Tuesday, May 7, 2013

OSPF Problem 3

Try to solve the lab problem in 10 minutes or less.
  • On SW1 enable OSPF area 27 on VLAN 27 and Loopback0 interfaces.
  • Do NOT use ‘network‘ statement or redistribution to accomplish the task.
  • On SW2 and R5 enable OSPF area 215 on their Loopback0 and all interfaces with VLAN 215 membership. Use ‘network‘ statement with the most specific wildcard mask to accomplish this.
  • Make sure SW2 is never elected a DR in VLAN 215. R1 should always be elected DR in case interfaces in VLAN 215 came up at the same time.


Extra Credit
Take as much time as you need to answer the following questions:
  1. Why does OSPF elect DR/BDR on certain types of networks?
  2. In what network types does OSPF elect DR/BDR?
  3. Does DR have to have full layer 2 reachability to other OSPF routers connected to the same segment? Why?
  4. What do we call a router that is neither DR nor BDR?
  5. If there are four routers connected to the same broadcast segment (the same broadcast domain), what are going to be OSPF states negotiated between them?
  6. In case of broadcast OSPF mode, what does LSDB show as far as the following are concerned (assuming default ospf mode): link connected to, link id, link data?
  7. What IP address is used when sending updates towards DR/BDR?
When you have solved the problem check the hint(s) below:

Lab Hint
  • Does R5 see R1 as the DR and SW2 as DROTHER?

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