[e2e] Extracting No. of packets or bytes in a router buffer

Alexandre Grojsgold algold at rnp.br
Thu Dec 14 12:05:01 PST 2006

> -----Original Message-----
> From: end2end-interest-bounces at postel.org [mailto:end2end-interest-
> bounces at postel.org] On Behalf Of Fred Baker
> Sent: quarta-feira, 13 de dezembro de 2006 18:17
> To: Craig Partridge
> Cc: end2end-interest at postel.org
> Subject: Re: [e2e] Extracting No. of packets or bytes in a router buffer
> You're talking about ifOutQLen. It was originally proposed in RFC
> 1066 (1988) and deprecated in the Interfaces Group MIB (RFC 1573
> 1994). The reason it was deprecated is not documented, but the
> fundamental issue is that it is non-trivial to calculate and is very
> ephemeral.

Sorry, but...

I really did not understand.

Of course, it´s ephemeral. The link occupancy is also an ephemeral
information. During the sending of a packet, it´s 100% busy. Between two
packets, it´s utterly idle. It doesn´t mean it's not possible to get some
statistics out of the link usage. Like mean byte rate, 5 minute mean byte
rate, variance, and so on.

The same way it should be possible to get queue statistics out of each
outgoing interface in the router. 

I am really impressed to know it is so difficult to grab this kind of
information, since router manufacturers claim they can do magic with  queue
managing, like diffser, traffic shaping, priority queueing, etc... all of
this looking at the queues and making tricks with them.

It´s amazing.

-- Alexandre.

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