🚀 go-pugleaf

In article <1993Jan25.182938.6414@novell.com> donp@novell.com (don provan) writes:
>In article <1993Jan25.095134.25886@ica.philips.nl> geertj@ica.philips.nl (Geert Jan de Groot) writes:
>>No, most certainly not. 10baseT is point-to-point. Which means that you
>>have to have a separate connection between the HUB and every apparatus
>>in your office. In my case, this would mean that I'd fill more than one
>>hub, just for my own equipment!
>
>In my building, they just give each engineer an eight port 10baseT
>fan-out unit (i guess the official term is "micro repeater").  I've
>got two in my office.  Am i breaking some 10baseT rule?

IEEE allows 4 repeaters between any two end stations.  I've seen two common
approaches.  For the site with the technical people that insist on using
thinnet or 10base2 in their offices or labs because it's "easier to work
with", 10baseT is used to feed the lab or office, and a 10baseT to 10base2
repeater is installed.  MIS gets the advantage of individual manageable
segments to each office or lab, and the engineers get to keep their coax,
but Bob removing a terminator or BNC tee in his office will not break the
LAN in John's office.

The second approach is the one Don mentioned, which is to structure the LAN
so each office or LAB can have one more layer of repeaters.

A legal topology diagram that abides by the 4 repeater, no more than 3 
tapped coax segments is as follows:

                     10base5 or 10base2 backbone
                   -------------------------------
                        |          |         |
                     --------  --------  --------
 Wiring Closets      | rptr |  | rptr |  | rptr |
                     --------  --------  --------
               _______| |          |         |<----FOIRL or 10baseT
-  -  -  -  - | -  -  - | -  -  -  | -  -  - | - -
              |         |          |         |     
          --------   --------  --------  --------
 Labs /   | rptr |   | rptr |  | rptr |  | rptr | 
 Offices  --------   --------  --------  --------
          |  |  |    |  |  |   |  |  |   |  |  |<---any media

If you draw the topology as a tree, with a coax backbone, you can go down
two levels of repeaters maximum, and the links between the two levels of 
repeaters must be link segments, or you will exceed the 3 populated coax
segment rule.  Note that with this topology, a large total number of
repeaters can be used, because you aren't restricted to how many repeaters
off the backbone segment, or how many repeaters off the first layer of
repeaters, just as long as between any two DTEs, you don't traverse more
than 4 repeaters.  The problem I've usually seen is using 10baseT hubs
and making three layers of repeaters, which puts five repeaters in the path
between two DTEs.  So Don, please be sure your second micro-repeater is not
daisy-chained off the first, and you're probably okay.

Joe Gervais
Joe_Gervais@Novell.com