Cisco® CCNA Exam Cram Notes : OSPFv3 for IPv6

X. Appendix

4. OSPFv3 for IPv6

OSPF for IPv6 is also known by OSPFv3. OSPF is an interior gateway protocol, widely used in both IPv4 and IPv6 networks.

The following are true about OSPFv3:

1. Multiple OSPF processes are supported as in OSPFv2

2. OSPFv3 supports IPv6 whereas OSPFv2 doesn't.

3. Uses multicast addresses FF02::5 and FF02::6

4. Type 3 and type 9 LSAs carry IPv6 prefix information, whereas IPv4 prefix information is carried in type 1 and type 2 LSAs

5. OSPFv3 uses the IPv6 multicast addresses FF02::5 (for all OSPF routers) and FF02::6 and are the multicast addresses used by OSPFv2.

6. OSPF for IPv6 requires the use of IPsec to enable authentication. The IPv6 AH (Authentication Hearder) and ESP extension headers are used to provide authentication and confidentiality to OSPF for Ipv6.

The correct sequence of steps required for enabling ospf in area 0 are (assuming that the interface Ethernet 0/0 is being configured):

Router#configure terminal
ethernet 0/0
Router(config-if)#ipv6 ospf
1 area 0

Note: The command ipv6 ospf <process-id> area <area-id> enables OSPF for IPv6 on an interface.

Configuration of OSPFv3 can also be accomplished through following commands

Router(config)#ipv6 router ospf <area-id>
Router(config-router)#router-id <router-id>

OSPF Packet Types:

1. LSA (Link State Advertisement): LSAs are included in the database description packets (DDPs or DBDs). LSA entries include link-state type, the address of the advertising router, the cost of the link, and the sequence number.

2. LSR ( Link State Request): When a slave router receives an DDP (Database Description Packet), it sends and LSAck packet. Then it compares the received information with the information it has. If the DDP has more recent information, the slave router sends a link-state request (LSR) to the master router.

3. LSU ( Link State Update): LSU packet is sent in response to LSR (Link-State Request) packet sent from a slave router to a master router. LSU contains complete information about the requested entry.

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