Video over IP (NAT)

Unanswered Question
Oct 30th, 2008

At present I have polycom gsx 6000 VCU and they break out via ISDN. I am now being asked to set up videoconference over the internet. This is where the issues begin I think. The firewall I maintain does not have a direct link to the internet. I NAT my internal address to a third party and then they NAT that address out to the internet. What issues am I likely to experience as the documents that I have read indicate that IP video and voice are not NAT friendly and can cause problems being NAT'd once never mind twice.

Is there any good documentation that someone can point me to?

Thanks

I have this problem too.
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smalkeric Wed, 11/05/2008 - 09:27

One way to work around this problem is to use an H.323-aware NAT firewall, which can rewrite the

addresses in the signaling payload. Using the proxy in NAT or firewall environments allows administrators to target a single IP address to terminate all H.323 video calls. All incoming and outgoing video calls that access the public network

will use the proxy. With the Cisco Pix Firewall, administrators can enable H.323 fixup and allow UDP

port 1720 traffic to access the IP address of the proxy. If the proxy were not used, the administrator would

have to configure UDP port 1720 to all videoconferencing devices. If you use a Cisco IP/VC 352X or

3540 gateway, port 1820 must be configured for the videoconferencing devices.

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