Re: BECN & FECN

Simply put a FECN is used to describe the reciever that the frame it
recieved encountered congestion on the way and BECN is used to notify the
sender regarding congestion in the circuit.

A FR switch need not always set the BECN,
Eg: If a router recieves a FECN, it reflects the FECN by marking a BECN in
the opposite direction towards the sender.
The router recieving the BECN will reduce the rates therby.

Foresight messages (control packets) also is a good know, used by Cisco FR
switches
The switch generates it in the opposite direction of the congestion on the
VC, which helps the sender to slow down.

Best Regards,
Tharak Abraham Luke

Sent from Dusseldorf, NW, Germany

On Mon, Sep 7, 2009 at 3:17 PM, Molomo <letjedilakopa_at_gmail.com> wrote:

> Experts,
> I have read a number of books on these two topics and I'm yet to find
> a uniform explanation. Below are my explanations correct me if I'm
> wrong,
>
> BECN- FR switch sets this bit in a frame header as the destination
> replies to the sender - to inform the sender of congestion.
>
> FECN - This bit is set when traffic is unidirectional (eg video
> stream), but only this is addressed to destination to generate a
> pseudo packet so that FR switch can set the BECN back to the sender.
>
> Am I correct?
>
> Thanks in advance.
>
> -Molomo
>
>
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Received on Mon Sep 07 2009 - 19:35:04 ART