Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!ukma!rutgers!bellcore!ka9q.bellcore.com!karn
From: karn@ka9q.bellcore.com (Phil Karn)
Newsgroups: comp.dcom.lans
Subject: Re: Token Ring (was: Re: Info on LANs)
Message-ID: <13172@bellcore.bellcore.com>
Date: 4 Jan 89 07:22:12 GMT
References: <12786@cup.portal.com> <920001@hposdl.HP.COM> <10777@s.ms.uky.edu> <13137@bellcore.bellcore.com> <1145@murtoa.cs.mu.oz.au>
Sender: root@bellcore.bellcore.com
Reply-To: karn@ka9q.bellcore.com (Phil Karn)
Organization: Secular Humanists for No-Code
Lines: 16

>> (The only time Ethernet *does* silently drop packets is when
>> the destination host is down or somebody pulls the plug on an intervening
>> repeater ...)
>
>This is not quite true, ethernets drop packets when the receiving
>controller isn't fast enough to handle the incoming packet rate.

True. But in my experience, this has never been a significant problem except
when the upper layer protocol code is seriously broken, or when the
receiving Ethernet controller design is terminally brain-damaged (e.g., the
notorious 3Com 3C501 and the even more infamous DEC DEQNA). With a sane
controller design having a reasonable amount of buffer memory, the
end-to-end flow control in the upper layer protocol is more than sufficient
to prevent appreciable packet loss.

Phil