[e2e] TCP, retransmissions, and ISPs with byte caps

David P. Reed dpreed at reed.com
Tue Jun 18 05:57:18 PDT 2002


At 08:17 AM 6/18/2002 +0200, Philippe Strauss wrote:
>But about delays, CATV systems have an interesting characeristic:
>a ~20ms minimum delay in the ACK path (direction from home
>to the hub, upstream or return path in catv speak).

I have been pinging various targets through my LANCity cable modem for 
years now and I have regularly gotten 7 msec. ping RTT to lcs.mit.edu which 
is a few hops (11 at the moment) away.  This morning the average is 13 
ms.   Where's the 20ms minimum?   How did you determine it?

Perhaps you meant 20 *micro* seconds?

Or maybe Swiss cable systems are really really slow.








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