AW: AW: [e2e] Queue size of routers

Michael Welzl michael.welzl at uibk.ac.at
Fri Jan 17 12:36:18 PST 2003


Dear Vladim,

Thanks a lot for your response! All that seems to make sense.


> Well, what you have for "delay" is characteristic RTT of the traffic mix,
> plus some extra to accomodate deviation; not the maximal RTT. I'm not
> aware of any tool for picking that parameter, it's pretty much "gut
> feelings" of backbone engineers.

Hmmm ... about time someone wrote such a tool!   :)

- randomly pick a packet that carries TCP (red alert! a layer
  violation straight ahead!  :)  )
- remember a lot of things ... state all over the place:
  source/destination, sequence numbers ... but that would
  only have to be done sporadically! Maybe in a separate piece
  of hardware.
- monitor subsequent packets from the same flow - examine the
  rate and sequence numbers ... it should be a little tricky,
  but possible.

Eventually, such a tool could be used to automatically adapt
the maximum queue length...

Cheers,
Michael




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