VCS DNS Zone - URI Dialing External

[Marek Tarnoci]

Hello,

I would like to configure calls via URI to external devices from devices registered on CUCM 9.1.1.

Scenario:

- I have Endpoint registered to CUCM 9.1

- created SIP trunk to VCS, SIP route pattern pointed to this trunk

- on VCS created DNS lookup zone

If I'm calling external endpoint (e.g. emea.trafficcam.tsec@cisco.com), it's not working. Call is routed from CUCM to VCS, but from some reason, if it's leaving VCS through DNS Lookup zone,  transport protocol for SIP on leg to internet (DNS zone) is UDP, even I have UDP disabled and everywhere configured TCP.

FYI:

- If I have same Endpoint registered on same VCS, it's working fine, i can reach endpoint on internet via URI. (e.g. emea.trafficcam.tsec@cisco.com)

Do you have any idea, why is transport protocol changed, or what should be configured to get it work?

Thanx,

Marek

[ahmashar]

if the domain of dialed URI is not the same as your domain, it's correct to go through DNS zone. The domain on your CUCM is the same as VCS, then you need to create search rule to direct the call to CUCM. I think your search rule is missing instruction on how divert the call to CUCM and that's why it hits the last resort and send out the call via DNS.

[Marek Tarnoci]

Hi Ahmad,

Thanks for your answer. URI dialing in my domain (domains) is working properly, I can call devices registerd to CUCM, VCS even Lync devices via URI in my enviroment without problem.

My aim is to be able reach devices which are reachable by URI via internet, from devices registered to CUCM.

Scenario:

Let say, I want to call from my MX200 to device reachable via URI somewhere on internet. For example testing device on internet - emea.trafficcam.tsec@cisco.com

1. Device Registered on VCS:

- If I have my MX200 registerd to VCS, it's working well. Call is routed via DNS Lookup zone. I can reach mentioned endpoint whitout problem.

see attachements

2. Same MX200 as before but registered to CUCM 9.1

I have created SIP trunk from CUCM to VCS which has configured DNS Lookup zone (Scenario mentoned earlier is working through this VCS)

What is problem:

If call is comming to VCS from CUCM Neighbor zone and is routed to internet through DNS Lookup zone, transport protocol is changed to UDP, DNS Lookup not searching for SRV record _sip._tcp.cisco.com, but for A record, get wrong IP address and call is not established.

see attachements

I have no idea, why when call is comming from Neighbor zone (CUCM) is behavior different as if call is comming from Local zone, and transport protocol is changed, even when on all devices is configured transport protocol TCP.

Any Idea?

Regards

Marek.

[ahmashar]

hi Marek,

that could be a software bug. I would suggest to open TAC case for log files to be closely look at and if it's identified as a bug to be fixed in feature software release.

regards, Ahmad

[Christin Varghese Issac]

Hi Marek,

Did you manage to resolve this?

I can see the destination in your search becomes "emea.trafficcam.tsec@cisco.com:5060" when call comes from CUCM. You need to create a search rule which will strip the suffix ":5060".

Apply this in your VCS Control and sent it to Expressway.

Make sure in CUCM you have the SIP route pattern pointing to you VCS Control.

Rgrds,