Cisco 2950 Software Configuration Guide - Page 287

Chapter 13 Configuring LRE Configuring LRE Ports Step 4 Step 5 Step 6 Command end show controllers lre status interleave copy running-config startup-config Purpose Return to privileged EXEC mode. Verify the change. (Optional) Save your entries in the configuration file. 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 power back-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 carrier frequency of 4.8 MHz. • 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 reference 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: Step 1 Step 2 Command configure terminal lre upbo {noise-model | offset value} Purpose Enter global configuration mode. 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). 78-11380-10 Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide 13-21