>I have read in plenty of manuals that 5-4-3 rule must be followed while
>connecting 10Base2 (and 10Base5) segments.
>And only 3 of them can be populated, the others are so called IRL.
>Of course I understand that this is the way the standard goes, but what's
>the purpuse of these IRL?
>Why should not I populate the rest 2 segments?
>What's the physical (logical) limitation?
>If (Q==FAQ) then sorry();
Maybe Q==FAC, but anyway,
In the old days, there was coaxial ethernet and FOIRL, Fiber Optic Inter
Repeater Link. You can put multiple taps on a coax cable, but not an an
optical fiber. Collision detect is slightly slower on coax, compared to
cables with separate transmit and receive lines, like fiber and twisted
pair. In a twisted pair net, all segments count as IRL.
In any case, that is the rule if your 10base5 segments are 500m long,
and with 50m AUI cables. If not, you may be able to have five segments,
and still satisfy the rules. If you really want to know, you have to
use the Model 2 rules.
If you use only 10baseT, even with 150m cables, you can still satisfy
the model 2 rules with six segments and five repeaters. (The 6-5-0 rule?)
If you have FOIRL longer than 500m, or 10baseFP, 10baseFB, or 10baseFL,
you should also use model 2 rules.
With a long 10baseFL cable, you might only be allowed one repeater!
I hope this helps,