CISCO CCNA Exam – Q155

What are two enhancements that OSPFv3 supports over OSPFv2? (Choose two.)

A. It requires the use of ARP.
B. It can support multiple IPv6 subnets on a single link.
C. It supports up to 2 instances of OSPFv3 over a common link.
D. It routes over links rather than over networks.

Correct Answers: B, D

Here is a list of the differences between OSPFv2 and OSPFv3:

  • They use different address families (OSPFv2 is for IPv4-only, OSPFv3 can be used for IPv6-only or both protocols
  • OSPFv3 introduces new LSA types
  • OSPFv3 has different packet format
  • OSPFv3 uses different flooding scope bits (U/S2/S1)
  • OSPFv3 adjacencies are formed over link-local IPv6 communications
  • OSPFv3 runs per-link rather than per-subnet
  • OSPFv3 supports multiple instances on a single link, Interfaces can have multiple IPv6 addresses
  • OSPFv3 uses multicast addresses FF02::5 (all OSPF routers), FF02::6 (all OSPF DRs)
  • OSPFv3 Neighbor Authentication done with IPsec (AH)
  • OSPFv2 Router ID (RID) must be manually configured, still a 32-bit number