[54659] in North American Network Operators' Group
Re: fast ethernet limits
daemon@ATHENA.MIT.EDU (Mikael Abrahamsson)
Sat Jan 11 03:10:49 2003
Date: Sat, 11 Jan 2003 09:10:12 +0100 (CET)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: nanog@merit.edu
In-Reply-To: <5.2.0.9.2.20030110164841.00acaa60@mail.macronet.net>
Errors-To: owner-nanog-outgoing@merit.edu
On Fri, 10 Jan 2003, blitz wrote:
> 100 meters is supposedly the limit for ethernet, and "assuming" a 12'
> floor, your'e around 24 feet over spec.
100 meters is primarily a "timing limit" for half duplex, ie if you're
running half duplex, how large can your broadcast domain be before you
risk losing small packets due to the collission not reaching all speakers
on the wire (and this counting the max number of repeaters in a broadcast
domain). 100/half will do padding of small packets to achieve just this
effect.
I've seen 170meter CAT5 100 meg full duplex links working just fine. Of
course, as stated before, it's an interference thing, if you have a lot of
noise around the wiring you'll shorten the usable length.
Of course, this is a ethernet chipset issue, but there are definately
chipsets out there capable of electronically driving links much more than
100 meters just fine.
--
Mikael Abrahamsson email: swmike@swm.pp.se
