[j-nsp] router reflector clients and non-clients

[adamv0025 at netconsultings.com]

> Of Sander Steffann
> Sent: Wednesday, May 30, 2018 9:36 AM
> 
> Hi,
> 
> > But in this scenario, a client will send an update both to RR1 and
> > RR2, and RR1 will reflect this update to RR2, and RR2 will reflect it
> > to RR1, and voila! We have a routing loop.
> 
> The moment it loops back to an RR that it has already been through it will
see
> its own cluster-id in the list and ignore it. So RR1 and RR2 learn from
each
> other, but the update won't loop.
> 
The example suggested RR1 and RR2 with different Cluster-IDs -so it would
loop* -but will be dropped by the originating PE based on the Originator-ID.

That's why if you should not be connecting RR1 and RR2s (maybe with the
exception where BGP sessions = physical links, between all nodes involved)

*it will loop only in absence of PE1 route sent directly to RR2 -in which
case RR2 will be comparing PE1's route received via RR1 and route received
directly from PE1, the direct route will be selected based on the shorter
cluster-list and as such will not be looped/advertised back to PE1 based on
the split horizon rule.   

adam

netconsultings.com
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