SRST reference

[tarun.pahuja]

Folks,

Slightly confused about SRST reference point defined under the callmanager? why do we have to do that? i mean under the SRST configursation we do put the "IP Source-Addres" command in that points to the default gateway, then why do we have to create a SRST reference under callmanager and associate it with a device profile?

Thanks

[jasyoung]

The two facilities serve completely separate purposes.

The "SRST Reference" facility in CallManager is designed to help the phones locate their SRST router. Customers wanted the ability to have an SRST router that wasn't the default gateway for that subnet, so SRST References were created. In previous versions of CallManager, the phones could only look to their default gateway router as a potential SRST router; this is what you see as the "Legacy" option when choosing an SRST reference. You can now tell a group of phones exactly what their SRST fallback gateway should be.

The "ip source-address" facility in the SRST configuration mode of the router is designed to help it pick a source address. Routers by definition have multiple interfaces, so it's good practice to tell the router which interface it should offer its SRST services on.

So, SRST References tell phones where to look for SRST services, and the ip source-address command tells the router where to offer SRST services.