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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter13 Configuring LRE Configuring LRE Ports
To return the port to its default setting, use the no interleave downstream value upstream value
interface configuration command.
Configuring Upstream Power Back-Off
You can configure this feature only on a Catalyst 2950ST-24 LRE 997 switch.
The upstream power back-off mechanism allows for normalization of the upstream receive power levels
by requiring the CPE devices on shorter lines to send at a lower power level than the CPEs on longer
lines. You can change the upstream powe r b ack - off values by either selecting a standard noise model or
by setting an offset value for the default reference power spectral density (PSD).
Follow these guidelines for configuring upstream power back-off:
•The reference PSD number is based on an upstream carr i er f re quency o f 4.8 MH z.
•You can use the offset values to adjust the CPE transmit reference PSD relative to the default
reference of –140 dBm/Hz. A zero value for the offset corresponds to a ref eren ce PSD of
–140 dBm/Hz. The smallest offset is 30 dBm/Hz, and the corresponding value is 300.
When you enter the lre upbo global configuration command, all LRE links are reset to the UP state.
Before configuring the reference TX power level, follow these guidelines:
•Verify how this command affects the network in a lab environment.
•Make sure that all the CPEs in the production network are running the same LRE binary version.
Use the show controllers lre cpe version privileged EXEC command to display the binary version
on all CPE device interfaces.
Caution Changing the noise model while the switch is functioning in a network can disrupt the network
operation.
Beginning in privileged EXEC mode, follow these steps to configure upstream power back -off on a
Catalyst 2950ST-24 LRE 997 switch:
Step4 end Return to privileged EXEC mode.
Step5 show controllers lre status interleave Verify the change.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 lre upbo {noise-model | offset value} Enter the noise level or the offset value. Supported noise-model
values are etsi-a, etsi-b, etsi-c, etsi-d and etsi-f.
The offset value is calculated with reference to –140. For
example, if you require a reference PSD of –95 dbm/Hz, you need
to enter the offset of 45 (–95 – [–140] = 45). The supported value
range is 300 to 800.
Note The LRE CPE power spectral density (PSD) offset value
is in 10*dB (for example, 450 means 45 dB).