What are the different types of link-state advertisements (LSAs) that will be used in Open Shortest Path First (OSPF)?
The following are the types of LSAs you would usually find in an OSPF network:
LSA types found in OSPF networks
|Type 1||router LSA||A router sends this to describe neighbors and its own interfaces.|
|Type 2||network LSA||For broadcast networks only; this LSA is flooded by the DR and lists OSPF-speaking routers on the network.|
|Type 3||network summary LSA||Sent by an ASBR to advertise networks reachable through it. A stub area router will also use this for the default route.|
|Type 4||ASBR-summary LSA||Sent by ASBR, but only internally. This describes to the others how to get to the ASBR itself, and uses only internal metrics.|
|Type 5||AS-external LSA||Used to describe external routes to internal areas. Can be used to advertise "this is the way to the Internet" (or some subset of).|
|Type 6||Group summary||Used in multicast (MOSPF). Ignore this.|
|Type 7||NSSA area import.|
|Type 8||External Attributes LSA||This is very rarely deployed and is used when BGP information is carried across OSPF AS.|
|Type 9, 10, 11||All are Opaque LSAs.||They are designated for future specifically for application specific purposes.|
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