Link-state advertisements (LSAs)

OSPFv3 uses LSAs transmitted by each router to update neighboring routers regarding its interfaces and the routes available through those interfaces. Each routing switch in an area also maintains an LSDB that describes the area topology. (All routers in a given OSPFv3 area have identical LSDBs, and each router uses the LSDB to build its own shortest-path tree.) The routing switches used to connect areas to each other flood inter-area-prefix-LSAs, inter-area-router-LSAs, and AS-external-LSAs to backbone area to update it regarding available routes. Through this means, each OSPFv3 router determines the shortest path between itself and a desired destination router in the same OSPFv3 domain (AS). Routed traffic in an OSPFv3 AS is classified as one of the following:

Intra-area traffic
Inter-area traffic
External traffic

The routing switches support the LSAs listed in the following table. For more information, see RFCs and 3101 (for Type-7-LSA).

Table 15: OSPFv3 LSA types
LS type	Description	Use	Flood scope
0x2001	Router-LSA	Describes the state of each active interface on a router for a given area. (Excludes loopback interfaces and interfaces that have not achieved full adjacency.)	Area
0x2002	Network-LSA	Describes the OSPFv3 routers in a given network.	Area
0x2003	Inter-area-prefix-LSA	Describes the route to a prefix in another OSPFv3 area of the same AS. Propagated through backbone area to other areas.	Area
0x2004	Inter-area-router-LSA	Describes the route to an ASBR in another OSPFv3 normal area (including the backbone area) of the same AS. (Excludes prefixes for link-local addresses.) Propagated through backbone area to other areas. (Excludes any ASBR in the same area as the router sending the LSA.)	Area
0x4005	AS-external-LSA	Describes the route to a destination prefix in another AS (external route). (Excludes prefixes for link-local addresses.) Originated by ASBR in normal or backbone areas of an AS and propagates through backbone area to other normal areas. Does not flood over virtual links and is not summarized in virtual links. For injection into an NSSA, an NSSA ABR generates a type-7-default-LSA advertising the default route (::/0).	AS
0x2007	NSSA-LSA	Describes the route to a destination in another AS (external route). Originated by ASBR in NSSA. ABR translates type-7 LSAs to AS-external-LSAs for injection into the backbone area.	NSSA
0x0008	Link-LSA	For other routers on the same VLAN interface, describes the router's link-local address and any other IPv6 prefixes reachable on the VLAN. Link LSAs are not flooded over virtual links.	Link-local
0x2009	Intra-area-prefix-LSA	Generated on transit links within an area by the DR operating on those links. Also, every OSPFv3 router generates this LSA to refer to stub and loopback prefixes on the router.	Area

NOTE:

There is a software limitation for sending LSAs from OSPFv3 database to SNMP/CLI. A single query can take a maximum of 128 links. So, it is only viable to display up to 128 link entries per router LSA.