Comparison between OSPFv2 vs OSPFv3

OSPFv2 stands for Open Shortest Path First version 2 and OSPFv3 stands for Open Shortest Path First version 3. OSPFv2 is the IPv4’s OSPF version, whereas OSPFv3 is the IPv6’s OSPF version. In OSPFv2, many OSPF instances per interface are not supported, whereas in OSPFv3, many OSPF instances per interface are supported. 

There are few similarities present between OSPFv3 and OSPFv2, which are: 

1. Packet Type
2. Interface Type
3. Neighbor Discovery Pattern
4. LSA flooding & aging

Besides these similarities, there are some differences which are given below: 

S.NO	OSPFv2	OSPFv3
1.	OSPFv2 is the IPv4’s OSPF version.	While OSPFv3 is the IPv6’s OSPF version.
2.	The header size of OSPFv2 is 24 bytes.	While the header size of OSPFv2 is 16 bytes.
3.	OSPFv2 have seven link-state advertisement.	OSPFv3 have nine link-state advertisement.
4.	There is only one instance per link, in OSPFv2.	While there are many instances per link, in OSPFv3.
5.	In OSPFv2, many OSPF instances per interface are not supported.	Whereas in OSPFv3, many OSPF instances per interface are supported.
6.	There is no flooding space in OSPFV2.	While there is present flooding space in OSPFv3.
7.	OSPFv2 runs on subnets rather than links.	While OSPFv3 runs on links rather than subnets.
8.	Need network mask for adjacency formation.	Doesn’t need network mask for adjacency formation.
9.	MD5 Hashing is used for Authentication.	IPSec is used for Authentication.
10.	Nodes from different subnets can’t communicate.	Nodes from different subnets can communicate.