Path: utzoo!attcan!uunet!husc6!bu-cs!kwe
From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England))
Newsgroups: comp.dcom.lans
Subject: Re: Can ethernet TCP/IP lock up?
Summary: Specify 802.3 compliance for repeaters
Message-ID: <22766@bu-cs.BU.EDU>
Date: 20 May 88 16:51:37 GMT
References: <299@fedeva.UUCP> <21674@amdcad.AMD.COM> <21680@amdcad.AMD.COM> <10303@ulysses.homer.nj.att.com>
Reply-To: kwe@buit13.bu.edu (Kent England)
Followup-To: comp.dcom.lans
Organization: Boston Univ. Information Tech. Dept.
Lines: 26

In article <10303@ulysses.homer.nj.att.com> smb@ulysses.homer.nj.att.com (Steven Bellovin) writes:
>This afternoon, we had some sort of network lockup that could have been
>a two-point failure.  Ulysses (a Sun-3/280) suddenly started muttering
>``ie1: Ethernet jammed''.  
>
>The particular net in question is a very difficult one to debug.  It's
>our backbone, and consists of a very short segment of coax with lots of
>repeaters to other segments.  Some of those repeaters and transceivers
>are ancient; our segment may be connected via a 5 or 6 year-old 3Com
>transceiver.  I have no idea which host was misbehaving; it could even
>have been Ulysses, since the repeater may have isolated such a failing
>segment.
>
	Old transceivers may not implement jabber control.  Old
repeaters do not provide fault isolation.

	For new equipment, specify 802.3 compliance and test
compliance.  Transceivers should implement jabber control and new
repeaters should implement the new IEEE 802.3 repeaters specification
which provides a degree of fault isolation and should interrupt
repeating of jabbering [illegal] signals.  I believe all implementations
of the multiport repeater follow the new 802.3 repeater rules.  I
think all new implementations of Ethernet concentrators (ala the new
twisted pair concentrators) should implement the new rules.

	Kent England, Boston U