RI/RO Max distance using cat 5 ?

[James Kovaly]

Has anyone out there tried connecting two hubs via the RI/RO connections using
cat 5 cable ?

We have a Synoptics 3000 and a Synoptics 2712 hub that we would
like to connect using cat 5 cabling over a distance of 479 ft. Baynetworks
claims that a non-repeated STP type 1 cable will work up to 600 ft. They do
not know if cat 5 cable will work...

Thanks,

Replies to:
cps.j...@capital.ge.com

[Karsten Hiemstra]

If you are not using a repeater then your total allowable lobe length
(to meet the TR spec) is:

600ft minus ring length (for 4Mb Token Ring)
328 ft minus ring length (for 16Mb Token Ring)
I believe this lengths are for STP or CAT 5 (CAT 3 is only for 4Mb)

For example, if you have two hubs with 20 ft. RI/RO cables then your
ring will be 40 ft long. If you are running 16Mb then your total
allowable lobe length in this case is (328 - 40 = 288 ft). You should
then make sure that the distance for any lobe run from MAU to
workstation is less than 288 feet.

If you are running your RI/RO over a distance of 479 ft. then your
ring will be over 900 ft long *before you even begin any lobe runs!*
This could very well cause problems unless you are using repeaters.

However, the distances above are only the numbers required to meet the
TR specifications. In actual practice you can often exceed these
distances, but be prepared for more errors on your ring. I have done
lobe runs over 600 ft without any major problems. If you have a
sniffer, then I would monitor the ring for a while after making the
change.

This is how it was explained to me years ago but I think it is more or
less correct.

Karsten Hiemstra