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From: bruce@ssc-vax.UUCP
Newsgroups: comp.dcom.lans
Subject: RE: BASEBAND vs BROADBAND
Message-ID: <1148@ssc-vax.UUCP>
Date: Thu, 26-Feb-87 00:11:36 EST
Article-I.D.: ssc-vax.1148
Posted: Thu Feb 26 00:11:36 1987
Date-Received: Sat, 28-Feb-87 03:16:38 EST
Organization: Boeing Aerospace Corp., Seattle WA
Lines: 64
Keywords: baseband broadband


I manage a broadband LAN here at Boeing and deal with ethernet and some other
LANs as well.  Most of the original flack about why baseband is a better
system than broadband (or vice versa) has died down in recent years due to
the overwhelming acceptance of baseband ethernet as the LAN of choice.  Lets
face it, if you want an ethernet interface for any misbegotten unloved piece
of digital gizmo, you can probably get it.  Try that with broadband!

Having said that, I still like broadband.  But I agree with the poster who said
that you are better off with a broadband guy on your staff if you run a
broadband net.  But this certainly doesnt have to be a "trained, experienced
professional".  My background included RF communications some 15 years back,
so I was no stranger to Spectrum Analyzers and sweep generators.  I find
broadband a snap.  It can be learned by anyone who takes the time to put the
same sort of study into broadband that he would into learning a new programming
language or a new logic family.

But back to the subject.  I feel that baseband and broadband have definite
niches and should not compete, but rather coexist.  Each does certain things
superbly.  Rarely, however, is either sufficient as the sole networking
solution.

As a practical example, we have both RF broadband and baseband ethernet trunks 
serving a multi-building campus.  There has never been a single failure of the 
broadband trunk in 6 years of operation.  In contrast the ethernet trunk is 
renowned for its ups and downs.  Why is the ethernet less reliable?  Because 
of bad vampire taps and loose transceiver cables.  The same wonderfullness that
allows a tap to be simply installed allows a simpleton to bring down a whole 
network (or large part thereof).  Ethernet distribution technology has a long 
way to go to match the maturity and reliability of RF broadband.  But on the 
other hand, I am severely limited in the computing device interfaces available 
for broadband.

So why has there been all the bad press on broadband?  For one thing, because 
it is not understood by the majority of digital folks and they have not 
bothered to learn about it (" +35dbmv ?  What the &^%$# does that mean?").  
Secondly it is true that broadband can be critical to maintain, BUT (IMPORTANT 
PLEASE NOTE--> ) this is primarily in fully loaded systems, covering large 
distances, in environmental conditions which would frost your manhood.  Ie, 
situations that ethernet would be at a loss to cope with.  For simple, lightly 
loaded systems, broadband is relatively simple and very forgiving  (a prime 
example being the guy who didnt bother to calculate tap values -- he just 
swapped until he got one that worked! ).

If I were starting all over again from scratch I would use broadband for 
highly reliable trunking between buildings and (where right of way could be 
had) between sites.  Within buildings the LAN of choice would be baseband 
(probably ethernet).  This would be bridged onto the broadband trunk at each 
building.  The ethernet topology would be designed to minimise the ability of 
the unwashed to either short or open the cable.  It would further be easily
segmentable either manually or electronically to facilitate maintainability.
The only broadband distribution within buildings would be for video, which 
would go only to selected sites such as media rooms, conference rooms, 
learning centers, etc.  

Please note that the "real world" topology and specific user requirements
will be the final arbiters of what is the best technology to use.  LANS are
too complex for simple homilies such as "baseband is better than broadband"
or "token ring is better than CSMA/CD" to be more than half-truths.


				Bruce E. Stock
				Boeing Aerospace Co.
				uw-beaver!ssc-vax!bruce