[c-nsp] Internet in VRF

[Adam Vitkovsky]

Hi Dan,
 
> Sure it's a drawback deploying a new feature but it depends on the
> network/situation. If you have a network that already has Internet in GRT
> and you want to improve routing diversity and convergence, then add-paths
> is a lot less painful than trying to move Internet into a VRF.
I concur 
 
 
> Internet in VRF has it's merits and I'm not against it but personally I
> prefer Internet in GRT - I've never come across a situation where I
> couldn't achieve something with Internet in GRT vs. in a VRF and I'd prefer
> to avoid the extra resource usage it entails and the potential for someone
> to sausage finger something and import the full table into another VRF and
> kill the FIB.
Well I always deploy per VRF route-limit (not just bgp session limit) to make sure none of the VRFs can kill the whole PE.


> IIRC, enabling add-paths overrides best-external (enables it anyway) but
> that may be platform dependent.
Might be so as best external exception to the BGP best path selection is a must in order to advertise alternate AS-exits to iBGP neighbours.
  
> I don't know why PIC would be required - I don't see any need for
> sub-second convergence of Internet prefixes (and more than a single FIB
> entry for an Internet prefix). I'm sure someone will come along with a use
> case... :)
> 
Not sure what the exact numbers for ASR9k are but on MX960 It takes around a minute to reprogram next hops for 500k prefixes.
Hence my earlier assumption that some just don't care since its Internet service.

adam  
 
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