Configuring Link Noise Monitoring

Transcription

1 CHAPTER 19 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: Feature History of Link Noise Monitoring, page 19-1 Restrictions for Link Noise Monitoring, page 19-1 Configuration Tasks for Link Noise Monitoring, page 19-2 Verification Example for Link Noise Monitoring, page 19-5 Feature History of Link Noise Monitoring Cisco IOS Release Description Required PRE 12.2(33)XNE This feature was introduced on the Cisco series router for the following line cards. PRE3 and PRE4 1-port Channelized OC-12 line card 4-port Channelized OC-3/STM-1 line card 2-port Channelized OC-12 shared port adapter (SPA) Restrictions for Link Noise Monitoring The LNM feature has the following restrictions and limitations: 19-1

2 About Link Noise Monitoring Chapter 19 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. We do not recommend a low duration (set to a level as low as 4 seconds, when the default is set to 10). If the errors on the links fluctuate, the low duration value that is set triggers more events from the line card (LC) to the route processor (RP). The flood of syslog messages (if enabled) generated by the RP increases the load on the router CPU and the syslog server. A low duration value averages out errors and leads to inaccurate results. The Cisco series router only supports a maximum of 4000 TI links. An LC supports 336 T1 links and a SPA supports 772 T1 links. When many events are exchanged between the LC and RP, some events can get lost. The LNM feature does not account for lost events sent from the LC or SPA to the RP. If LNM is disabled on the T1/E1 link that is removed from the multilink bundle, the link can be added to the bundle through the LNM feature. If the ppp multilink links minimum num mandatory command is configured on an MLP bundle with LNM enabled on a member T1/E1 link, all links get removed from the bundle through LNM. Note If this command is configured, there is the danger of all links being removed from the bundle. The 2-port Channelized OC12/DS0 SPA only monitors the PCV count for LNM. Configuration Tasks for Link Noise Monitoring The LNM feature can be configured on thet1/e1 links of a line card or a SPA. To configure T1/E1 links on a SPA (2-port Channelized OC12 SPA) refer chapter Configuring a Channelized SPA in the Cisco Series Router SIP and SPA Software Configuration Guide. To configure T1/E1 links on a line card (1-port Channelized OC12 or 4-port Channelized OC3/STM-1 line cards) refer chapters 1-Port Channelized OC-12/STM-4 Line Card Configuration and 4-Port Channelized OC-3/STM-1 Line Card Configuration in the Cisco Series Router Line Card Configuration Guide. To configure the Link Noise Monitoring feature on a T1 link of a line card, perform the following configuration tasks: 19-2

3 Chapter 19 About Link Noise Monitoring Step 1 Command t1 t1-number channel-group channel-group-number timeslots list-of-timeslots Router(config-controller)# t1 1 channel-group 0 timeslots 1-24 Step 2 t1 t1-number span {minor-warn {remove major-warn}} [{[lcv value [pcv value]] [duration seconds]} set clear] Router(config-controller)# t1 1 span minor-warn lcv 20 pcv 10 duration 10 set Description Specifies the channel group and timeslots on a T1 interface. t1-number The T1 interface number from 1 to 28. Channel-group channel-group-number Identifies the channel group with any number from 0 to 23 Timeslots list-of-timeslots T1 is divided into 24 timeslots (or DS0s). Generates a minor-warn, a major-warn or a remove event based on the defined thresholds, for the T1 interface. t1-number The T1 interface number from 1 to 28. minor-warn Enables link warning (minor) monitoring on the link. major-warn Enables link warning (major) monitoring on the link. remove Enables Link Removal monitoring on the link. lcv value The Line Code Violation (LCV) threshold value in bit error per second. The valid range on a T1 link is 5 to 1544 seconds. The valid range on an E1 link is 7 to 2048 seconds. The default LCV value for minor-warn on a T1 link is 154 seconds and an E1 link is 205 seconds. The default LCV value for major-warn or removal on a TI link is 1544 seconds and an E1 link is 2048 seconds. pcv value Number of time slots in error per second. If not specified, this value is calculated from the LCV threshold based on a Gaussian distribution. The default PCV value for minor-warn on a T1 link is 145 seconds and an E1 link is 205 seconds. The default PCV value for major-warn or removal on a TI link is 320 seconds and an E1 link is 832 seconds. duration seconds The number of consecutive seconds that a threshold is exceeded or improved for a condition to occur. The valid range on a T1/E1 link is 4 to 600 seconds. The default value for T1 and E1 links is 10 seconds. set Specifies the set condition. Set is the default when no conditions are specified. clear Specifies the clear condition. Enabling Syslog Messages To enable the generation of syslog messages on a particular T1/TE1 link use the following command syntax. Use the no form of the command to disable generation of syslog messages. 19-3

4 About Link Noise Monitoring Chapter 19 Step 1 Command Router# t1 <1-28> span syslog Router# e1 <1-21> span syslog Description Generates syslog messages for the specified T1 link. A T1 link has 28 channels. An E1 link has 21 channels. Step 2 Router# t1 3 span syslog Router# no [e1 <1-21> span syslog] Router# no [t1 <1-21> span syslog] Disables generation of syslog messages for the specified T1/E1link. Router# no e1 3 span syslog For more information on the Link Noise Monitoring feature, see the Link Noise Monitoring feature guide. Configuration Examples for Link Noise Monitoring This section provides the following configuration examples: Example of LNM Configuration on a Line Card, page 19-4 Example of LNM Configuration on a Shared Port Adapter, page 19-5 Example of a Syslog Message, page 19-5 Example of LNM Configuration on a Line Card Example 1 shows how to configure the LNM feature on the 4-port Channelized OC-3/STM-1 and 1-port Channelized OC-12 line cards. Example 1 Sample Output of LNM Configuration on a Line Card Router# configure terminal Router(config)# controller sonet 7/0/0 Router(config-controller)# framing sonet Router(config-controller)# clock source internal Router(config-controller)# path 1 controller t3 Router(config-controller)# exit Router(config)# controller t3 7/0/0.1 Router(config-controller)# t1 1 channel-group 0 timeslots 1-24! Once a T1/E1 is created, LNM can be configured using 'span' CLI Router(config-controller)# t1 1? bert Start BERT test channel-group Specify a channel-group mapping on a T1 interface clock Specify the clock source for a T1 fdl Specify the Facility Data Link for a T1 framing Specify the type of Framing on a T1 loopback Put the T1 line into loopback span Noise monitor for managing noisy T1 spans Router(config-controller)# t1 1 span 19-4

5 Chapter 19 About Link Noise Monitoring Example of LNM Configuration on a Shared Port Adapter Example 2 shows how to configure the LNM feature ona 2-port Channelized OC12/DS0 SPA. Example 2 Sample Output of LNM Configuration on a SPA Router# configure terminal Router(config)# controller sonet 5/1/0 Router(config-controller)# framing sonet Router(config-controller)# clock source internal Router(config-controller)# sts-1 1 Router (config-ctrlr-sts1)# mode ct3 Router (config-ctrlr-sts1)# t1 1 channel-group 0 timeslots 1-24! Once a T1/E1 is created, LNM can be configured using 'span' CLI Router (config-ctrlr-sts1)# t1 1? channel-group Specify the timeslots to channel-group mapping for an T1 interface clock Specify the clock source for a T1 fdl Specify the Facility Data Link for a T1 framing Specify the type of Framing on a T1 loopback Put the T1 line into loopback shutdown Shut down a T1 interface (send AIS) span Noise monitor for managing noisy T1 spans <Ð= yellow Yellow Alarm Configuration for a T1 Example of a Syslog Message The following is a sample output of a generated fault notification on a serial interface: LNM-3- MINWARNEXCEED: Interface Serial7/0/0.1/1:0, noise exceeded above minor warning threshold. Verification Example for Link Noise Monitoring Example 3 shows the sample output when the LNM feature is configured. Use the show controllers t3 command to view the configuration information. Example 3 Sample Output for Verifying LNM Configuration Router# show controllers t3 7/0/0.1 lnm Channel Monitoring type Thresholds (lcv/pcv/duration) minor-warn (syslog disabled) Set(154 /145 /10 ) Clear(154 /145 /10 ) remove (syslog disabled) Set(1544/320 /10 ) Clear(1544/320 /10 ) 2 Channel not configured for E1/T1 3 Channel not configured for E1/T1 4 Channel not configured for E1/T1 5 minor-warn (syslog disabled) Set(154 /145 /10 ) Clear(154 /145 /10 ) 6 Link Noise Monitoring is disabled 7 Channel not configured for E1/T1 8 Channel not configured for E1/T1 9 Channel not configured for E1/T1 10 Channel not configured for E1/T1 11 Channel not configured for E1/T1 12 Channel not configured for E1/T1 13 Channel not configured for E1/T1 14 Channel not configured for E1/T1 19-5

6 About Link Noise Monitoring Chapter Channel not configured for E1/T1 16 Channel not configured for E1/T1 19-6