Cisco WS-C2960S-24PD-L Software Guide - Page 218

Configuring the LRE Ports Chapter 7 Configuring the Switch Ports • We recommend using one of these six private profiles (LRE-5, LRE-10, LRE-15, LRE-10-1, LRE-10-3, and LRE-10-5) when the link between the LRE switch and the CPE does not need to coexist in the same cable bundle as Asymmetric Digital Subscriber Line (ADSL) signaling. For these profiles, the LRE downstream channel operates between 900 kHz and 3.5 MHz and between 4 MHz and 8 MHz. • The symmetric profiles (LRE-5, LRE-10, LRE-15) provide full-duplex throughput on the link between the LRE switch and CPE. Under ideal conditions, this can mean up to 30 Mbps of bandwidth on the LRE link if you are using the LRE-15 profile. Note Avoid using the symmetric profiles when the LRE switch and CPE link need to coexist in the same cable bundle with ADSL signaling. Cross talk and interference across wire pairs in cable bundles can degrade Ethernet performance. Note All POTS telephones not directly connected to the CPE require microfilters with a 300-ohm termination. Microfilters improve voice call quality when voice and data equipment are using the same telephone line. They also prevent nonfiltered telephone rings and nonfiltered telephone transitions (such as on-hook to off-hook) from interrupting the LRE connection. • We recommend using the ANSI and ETSI asymmetric public profiles for North America and other countries, respectively, when LRE signaling needs to coexist with ADSL signaling. We also recommend using a public profile when the PBX is not on-site and the POTS splitter directly connects to the PSTN. This guarantees that the LRE upstream frequency band cuts off at 5.2 MHz allowing the LRE upstream signal to be spectrally compatible with ADSL in the same cable bundle. Note LRE signaling can coexist with ADSL signaling in the same cable bundle. However, LRE signaling is not compatible with T1 signals in the same cable bundle. • The LRE link must have a minimum signal-to-noise ratio (SNR) to operate. Link is not established if the SNR is insufficient. Each profile requires a different minimum SNR ratio (Table 7-2). Table 7-2 Minimum SNR Ratios Profile Minimum SNR Public-ANSI Local 19 db, remote 25 db Public-ETSI Local 19 db, remote 25 db LRE-5 and LRE-5LL Local 13 db, remote 19 db LRE-10, LRE-10-1, LRE-10-3, LRE-10-5, and LRE-10LL Local 19 db, remote 25 db LRE-15 and LRE-15LL Local 25 db, remote 31 db Use the show controllers lre privileged EXEC commands to display the LRE link statistics and profile information on the LRE ports. For information about these commands, refer to the switch command reference. 7-20 Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide 78-6511-08