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7-2
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
OL-20002-02
Chapter 7 Configuring OSPFv3
Information About OSPFv3
OSPFv3 supports IPv6. For information about OSPF for IPv4, see Chapter 6, “Configuring OSPFv2”.
This section includes the following topics:
• Comparison of OSPFv3 and OSPFv2, page 7-2
• Hello Packet, page 7-2
• Neighbors, page 7-3
• Adjacency, page 7-3
• Designated Routers, page 7-4
• Areas, page 7-5
• Link-State Advertisement, page 7-5
• OSPFv3 and the IPv6 Unicast RIB, page 7-8
• Address Family Support, page 7-8
• Advanced Features, page 7-8
Comparison of OSPFv3 and OSPFv2
Much of the OSPFv3 protocol is the same as in OSPFv2. OSPFv3 is described in RFC 2740.
The key differences between the OSPFv3 and OSPFv2 protocols are as follows:
• OSPFv3 expands on OSPFv2 to provide support for IPv6 routing prefixes and the larger size of IPv6
addresses.
• LSAs in OSPFv3 are expressed as prefix and prefix length instead of address and mask.
• The router ID and area ID are 32-bit numbers with no relationship to IPv6 addresses.
• OSPFv3 uses link-local IPv6 addresses for neighbor discovery and other features.
• OSPFv3 can use the IPv6 authentication trailer (RFC 6506) or IPSec (RFC 4552) for authentication.
However, neither of these options is supported on Cisco NX-OS.
• OSPFv3 redefines LSA types.
Hello Packet
OSPFv3 routers periodically send Hello packets on every OSPF-enabled interface. The hello interval
determines how frequently the router sends these Hello packets and is configured per interface. OSPFv3
uses Hello packets for the following tasks:
• Neighbor discovery
• Keepalives
• Bidirectional communications
• Designated router election (see the “Designated Routers” section on page 7-4)
The Hello packet contains information about the originating OSPFv3 interface and router, including the
assigned OSPFv3 cost of the link, the hello interval, and optional capabilities of the originating router.
An OSPFv3 interface that receives these Hello packets determines if the settings are compatible with the
receiving interface settings.Compatible interfaces are considered neighbors and are added to the
neighbor table (see the “Neighbors” section on page 7-3).
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