RE: hubs and switches

["Fulp, J.D. USA" <jdfulp () nps edu>]

FYI, 

One quick way to identify a "true" hub (i.e., one that works at layer 1
only... and is not really making forward/block/flood decisions based 
upon layer 2 [MAC] information) vice a switch is to see if the device
has an led on the front labeled "col".  

"col" is short for collision... and switches do not have collisions. 
Instead, switches will buffer the second frame that enters it rather 
than permitting the two (or more) simultaneously tranmitted frames to
go out on the same wire at the same time. 

So... bottom line... if there is a "col" led (light-emitting diode) on
the device, you can be 99% sure you've got a true "dumb" hub.

:-)

JD

-----Original Message-----
From: Ron Gula [mailto:rgula () tenablesecurity com]
Sent: Thursday, August 05, 2004 11:04 AM
To: focus-ids () securityfocus com
Subject: hubs and switches


I know there are a lot of NIDS old-timers on here, but
for the folks getting into monitoring, please be aware
that many times, if you go to Best Buy or CompUSA (at least
here in the US) and buy a hub, you may actually be
getting a cheap switch. If you can find the documentation
online for the hub, you may be able to tell if it behaves
as a switch or is a real hub.

Ron Gula, CTO
Tenable Network Security
http://www.tenablesecurity.com


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