In this post, I will show you a LAB how you can manipulate the OSPF Hello packets in Cisco IOS and check how the OSPF neighborship will be lost between the 2 OSPF routers.
Here are the points of the LAB with the LAB scenario:
1. All IP addresses are already configured as on the picture
2. Ping from R1 to Eth0/0 of R2. Do you have a reply?
3. Configure OSPF on R1 and advertise the connected network.
4. Configure OSPF on R2 and advertise the connected network.
5. Check if both routers formed neighborship in OSPF.
6. Change the hello interval on R2 to 12 sec. Do the routers have neighborship?
7. Change the hello interval on R2 back to 10 sec. Is the neighborship formed again?
8. Put R2 in area 1. Did the 2 routers lose their neighborship?
9. Put R2 is area 0 again and check whether R1 and R2 formed neighborship again.
10 .Change the authentication in R2 from none to plain-text and put a password of 123456.
11. Did R1 and R2 lose neighborship?