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?
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.
Hellos are always multicast unless you configure an explicit neighbor.
All this is explained in the documentation that I recommend you to read.