Re: [mpls] ahRE: draft-bashandy-mpls-ldp-bgp-frr-00 motivation

[Ahmed Bashandy <[e-mail]>]

see comment inline about P routers having VPN level knowldege

Thanks

Ahmed


On 3/27/2012 10:55 AM, Ilya Varlashkin wrote:
>> -----Original Message-----
>> The best current available mechanism is BGP PIC Edge that relay on IGP
>> convergence to detect that remote PE is no longer reachable : PIC Edge
> result
>> mainly depends on how fast your IGP is converging (sub sec or more).
>>
> I've been recently measuring convergence on not very fast RP and found that
> even for 10 000 nodes it's less than 900ms. Clearly 10K nodes is unlikely to
> be seen in many networks if in any at all. And for real-world sized nets
> convergence is like few tens of ms - not really to worry about.
>  
>> Ahmed solution is an FRR solution so doesn't rely on convergence. As soon
> as
>> a P router detects that the link to the protected PE fails, it will switch
> (using
>> pre-programmed backup NHLFE), so there you are in FRR numbers ... 50msec
>> - 100msec depending of implementation ...
>>
> If _P_ node needs to do fail-over to backup PE depending on VPN (L3VPN, PWE,
> L2VPN etc) then _P_ node needs to have VPN-level knowledge, and that
> contradicts with original idea of P nodes (they shouldn't care what's
> inside, only how to get to the edge independent of "payload").
The solution defined in draft-bashandy-bgp-edge-node-frr ensures that
the core routers do NOT have VPN level knowledge. We are also working on
a solution that would actually bring down the information stored in the
core router to a very small number, much smaller than what is proposed
in version 02 of the draft.
So lookout for version 03


>
>> Clearly the solution is today complex, and I hope it could be a bit
> simplified :)
> Because of previous statement I see proposed solution as complication rather
> than simplification, and because of above mentioned IGP convergence times
> the gain seems to be too little when balanced against complexity.
>  
> /iLya
>
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