Couldn't you just use voice class sip options/keepalives to mark when the ITSP
is down, so CUCM marks the trunk out of service and fails to the next route
group member immediately (ideally, your secondary CUBE)? Seems like thats a
more natural way of doing it versus using IP SLAs...
Thanks,
- Ryan
________________________________
From: cisco-voip <cisco-voip-boun...@puck.nether.net> on behalf of Erik
Anderson <erik.anderson...@gmail.com>
Sent: Thursday, December 20, 2018 12:03 PM
To: cisco-voip voyp list
Subject: [cisco-voip] SIP Fail over
Morning Folks,
We have implemented a new SIP solution with Level 3 and found that we have
outbound calling failover issues. When a CUBE loses its ability to talk to its
Level 3 Peer, but can still talk to CUCM outbound calls will still connect to
the CUBE, but fail connecting to Level 3. In turn CUCM still thinks the call is
connected since the CUCM SIP trunk remains up to the CUBE.
Architecture Notes:
4 Locations with 1 CUBE Each
4 CUCM SIP Trunks with each connecting to one of the 4 CUBEs
4 CUCM Route Groups with Various CUBE/SIP Trunks assigned a Distribution
Algorithm of Top Down
Each CUBE has 2 SIP Peers
Each CUBE can only talk to its respective SIP peer via its local Level 3
Transport to reduce call control latency by not allowing it to use the DMVPN
backup network
Level 3 does not support SIP Options Ping
CUCM Trunks have SIP Options Ping enabled
Call Flows:
Working Flow:
Phone ----> SLRG ----> Route Group Member #1 ----> CUBE SIP TRUNK ----> CUBE
----> Level 3 Transport ----> Level 3 SIP Peer #1/#2 ----> Call Completes
CUBE Failure:
Phone ----> SLRG ---->
Route Group Member #1 ----> CUBE SIP TRUNK --X--> CUBE (CUCM Cant
Reach CUBE)
CUCM Routes Call to Next Route Group Member
Route Group Member #2 ----> CUBE SIP TRUNK ---->
CUBE ----> Level 3 Transport ----> Level 3 SIP Peer #1/#2 ----> Call Completes
Level 3 Transport Failure/SIP Server Failure:
Phone ----> SLRG ---->
Route Group Member #1 ----> CUBE SIP TRUNK ----> CUBE --X--> Level 3
Transport (CUBE Cant Reach Level 3 SIP Server)
CUCM Thinks Call Connects since the CUBE accepts the call, Phone gets
dead air, never tries the next RG Member
My idea to fix this is to use an IPSLA to ping the pingable address on the
Level 3 SIP Servers. If both address are unreachable then shutdown the CUCM
Dial-Peers. This doesn’t sounds like the best way of fixing it, but it should
work.
If any has any other better ideas please let me know.
--
Erik Anderson
Telecom Manager
Some Random Corp.
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