IBM 8285 Nways, Installation And User Manual

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Planning Cabling Distances in a Fiber Network
This section describes how to plan the cabling distance between two 155Mbps ATM ports (or between a
155Mbps I/O Card feature and an ATM user device) in a fiber network. To ensure that a 155Mbps link
will be valid for data transmission, collect the following information:
Ÿ Type and length of fiber cable
Ÿ Type and number of connectors used
Ÿ Type and number of splices used
Ÿ Type and number of patch panels used
Ÿ Number of jumper cables used
Once you have the necessary information, you can plan the cabling distance between ATM ports by
following these steps:
1. Determine the optical power budget for the 155Mbps port and cable size using Table 11 and
Table 12 on page 201.
2. Verify that the overall power loss in the 155Mbps link due to connectors, splices, fiber cable type,
patch panels, and jumper cables is less than the optical power budget.
Each step is described in the following sections.
Note: When you use fiber cable, the (conservative) recommended distances between workgroup switch
ports and transceivers are:
Multimode fiber 2 kilometers (1.24 miles)
Single mode fiber 20 kilometers (12.4 miles)
If the distance is greater than two kilometers (for multimode) or twenty kilometers (for single mode), you
must carefully calculate the total power loss across the link to make sure that it does not exceed the total
power budget.
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IBM 8285 Nways ATM Workgroup Switch: Installation and User’s Guide