[e2e] TCP flow count estimation

[Jon Crowcroft]

almost all TCP modeling is for elephants



but note that if you have a congestion manager, mice can grow


In message <200111291812.fATICek85728 at c527597-a.cstvl1.sfba.home.com>, Bruce A.
 Mah typed:

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 >>If memory serves me right, Jon Crowcroft wrote:
 >>
 >>>  >>  Has the IP layer's function been redefined so that it guarantees that al
 >>> l 
 >>>  >>datagrams must be sent along the same physical path and through 
 >>>  >>order-preserving queues?
 >>> 
 >>>  >>We know that IP does not have order preserving queues in general - fast 
 >>>  >>path processing and service-types violate order.  We also know that in som
 >>> e 
 >>>  >>cases, path stability is violated even in the short term.
 >>> 
 >>> well its easy to try look at this with traceroute - time for some experiments
 >>> 
 >>> but the various pathchar programs rely on this hack, and the tiems when i hav
 >>> e seen them
 >>> break are always when there's a level two hop with some type of bandwidth on 
 >>> demand
 >>> (e.g. ATM VC, or frame relay hop with committed access rate policing via a wi
 >>> ndow/token
 >>> bucket scheme).....
 >>
 >>Two knee-jerk-reaction thoughts:
 >>
 >>I've also seen {p{,ath}char,clink} break (or at least give odd results)
 >>where packets can take multiple links between two hops (i.e. stripe a
 >>couple of T-1s together for more bandwidth).  Another problem is
 >>store-and-forward switched networks (with or without fancy CAR/QOS/
 >>whatever).
 >>
 >>Also it strikes me that this technique only works for "elephant"
 >>connections because it'll take a bunch of measurements to try to get rid
 >>of all the queueing delays.
 >>
 >>Bruce.
 >>
 >>
 >>
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 cheers

   jon