10-2
Catalyst 2950 Desktop Switch Software Configuration Guide
78-14982-01
Chapter 10 Configuring LRE
LRE Links and LRE Pr ofi les

LRE Links and LRE Profiles

The LRE link settings define the connection between the switch LRE port and the CPE RJ-11 wall port.
The LRE link provides symmetric and asymmetric bandwidth for data, voice, and video traffic.
Symmet ric transmission is when the downstream and upstream bandwidths are the same. Asymmetric
transmissio n is when the downstream and the upst ream ba ndwidth s differ. Downstream transmission
refers to the traffic going from the LRE switch to the CPE dev ice. Upstream transmis sion refers to the
traffic going from t he CPE device to the L RE swit ch .
The sw itch co nt rols up stream a nd downstream rat es on the L RE l ink by usi ng c on figuratio ns calle d
profiles. Dependi ng on the profile, the upstr eam and downstream bands on an LRE link can range from
appro ximatel y 1 Megabit per second (Mbps ) to 18.75 0 Mbps.
This section discusse s these topics:
•LRE Profiles, pag e 10-2
•LRE Seq uences, page 10-4
•CPE Ethernet Links, page 10-5

LRE P rofi les

You can assign prof iles on a per-port or switch-wide basis. When the LRE switch establishes a link with
the CPE device, the switch downloads its profile settings to the CPE device so that the switch and CPE
device operate w ith the sam e configuration.
The LR E switches are shipped w ith system-de fined profiles. You c an configure a profile on eithe r a
global or pe r-port ba sis. By de fau lt, al l LR E port s on the switc h a re en ab led with t he L RE -10 profile.
This default profile allows the upstream and downstream transmission rate on the LRE link to be
12.5 Mbps.
Table 10-1 contains the full list of LRE profiles, as well as their downstream and upstream rates (in Mbps
and their theoretical upstream and downstream signal-to-noise (SNR) rates (in decibels).
Note Consult the regulations for connecting to the PSTN in your area.
Note Use the rates and distances in Table 10-1 as guidelines only. Factors such as the type of cable that you
use, how it is bundled, and the interference and noise on the LRE link can affect the actual LRE link
performance. Contact Cisco Systems for information about limitations and optimization of LRE link
performance. The downstream and upstream rates in the table are slightly less than the gross data rates
displaye d by the show controllers lre profile names priv ileged EXEC command.