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ATM 155Mbps
Using Patch Cables
52
IBM 8265: Planning and Site Preparation Guide
This section details the supported cables and maximum allowable distances for
attaching 155Mbps ATM devices. These devices follow the cabling rules established
in EIA/TIA-568 Commercial Building Telecommunications Cabling Standard and
ISO/IEC DIS 11801, for horizontal cabling Class D.
Table 34. Maximum Link Distance over ATM (155Mbps)
Cable Type
100 ohm UTP Category 5
120 ohm FTP
150 ohm STP Type 1
Patch cables are often used in the twisted pair link between ATM devices.
Installations using patch cables to connect devices to the main trunk cable must
reduce the maximum cable distances given in Table 33 and Table 34 to ensure
reliable operation.
UTP/FTP Category 3, 4, and 5 patch cables assembled from patch cord and
connectors of the same category that meet the U.S. or Canadian standards should not
exceed 80 percent of the distances in Table 33 and Table 34. For countries where
cabling is manufactured according to the less stringent ISO standard, the maximum
distances for such assemblies should be no more than 50 percent of the distances.
Installations using 150-ohm STP patch cables (IBM Type 6) should not exceed 70
percent of the maximum allowable distance using STP Type 1 cable.
For example, the 155Mbps link using patch cables will have a maximum link distance
of 105 m (150 x 70%). This allows a main trunk of 95 m when using two patch cables
of 5 m each.
Generally, it is not good practice to build networks with patch cables that even
approach these maximum distances, because the cable is often unprotected and
exposed to physical damage that might affect transmission performance.
Maximum Allowable Distance
100 m (330 ft)
100 m (330 ft)
150 m (493 ft)
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