SRST and HSRP

[tlomonaco]

When using SRST, is it possible to implement HSRP and SRST to avoid a single point of failure for a remote node, i.e. both remote routers are running HSRP. The phone's default gateway is the HSRP address. The active router with the WAN connection goes into SRST mode on a WAN failure. If there is a failure of the Active router, the backup router begins responding to the HSRP address, and is the new default gateway, to which the phones fail over to in SRST mode.

[tlomonaco]

If HSRP and SRST is not possible, would it be possible to run the backup switch with Ip Telephony Services (IP Keyswitch) as a backup solution? In the case of a failure of the primary SRST router, the backup router could be brought online to run as the voice router until the primary is brought back online. I am trying to provide a solution that will not have a single point of failure at a remote node.

[tringwelski_2]

Interesting Question, I guess if a site is large enough to have 2 diverse wan connections, then placing redundant call manager server on site is probably in line. I would at lease have 1 CCM and SRST from that server.

[jeff_caprock]

The only time SRST is going to kick in is when the IP phone cannot reach call manager via IP. This usually results when the connectivity from the gateway to Call Manager is lost, irrespective of what that connectivity is, usually a WAN.

To avoid that, and if your site needs that kind of redundancy, I'd establish a dual WAN pipe from this site to the Call Manager(s) and SRST would never be needed unless there was a total site outage.

-Jeff

[tlomonaco]

My issue is that the customer is trying to keep the cost down. There is only a single link to the site. The routers already exist, so not much cost there. Will SRST work with HSRP in tandem, that is the question. Will the current Active router run SRST when the phone can not communicate to the Call Manager? Here is the scenario, as I see it. Active router has primary Wan and PSTN E1 connection. Standby router has POTS connection to PSTN. If the active router which has the WAN connection experiences a WAN failure, the phone should home in on it and come back on line. If the Active Router with the WAN link fails (the actual router fails), the standby router will come online and become active. The phone should see this new router as its default gateway, and home in on it for SRST unitl it can re-establish communication to its primary Call Manager. This is how I would think it should work. If anyone knows of any reason why this would not work, please let me know. Thanks....