RE: LL ARQ on LD links [was: PILC: prioritization]

From: Nitin H Vaidya (vaidya@cs.tamu.edu)
Date: Thu Feb 11 1999 - 15:51:11 EST


Sanjoy:

>> From sanjoy@nortelnetworks.com Thu Feb 11 14:20:06 1999
  ...
>> into a number of RLP frames) due to the low air link bandwidth. This
>> inflates the RTT considerably, and if you add the delay variations
>> encountered by previous RLP retransmissions (however frequent they may be),
>> we've a RTO estimate which is at least about 1.5 times this (inflated) RTT.
>> This gives a more than sufficient margin to avoid spurious timeouts.

By the way, I now remember Reiner's explanation, which
probably also explains your observations.

He noted that when TCP sender receives an ack for a timed
packet, the timeout is reset (to its original value)
to time the next unack'd packet. This results in a much
larger timeout interval for the the next packet, allowing
plenty of slack for retransmits.

- nitin



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