Module 7 OSPF - absentee-neptune/NET-330 GitHub Wiki

OSPF in Packet Tracer

Means Open Shortest Path First
It is a Link State Interior Gateway Protocol that does not use a Transport Protocol
It uses Areas to determine which routers listen and talk to each other

Step 1

Create an OSPF instance on the router
- >enable
- #conf t
- #(config)router ospf instance-number

Step 2

Add all of the Directly Connected Networks on that router with an Area
- #(config-router)network network-address wildcard-mask area #

OSPF Authentication

Two main methods of authentication:
- Plain Text
  - A password in plain text is added to the OSPF area which is used for OSPF routing traffic authentication
  - Plain Text Authentication is enabled with this command in each router OSPF configuration:
    - #(config-router)area 0 authentication
  - Then a password is set on all interfaces that use the same OSPF area:
    - #(config-if)ip ospf authentication-key password
- MD5
  - Uses a key and key-id. These are configured on the routers that are using them, which creates a hash value that is added to the appropriate routing traffic. The created hash value is what is used when authenticating OSPF routing traffic.
  - MD5 Authentication is enabled with this command in each router OSPF configuration:
    - #(config-router)area 0 authentication message-digest
  - Then a password is set on all interfaces that use the same OSPF area:
    - #(config-if)ip ospf message-digest-key 1 md5 password

Side Notes

There can be multiple networks on the same instance for the same Area
- For me, it only worked that way when configuring a network with one OSPF Area
The Area must be the same among all routers that need to share info within a particular instance
For the wildcard mask just switch the ones and zeros for the subnet mask

Commands to Help Check OSPF Information on the Router

#show ip ospf database
#show ip ospf interface ...
#show ip ospf instance-number
#show ip route
#show ip route ospf #