Re: uPRF strict more

[Anoop Ghanwani <anoop () alumni duke edu>]

This is not true for all ASICs.  Some ASICs choose to incur the penalty in
a different way, e.g., by halving the prefix tables.  The prefix table is
then duplicated so that uRPF SA and forwarding DA lookups can happen in
parallel.  What kind of penalty is incurred is a question worth asking the
equipment vendor.

On Wed, Sep 29, 2021 at 1:10 PM Jean St-Laurent via NANOG <nanog () nanog org>
wrote:

> Thanks a lot for sharing.
>
> So 100 Gbps at line rate with 80B frames is about ~150 Mpps.
>
> 100 Gbps at line rate with 208B frames is about ~60 Mpps.
>
> It's a significant penalty.
>
> Jean
>
> -----Original Message-----
> From: brad dreisbach <bradd () us ntt net>
> Sent: September 29, 2021 3:33 PM
> To: Jean St-Laurent <jean () ddostest me>
> Cc: 'brad dreisbach' <bradd () us ntt net>; 'Phil Bedard' <
> bedard.phil () gmail com>; 'North American Network Operators' Group' <
> nanog () nanog org>
> Subject: Re: uPRF strict more
>
> On Wed, Sep 29, 2021 at 02:54:43PM -0400, Jean St-Laurent wrote:
> > Hi Brad,
> >
> > I'd be interested to hear more about this pps penalty. Do we talk about
> 5% penalty or something closer to 50%?
> > Let me know if you still have some numbers close to you related to PPS
> with uRPF loose.
>
> iirc, strict vs loose doesnt matter, its still an extra lookup which
> effects the performance. i was able to find some numbers to give an example.
>
> the 4x100G tomahawk card was able to pass min frame size(which iirc on
> ixia is
> 80B) at line rate with no features enabled. turn on uRPF and it is only
> able to pass 208B frames at line rate.
>
> similar results were seen with several generations of cisco and juniper
> line cards(if i tested nokia i cant recall, we had stopped doing urpf when
> they were introduced into the network).
>
> -b