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Implementing OSPF for IPv6
Copyright © 2010, Juniper Networks, Inc.
OSPF version 3 (OSPFv3) specifies IPv6 support in the OSPF protocol. Compared with
OSPF version 2, the fundamental mechanisms for OSPF remain unchanged. These
mechanisms include the following:
OSPF designated router/border designated router election
OSPF adjacency maintenance
OSPF interface states, events, and interface state machine
OSPF flooding mechanism
OSPF LSA management
SPF calculation
Understanding the OSPFv3 Difference
OSPFv3 changes the way it describes the network topology. All addressing semantics
have been removed from the LSA header and from router-LSAs and network-LSAs. These
two LSAs now describe the topology of the routing domain in a
network-protocol-independent manner (using interface identifiers and router identifiers).
New LSAs have been added to distribute IPv6 address information and data required for
next-hop resolution.
In addition to the obvious address and processing modifications to handle IPv6 addressing,
changes in OSPFv3 include the following:
Authentication-related information is removed from the OSPF packet headers. Instead,
OSPFv3 uses an authentication header in IPv6.
OSPFv3 requires that each OSPF interface attached to a link be assigned a link-local
unicast address.
The option field for hello packets, database description (DD) packets, and LSAs has
been expanded from 8 bits to 24 bits. In addition, two new LSA types have been
added—link LSAs and intra-area prefix LSAs.
The LSA flooding scope is more explicit in OSPFv3 and now appears in the LS type
field. The LS type field also encodes a specific action to take for unknown LS types,
allowing OSPF to function with unknown LS types instead of simply discarding them.
The flooding process is modified to manage unrecognized LSAs and the new LSA
flooding scope.
The route calculation has been updated to handle modifications in the LSA database.
Supported LSA Types
OSPFv3 supports the following LSA types:
Chapter 5: Configuring OSPF
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