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 problem is solved. But of course we do not have access to the upstream equipments. Anyone has comments about the TCP window theory? 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
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
limit 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