Routing issue for IPT phones:

[Vinayaka Raman]

All of our remote sites have mpls as primary (eBGP)and DSL (eigrp) as backup link.  When both wan links are up, the ipt phones will register to the call manager which is located at the hub data center.

When MPLS is down, the IPT phones should register on the the local router. This happens when the IPT phones is not able to reach the call manager (located in hub data center). So it relies on routing. We have both router on stick model and collapsed core model in our remote sites.

Let us take a collapsed core model. The ipt vlan is created on the core switch. It is advertised into eigrp of core switch peering MPLS and DSL.
The MPLS injects the sites prefix using eBGP.

On the core switch, I think of implementing a distribute-list not to advertise vlan 2 to specific neighbhor (to dsl)..so the callmanager will not respond back to the phones in the event of MPLS link failure..

DO you see any other opportunity to resolve this ?

Does IPT phones should rely on this kind of routing or any other options are there ?

[Pawan Sharma]

Hi,

If we go by the standard IPT SRND guide then SRST would be anytime the best solution for your problem.

Regards,

Pawan Sharma

http://www.ebrahma.com

[Marwan ALshawi]

If the adsl link us enough to Handel your voice traffic then it is good practice to put the remote site in srst mode when the mpls link is down

This can be done using routing as you described it above

Or ACL to block sccp and TFTP to CUCM over the dsl link

Hope this help

[Vinayaka Raman]

Thanks for your replies !

Sorry for not being clear !! Let me try to explain clearly.When mpls link goes down,the IPT phones should not reach the call manager through back up link so that it can get into SRST mode and register on the local MPLS router. But this is not happening. In some sites the IPT phones are reaching the call manager through back up link. We have both router on stick (IPT VLAN on router) and collapsed core model (IPT VLAN on core switch) in our remote sites.

To prevent this from happening,

One solution I can think of is a implementing distibute list on core switch to filter vlan X (IPT phones) routes beng advertised to DSL router or should i implement an ACL..

However, I have to maintain prefix length advertised on both mpls and dsl to be same..otherwise i will end with assymmetric routing.