[SR-Users] Loose Routing with Cisco router

[David Wilson]

Hello All,

I'm running Kamailio 4.0.2 on Ubuntu 12.04 (precise).

I have SIP messaging flowing nicely, with UACs registering via Kamailio (as a proxy) to a Registrar.  

Now having problems trying to route messages via a Cisco router (12.4(25g)) using loose routing.  The plan is to allow the router to see the SIP messaging but forward it to the original location.

RFC 3261 seems to cover this case in Section 16.6 part 6: "A proxy MAY have a local policy that mandates that a request visit a specific set of proxies before being delivered to the destination."

Cisco documentation (SIP Configuration Guide, Cisco IOS Release 12.4) states that it implements RFC 3261, including Loose-routing.   However, from my observation the router doesn't like a request-URI with anything other than its own IP address (it returns 400 Bad Request - 'Invalid IP address'), but with any attempt to 'decorate' the URI with lr and/or maddr= parameters it returns 400 Bad Request - 'Malformed/Missing' URL.  One of these messages is returned regardless of anything I've tried with Via, Record-Route or Route headers.

Desired behaviour is for the router to remain in the route-set.  A different configuration has shown me that this will achieve the required outcome, the tricky part now is just getting that first request to route.  I know several ways to make Kamailio send to the router, but the router is not behaving as I expect when I preload a route set (with Route: headers).

Recognising that this is probably more of a Cisco problem than Kamailio, can anyone confirm whether a Cisco router implements loose-routing when receiving messages, or only when sending?

Regards,
Dave.