Cisco 2950G 24 Software Configuration Guide - Page 262

Configuring LRE Ports Chapter 10 Configuring LRE Note The margin command is effective with any profile, but only in conjunction with rate selection and only when a link is being activated. LRE Link Persistence A brief LRE link down and up transition can cause the rest of the IOS modules to react immediately, for example, the Dynamic MAC addresses are removed from that ports table. You can use the link persistence feature to configure a delay duration on the Catalyst 2950 LRE of up to 20 seconds before link failure is reported. Step 1 Step 2 Command configure terminal interface LRE-interface Step 3 persistence time Step 4 end Step 5 show controllers lre status persistence Purpose Enter global configuration mode. Enter interface configuration mode, and enter the number of the LRE port to be configured. Enter the length of time (in seconds) you wish to set for the persistence. (The default is 3 seconds) Return to privileged EXEC mode. Verify the change. Refer to the lre persistence reference pages in the Catalyst 2950 Desktop Switch Command Reference for further details. LRE Link Monitor You can use the link monitor feature to track undesirable or interesting conditions on a link and to take system-defined actions after certain thresholds are reached. The link monitor can track these conditions: • SNR, in decibels (db): The link must have a minimum SNR to function; a higher SNR value means a better noise margin on the link. Links are not establish if the SNR is insufficient. (See the "Link Qualification and SNR Margins" section on page 10-12 for more information.) • Reed-Solomon (RS) errors: The RS Forward Error Correction circuit corrects small bursts of errors so that noise events do not cause Ethernet FCS errors. This is implemented in the octal chip as a 32-bit counter. The count resets on read. • Transmit (TX) Power, in dBm/Hz: This is fixed for the switch and adjusts automatically for the CPE device. The local transmit power is always constant and the same for a given profile. The remote transmit power varies according to distance from the switch to the CPE device, with a minimum transmit power of 91.9 dBm/Hz (corresponding to short distances) and a maximum transmit power of -55 dBm/Hz (corresponding to longer cable lengths or greater cable attenuation). The CPE device's power can reach its maximum at distances between 1500ft/450m and 3000ft/900m. • Software controlled Automatic Gain Control (SW AGC Gain), in dBm: This gives an indirect measure of the received power level. Higher values mean that the receive power is lower (and thus in need of more boost). 10-14 Catalyst 2950 Desktop Switch Software Configuration Guide 78-14982-01