Precedence; Profile Locking - Cisco Catalyst 2950 Software Configuration Manual

Chapter 12 Configuring LRE
When rate selection is enabled, the LRE switch executes rate selection in these scenarios:
•
•
•
•
•
In any of these cases, rate selection obtains the optimal profile for your line conditions.
When an LRE link is lost for fewer than 25 seconds, the switch does not execute rate selection to
Note
re-establish the link. The link is re-established at the profile used before link loss.
The switch chooses the appropriate profile for an LRE interface when it executes rate selection. If line
conditions of the LRE interface change, rate selection must be executed again.

Precedence

The rate selection feature can be applied at both the port level and at the switch level. Profiles and
sequences have a system-defined priority level that work with rate selection to determine the rate for a
port or the entire switch. Port sequences have the highest priority; that is, they take precedence over any
other profile or sequence. The priority levels, from highest to lowest, are as shown:
1.
2.
3.
4.
See
page 12-5
commands to define your own sequences.
If rate selection is disabled for a port, profiles are used.
Note

Profile Locking

You can also use rate selection as an installation tool to lock in a particular profile. In this case, you
execute rate selection only once at installation; afterwards, rate selection is never executed, even if one
of the four listed events occur. You use the rate selection profile lock interface configuration command
to lock the profile chosen by rate selection. You can also enter the clear lre rate section [lock]
[interface-id] privileged EXEC command to rerun rate selection on the interfaces that have locked the
profiles, as needed.
An advantage to profile locking is that the convergence time during bootup is faster if a profile is locked
on an LRE port rather than having to go through a profile sequence.
Beginning in privileged EXEC mode, follow these steps to lock a profile in an LRE port that has rate
selection enabled:
78-11380-12
When the switch is started up
When you enable the rate selection feature
When you connect a new CPE device to the switch
When a link is lost for 25 seconds before being restored
When a configured sequence is modified
Port sequence: rate selection is enabled on the given port only with the given sequence.
Global sequence: rate selection is enabled for the entire switch with the given sequence.
Port profile: rate selection is enable for the given port only with the given profile.
Global profile: rate selection is enabled for the entire switch with the given profile.
Table 12-1 on page 12-3 and
and Table 12-4 on page 12-6
Table 12-2 on page 12-4 for the list of profiles and
for the list of system-defined sequences. You can also use CLI
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
Configuring LRE Ports
Table 12-3 on
12-15