Ethernet question

Matthew J. Brodeur mbrodeur at NextTime.com
Tue Aug 27 12:17:01 EDT 2002


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On Tue, 27 Aug 2002 pll at lanminds.com wrote:

> Ohhhhhh!  Okay, I get it.  So 100Mbit doesn't use 4 pair any more?
> Then why they heck are we still spending all that money on 8-strand 
> cat 5?  Cut the prices in half and waste half the amount resources :)

   Well, 100Base-T only uses 2 pair, but I'm sure someone is still using 
a "standard" that needs all 8 wires.
   Of course, you still need an 8-pin plug since the signals are on pins 
1,2,3 and 6.  In light of that it makes sense to use 8 conductor cable, 
and using cat-5 or better leaves you room to upgrade to 1000Base-T which 
does use all 4 pair.
   

> The fiber part actually doesn't bother me, since I've dealt with it 
> before.  Always go MM, and use the little square connectors (sc) if 
> you can, they're easier than the screw-n-twist (st) and a lot better
> than GBIC :) ( I think I got those correct :)

   Almost.  GBICs (GigaBit Interface Converter) are the matchbox-size 
modules that plug into the matchbox-shaped holes in switches to give you 
something to plug your cable into.  In theory this allows you to customize 
your Gig-E connections to fit your network.  In practice I'd say that 
about 99% of the GBICs in use are 1000Base-SX, or short-haul fiber, with 
SC connectors.
   It is possible to get a wide variety of modules, but in my experience 
they tend not to work with anything other than the switch they were 
purchased for (or with).  Yet another thing that looks like a standard, 
but really isn't.
 

- -- 
     -Matt

All generalizations are false, including this one. 
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