IBM 8265, Руководство по подготовке площадки

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IBM 8265: Planning and Site Preparation Guide
Verifying ATM Fiber Connections
To verify that a fiber connection is valid for ATM data transmission, you check that the
total power loss for a given link is less than the optical power budget for that link.
In the previous example, the total power losses for each link were:
The links between ATM Desktop A and 8265B, and 8265 C to ATM Desktop D are
valid, because the total power loss for the link is less than the optical power budget for
that link.
The link between 8265 B and 8265 C is invalid, because the total power loss is greater
than the power budget. If the link used singlemode fiber instead of multimode fiber,
then the connection would be valid because the power budget would be 13 (see Table
37 on page 59.
Maintaining Fiber Connections
After calculating the optical power loss for links and allowing for ‘worst case’
scenarios, the data transmission in the ATM connections in your network should be
reliable. To ensure that the optical power transmission does not exceed the optical
power budget and disrupt the quality of data transmission for your current fiber
configuration, IBM recommends that you:
•
Do not install additional links (for example, patch panels or jumper cables) in each
connection without verifying that the additional link will not cause the optical power
budget to be exceeded.
•
Maintain the homogeneity of links by using the same category of fiber cable for
each link of a connection.
•
When the margin between the total power loss on a connection and the optical
power budget is less than, or equal to, 1 dB, check with your vendor to make sure
you are using the power loss value set by the manufacturer for your cable, and
recalculate the total power loss including the variance value for each component.
The variance value for each optical fiber component (splices, connectors, cables,
and so on) is given in previous sections of this chapter.
Table 26. Verifying Fiber Link Validity (Example)
Link Total Power Loss (dBm) Optical Power Budget
ATM Desktop A
to
155Mbps Port in 8265 B 5.7 7.0
622Mbps port in 8265 B
to
622Mbps port in 8265 C 10.05 6.0
155Mbps port in 8265 C
to
ATM Desktop D 6.25 7.0