- From: Jeffrey Mogul <mogul@pa.dec.com>
- Date: Tue, 13 Aug 96 13:51:09 MDT
- To: Koen Holtman <koen@win.tue.nl>
- Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
As for the high RTT on some of Digital's internal links: RTTs are
irrelevant for this discussion. If anything, they will make the
savings less noticable. If Digital's internal links were highly
_saturated_, that would be another thing.
Precisely. In the absence of high bit-error rates (such as on wireless
links), high RTTs come from two sources: speed-of-light delays, and
queueing delays. Although Digital is on a serious cost-cutting kick,
it's not possible to pay less and get slower light, so we use the same
300,000 KM/sec that everyone else has. But extra bandwidth does cost
money, so in some places we are undersupplied, which means queueing
delays, which means high RTTs.
In other words: high RTTs imply link saturation.
-Jeff
Received on Tuesday, 13 August 1996 14:05:42 UTC