[ih] Throwing packets away

John R. Levine johnl at iecc.com
Mon Nov 2 23:39:41 PST 2009


[ Feel free to point me at documents or archives I should have read if
   this is a FAQ. I have at least read RFC 635. ]

I'm trying to understand the origins of the TCP/IP approach to congestion 
management by throwing excess packets away, which I gather was a pretty 
radical idea.

It is my impression that the ARPAnet used a reservation approach so that 
the source end wasn't supposed to send a packet until the destination end 
said it had room for that packet, with resends primarily for line errors. 
TCP went to byte windows and congestion discarding partly to make it more 
adaptable to varying network speeds, partly to unify the virtual circuit
management, and that it took a fair amount of twiddling of the details of 
TCP to get good performance out of it.

CYCLADES had a lot of these features.  Did the window and congestion 
discards come from there, or somewhere else, or some combination?

Signed,
Confused in Trumansburg



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