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Supported LSA Types
OSPFv3 supports the following LSA types:
- Router LSA—Describes link state and costs of router
links to the area; flooded within an area only
- Network LSA—Originated by the designated router
for every broadcast or nonbroadcast multiaccess (NBMA) link having
two or more attached routers; lists all routers attached to the link
- Interarea prefix LSA—Known as the type-3 summary
LSA in OSPFv2; describes a prefix external to the area, yet internal
to the AS
- Interarea router LSA—Called type 4 summary-LSAs
in OSPFv2; describes a path to a destination OSPF router (that is,
an AS boundary router) that is external to the area, yet internal
to the AS
- AS-external LSA—Describes a path to a prefix external
to the AS
- Link LSA (new for OSPFv3)—Provides the router’s
link-local address to all other routers attached to the link; informs
other routers attached to the link of a list of IPv6 prefixes to associate
with the link; enables the router to assert a collection of options
bits in the Network-LSA to be originated for the link
- Intra-area prefix LSA (new for OSPFv3)—Associates
a list of IPv6 address prefixes with a transit network link by referencing
a network LSA, or associates a list of IPv6 address prefixes with
a router by referencing a router LSA
An LSA in OSPFv3 is still identified by its type,
link-state ID, and the advertising router ID. However, the link-state
ID (for all LSA types) no longer carries IP address information. Instead,
the LSA carries either an arbitrarily assigned number or an interface
ID.
The link-state ID always has a fixed length of
4 bytes. The LS type field is extended to 16 bits and encodes LSA
flooding scope and specific actions to take when the router encounters
unrecognized LS types.
An IPv6 address, if it is specified in an LSA, is represented
by its prefix length, prefix options, and prefix address.
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