RouteExplorer™ Tutorial – Monitoring and Alerts

Place important end-to-end service routes on a watch list and receivealerts when they reroute

There may be service paths of high importance in yournetwork such as a VoIP path between an IP PBX and a PSTN media gateway thatcannot tolerate increased delay resulting from a possible rerouting due to linkfailures.  There may be other hightraffic paths between ASes in your multi-domain network that normally traverseyour own transport network, but may on occasion be rerouted via a transitprovider that could be costing you extra money or may be traversing a lowbandwidth link.

 

The only way to monitor these situations until now has beenwith application level polling or “traceroute”. These methods are either costlyin terms of traffic added to the path or in the delay incurred by the pollingcycle.  Route Explorer can watchend-to-end paths and alert you instantly and without network overhead.

 

 

Figure 1

The end-to-end path illustrated in Figure 1 at left gets rerouted when a link fails, to the routeon the right.  The number of hopshas increased by one but the extra hop is going over a slower link with thepath latency having increased. Route Explorer can watch this end-to-end path and others including onesthat span AS boundaries, and send an alert when it reroutes – either due to alink outage or a metric change.  Figure2illustrates the alert configuration.

Figure 2

 

HOW TO:

  1. To enable watching the end-to-end routes, use the IGP Route Flap alert
  2. Select Route Flap in the Alerts page of the Route Explorer Admin page
  3. Select the alert notification options (SNMP and/or Syslog)
  4. Enter the flap frequency -- normally 1 per second
  5. Because the total number of end-to-end routes in even a small router network can be very large, Route Explorer requires the use of the watch list associated with this alert.  Enter the source and destination router for the end-to-end path to watch and click “update”
  6. 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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