Cisco 2950 Software Configuration Guide - Page 270

Understanding LRE Features Chapter 13 Configuring LRE Table 13-2 LRE Profiles for the Catalyst 2950ST-24 LRE 997 Switches Profile Name LRE-12-9 LRE-12-3 LRE-9 LRE-9-6 LRE-9-4 LRE-9-3 LRE-6 (default) LRE-6-4 LRE-6-3 LRE-4 LRE-4-3 LRE Link LRE Link Upstream Rate Downstream Rate (Mbps) (Mbps) 12.500 9.375 12.500 3.125 9.375 9.375 9.375 6.250 9.375 4.688 9.375 3.125 6.250 6.250 6.250 4.6888 6.250 3.125 4.688 4.688 4.688 3.125 Theoretical Theoretical Minimum Minimum SNR SNR Downstream Upstream 31 25 31 13 25 25 25 19 25 16 25 13 19 19 19 16 19 13 16 16 16 13 Your data rates will always be less than the gross data rate listed in tables. A small percentage of the link rate is used by the Catalyst 2950 LRE switch for supervisory functions with the CPE device connected remotely. In general, profiles are named for the data rate that you expect to achieve and not the gross data rate as given in the table. All system-defined profiles have the prefix LRE, followed by the downstream user data rate and then the upstream user data rate. If the profile is symmetric, only one data rate is given. The two profiles defined to comply with public frequency usage plans 998 and 997 (LRE-998-15-4 and LRE-997-10-4) are exceptions to this. These two uniquely named profiles also work in any private deployment. • If you are not using sequences and you have not assigned a profile to an LRE port, the port has a default profile of LRE-10 or LRE-6 (see Table 13-1 and Table 13-2). Port profiles have priority over global profiles. If you assign a global profile to the switch, the switch uses the global profile except on any LRE ports on which a specific profile was assigned. When you assign a different profile to a switch LRE port, the port immediately resets and uses the newly assigned profile. • Use the LL profiles (LRE-5LL, LRE-10LL, and LRE-15LL) on the Catalyst 2950ST-8 LRE and 2950ST-24 LRE switches with care. These profiles have the low-latency (LL) feature enabled and the interleave feature disabled. The LL feature does not delay data transmission, but it makes data more susceptible to interruptions on the LRE link. All other profiles have the interleave feature enabled and the LL feature disabled. The interleave feature provides maximum protection against small interruptions on the LRE link but delays data transmission. For information on configuring the interleaving delay on the LRE ports, see the "Configuring LRE Interleave" section on page 13-20. • The symmetric profiles (LRE-5, LRE-10, LRE-15, LRE-8, LRE-7, LRE-4, LRE-3, and LRE-2) on the Catalyst 2950ST-8 LRE and the 2950ST-24 LRE switches provide full-duplex throughput on the link between the LRE switch and CPE device. Under ideal conditions, this can mean up to 30 Mbps of bandwidth on the LRE link if you are using the LRE-15 profile. 13-4 Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide 78-11380-10