[c-nsp] Unicast Reverse Path Forwarding - Loose Mode

[Youssef Bengelloun-Zahr]

Hey,

Our 6509 boxes are equiped with SUP720-3BXLs, so it shouldn't be a problem.

I am more concerned about the 7204VXRs equiped with NPE-400s or NPE-G1s. I
haven't been able to find docs on the Internet related the URPF impact on
performances.

Thanks.

Y.



2010/5/12 Jared Mauch <jared at puck.nether.net>

>
> On May 12, 2010, at 6:21 AM, Phil Mayers wrote:
>
> > On 05/12/2010 10:55 AM, Youssef Bengelloun-Zahr wrote:
> >
> >> We have a bunch 6509s acting as core routers and a bunch of 7204VXRs
> >> (NPE-400 / NPE-G1) acting as LNS border routers.
> >>
> >> Problem Is : I am concerned about performance issues. Is uRPF a big
> consumer
> >> of CPU / Memory ?
> >
> > On 6500, I believe the older sup2 has half the routing table capacity
> with uRPF enabled, but it's otherwise done in hardware.
> >
> > 6500/sup720 uRPF is "free". There's no CPU/memory load.
> >
> > I don't know about the other platforms but I would be surprised if uRPF
> significantly affects their forwarding performance.
>
> FYI:
>
> In sup720, if you already have interfaces in loose mode and toggle one to
> strict any interface with uRPF enabled goes to strict.
>
> re: SUP2, you are correct, tcam is halved in size from 256k to 128k when
> uRPF is enabled, if you are running bgp this can trigger software switching
> of packets and high cpu utilization.
>
> - Jared
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-- 
Youssef BENGELLOUN-ZAHR ………………………………………………
Ingénieur Réseaux et Télécoms


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