My CCNA Journy: Configuring OSPF (Exam topic 4-G)

How does OSPF work?

OSPF is much smarter than RIP. OSPF requires an ack.
How does it communicate once configured? It sends out a hello package
If both hello packets match then hello will be accepted by each router then a relation will form

What’s inside the hello package?

· Timer

Hello timer in seconds (must match on both end)

Dead timer (must match on both end)

· Area

Must match (area helps manage OSPF you must assign routers to area when using OSPF)

Area represents summarization

· Authentication

Must match

· Subnet mask

Must match

Turn on OSPF

1. Enter global config mode Use the following command router OSPF process_ID
Assigning a process ID
· chose a random number between 1-65535)
· process ID identifies the OSPF process on the router
· does not have to match on all routers but will be easier to identify if it is the same on all routers

2. Tell it what interface to send hello packets on A (setting interface to passive)
· You want to enable only on interfaces where you have a Router connected on the other end
· Set interface of network you want to advertise to passive using passive-interface command (Good practice to control which interface you will send hello packets)
· You can set all interface to passive by using the pass-int default then use the no passive-interface fas0/1 to set fas 0/1 to allow hello packets (or interface of your choice for hello packets)

4. Using the network command
· Use the command network 192.168.0.0 0.0.255.255 area 0 (using wildcard mask)
· Best practice is to turn on OSPF on specific interface ex net 192.168.1.1 0.0.0.0 area 0 (want to include multiple interfaces)