OSPF Core Configuration

1. Configure OSPF for the above network diagram. R1 will acts as an ASBR by redistributing a series of static routes into the OSPF network. These routes should NOT increment their metric as they pass through the network and should have an initial OSPF cost of 200. All routers should have a router-id reflecting their hostname; you should be able to ping this router-id throughout the entire OSPF network.

2. After completing the initial step of the lab, one of the routers in Area0 will become the DR and one will become the BDR, for the Ethernet segment. Which router will become the DR and BDR? Write DR and BDR next to the respective router below.

  • R1
  • R2
  • R3

3. Ensure R1 becomes the DR on the Ethernet segment in Area 0. R2 and R3 should not become DR or BDR for the Ethernet segment in Area 0. After this change is made, what type of neighbor relationship should exists between R1 and R2? What about R2 and R3?

4. Implement summarization at the ABRs in the network to make the routing tables throughout the network as efficient as possible.

5. Implement summarization at the ASBR. The summary route should have the same attributes as the original, individual routes redistributed into the network.

6. The organization plans to upgrade to Gigabit Ethernet int he coming months. OSPF should accurately calculate its metric assuming Gigabit Ethernet will be fastest link in the network.


To configure the static route:
R1(config)# ip route null0
R1(config)# ip route null0
R1(config)# ip route null0
R1(config)# ip route null0
To redistribute:
R1(config)#router ospf 1
R1(config)# redistribute static subnets metric 200 metric-type 2



OS Notes (Draft Version)

Hello Guys, please have a look on this draft  version of Operating System notes. Complete version will be available within 2 weeks.







Open Shortest Path First


Boarder Gateway Protocol:

Routes Manipulation in Cisco Routers

Manipulating Route Updates:
Three ways:
1.using distribute lists.
3.using administrative distance
Since routing protocols sends all of the routes to its neighbor and you wants some of the route are to be filtered. For this you use any one of the methods for route manipulations.

1. distribute lists:

a. Distribute lists allows you to apply acl filtering to routing updates.
b. can be applied inbound and outbound under a routing process.
c. Works slightly different with OSPF and IS-IS (not outbound filter (All have same link state databases. distribute list only prevent network doesn’t appear in routing table.

1.create an acl
2.apply distribute-list either inbound or outbound


1. Network 10.501.0 and should not reach R2
2. Network and should not cross R2
(Distribute list is always associated with the ACL)
All of the routers are pre-configured with respective ip and routing protocols.

Task 1 solution:
R1(config)# ip access list standard ROUTE_FILTER
R1(config)# deny
R1(config)# deny
R1(config)# permit any
R1(config)# router rip
R1(config-router)# distribute-list ROUTE_FILTER out serial 0/0
If serial0/0 is not used it is applied to all of the interface of the router.
(Distribute-list is applied close to the source, It can also be applied in the router R2)