Strange behavior with MXP 1700 in remote office

[Douglas Baggett]

I have an MXP in a remote office that is NAT'd and registered SIP/H.323 with our VCS-E. (running latest software). We have a standard VCS-E/VCS-C configuration at the home office. If a Jabber user (or any registered endpoint) at the home office tries to call the MXP (or vice versa) I get a half connection with audio working but video not working.

Here is the strange thing...

I have our VCS-E set with a default fallback alias which is our 8510 MCU autoattendant page. If I reconfigure the MXP so that it's no longer using our Gatekeeper (in direct mode) and I have them direct dial our VCS-E, they get the MCU autoattendant page and can join an MCU room without any problem at all.

thoughts on troubleshooting? Any help in advance is appreciated.

[Zac Colton]

There appears to be media flow/connection issues. Can you please describe your Expressway configuration? Behind firewall? NATed? Etc...

Zac Colton

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[Douglas Baggett]

It's a standard VCS-E/VCS-C configuration. No clustering. The VCS-E is in a DMZ. What I'm confused about is why there would be flow issues when it's registered but none when it's not (in direct mode).

What other information would you like?

[Zac Colton]

Does the VCS Expressway have the Dual NIC option? Are you running both interfaces? What kind of external firewall is it? Is it running and ALG or inspection for SIP of H323?

- Zac Colton

[Douglas Baggett]

One NIC. (no dual interface)

The Firewall (On our end) is a CISCO 5540

on the far end I really don't know what kind of router. It was provided by the ISP (home router). We've not had any other problems with endpoints dialing in. So it seems to point to the router at the far end. Should I possibly set it for SIP to dial us (instead of H.323) and turn on STUN/TURN?

[Zac Colton]

If the VCS Expressway is in a DMZ and is being NATed by an external firewall, you will need the Dual NIC Option on the Expressway so that you can configure the NAT address on the Expressway. For a detailed explanation of the design options, please take a look here:

http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Basic_Configuration_Control_with_Expressway_Deployment_Guide_X7-2.pdf

Please take a look at Appendix 4 starting on page 56.

- Zac Colton

[Douglas Baggett]

My mistake..the Expressway is not NAT'd, the problem endpoint is.

[Zac Colton]

If the VCS Expressway is not NATed (it has a publoic IP address assigned to it and resides outside the external firewall), I would suggest running a diagnostic log and tcpdump on the Expressway and capture a failed call from start to finish. Within the diagnostic log and packet capture, you can review the media negotiation and the media streams that are being sent and received.

- Zac Colton