RouteExplorer™ Tutorial – Monitoring and Alerts

Monitor the redundancy between ASes

From large multi-AS enterprises to multi-homed enterprisesof all sizes to service providers with multiple peers, maintaining constantconnectivity between ASes is a business imperative.  Multiple BGP connection points between ASes for redundancyare the norm and monitoring the availability of these routes is key.

 

Like IGP prefix monitoring discussed above, Route Explorercan provide unmatched capability in watching, analyzing and alerting on BGPprefix redundancy.  Route Explorerautomatically calculates a baseline of stable prefixes over several days.  Figure1illustrates an example AS redundancy report.  The report shows all reachable ASes from this network, thenext hops for each redundant path and the AS-PATH.

 

Figure 1

In this example, the report has been sorted to show theprivate ASes at the top.  Note thatthere are several.  Two aredirectly connected and others via a transit provider at multiple peeringpoints.  Also note that one of theprivate AS’s connection is not redundant.

 

Let us assume that this network that Route Explorer ismonitoring provides transit for the two directly connected private ASes, whichmay be business units of an enterprise or research labs associated with auniversity.  If transit is indeedbeing provided for these networks, making sure that the two connections fromeach are always available is very important. Route Explorer’s UI helps youlocate the prefixes advertised from these ASes.  Figure 2shows a list of neighbor ASes (at left), including the two private ASes and allthe routes from one of them (at right).

 

 

Figure 2

Based on its learned baseline of prefixes and ASconnectivity, Route Explorer can help monitor redundancy to these prefixes. Figure3shows the configuration of Route Explorer’s BGP Lost Redundancy Alert.

 

Note that any level of redundancy that you consider to be“impaired” can trigger the alert, not just singly connected.  Also note that there is a watch listassociated with this alert.  Sincethe total number of BGP prefixes in the full Internet route table can be verylarge, Route Explorer requires the user to select the specific prefixes towatch.

 

Figure 3

Watching the history of BGP routes, learning a baseline ofstable routes, and generating proactive prefix redundancy alerts from thisknowledge is a capability not available from any network management solutionother than Route Explorer.  Havingthis capability can mean substantially reduced risk of outage in your BGP-connectednetworks and much higher ROI on the investment you’ve made in redundancy.

 

HOW TO:

  1. To see BGP Baseline AS redundancy, go to Route Explorer’s BGP reports web page
    1. Select the report by clicking on the “Baseline AS Reachability” link
    2. Select a database from the DB drop-down menu
    3. Select the time of the baseline (“latest” or a time in the past)
    4. Click “Submit Query”
  2. To see the neighbor ASes in the Route Explorer UI and get a list of route from each:
    1. Open the Route Explorer UI
    2. Open the online and recording network topology
    3. To access the RIB Browser, open Tools-> History Navigator
    4. In the History Navigator window, click “Analysis” drop down menu and select “RIB Browser”
    5. The current RIB will be analyses and summarized in a window.
    6. Click the “NeighAS” tab at the left.
    7. Select the AS of interest, and right click on the row
    8. Select Show Details in the pop-up menu.  A second window will appear with the list of prefixes from that AS.
  3. To place a prefix from the neighbor AS on the BGP Prefix Redundancy watch list be alerted, select “Bgp Lost Redundancy” in the Alerts page of the Route Explorer Admin page
    1. Select the alert notification options (SNMP and/or Syslog)
    2. Enter the number of next hops remaining when you wish to be alerted.  Normally this would be one.
    3. Enter the prefix you wish to watch into the watch list.
    4. 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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