Re: making satellite channel loss transparent

From: Jamshid Mahdavi ([email protected])
Date: Fri Jul 23 1999 - 10:22:08 EDT


"ketan bajaj" <[email protected]> writes:

> Still we don't have a protocol which is completely transparent and preserves
> all existing semantics of tcp.
> What i'm trying to say is why not attack the real problem. The root cause
> for tcp's poor performace over satellite channels is that it fast
> retransmits on receiving 3 duplicate acks (reducing its window), and as the
> delay*bandwidth product over a satellite channel is large, the no. of data
> packets in the end-to-end pipe are large, so a loss due to corruption,
> results in a number of duplicates acks being generated, moving the sender
> tcp to fast retranmission, and thus poor performance.

In the absense of explicit information, the sender *must* assume that
a lost packet is an indication of congestion. You can't change this
aspect of TCP, although you could try to find a way to let the sender
know that a particular packet loss was due to corruption rather than
congestion.

Alas, I think this is probably not the only cause of poor TCP
performance over satellite...

--J



This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:55 EST