[Iccrg] Heresy recapped
Eddy, Wesley M. (GRC-RCN0)[VZ]
wesley.m.eddy at nasa.gov
Thu Apr 17 14:11:10 BST 2008
>From: iccrg-bounces at cs.ucl.ac.uk
>[mailto:iccrg-bounces at cs.ucl.ac.uk] On Behalf Of Michael Welzl
>Sent: Thursday, April 17, 2008 1:38 AM
>>I will just point out that fairness is not a goal of VJ CC; avoiding
>>packet loss is.
>>The inputs to VJ CC are "some bytes were not lost" (an ACK) and "some
>>bytes were probably lost" (an RTO or 3-dupack). They are not "someone
>>is sending faster than me" or "I'm sending faster than someone else",
>>or any other metric or inference useful for acheiving any form of
>>fairness, because that is not its goal.
>Now that ain't true. The choice of AIMD in the Cong. Avoid & Control
>paper is based on the Chiu/Jain paper (this paper is cited in Van's),
>where AIMD was found to be the only control leading to efficiency
>*and fairness* among the four simple linear ones that they looked at.
The message at:
only briefly mentions fairness, and actually labels it as something
for the router to decide, not the end hosts.
"While algorithms at the transport endpoints can insure the network
capacity isn't exceeded, they cannot insure fair sharing of that
capacity. Only in gateways, at the convergence of flows, is there enough
information to control sharing and fair allocation."
Both references describe the selection of AIMD without reference to
fairness, but specifically for stability.
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