[c-nsp] Internet in VRF

[Adam Vitkovsky]

> From: Mark Tinka [mailto:mark.tinka at seacom.mu]
> Sent: 05 May 2015 10:11
> 
> On 5/May/15 11:02, Adam Vitkovsky wrote:
> 
> 
> 
> Hi folks,
> 
> Assuming you have more than one AS-exit and you don't have full-mesh
> between all BGP speakers, then how do you get the alternate/backup AS-
> Exit paths for Internet prefixes to all the PEs please?
> Although I admit that the convergence times of Internet services might not
> be a cause for concern so a minute of downtime might be acceptable.
> 
> We have several transit interconnects as well as lots of peering in Africa and
> Europe. These are all separate devices as unique PoP's are involved.
> 
> Each PoP has an RR cluster, handling iBGP routing for that PoP. Of course,
> full-mesh iBGP between the RR's across the network.
> 
> We allow the RR's to do best-path selection, and the edge routers end up
> with the best path as seen from its point of view. 

Nice that's clever. 
And since you are using CSR1000v you don't need to worry about the cost of HW for RRs.
I see, so RRs do the routing decision on behalf of the PE routers in a particular PoP.
Since RR cluster is local to the PoP the AS-exit proximity is accurate, in other words what is good for the RR has to be good for the PEs within the PoP.
But still you'd have to use add-path to advertise backup paths from RRs to PEs in a local PoP whereas with MP-BGP you'd just use unique RDs.

 
> It does not concern us to be able to hold the full table of every peering
> relationship we have in the edge (which is where "Internet VRF's" would
> come in handy). We offer our customers the best route possible to any
> destination. 

I see it as more of a good practice not to hold default route or full inet table on a peering box but as I said before peer pointing a default at you is rather a corner case I guess.

> If they want the full routing from a specific AS or exchange point,
> we can help them arrange an EoMPLS circuit between them and that AS or
> exchange point, and they can peer directly without us being involved at Layer
> 3 - which is another service we sell.
> 
> Mark.

Yeah been doing EoMPLS PW to provide full internet feed to customers behind MEs didn't have the confidence to use the table-map/SRD :)

adam
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