OSPF and EIGRP hello on serial link

[bapatsubodh]

Hi,

When OSPF is enabled on serial point-to-point link how hellos are sent to other end router? Are hello packets are sent as multicasts?

If yes what is the IP address as destination and source ( source - most likely IP address of serial interface )

To form a neighbor relationship intial hellos are to be received from neighbor and periodic hellos are requred to sustain the already formed

adjacency.  What are the IP address of the hellos after adjacency is established or is it the same? Is it so that once adjacency is established hellos are sent as unicast to other end of router?

In short

Case 1. OSPF  Hello packet - source IP and Destination IP while adjacency is getting established ?

Case 2. OSPF Hello packet - soiurce IP and Destination IP after adjacency is established?

On similar lines how hellos are sent in EIGRP case?

Please share the experience.

Thanks

Subodh

[paolo bevilacqua · Accepted solution]

Hellos are always multicast unless you configure an explicit neighbor.

All this is explained in the documentation that I recommend you to read.

[vinodsharma7]

hello,

Ospf destination address for all routers: 224.0.0.5

ospf destination address for DR/BDR: 224.0.0.5

Eigrp multicast address : 224.0.0.10

thanks

vinod

[paolo bevilacqua]

small typo, ospf dr is 224.0.0.6

[Muhammad Anser Khan]

Dear Subodh,

You can also see the multicast packets by the following debug commands:

#debug ip packet detail

#debug ip ospf hello

Regards,

Anser

[Muhammad Anser Khan]

Dear Subodh,

You can also see the multicast packets by the following debug commands:

#debug ip packet detail

#debug ip ospf hello

Regards,

Anser