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Delay in SIP failover calls

We have CVP comprehensive setup with side A and Side B in different geographical location
namely Side A in Baroda and Side B in Bangalore.

Side A has separate Voice Gateways, CVP and Communication Manager Cluster
Side B has separate Voice Gateways, CVP and Communication Manager Cluster

Please find the attached doc to understand the call flow.


Problem Details:

Bangalore CVP is down at this time call should go to Baroda CVP i.e., the call has to go
from  Side B Voice Gateway to Side A CVP It is taking nearly 30s for changing dial-peer
preference 1 to preference 2.

Is there any possibility to reduce the delay in CVP failover calls.

Dial-Peer configuration:

dial-peer voice 21 voip
description
preference 1
destination-pattern 215510
session protocol sipv2
session target ipv4:172.30.17.84
voice-class codec 1
dtmf-relay rtp-nte h245-alphanumeric h245-signal

dial-peer voice 22 voip
description
preference 2
destination-pattern 215510
session protocol sipv2
session target ipv4:172.30.68.24
voice-class codec 1
dtmf-relay rtp-nte h245-alphanumeric h245-signal
no vad

1 REPLY
Green

Re: Delay in SIP failover calls

what you need to make sure is you turn down the retries in the SIP user agent. I use the following:

sip-ua

retry invite 1

retry response 1

retry bye 1

retry cancel 1

timers expires 60000

sip-server ipv4:a.b.c.d:5060

reason-header override

The default is 6 - you can see these INVITES on the wire. It's doing all those retries until it determines that the SIP B2BUA on CVP1 is not responding and then it goes to your second preference dial peer.

I'm surprised you deployed this without a pair of SIP proxies. The proxy will handle this in a slightly better way because it is alternating CVPs anyway, so only half the calls need to detect a "no response" to the INVITE and flip to the other. But retries must be turned down in the proxy too.

Regards,
Geoff
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