Common link-state advertisement (LSA) types of OSPF are as follows:
- Type 1 LSA: router LSA;
- Type 2 LSA: network LSA;
- Type 3 LSA: summary LSA;
- Type 4 LSA: ASBR-summary LSA;
- Type 5 LSA: AS-external-LSA;
- Type 7 LSA: NSSA AS-external-LSA
The original OSPF packet coding is not Type Length Value (TLV)-based. For the extension of OSPF functions, only the LSA types of OSPF can be extended.
Type 6 LSAs are Group-Membership-LSAs used to identify multicast group membership in the Multicast Open Shortest Path First (MOSPF) protocol. Type 6 LSAs are not supported on the switch.
Type 8 LSAs are External-Attributes-LSAs used to redistribute Border Gateway Protocol (BGP) routes into OSPF and reserve the BGP autonomous system (AS) path information. Type 8 LSAs are not supported on the switch.
RFC 2370 defines an important LSA type, namely, Opaque LSA, which allows for TLV-like structures. OSPF applications, such as OSPF traffic engineering, are based on the Opaque LSA extension abilities:
- Type 9 LSAs are Opaque LSAs that are advertised within the local link only;
- Type 10 LSAs are Opaque LSAs that are advertised within the local area only;
- Type 11 LSAs, similar to Type 5 LSAs, are Opaque LSAs that are advertised within the local AS.
