Questions about VCS-E/C proxying media

[Nick Halbert-Lillyman]

I'm trying to figure out a way to get VCS-E to proxy media to a neighbour zone.  We currently use VCS-E to connect to other organisations via VCS traversal zones, however a new organisation wants to peer with us via an SBC instead.

My understanding is that this would need to be a neighbour zone rather than a traversal zone as the SBC doesn't support H460, however this presents us a problem as the neighbour zone doesn't proxy media unless the call is interworked or onto another traversal zone.

As we have an MCU and some other legacy systems either directly registered or neighboured with the VCS-E, this would case calls to fail as the external firewall will obviously only allow traffic to and from the VCS-E's IP address.

So is there a way to get VCS-E to proxy media without a traversal zone or forcing H323 to SIP interworking?

[Martin Koch · Accepted solution]

What kind of deployment is behind that SBC?

If you want to archive a traversal zone behavior, incl sip and especially h323 you should stick with

a VCS model. If its a pure CUCM install the expressway deployment model might be something to look into.

If they really desperately want a SBC but media and signaling they should deploy a VCS-C, have a

traversal zone to you and a neighbor zone through their SBC to whatever they have then.

For a SIP only zone you have a media latching option as a command line parameter,

this + setting routed to always for this zone will force media and signaling to stick to the VCS.

But thats only for SIP and requires bideirectional firewall openings.

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[Nick Halbert-Lillyman]

Hi Martin,

I'd definitely prefer them to use a VCS, but they are going to use an SBC regardless

I forgot about SIP media latching... I'll give that a go (it's SIP only).  I was talking to someone from Cisco who also mentioned that as of X7.2, setting a media encryption policy would also do the trick, but I'd prefer to leave it as "auto" if I can so I'll try your suggestion first.