CALCULATING RING LENGTH
Page C-2
• Wherever Type 6 or Type 9 cable is used, the length must be
converted to the equivalent Type 1 cable length as follows:
(Length of Type 6 or 9 cable) x 3/2 =
Equivalent Type 1 or 2 length
C.2 SINGLE WIRING CLOSET NETWORKS
In a single wiring closet application, all of the trunk cabling is
contained inside the closet, and the cable length of interest is the
longest lobe length (the cabling between the concentrator’s TCU
port and the most distant Token ring station). Use the UTP Cable
Length Worksheet, Single Wiring Closet form at the end of this
section to calculate your longest lobe cable length. Choose the column
that matches your ring speed and complete the worksheet as follows:
1.
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
Type 1 STP cable.
2.
Refer to the table at the bottom of the worksheet to find the
Internal Trunk Length for your wiring closet configuration.
3.
Subtract the Internal Trunk Length from the Maximum
Drive Limit to obtain the Type 1 Cable Budget:
Type 1 Cable Budget =
Maximum Drive Limit – Internal Trunk Length
4.
Since we are trying to determine the UTP Lobe Length for your
network, the Type 1 Cable Budget must be converted to a
Maximum UTP Cable Length using a conversion factor of .39
for networks operating at 4 Mbit/s or by .34 for 16 Mbit/s.
5.
Multiply the Type 1 Cable Budget by the conversion factor.
Type 1 Cable Budget x (.39 or .34) =
Maximum UTP Lobe Length
