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SRST Across two 3925 ISR Rputers

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

3 REPLIES
Cisco Employee

Re: SRST Across two 3925 ISR Rputers

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

New Member

Re: SRST Across two 3925 ISR Routers

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...

Cisco Employee

Re: SRST Across two 3925 ISR Routers

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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