Hi,
We've been testing the UPDATE method for refreshes since we removed it on the CUBE at initial install some years ago. Our interrop team has requested us to help test if we can re-enable the UPDATE method between CUBE and SP but we are still faced with calls being dropped at 1/2 session-expires timer setting, same as all those years ago.
Since our initial install we've upgraded our CUBE IOS from 15.1 to 15.4 so I was hoping it would work this time around. Here are my findings:
LAB Setup: MIN-SE set to 90 on CUCM and CUBE.
When we make test calls traces show session-expires is accepted at 90s. The SP makes an inbound call and is set to refresh as UAC. When the first UPDATE comes in from the SP, the CUBE sends a Re-Invite onwards to CUCM but the session-expires field is missing. The Min-SE field is there but nothing more. From this point onwards I can only speculate what happens as 900s (yes 900, not a typo) later the call drops.
From rfc4028 is states that if the session-expires timer field is missing then CUCM does not expect updates anymore so I assume it defaults back to 1800s. The SP still expects refreshes and at roughly 900s it drops the call because CUCM did not send any updates that was expected at 90s intervals as negotiated in the initial INVITE shown below.
Min-SE: 90
Cisco-Guid: 4253898488-2458391013-2889204248-3239308476
User-Agent: Cisco-SIPGateway/IOS-15.4.3.M4
Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY, INFO, REGISTER
CSeq: 101 INVITE
Timestamp: 1448441677
Contact: <sip:+27122267002@10.231.227.6:5060>
Expires: 180
Allow-Events: telephone-event
Max-Forwards: 35
Session-Expires: 180;refresher=uac
Any ideas why the CUBE does not send the session-expires field to CUCM? Calls from In to Out works fine for some reason as we, the CUBE, is now NOT the refresher, its the SP SBC that is the refresher. It's all a bit confusing but hey, maybe someone has an idea.
Below is the first Re-Invite/Update from CUBE to CUCM. Notice no Session-Expires field. From this point +-900s later the call drops.
Min-SE: 90
Cisco-Guid: 4253898488-2458391013-2889204248-3239308476
User-Agent: Cisco-SIPGateway/IOS-15.4.3.M4
Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY, INFO, REGISTER
CSeq: 102 INVITE
Max-Forwards: 70
Timestamp: 1448441768
Contact: <sip:+27122267002@10.231.227.6:5060>
Expires: 180
Allow-Events: telephone-event <-- Somewhere here should be Session-Expires
Content-Type: application/sdp
Content-Length: 294
v=0
Thanks,
Ingo
