CAR

Thu Apr 18 16:40:38 UTC 2002

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 at aurumtechnology.com
>