Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!lll-crg!nike!ucbcad!ucbvax!ANDREW.CMU.EDU!leong From: leong@ANDREW.CMU.EDU (John Leong) Newsgroups: mod.protocols.tcp-ip Subject: Re: DELNI characteristics Message-ID: Date: Mon, 15-Sep-86 18:49:31 EDT Article-I.D.: andrew.MS.leong.0.leong.1221.0 Posted: Mon Sep 15 18:49:31 1986 Date-Received: Tue, 16-Sep-86 09:21:50 EDT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 12 Approved: tcp-ip@sri-nic.arpa On the subject of cascading DELNI, one has to be careful about one quirk. The Intel 82586 chip has, by default, a check that is not really in conformance of the Ethernet spec. It measures the time between transmit and receiving the signal back from the transceiver and signals whether the round trip time equates roughly to 50 meter of drop cable (nothing to do with the Ethernet slot time of 51.2 micro seconds or roughly 2.5Km). This test is quite bogus but some earlier version of DECNET software actually check for that return code and declares the world is sick accordingly. We have ran into that problem earlier on when we cascaded DELNI's since they introduced roughly 10 meter of cable worth of delay and we ran over the 50 meters.