[c-nsp] BGP convergence in VRF vs. global routing table on 7600router

[Rodney Dunn]

Can you try SRB2?

On Fri, Oct 19, 2007 at 02:31:03PM +0200, Christian Bering wrote:
> >From: Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com] 
> 
> Hi Oliver,
> 
> >Can you pls describe which "convergence" you are referring? Time it
> >takes after bringing up the session until every other PE has 
> >the routes?
> >Or the table version on the CE and the receiving PE is the same?
> 
> Time it takes for PE1's CPU to fall back to normal utilisation and all
> destinations reachable again after PE2 loses an upstream provider.
> 
> Given that PE1 is a "normal" PE terminating customers and PE2 a border
> router-like PE terminating an upstream provider.
> 
> >If you talk about a distant PE receiving the full table from the RR via
> >iBGP, the overhead will likely depend on the RD setup. I assume you use
> >a common RD for the "internet" VRF on all your PEs, right? 
> 
> Correct.
> 
> And the RRs (7301s) take very little time to converge. After a minute or
> so, the BGP process has fallen to normal levels. The CPUs in SUP720s
> aren't overly fast - I am aware of that.
> 
> >This could be one reason. CEs advertising > 200k prefixes are 
> >not widely seen in 2547bis environments :-)
> 
> I know. :-/  It's somewhat of a shame because on a sheet of paper, it
> seems like a good approach. In reality, it's not widely used and doesn't
> seem to get tested well or have the code optimised for it.
> 
> >next to PMTUD, none I could think of without knowing more details.
> 
> Already done.
>  
> >>Any improvements to this behaviour in SRB2 over SXE, SXF or SRA?
> 
> >need to know more details..
> 
> Alright; hope I supplied them. :)
> 
> >From: Rodney Dunn [mailto:rodunn at cisco.com] 
> 
> Hi Rodney,
> 
> >I need to check this in the lab but if you look at the vpn table are
> >we not allocating a VPNV4 label for each prefix when it's in the
> >VRF?
> 
> On PE2 ("border router"), there's an "in label" for every prefix, yes.
> No "out label" for locally learned prefixes (from upstreams).
> 
> On PE1 ("normal" PE), there's an "out label" for all prefixes learned
> from PE2 and other "border routers". "in label" for locally terminated
> prefixes.
> 
> As I wrote initially, it's only the BGP process that chews up CPU during
> convergence on PE1 and other "normal" PEs.
> 
> -- 
> Regards
>  Christian Bering
>  IP engineer, nianet a/s
>  Phone: (+45) 7020 8730
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