CALCULATING RING LENGTH
Page C-8
5.
Add the Equivalent Type 1 Lobe Length (step 3) to the
Combined Trunk Length (step 4) to find the Internal Drive
Distance, and enter the sum here and on line 4a.
Internal Drive Distance =
Combined Trunk Actual Longest Lobe
6.
The Maximum Drive Limit, when considering ARL, is one-half
the maximum drive distance (2525 feet at 4 Mbit/s or 1138 feet at
16 Mbit/s) or 1263 feet at 4 Mbit/s or 569 feet at 16 Mbit/s for STP
cable.
7.
Subtract the Internal Drive Distance (step 5) from the
Maximum Drive Limit to obtain cable length available for the
External Trunk Cable Budget (outside the closets) in your
configuration:
External Trunk Cable Budget =
Maximum Drive Limit - Internal Drive Distance
8.
Find the total length of the Actual Trunk Cable lengths
between wiring closets.
9.
Compare the Actual Trunk Cable length with the External
Trunk Cable Budget (step 7). When your Actual Trunk
Cable length exceeds the External Trunk Cable Budget
(negative result in step 9), you must either adjust your lobe/trunk
lengths or add active components (repeaters) to extend the
available trunk cable length.
If you need further assistance with your network design, contact
Cabletron Systems Technical Support.