OSPF Lab Tips

  • When peering between a router and a switch, use ip/ipv6 ospf mtu-ignore under the interface otherwise adjacency may be stuck in the exstart state.
  • Good practice is to manually set the router ID e.g. for R1.
  • Make the frame-relay hub the ip ospf priority 255 and the spokes ip ospf priority 0
  • Use neighbour statements on the HUB or point-to-multicast network type when dealing with OSPF over Frame-Relay. The latter will show the hub as the next-hop where as neighbour statements won’t.
  • Virtual-Links will be treated as area 0 so do not forget authentication for area 0 etc for the virtual links.
  • auto-cost reference-bandwidth is the command to use to change globally how OSPF allocate cost to various interface speed e.g. 10Mbps, 100 Mbps etc. Usually Auto-cost Reference-bandwidth / Interface bandwidth will EQUAL OSPF Cost This can be verified with show ip ospft interface and look at cost to see if it has been changed. This will need to be done on EVERY OSPF ROUTER.
  • Anything really to do with LSA can been seen with show ip ospf and configured at the router-process with timers lsa arrival and timers pacing
  • Use domain-id to connect two different OSPF processes to appear at inter-area routes rather than external routes.

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