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PRI Utilization in SIP Dialer

Unanswered Question
Aug 5th, 2013
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Hi All - Is there any way to achieve Utilization of Multiple PRI in Single Gateway with CUSP Deployment.


Let's say i have 5 PRI'S in same VG, Suppose if one of the PRI goes down is there any option to utilize remaining 4 PRI'S in the same VG.


I checked SRND, where i can see IF VG is overloaded and loses it's WAN connectivity with PSTN it will return error code as 503


In CUSP we can configure Failure response code as 503 so that CUSP will take alrenate element and route it accordingy.


If that is the case, We are not utilizing remaining 4 PRI'S in the first VG.


Is there any way to achieve the remaining 4 PRI'S without jumping to alternate element in CUSP.



SIVANESAN R       

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Senthil Kumar Sankar Mon, 08/05/2013 - 18:42
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Hello Sivanesan,


If you have 5 PRI's. Do you have 5 different dial-peers in the Voice Gateway for the same destination pattern ? Do you have Preference command given in the dial-peer ? Basically If a Call matches more than one outbound dial peer, the router itseld hunt them in order as per your configuation. If the Call setup failed for some reason, the next dial-peer will be attempted. Its based on the hunt order you specify.


In the voicegateway global config mode use the below command, you should see 7 options, based on your configuration the dial-peer will be hunted. This happens within the Gateway/Router before sending the response to CUSP


VG3845(config)#dial-peer hunt ?

  <0-7>  Dial-peer hunting choices, listed in hunting order within each choice:

  0 - Longest match in phone number, explicit preference, random selection.

  1 - Longest match in phone number, explicit preference, least recent use.

  2 - Explicit preference, longest match in phone number, random selection.

  3 - Explicit preference, longest match in phone number, least recent use.

  4 - Least recent use, longest match in phone number, explicit preference.

  5 - Least recent use, explicit preference, longest match in phone number.

  6 - Random selection.

  7 - Least recent use.


Regards,

Senthil

Sivanesan Rethinam Mon, 08/05/2013 - 22:11
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Hi Senthil - Yes, You are right We can achieve by usind dial-peer hunt globally / trunk group configuration in dial-peer level.


But my only doubt is if one of the PRI is goes down, CUSP will receive 503 at that time CUSP will start using alternate element based on Q value or Weightage right or loadbance type in server group level.


So how we can utilize alternate PRI'S in the same gateway.





SIVANESAN R

Senthil Kumar Sankar Mon, 08/05/2013 - 23:50
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CUSP routing Logic is different and Gateway Routing Logic is different.


1) Say now CUSP have sent the Call 11002233 to the Gateway where you have 5 PRI's

2) Gateway receives that Call from CUSP and identifies that it has 5 outbound dial-peers with same destination-pattern but different PRI's or Voice Ports

3) Say you have Preference 1,2,3,4,5 configured in the dial-peer

4) Gateway will use the first Preferred Dial-peer and if it is down or all the channels are busy and utilized.

5) Gateway will not immediately send a response to the CUSP that call is failed and this is the response code. Instead it will hunt for the next dial-peer in its routing list and then finally it will send the result to CUSP.


Regards,

Senthil

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