[c-nsp] BGP-ORR vRR/IOS-XRv

[Saku Ytti]

One thing to be aware of is that ORR in Cisco won't reflect anything
if next-hop is not IGP next-hop.

If you, like many networks do, have BGP routes with BGP next-hop,
which recurses to IGP next-hop, these won't be reflected.

Obviously the RR cannot know for a fact where the BGP next-hop would
recurse at client's POV, but I'd settle for a best guess.

JunOS ORR implementation does this.


Clients of ORR RR will see at most as many copies of routes as there
are RR peers, in absence of AddPath.

I'm not ready to re-explain how RR in basics work, after the previous
thread is so young, regarding your question of how to mesh and such.

On 21 March 2018 at 16:33, Curtis Piehler <cpiehler2 at gmail.com> wrote:
>  BGP-ORR looks to be an attractive technology to utilize instead of full
> meshing many standard RRs.  I was hoping people could share some insight on
> this topic since there is not so much real world scenarios out there
> documented.  This is geared towards an IOS-XRv ASR9K deployment.
>
>
>    - When running BGP-ORR a vRR computes the shortest path for a given
>    BGP-ORR enabled client from the perceptive of the client utilizing the root
>    node of a BGP-ORR
>    - For this reason is it suggested that BGP-ORR groups are configured
>    with respect to common views of the network (IE: grouped by POP/Region)
>    instead of having one or two ORR Groups?
>    - What is the suggested max number of BGP-ORR groups per vRR?
>    - What is the suggested max number of clients per BGP-ORR group?
>    - If all clients in the network peer with say 2 vRR as the center will
>    those clients only see maximum two BGP paths (This is assuming add-path is
>    not utilized)
>    - Do all clients need to peer with all vRRs as long as the vRRs are
>    fully meshed?
>    - Can anyone share general experience they had with BGP-ORR deployed in
>    a production backbone?
>    - Are there any substantial gotchas to be concerned with?
>
>
> As per Cisco documentation when running OSPF a basic MPLS-TE configuration
> is required on all root nodes, correct?
>
> Specific to IOS-XRv does anyone know how the new "SUB" licence models
> work?  I have not been able to find Cisco documentation that explains
> this.  The perpetual/term licence model goes End of Sale Q3 of this year.
>
> https://www.cisco.com/c/en/us/td/docs/routers/virtual-routers/xrv9k-62x/general/release/notes/b-release-notes-xrv9k-623.html
>
> Thanks
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  ++ytti