RouteExplorer™ Tutorial – Troubleshooting and Diagnostics

Where and when did the routing change?

If the routing between a user and the server is broken,route explorer can tell you exactly when and where the break occurred. In RouteExplorer’s topology map, highlight the prefix route as shown in the previousexample.  You may see no route, anincomplete route or a routing loop. In a previous example we showed how the list of highlighted paths couldlocalize the break. To find out when and how the route was broken, run theRoute Explorer’s history monitor backwards to time when the route was lastcomplete and prefix reachable.

 

Figure 1shows the history monitor.  Thecursor marks the time of display in the topology map.  Note the VCR-like controls at the bottom left. 

Figure 1

To replay the event history of the network, including anyhighlighted paths, select the “Animate” mode and click on the rewind button(left pointing single arrow).  Thenetwork map will be updated at each step including the highlighted paths.  When you see the path whole again,click the stop button (center). The map will show the complete route at that time.  The “current” time will be shown in thelower left of the history monitor.

 

If you continue to playback the animated replay of thenetwork, you may see more information pertaining to the problem, such as aflapping link in the highlighted path (or the prefix itself flapping).  At any point in this playbackdiagnosis, you may stop and look at the complete picture of the network at thattime, including the list of links, routers and prefixes.  Route Explorer can also show a summaryof events just prior to the outage.

Figure 2

Figure 2shows the event summary from history navigator’s event analysis menu.  Note that our prefix has actually seena significant number of events before the outage.  This may be a flapping route caused by failing hardware inthe server network.

 

Having thus localized the outage from Route Explorer’shistory playback, in the next section we show how to drill-down and see theexact routing events that took place before the outage.

 

HOW TO:

  1. Open an X Windows or VNC session to the Route Explorer.
  2. Open the topology of interest (see above)
  3. Highlight the prefix path of interest (see above)
  4. Open History Navigator:

§       Clickon Tools->History Navigator

§       Selectthe protocol of interest by clicking its tab at the top. See Figure3.

  1. Animate history:

§       Clickon the Animate radio button in the lower-left. (see Figure3)

Figure 3

§       Selectthe step size (default is 10 minutes)

§       Clickthe Left Arrow to start playback (Figure 3)

§       Tosee the changes to path during history playback, make sure the topology map isalso visible

§       Tostop playback, click on the stop button

  1. Events Analysis:

§       Inthe History navigator window click Analysis->Event Analysis

§       Selectthe time period start and end in the timeline.

§       Eventsummary window will be displayed.


 

 

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