Reduce time in SRST

Unanswered Question
Aug 22nd, 2007
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I've a customer who is complaining about the time it takes to IP Phones in a remote site to register with the SRST router during a WAN failture (2 minutes aprox)

Is there any way to reduce the time it takes to an IP Phone to register with an SRST router? or Is there any way to reduce the keepalive timer between the callmanager and the IP Phone?

Tanks in advance

Best Regards,

Francisco Valle

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AJAZ NAWAZ Thu, 08/23/2007 - 04:35
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Dear Francisco Valle

The time taken to reestablish connection to a remote Cisco CallManager depends in part on the keepalive period set by Cisco CallManager itself. Typically, three times the keepalive period is required for a phone to discover that its connection to Cisco CallManager has failed. The default keepalive period is 30 seconds. If the phone has an active standby connection established with an SRS Telephony router, the fallback process takes 10 to 20 seconds after connection with Cisco CallManager is lost. An active standby connection to an SRS Telephony router exists only if the phone has the location of a single Cisco CallManager in its CallManager list. Otherwise, the phone activates a standby connection to its secondary Cisco CallManager.

If a Cisco IP phone has multiple Cisco CallManagers in its CallManager list, it progresses through its list of secondary and tertiary Cisco CallManagers before attempting to connect with its local SRS Telephony router. Therefore, the time that passes before the Cisco IP phone eventually establishes a connection with the SRS Telephony router increases with each attempt to contact a Cisco CallManager. Assuming that each attempt to connect to Cisco CallManager takes around 1 minute, the Cisco IP phone in question could remain offline for 3 minutes or more following a WAN link failure.




AJAZ NAWAZ Thu, 08/23/2007 - 06:39
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Hi Francisco

Just in case you still experience the problem please get back to us so I can continue to look into this for you.

Alternatively, if you no longer need any help it would be an idea to rate the post if it was helpful.



fcovallem Thu, 08/23/2007 - 08:01
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Hi Ajaz,

Thanks for your response.

I read about the time it takes to an IP Phone to receive the keepalive from the CallManager and the fact that the IP Phone needs to lose 3 of this keepalives to try to find another CallManager.

My question is if I can reduce the 30 seconds time between each keepalive from the callmanager to the IP Phone to know faster when the CallManager or the WAN link is down.

Thanks again.

Best Regards,

Francisco Valle

AJAZ NAWAZ Thu, 08/23/2007 - 11:41
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Is your gateway h.323 or mgcp ?



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