[46948] in North American Network Operators' Group
Re: CAR
daemon@ATHENA.MIT.EDU (Christopher L. Morrow)
Thu Apr 18 18:09:55 2002
Date: Thu, 18 Apr 2002 22:09:20 +0000 (GMT)
From: "Christopher L. Morrow" <chris@UU.NET>
To: Ken Yeo <kenyeo@on-linecorp.com>
Cc: "Christopher L. Morrow" <chris@UU.NET>, <nanog@merit.edu>
In-Reply-To: <002301c1e724$01997e40$020710ac@kenyeolt>
Message-ID: <Pine.GSO.4.33.0204182207120.11583-100000@rampart.argfrp.us.uu.net>
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Errors-To: owner-nanog-outgoing@merit.edu
On Thu, 18 Apr 2002, Ken Yeo wrote:
>
> Hi Christopher,
>
> If CAR is applied to the routers closest to upstream provider, the traffics
> can still consume the link to the provider. Plus the rate limit ACL will be
> huge. If we can apply CAR to the router at the upstream provider, the
Yes, car isn't a solution... which was my point... I made it obliquely
sorry. Somewhere the packets have to backup, you can't tell the sources to
stop so somewhere in the middle the traffic must backup :(
> problem is solved. But of course we do not have access to the upstream
> equipments. Anyone has comments about the TCP window theory?
>
I venture to guess your upstream won't CAR for you either :)
> Suan "Ken" Yeo
> Network Engineer
> Aurum Technology
> ken.yeo@aurumtechnology.com
> ----- Original Message -----
> From: "Christopher L. Morrow" <chris@UU.NET>
> To: "Ken Yeo" <kenyeo@on-linecorp.com>
> Cc: <nanog@merit.edu>
> Sent: Thursday, April 18, 2002 11:40 AM
> Subject: Re: CAR
>
>
> >
> >
> > On Thu, 18 Apr 2002, Ken Yeo wrote:
> >
> > >
> > > Hi Nanog,
> > >
> > > Scenario:
> > >
> > > Transits -----(router A)Backbone(router B)----- Customers
> > >
> > > We applied Cisco CAR at the edge routers (B) in the Backbone to rate
> limit
> > > inbound and outbound traffics to/from Customers. If transmission rate is
> > > higher than the rate limit threshold, IP packets are being dropped by
> router
> > > B. How do we prevent the excess IP packets to consume the transit links
> and
> > > the Backbone? Here is my understanding:
> >
> > You can't unless you CAR on all ingress interfaces on your network toward
> > the customers... so:
> >
> > Ingress-Provider->RTA->RTBB->RTB->Customers
> >
> > You need to CAR on all 'Ingress-Provider' links, this is a very sticky
> > problem (obviously)
> >
> > >
> > > -For TCP traffics (HTTP, FTP), TCP senders will stop sending packets
> when
> > > the TCP windows threshold is reached.
> > > -For UDP based audio/video trafffics, if the applications use RTSP and
> > > H.323, RTCP/H.245 will signal the sender to slowdown the transmission if
> the
> > > receiver lost packets.
> > >
> > > Did I miss anything? How about UDP traffics that are not using
> RTSP/H.323?
> > >
> > > Thanks.
> > >
> > > Suan "Ken" Yeo
> > > Network Engineer
> > > Aurum Technology
> > > ken.yeo@aurumtechnology.com
> > >
>
