[c-nsp] BGP Next-hope convergance

[Phil Mayers]

Mikael Abrahamsson wrote:
> On Mon, 8 Sep 2008, Peter Rathlev wrote:
> 
>> Does this have an effect on the convergence times? I seem to remember 
>> having been told that this is a good idea generally, but never really 
>> understood why. Can anybody shed light on why this is?
> 
> What Ytti said, and let me give you an example:
> 
> PE1 and PE2 uplinks a redundantly connected customer.
> PE3 has another customer connection in the same VPN.
> 
> Using unique RDs per PE, will ensure that PE3 has routes to both PE1 and 
> PE2 in a route reflector structure, and if PE1 goes away then PE3 will 
> have PE2 route in RIB and can update FIB without RR involvement.
> 
> In case PE1 customer link goes down, it can change FIB to point to PE2 
> without RR involvement meaning packets will be forwarded continously as 
> soon as the link-down is detected and FIB is updated, instead of the RR 
> noticing it and sending updates.
> 
> So yes, you want to use PE unique RDs, there little downside apart from 
> a bit higher memory usage.
> 

Can someone clarify that RD versus route-target are unrelated, i.e. that 
I can have:

PE1:

ip vrf BLAH
   rd PE1-loop:1
   route-target both 65000:1

ip vrf FOO
   rd PE1-loop:2
   route-target both 65000:2

PE2:

ip vrf BLAH
   rd PE2-loop:1
   route-target both 65000:1

ip vrf FOO
   rd PE2-loop:2
   route-target both 65000:2