ISDN E1 (PRI) - Still experienced the same result
Step 4: Downgraded the ISDN GW to version 2.0 - Still experienced the same result
Step 5: Downgraded the C-Series Codec's to TC5.0 - Still experienced the same result.
Step 6: Downgraded the C-Series Codec's to TC4.2.2 - Start getting better results
Step 7: Upgrading ISDN GW back to 2.1 - Experienced the same results as other steps.
After downgrading the ISDN GW to version 2.0 and the C-Series Codec's to 4.2.2, the video started staying up.
1. Is the ISDN GW's backward compatible?
2. Is this a known bug that I am missing in the release notes?
3. When will a new software build or patch be released as the last one was September 2011?
I disabled and enabled all video and audio protocols, but nothing.
What i did see is that if you have two sites with ISDN GW both on 2.1 and the codec's on TC 5.1, the calls work 100%, as soon as you dial to a older software build or a 3rd party ISDN GW, the problems starts.
I had a look at the Release notes of the C-Series TC 5.1, under compatibility section they show more than one software version for certain infrastructure but for the ISDN GW 3241 they only show software version 2.1
Also under the open caveats in the document they have one for video not working with the old Tandberg ISDN GW and older Tandberg VC units, so it might be a problem with other systems as well.
Just hoping that a new software build will resolve this.
I know since the release of our ISDN GW 2.1 sw version and TC4 and above, we have dramatically improved the interoperability with our C series endpoints.
Unfortunately off the top of my head I cannot pinpoint a specific bug for you to reference, but i had previously experienced problems myself in our lab with back to back ISDN GW calls from C series endpoints and the new sw releases had improved this functionality.
This is why we ALWAYS recommend customers to be on the latest sw releases as there are many additional bugs that are fixed, but unfortunately we cannot fit them all into the software release notes.
I will keep searching our database for you and if i come across the specific bugs i am looking for in reference to this scenario i will post them here for you
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