Auto Route announce feature for Tunnels

[maanyagoel]

Hello Everybody,

I have a question regarding Auto-route announce feature.

If Auto-route feature is enabled to advertise the subnets in a Tunnel use it in SPF calcualtion, then will I be able to use PIM protocol on the global network( on which Auto-route announce is enabled?

[Harold Ritter]

Maanya,

This is correct but you will need the following command under the ospf or isis process to allow the reverse path forwarding to succeed when the route back to the source points at the tunnel interface:

mpls traffic-eng multicast-intact

Please refer to the following url for more information about this command:

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/mplstemi.html

Regards

[ulatif]

Harold,

If the tunnel is only one-way ? do you still need this command ? :)

e.g. lets say we have:

Src----PE1----P1----PE2---Receiver

If there is only one TE tunnel configured from PE1 -> PE2 but on the way back from PE2 to PE1 there is no tunnel?

I would think that you would not need this command in this scenario ?

So multicast is not LS like unicast is and therefore if the route back to source points to tunnel interface, the command is needed to make RPF successful.