The characteristics of OSPF follow:
Link-state routing protocol.
Uses Dijkstra algorithm to calculate SPF tree, which is Built around a well-known algorithm from graph theory, E. W. Dijkstra's shortest path algorithm.
Uses IP protocol 89.
Classless protocol (supports VLSMs and CIDR).
Metric is cost, based on interface bandwidth by default (10^8 / BW in bps).
Sends partial route updates only when there are changes.
Use LSA messages, LSA are sent in a Sequence manner. ( sequence number )
Send hello packets every 10 sec with dead timer of 40 sec over P-P & BC networks.
Send hello packets every 30 sec with dead timer of 120 sec over NBMA networks.
If the network is stable and there have been no updates within 30 min (LSRefreshTime), a compressed update is sent.
MaxAge (60 min), LSRefreshTime (30 min) and MaxAgeDiff (15 min) are OSPF architectural constants.
LSRefreshTime is used to reset the MaxAge timer.
The numbering scheme is a 4-byte number that begins with 0x80000001 and ends with 0x7FFFFFFF.
Routes labeled as intra-area, interarea, external Type 1, or external Type 2.
Support for authentication.
Default administrative distance is 110.
Uses multicast address 220.127.116.11 (ALLSPFRouters).///mac adresss
Uses multicast address 18.104.22.168 (ALLDRouters). ).///mac adresss
The reply for the hello is done in a unicast way./////////
Up to 16 Links for load balance, Over equal Cost metric for same paths type default is 4 paths
Recommended for large networks.
For 2 routers to be adjacent :
1st. Hello packets must be sent & received.
2nd They must have the same hello & dead timers
also same Net ID with subnet mask.
3rd They must be in the same area.
Check attachment for more info.
Hope it might help