[c-nsp] IOS XR and router rib rump always-replicate

[Oliver Boehmer (oboehmer)]

On 01/03/2013 10:58, "Mikael Abrahamsson" <swmike at swm.pp.se> wrote:

>On Fri, 1 Mar 2013, Christian Meutes wrote:
>
>> On 01.03.2013, at 10:01, Mikael Abrahamsson <swmike at swm.pp.se> wrote:
>>
>>> On Fri, 1 Mar 2013, Christian Meutes
>>> Do you have your sources addresses in IGP?
>>
>> Nope, BGP SAFI unicast.
>
>Well, your experience contradicts mine. I have had to solve issues with
>multicast not working and started working when the sources were put in
>SAFI multicast with as late software as XR 4.2.1.
>
>I'll defer to someone more knowledgable to explain how this really works.

Once you enable the mcast AF in your IGP or BGP, IOS-XR will populate the
muRIB, and PIM will use this one for RPF (before it used the unicast
RIB/uRIB). This requires that all sources will be in the muRIB. This is
different from IOS where RPF would fall back to the unicast RIB, as
Michael described. 

The "rump always-replicate" command will replicate uRIB to muRIB, so we
effectively achieve the IOS behaviour.

	oli