RouteExplorer™ Tutorial – Monitoring and Alerts
Get alerted on possible routing instabilities, router configuration errorsor routing policy violations
Many network outages caused by routing instabilities,configuration errors or broken policy are accompanied by a high rate of networkevents. Consider:
- A BGP neighbor AS withdraws the full Internet routes when its border router goes down.
- A BGP peer coming back up similarly floods the full Internet routes
- A route oscillation occurs when route reflectors repeatedly announce the same route with different MEDs. Being internal to the AS, no flap dampening occurs.
- BGP routes are mistakenly flooded into the IGP
Event churn caused by these incidents may not be noticed ifhigh performance core routers are involved. But in most cases there is a route,prefix, customer or user that is experiencing an outage of service.
Based on a learned baseline of stable routes in the network,Route Explorer can watch for and alert on high churn events in BGP or IGP:
- BGP Prefix Flood alert – sent when the number of routes increases by a configured percentage from baseline.
- BGP Prefix Drought alert – sent when the number of routes is reduced by a configured percentage from baseline.
- IGP Excess Churn alert – sent when the rate of IGP events exceeds a configured maximum.
Figure 1illustrates the alert configurations.
Figure
HOW TO:
- To enable the BGP Route Flood or Drought alert, select appropriate link in the Alerts page of the Route Explorer Admin page
- Select the alert notification options (SNMP and/or Syslog)
- Enter the percent drop in the number of BGP routes from baseline (drought) or increase from baseline (flood) to trigger the alert, and click “Configure Threshold”
- To see the alert from Route Explorer, you must also enable it in your SNMP manager, or view it on your Syslog server
- To enable the IGP Excess Churn alert, select it in the Alerts page of the Route Explorer Admin page
- Select the alert notification options (SNMP and/or Syslog)
- Enter the event rate to trigger the alert and click “Configure Threshold”
- To see the alert from Route Explorer, you must also enable it in your SNMP manager, or view it on your Syslog server
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