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

[Christian Meutes]

On 01.03.2013, at 13:06, "Oliver Boehmer (oboehmer)" <oboehmer at cisco.com> wrote:

> 
> 
> 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. 

This may explain why both of us have different experiences with this. We never enabled the Multicast RIBs under BGP nor IGP, hence it worked. Seems that Swedemike was using SAFI unicast for RPF instead, but had also enabled multicast RIBs without any routes in them.