RouteExplorer™ Tutorial – Network Planning and Maintenance

Adding a secondary server – Will it be available after a primary serverfailure?

Another common design practice in today’s high availabilitynetworks is redundant servers -- DNS servers, IP Multicast Rendezvous Points(RPs), redundant backup and disaster recovery centers, etc. to name a few.  Route Explorer can be a great help inverifying the reachability of such redundant servers and tuning the network forload sharing between the redundant servers.  Here is an example.

 

Figure 1shows a network with two “anycast” DNS servers – servers with the same IPaddress.

 

Figure 1

Please note that the two servers are at prefixes128.32.136.9/32 and 128.32.136.12/32 and both of the routers 169.229.128.170 and169.229.128.130 are advertising both. However, router 169.229.128.130 is advertising both prefixes at aslightly lower cost (999 vs 1000). Route Explorer can show the preferred DNS server from all parts of yournetwork using the Tools -> Highlight Exit Router command.  Figure2shows the result for the server 128.32.136.9.  All “red” marked routers are using the DNS server off therouter 169.229.128.130.  All“green” routers use 169.229.128.170.

 

Figure 2

Route Explorer’s “what-if” capability can now show you theeffect of an outage on this accessibility map.  Figure 3shows the result of simulating a key router outage in the path to one of theDNS servers via router 169.229.128.130. Note that nearly all routers in the network are now using the “green”server. The same “what-if” analysis can be done with different link metrics tosee how they affect the network-wide reachability.

 

Figure 3

This is another example of Route Explorer’s unique networkplanning capabilities to help optimize the routing performance of the IPnetwork.

 

HOW TO:

  1. Open an X Windows or VNC session to the Route Explorer.  See Route Explorer User Guide Chapter xx.
  2. Click on File->Open Topology
  3. Select the topology domain “UCBJul03a” from menu and click Open.
  4. Show “Exit” Routers to “anycast” servers:
    1. Select Tools->Highlight By Exit Rtr…
    2. Enter the IP address (as a /32 prefix) and click “OK”
  5. Down a router:
    1. Right-click on a router
    2. Click “Down” in node pop-up
  6. Show all link/router simulated changes: Select Tools->List Router/Link Edits
  7. Restore edits:
    1. Click on “Restore All” in list of edits

Up the individual nodes via pop-up menu (right-click onitem)

 

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