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From: jmg@cernvax.UUCP (jmg)
Newsgroups: net.lan
Subject: Mixed Ethernets and DELNIs
Message-ID: <133@cernvax.UUCP>
Date: Thu, 14-Feb-85 15:31:02 EST
Article-I.D.: cernvax.133
Posted: Thu Feb 14 15:31:02 1985
Date-Received: Sun, 17-Feb-85 06:19:46 EST
Reply-To: jmg@cernvax.UUCP ()
Organization: CERN, Geneva/Switzerland
Lines: 30
Keywords: Ethernet, DELNI

We have a real mixed bag of Ethernet hardware hung on one cable: DEC, 3-Com,
Interlan transceivers, DEC and Sension repeaters (local and remote), Vaxes
(VMS and 4.2BSD), workstations, PCs etc. etc. etc.

We have experimented with Cheapernet cable: seems to work OK when connected
via repeater, and even when connected end-on to normal Ethernet cable!

Have also a mixture of version 1.0, version 2.0 and (what is called) 8802.3
standard. It all seems to work (apart from one minor glitch when the same
value for a protocol ID field was used by two different systems). Note,
however, that we try not to mix transceiver and controller.

BUT:

We make a lot of use of DELNIs as fan-out boxes. This, of course, means that
often a non-DEC controller goes onto a DELNI as transceiver. I have the
impression that this can cause problems: sometimes we have a phenomenon
whereby packets can be sent but not received. Changing the DELNI, or
using shorter transceiver cables, often cures the problems.

Question, therefore. Does anyone have any recipe for what one can or cannot
do when putting equipment onto DELNIs? Also, the DELNI manual says that
one can hang DELNIs off a DELNI or off a real cable, but a DELNI off a DELNI
off a real cable is supposed not to be allowed (even though we have tried it
and it seems to work). Of course, the DEC DELNI manual is sometimes rather
vague in its specifications.

Over to you, World. While you ponder it I shall go off for a week of skiing.

Mike (Back off, man, I'm an Ethernetbuster) Gerard.