[e2e] seeking help recalling a network term

Jon Crowcroft Jon.Crowcroft at cl.cam.ac.uk
Wed Jun 14 01:06:38 PDT 2006

In missive <e715d03bb4a90c2eee0bd1707a6e4adf at cs.utexas.edu>, Chris Edmondson-Yu
rkanan typed:

 >>I know how much you like history, so here's some fun:
 >>That was Donald Davies concept (who independently invented packet 
 >>switching in the UK in 1965); he used the term isarithmic, the Greek 
 >>term for "equal").

it was part of the french 1st packet switched net hop-bu-hop traffic
management (flow, congestion and crowd control) technology.... its way
cool and the idea has been re-invented lotsa times including in other
areas like road-trains

also bittorrent incentive matching technology is basically the same

the closed loop e2e feedback that TCP uses isnt, but with ECN or
re-feedback, it starts to sound like a (weak) approxiamtion

davies was very very very clever
 >>John McQuillan's 1974 dissertation on routing describes it as follows:
 >>"One major thrust of the research at NPL has been a study of so-called 
 >>"isarithmic" networks in which the number of packets and packet 
 >>"containers" is held constant.  This is essentially a flow control 
 >>mechanism designed to prevent congestion.... but such a technique does 
 >>have an impact on the appropriate routing doctrine..."
 >>This concept was first published in 1971:
 >>ACM second symposium on Problems in the optimizations of data 
 >>communications systems.
 >>(at SIGCOMM's 2nd sponsored conference ;-)
 >>Davies wrote in the paper:
 >>The Control of Congestion in Packet Switching Networks
 >>(which has  a 72 version in IEEE Trans. on Communications)
 >>"Since data-carrying packets must be created and destroyed, the balance 
 >>is kept by using empty packets.  Thus when a normal, data-carrying 
 >>packet arrives at its destination it is replaced by an 'empty' which, 
 >>is put back into the system.  When data is ready to enter the network, 
 >>an empty packet must be found and replaced by a data-carrying 
 >>Eventually, they switched to permits to avoid the unnecessary traffic 
 >>of empties.  And as routing algorithms improved, isarithmic congestion 
 >>control no longer helped.
 >>Donald Davies Oral History 1986:
 >>"As a means of controlling the number of packets, it occurred to me to 
 >>give them a permit before they could get into the network.  The idea 
 >>was, I think a good one, and in simulation it seemed to work, but it 
 >>had the danger that permits could get lost and so the thing had a nasty 
 >>collapsing process if some part of the network was doing the wrong 
 >>thing... I don't think the idea was ever more than a theoretical one... 
 >>quite interesting to statisticians who liked the idea of this...
 >>that's it,
 >>On Jun 13, 2006, at 7:27 PM, Joe Touch wrote:
 >>> PS - found it via some indirect means; it's isarithmic ;-)
 >>> Joe
 >>> Joe Touch wrote:
 >>>> Hi, all,
 >>>> I apologize if this is a simple question:
 >>>> I'm trying to recall the name for a network where the number of
 >>>> packets/tokens/empty-frames inside the net is a constant, i.e., where
 >>>> real data can be put into these units when empty, and emptied at the
 >>>> destination, but that the whole net is otherwise just shuffling around
 >>>> these 'holes'.
 >>>> I'm recalling a term akin to "idempotent" or "isomorphic" - though I
 >>>> know both are wrong ;-) Does anyone recall the term for these nets?
 >>>> (I recall their being vogue in the late 1980's, but not much after 
 >>>> that).
 >>>> Thanks,
 >>>> Joe
 >>Chris Edmondson-Yurkanan
 >>(chris at cs.utexas.edu)
 >>Contact info:  www.cs.utexas.edu/~chris/



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