Non-Traversal calls issues

Answered Question
Mar 23rd, 2014
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Hello all,

I'm implementing some new Telepresence devices:
Site A
VCS-Control (X8.1)
VCS-Expressway (X8.1)
MCU 5310 (4.4)
C40 codec (7.0.2)

Site B
C20 codec (7.0.2)
Different subnet from site A

I've enabled H.323 & SIP on the VCS-C and have tested multiple calls between Site A & B. Whenever the calls go out H.323 to SIP, or SIP to H.323 from the C40 to the C20 or the other way around, there's no problem. Both sites receive video and audio.
Whenever I force the same protocol. i.e, H.323 to H.323 or SIP to SIP and make the same calls, site B (C20) doesn't get video from Site A (C40). However the C40 is receiving both video & audio from the C20. What's interesting is that if I make the same calls from the MCU, which is also at Site A, then there's no problem. So the problem is between the C40 and C20.
Since I'm not physcally at the sites because I'm doing this implementation remotely, I can only rely on the stats I get from the GUIs. I have attached a picture the customer took from the C20 screen. 

Calls:
Traversal calls
C40-C20 H.323-SIP - call ok
C20-C40 H.323-SIP - call ok

C40-C20 SIP-H.323 - call ok
C20-C40 SIP-H.323 - call ok
MCU-C20 H.323-H.323 - call ok

Non-Traversal calls
C40-C20 H.323-H.323 - No video received on C20
C40-C20 SIP-SIP - No video received on C20
C20-C40 H.323-H.323 - No video received on C20
C20-C40 SIP-SIP - no video received on C20

So it seems that there's only a problem on the C20 during non-traversal calls. I do not want to use a Traversal license between these 2 endpoints.

Thank you for your help. Any input would be greatly appreciated.

-Greg



 




 



 

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Correct Answer by Chris Swinney about 3 years 4 months ago

Hi Greg,

I see that there is duplicate thread on this (there are problem on the forum regarding multiple posts) and I see that other have suggested similar things to what I have done.

I would suggest that there is an issue on Site A not allowing traffic from Site B. I also see that your "ping" does not work, however, be aware that an ICMP ping may be blocked yet UDP traffic can pass. I can't remember if the C series CODEC allow for UDP pings when you enable root mode and login as root (I know the VCS does), however, I would ask, why the firewall is so restrictive if Site A trusts Site B?

Chris

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Greg Jaubin Sun, 03/23/2014 - 10:31
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I should have mentioned that we are not using the VCS-Expressway yet. All the calls are internal. Site A & B are on the customer's network.

-Greg

Chris Swinney Sun, 03/23/2014 - 11:28
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Hi Greg,

Are there firewalls in place between the two sites?

When you interwork a call (i.e. go from SIP --> H.323 or vice versa), the media for the call will get routed via the VCS. When you place a call using the same protocol, whilst the signalling may go through the VCS, the media streams would be routed directly between the endpoints. The VCS essentially says "hey, these guys are connected to me locally so they both must be able to talk to each other directly - I'll just step out of the media path and let them get on with it". Of course, if you have firewall between the sites then you may not expect that these media streams are coming direct from the CODECs to each other.

Essentially, the VCS in you deployment only see's one site and would expect that everything to be directly rotatable.

On the "Call Routing" page in the VCS "Configuration" menu, click the help link top left to view more info, or check out the VCS admin guide.

Cheers

Chris

P.S . Due to the rubbish new forums that have been implemented by Cisco  (IMHO), it seem as though multiple post are not uncommon. I would go back the the Telepresence main discussion and delete your other duplicate post.

Greg Jaubin Sun, 03/23/2014 - 11:44
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Chris,

 Thank you for your prompt response. As far as i know there's a firewall at Site A. We gave the customer a list of standard ports to open. No firewall at site B. Also as I mentioned, the same calls via the MCU work ok. And the MCU and C40 are at the same site. 

What I could try to do is unregistering the endpoints from the VCS-C and see how the non interworking calls behave.

-Greg

Correct Answer
Chris Swinney Mon, 03/24/2014 - 02:34
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Hi Greg,

I see that there is duplicate thread on this (there are problem on the forum regarding multiple posts) and I see that other have suggested similar things to what I have done.

I would suggest that there is an issue on Site A not allowing traffic from Site B. I also see that your "ping" does not work, however, be aware that an ICMP ping may be blocked yet UDP traffic can pass. I can't remember if the C series CODEC allow for UDP pings when you enable root mode and login as root (I know the VCS does), however, I would ask, why the firewall is so restrictive if Site A trusts Site B?

Chris

Greg Jaubin Mon, 03/24/2014 - 07:30
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Thanks Chris,

I cound't find where you can even remove a discussion.

I'm going to speak with the customer today. The fact that both sites can't ping each other isn't normal, at least part of my installation check list.

-Greg

Chris Swinney Mon, 03/24/2014 - 08:42
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WRT deleteing threads, at the very top of a thread started by you, there is an Edit and Delete button.

Yep. I think it you have two separate sites (probably connected via VPN of some description???) then as far as the routing from one subnet to another is concerned, I would expect them to be open. Of course, this is not always practicable or desirable, but then you will face restrictions and limitations.

Greg Jaubin Mon, 03/24/2014 - 21:36
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Thank you Chris,

The endpoints couldn't ping each other. I asked the customer to check and they remember seeing a small network switch between the C40 at site A and the wall jack. Somehow it prevented the pings. After removing it, I was able to ping and the calls connected fully between the sites.

Thank you for your help!

-Greg

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