clay@claris.UUCP (Clay Maeckel) (07/22/88)
[ Please note followups go to comp.dcom.lans ]
We here at Claris just finished installing, testing, and evaluating
some of the 3Com Ethernet products. Having noticed some queries on the net
about twisted pair ethernet I decided to post some of my observations. The
products Claris received from 3Com included a Multiconnect Repeater with ten
thin and one thick ethernet boards, ten PairTamers (single pair ethernet) and
EtherLink/NB (reworked original) boards for the Mac II. Also Claris had
use of, for one week, a LanScanner for the purpose of debugging some of
our longer runs of twisted pair cable.
First a little info on the network setup here. There is one thin
ethernet backbone connecting fourteen Kinetics boxes, a Sun, a Vax, six
DECServers, and now ten Mac IIs. Also in the net is a DELNI connecting a
majority of the DECServers and a pair of TransLAN IIIs connecting a
remote building through a 59K BPS line. Each Kinetics box (except one)
is connected to a PhoneNet StarController which connects on the average
20 Macs.
Installation of the first three Mac II/PairTamer setups was a quite
easy. First open all the PairTamers up and move the jumper cables from
the innermost pair to the next pair out to match what PhoneNet uses,
then remove the jack from the PhoneNet connector behind the Mac and plug
it into the PairTamer. In the phone closet, take the jack out of the
StarController's patch panel and plug it into the matching PairTamer.
Install the boards and software, turn on the Macs, and voila; bye bye
1/4 and hello 10 megabits.
I was also lucky with the first three in that each pair of wires
did not change orientation through all the punch down blocks, the
PairTamers use a DC signally scheme while PhoneNet doesn't care. The
next five Macs proved to be troublesome because impedance mismatches in
the twisted pairs. The problems were easily pointed out by the
LanScanner and even though I never got three of the lines into specs,
they still worked after cleaning up the punch down blocks.
Currently nine PairTamers are up and running with Mac IIs and one
Sun at the end of them plus two Mac IIs that are connected directly to
the backbone. The furthest run is 300' into a nearby building connecting
one Mac II. EtherLink/NB boards are used for a Mac II running A/UX,
an AppleShare server, an Intermail server, and with the remander in
user's Mac IIs. Other software in use includes NCSA Telnet 2.2
(to the Sun and A/UX), CAP 4.0 (on the Sun), KIP 6/88 code (only in
one KBox and on the Sun), and AlisaShare (on the Vax).
The most notable performance improvement is seen with the
AppleShare server being directly on the backbone. Not only is the
bandwidth wider in the usual bottleneck point, but all traffic from Macs
connected to PhoneNet only travel through one bridge instead of the
original two. The InterMail server seemed to run better directly on the
ethernet but major design flaws in that product holds it back. User's of
the ethernet cards also notice speed improvements, especially to the file
server.
Hope this of use for some people and I'll try answering any
questions people have. I do not know that much about the VAX/DECNet/AlisaShare
side of things, that is handled by MIS and no telling if anyone down there
will say a word.
--
Clay Maeckel * UUCP: {ames,apple,portal,sun,voder}!claris!clay
(I know nothing!) * Arpanet: claris!clay@ames.arc.nasa.gov
Claris Corporation * AppleLink: Maeckel1 * CompuServe: 73057,255