Xref: utzoo comp.dcom.lans:1157 comp.protocols.tcp-ip:2827
Path: utzoo!mnetor!uunet!husc6!bbn!rochester!cornell!uw-beaver!fluke!jeff
From: jeff@tc.fluke.COM (Jeff Stearns)
Newsgroups: comp.dcom.lans,comp.protocols.tcp-ip
Subject: Re: ethernet monitor needed?
Message-ID: <3185@fluke.COM>
Date: 22 Mar 88 22:15:39 GMT
References: <3447@cbmvax.UUCP>
Sender: news@tc.fluke.COM
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 34

In article <3447@cbmvax.UUCP>, grr@cbmvax.UUCP (George Robbins) writes
about his search for Ethernet test gear.

I'll put in a plug for the Cabletron LAN-MD.  It's a suitcase-sized box that
can thoroughly test cables and transceivers.  A pair of LAN-MD's can exercise
transceivers in place and tell you things that you'll never otherwise know.

Which of your transceivers have broken or out-of-spec collision detect
circuitry?  How will you find them?  Hint: Can a computer tell if its
transceiver has this problem?

Now that we're in the age of level I vs level II vs 802.3, we have abundant
opportunities to pair up Ethernet controllers with the wrong kind of
transceiver, multiplexor, or cable.  Physical and link-level problems like
this are often inscrutable to higher-level tools.

Imagine a chart of the ISO reference model.  Stick a pushpin in it for every
Ethernet problem you've had.  Here's a starter drawn from recent memory:
    Controllers that don't conform to the Ethernet spec, wrong cable type for
    transceiver level, out-of-spec transceivers, defective transceivers,
    broken Ethernet controllers, buggy controllers, buggy device drivers,
    improperly-installed vampire taps, noise-sensitive transceivers, loose
    transceiver cables, bugs in TCP/IP, NFS, ND, and ftp.

That puts a lot of pins down at the bottom of the chart, below the level of
monitors and protocol analyzers.  The LAN-MD works well down there.
I wouldn't be surprised if Cabletron were working on something newer than
the LAN-MD; you might also want to ask 'em that.
-- 
		 Jeff Stearns
	 Domain: jeff@tc.fluke.COM
	  Voice: +1 206 356 5064
    If you must: {uw-beaver,microsoft,sun}!fluke!jeff
	   USPS: John Fluke Mfg. Co. / P.O. Box C9090 / Everett WA  98206