Specifications

CHAPTER
26-1
Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR
OL-26895-01
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Configuring Link Noise Monitor
Noise on T1 and E1 links that span between the BTS and central office can affect voice quality for
mobile users to the point where it becomes unacceptable. To monitor the quality of individual links in a
multilink bundle, you can configure the Link Noise Monitor (LNM) on your Cisco MWR 2941 router.
The LNM detects, alerts, and removes noisy links from a bundle based on user-defined thresholds and
durations. In addition, the LNM notifies the operator once the quality of the line has improved, and
restores the link service if the link has been removed.
To detect noise on a link, the LNM monitors the following two types of errors which make up the Bit
Error Rate (BER) and compares the number of errors with the user-defined thresholds:
• Line Code Violation (LCV)—A Bi-Polar Violation (BPV) or Excessive Zeroes (EXZ) error has
occurred.
• Path Code Violation (PCV)—A Cyclic Redundancy Check (CRC) error, which is generally caused
by one or more LCV or logic errors, has occurred in a time slot.
The LNM provides the following types of noise monitors:
• Link Warning—Issues a warning when the noise level of a link exceeds a user-defined threshold and
notifies the operator when the noise level improves to the point that it drops below a second
user-defined threshold.
• Link Removal—Issues an error and removes a link from service when the noise level of the link
exceeds a user-defined threshold and restores the link and provides notification when the noise level
improves to the point that it drops below a second user-defined threshold.
Note If the noise level on the last active link in a multilink bundle exceeds the Link Removal
threshold, an alert is issued but the link will not be removed from service. If this situation
occurs, the standard T1 error rate is used to determine if the last active link must be
removed from service.
To configure the LNM feature, issue the span command from controller configuration mode of each T1
or E1 link in the bundle that you want to monitor. To disable LNM on a link, issue the no version of the
command from controller configuration mode of the link.
span { warn | remove } [ { [ lcv value [ pcv value ]] [ duration seconds ] } set | clear ]
where:
• warn—Enables Link Warning monitoring on the link.
• remove—Enables Link Removal monitoring on the link.