[e2e] Question about propagation and queuing delays

RJ Atkinson rja at extremenetworks.com
Tue Aug 23 11:30:36 PDT 2005

On Aug 22, 2005, at 12:13, David Hagel wrote:
> Thanks, this is interesting. I asked the same question on nanog and
> got similar responses: that queuing delay is negligible on todays
> backbone networks compared to other fixed delay components
> (propagation, store-and-forward, transmission etc). Response on nanog
> seems to indicate that queuing delay is almost irrelevant today.
> This may sound like a naive question. But if queuing delays are so
> insignificant in comparison to other fixed delay components then what
> does it say about the usefulness of all the extensive techniques for
> queue management and congestion control (including TCP congestion
> control, RED and so forth) in the context of today's backbone
> networks? Any thoughts? Are the congestion control researchers out of
> touch with reality?

Congestion still exists today.  However, it tends to exist
not inside the network core, but instead in the access link
(i.e. the link between the campus network and the upstream ISP).
In many cases, this congestion is a policy choice on the part
of the end site (e.g. pay for NxT1 uplink rather than T3 uplink
in order to save money).


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