>From a document at U Texas:
(http://wwwhost.ots.utexas.edu/ethernet/ch13-ora/ch13.html)
----------Begin Quote-----------------------------------
The "5-4-3" Rule
An over-simplified version of the 10 Mbps Model 1 rules, called the "5-4-3"
rule, has been circulating for some years. Various forms of the 5-4-3 rule
have been published, and some of them include misleading terms that are
incorrect. To quote from one widely distributed configuration guide, the
5-4-3 rule means that there may be as many as five segments connected in
series in a network. This guide further states that up to four repeaters may
be used, and up to three "populated segments." A populated segment is
defined as a segment that is "attached to PCs."
While this may sound like an easy to remember rule of thumb, the "5-4-3"
rule is an over-simplification of the actual configuration rules described
above. Worse, the use of the term "populated segment" is misleading. This
definition means that a coax segment could be regarded as an "unpopulated"
segment in a network system as long as two conditions were met. First, the
coax segment was not used to support PCs and, second, the segment was only
used as a link segment to connect to a repeater at each end. However, this
is incorrect.
A link segment is specifically defined in the 802.3 standard as a segment
based on a point-to-point full-duplex media type that connects two--and only
two--MAUs. A full-duplex medium means that the medium provides separate
transmit and receive data paths. This is important, since collision
detection occurs faster on a full-duplex medium than it does on coaxial
segments. This difference in timing is factored into the total round-trip
timing delays that are incorporated in the Model 1 configuration guidelines.
That's why the notion of an "unpopulated" coax segment that could be used as
a link segment is misleading and incorrect.
To recast the 5-4-3 rule into something closer to reality, we can define it
to mean that you can have up to five segments in series, with up to four
repeaters, and no more than three "mixing" segments. If three mixing
segments are used, then the remaining two segments must be link segments as
defined in 802.3. Actually, you can have up to four mixing segments under
some circumstances as described in the real 802.3 rules above, so even our
corrected 5-4-3 rule is still an over-simplification.
------End Quote-----------------------
So, I hope that helps...
Dale
[=`)
>From: John Hays <[EMAIL PROTECTED]>
>Reply-To: John Hays <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: OT: 5-4-3 rule
>Date: Wed, 18 Oct 2000 07:50:06 -0700 (PDT)
>
>Using the 5-4-3 rule, why can only 3 segments be populated
>
>__________________________________________________
>Do You Yahoo!?
>Yahoo! Messenger - Talk while you surf! It's FREE.
>http://im.yahoo.com/
>
>_________________________________
>FAQ, list archives, and subscription info:
>http://www.groupstudy.com/list/cisco.html
>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.
Share information about yourself, create your own public profile at
http://profiles.msn.com.
_________________________________
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
