Cisco 10000 - Manual (Page 363)

C H A P T E R
17-1
Cisco 10000 Series Router Software Configuration Guide
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17
Configuring Link Noise Monitoring
About Link Noise Monitoring
Link Noise Monitoring (LNM) feature monitors noise associated with T1/E1 communication links
between a base transceiver station (BTS) and the aggregation node (AN).
T1/E1 links are leased spans (lines) from service providers. Noise in these lines causes data loss.
Significant data loss affects the voice quality. When notified of such issues the system operator can move
the faulty span out of service.
The LNM feature monitors link noise by determining whether the error parameter associated with the
selected link has exceeded its predefined threshold.
The LNM feature is described in the following sections:
• Restrictions for Link Noise Monitoring, page 17-1
• Configuration Tasks for Link Noise Monitoring, page 17-2
• Verification Example for Link Noise Monitoring, page 17-5
Restrictions for Link Noise Monitoring
The LNM feature has the following restrictions and limitations:
• The LNM feature is supported only on T1/E1 links.
• The use of a repeater removes errors at the physical layer (Layer 1) before passing the data, and
renders the LNM feature ineffective.
• LNM provides the option of monitoring errors through LCV or PCV values, or both. If the LCV
value is specified, the router calculates the PCV value by a liner extrapolation of the Gaussian Curve.
Because of the extrapolation, the calculated PCV value can be the same for two close LCV values.
• LNM can be enabled to issue a minor warning, a major warning or a removal. You cannot
simultaneously configure a major warning and a removal on the same T1/E1 link. The removal
functionality only works when the link is part of a multilink bundle.
Note We do not recommend link removals. The reason being, if two end points of a T1/E1 link
disagree about the status of the last T1 link, there exists the possibility of each end point
independently concluding that it is safe to remove the remaining links. This could result in the
last link being removed.