Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!bellcore!ka9q.bellcore.com!karn
From: karn@ka9q.bellcore.com (Phil Karn)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: ICMP Multiple Echo Replies
Keywords: ICMP echo reply
Message-ID: <17125@bellcore.bellcore.com>
Date: 2 Jul 89 02:00:43 GMT
References: <1131@umn-d-ub.D.UMN.EDU> <25908@agate.BERKELEY.EDU>
Sender: news@bellcore.bellcore.com
Reply-To: karn@ka9q.bellcore.com (Phil Karn)
Organization: Secular Humanists for No-Code
Lines: 15


Here's one conceivable cause of the multiple echo phenomenon that I don't
think anybody has suggested yet. How about mismatched versions of Ethernet
between a host and a transceiver at some point along the path? Since IEEE
802.3 calls for a collision presence test signal to be generated by the
transceiver after each packet while controllers designed for Ethernet
version 1.0 have never heard of such a thing, is it possible that some
controllers might treat this as a collision even when the packet has been
sent successfully?

Let's hear it for standards bodies making gratuitous changes to established
de-facto standards. (You didn't think I'd resist the opportunity to say
this, did you?)

Pil