[rbridge] Back to ND/ARP optimization

[Silvano Gai]

Radia,

I agree that Arien didn't make a conclusion, and I am interested in
Arien opinion.

I read about the bursts.

I suppose that even during "the high peak rate" most of the ARPs are for
unknown destinations and this does not change my conclusions.

-- Silvano



> -----Original Message-----
> From: Radia Perlman [mailto:Radia.Perlman at sun.com]
> Sent: Saturday, May 05, 2007 3:11 PM
> To: Silvano Gai
> Cc: Arien Vijn; rbridge at postel.org
> Subject: Re: [rbridge] Back to ND/ARP optimization
> 
> Actually, I'm not sure that's the conclusion that Arien was making
(that
> ARP/ND
> optimization is not worth it), especially with the comment "peak rates
> much higher".
> 
> So Arien...was that actually your conclusion?
> 
> I think that ARP/ND optimization could be added in the future as an
> option, or
> even that an implementation can do something about it without having
the
> spec
> saying anything about it. Which would argue for not needing it in the
> spec now.
> 
> But just want to verify what Arien's conclusion is from the data
> presented...
> 
> Radia
> 
> 
> Silvano Gai wrote:
> > Arien
> >
> > Thanks for the real world data, which proves that ARP/ND proxy must
not
> > be implemented on RBridges.
> >
> > In fact, since the queries toward unused addresses are dominant, the
> > ARP/ND cache will almost always miss and the RBridge CPU will be
busy
> > trying to remotely resolve queries that will never complete.
> >
> > -- Silvano
> >
> >
> >> -----Original Message-----
> >> From: Arien Vijn [mailto:arien.vijn at ams-ix.net]
> >> Sent: Friday, May 04, 2007 10:04 AM
> >> To: Silvano Gai
> >> Cc: Arien Vijn; Radia.Perlman at sun.com; rbridge at postel.org
> >> Subject: Re: [rbridge] Back to ND/ARP optimization
> >>
> >> Hi,
> >>
> >> On May 3, 2007, at 10:55 PM, Silvano Gai wrote:
> >>
> >> [...]
> >>
> >>
> >>>> Does anyone have a handle on how much traffic is caused by
ARP/ND?
> >>>>
> >>>>
> >>> With an ARP cache of 30 minutes, typical in hosts today, even with
> >>> a 100
> >>> K hosts in a VLAN we get at most 55 ARP seconds. Since not all the
> >>> hosts
> >>> talk with each other, it is more typically like 5 ARP/sec.
> >>>
> >>> BASICALLY NOTHING.
> >>>
> >> Well... that might be the case if all your hosts are actually
> >> answering. But query rates are pretty much determined by queries
for
> >> unused addresses. In other words by the query rates hosts (routers)
> >> can achieve for addresses that are not in their caches.
> >>
> >> For what its worth. I am involved in a real network with 400+ BGP
> >> routers in one broadcast domain (/23 IPv4 subnet). The average rate
> >> is little over 13 queries/second. That is with ARP mitigation and
> >> peak rates are much higher.
> >>
> >> -- Arien
> >>
> >
> >
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> >