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SRST Across two 3925 ISR Rputers

Unanswered Question

I have two 3925 ISR routers with 4 pri's in each one.

I am hooked up to a Callmanager 7.1.5 under normal conditions  running MGCP what

I am curious about is when I go into SRST mode, I want to use one gateway for the phones but what is the best way to use the pri's

in both gateways. I am not concerned about load balancing just that I can semd calls thru both gateways.


Any sample configs or ideas  would be appreciated.


Thanks

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Felipe Garrido Wed, 10/20/2010 - 06:53
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  • Cisco Employee,

You'll need to configure dial-peers on both  of the gateways to allow call routing between them in an SRST situation.


For example,


GW1 has all the phones registered and two PRIs.(0/0/0:23 and 0/0/1:23)

GW2 has 2 PRIs and no phones registered. (0/0/0:23 and 0/0/1:23)

user dial 9 to make PSTN calls


Extension Range for GW1: 1xxx

Inbound DID for GW2 for calls from PSTN: 1xxx



GW2:


dial-peer voice 1 pots

destination-pattern 9.T

incoming called-number .

direct-inward-dial

port 0/0/0:23


dial-peer voice 2 pots

preference 1

destination-pattern 9.T

incoming called-number .

direct-inward-dial

port 0/0/1:23


dial-peer voice 3 voip

destination-pattern 1...

session target ipv4:

dtmf-relay h245-alphanumeric

incoming called-number 9T

codec g711ulaw

no vad



GW1:

dial-peer voice 1 pots

destination-pattern 9.T

incoming called-number .

direct-inward-dial

port 0/0/0:23


dial-peer voice 2 pots

preference 1

destination-pattern 9.T

incoming called-number .

direct-inward-dial

port 0/0/1:23



dial-peer voice 3 voip

preference 2

destination-pattern 9.T

session target ipv4:

dtmf-relay h245-alphanumeric

incoming called-number 1...

codec g711ulaw

no vad


For outbound calls, IOS will first try 0/0/0:23  and then 0/0/1:23 on GW1. If the call fails due to oversubscription, it will be routed to GW2 where it will try 0/0/0:23 and then 0/0/1:23.


Inbound calls that hit GW2 will be routed to GW1.


Let me know if you have any questions.


-Felipe

Thank You.. I was trying to make it work with trunk groups so I can cut down the dial-peers but for some reason the trunk groups do not seem to work in SRST mode. I have seen that issue reported in the forum with no fix that I found yet.


One of the reasons for trunk groups is one site has 8 pri's in each gateway so between the pots and voip dial peers the config starts to grow.. I did mangae to get away with one voip dial peer sending all patterns to gateway 2 which helped.


Thanks for the answer  It works fine...

Felipe Garrido Wed, 10/20/2010 - 08:34
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  • Cisco Employee,

Glad I could help. How were you trying to implement the trunk groups? What did you experience when trying to make calls through them while in SRST mode?


-Felipe

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