Subject: RE: Congestion avoidance Re: [Ieprep] draft-ietf-ieprep-framework -02.txt

From: "Nguyen, An" <[email-masked]>
Date: Fri, 1 Nov 2002 14:19:28 -0500

GETS also uses trunk queuing when there is a congestion at the LEC ( not
just alternate routing paths in the IXC). This queuing mechanism would not
drop GETS calls immediately when a congestion occurs. By the way, how are
you doing it in your network to accommodate emergency traffic when
congestions occur at the access nodes (not the distribution or the core)?
How about priority queuing or weighted fair  queuing ?

In my opinion, end-to-end QoS is still a big issue in the Internet.

Regards,

An

-----Original Message-----
From: Sean Donelan [mailto:[email-masked]]
Sent: Friday, November 01, 2002 1:29 PM
To: [email-masked]
Cc: [email-masked]; [email-masked]
Subject: Congestion avoidance Re: [Ieprep]
draft-ietf-ieprep-framework-02.txt

On Fri, 1 Nov 2002 [email-masked] wrote:
> >    > 3.1.  Alternate Path Routing
> [MAP] I can't imagine why you are questioning this requirement. It is a
> fundamental requirement of any network to be able to route around
congestion
> (and failures).

Because its not a fundamental requirement.

Routing around failures is a different requirement from routing around
congestion. In a packet-switched network, "congestion" is not a failure
condition.

In a circuit-switched world, congestion avoidance is a requirement because
circuit-switched networks are inherently blocking along a path.  Circuit
switched networks require alternate path routing during congestion.

On the other hand packet-switch networks are not inherently blocking along
a path under congestion conditions.  You can still send traffic through a
congested path with queue management.  At the first BOF Fred Baker
reported on some testing Cisco did on congested links and what effect it
had on the service delivery.

Both packet-switched and circuit-switch networks need to route around
circuit failures.  Circuit-switched networks use alternate path routing
around congestion. Packet switched networks use queue management during
congestion.

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