[e2e] trading acks...TRACKS

Lloyd Wood L.Wood at surrey.ac.uk
Sun Dec 3 14:10:02 PST 2006

At Sunday 03/12/2006 11:45 -0800, Joe Touch wrote:
>Mirco Musolesi wrote:
>>>> However, packet conservation through a router is something that
>>>> can be aspired to, under limited conditions - thinking about
>>>> a networking analogue of Kirchoff's electrical laws through the
>>>> router as a point can actually be useful, too.
>>> I'm not sure Kirchoff's laws are applicable here. It wouldn't make sense
>>> to create/destroy electrons without a source/sink; the same is not true
>>> for packets.
>> You may think to a representation of the network with connections to the
>> "ground" or a "voltage source" for each router to represent/quantify
>> packets that are created/lost in it.
>Right - but then Kirchoff's laws don't apply unless that connection to
>ground has some impedence 

resistance! (The impedance has to have a real part, otherwise everything's at ground.)

>(otherwise the entire net is grounded). What's
>the impedence of a router? :-) I.e., it's dynamic (which is OK) and
>content-sensitive (which seems hard to model).

The analogy would be that the router's input and output impedances are frequency-sensitive, and the content's sent at different frequencies (ports/addresses/QoS/whatever).

Talking of "impedance mismatches" between fat and thin pipes is quite common.


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