OSPF LSA TYPES

OSPF uses LSAs or Link state Advertisements to share information of each network and populate the LSDB (Link State Database). The main LSA types are :

LSA Type 1 (Router LSA):generated by each router for each area it is located.

LSA Type 2  (Network  LSA): generated by DR , link-state ID will be the interface IP address of the DR.

LSA Type 3 (Summary LSA): generated by ABR’s and flooded into other areas throughout the Autonomous System.

LSA Type 4  (ASBR Summary LSA): generated by ABR’s. To find the ASBR by other routers, ABR will generate a summary ASBR LSA including the router ID of the ASBR in the link-state ID field.

LSA Type 5  (Autonomous System External LSA): generated by ASBR and contains routes to networks that are external to current AS.

LSA Type 6  (Multicast OSPF LSA): not supported and not used(Used only for multicast applications).

LSA Type 7  (NSSA External LSA): generated by the ASBR in a not so stubby area.

LSA Type 8 (External attributes LSA for BGP): Used to work with BGP.

LSA Type 9,10,11 (Opaque LSAs)

Below table summarizes OSPF LSA Types –

Related – OSPF CHEATSHEET