CALCULATING RING LENGTH
Page C-9
6.
Find the total length of the Actual Trunk Cable lengths
between wiring closets.
7.
Compare the Actual Trunk Cable length with the External
Trunk Cable Budget (step 5). When your Actual Trunk
Cable length exceeds the External Trunk Cable Budget
(negative result in step 7), you must either adjust your lobe/
trunk lengths or add active components (repeaters) to extend the
available trunk cable length.
Use Figure C-2 and the STP Cable Length Worksheet for Multiple
Wiring Closets to follow the calculation in this example of a 4 Mbit/
sec ring:
Multiple Wiring Closets
4 Mbit/sec
1.
Actual Longest Lobe (given as 55 feet) 1. 55 ft.
2.
Combined Trunk Length
117' + 165' + 213' = 495'
2. + 495 ft.
3.
Internal Drive Distance
3. 550 ft.
4.
Maximum Drive Limit
4. 1263 ft.
4a. Internal Drive Distance
– 550 ft.
5.
External Trunk Cable Budget
5. 713 ft.
6.
Actual External Trunk Cable Length
95' + 70' + 175' = 340'
6. – 340 ft.
7.
Result
7. 373 ft.
The result is positive and no repeaters or cable adjustments are
needed.
If you need further assistance with your network design, contact
Cabletron Systems' Technical Support.
