Dell Configuration Guide for the S4048–ON System 9.14.2.5

• Type 1: Router LSA — The router lists links to other routers or networks in the same area. Type 1 LSAs are flooded across their own area only. The link-state ID of the Type 1 LSA is the originating router ID.
• Type 2: Network LSA — The DR in an area lists which routers are joined within the area. Type 2 LSAs are flooded across their own area only. The link-state ID of the Type 2 LSA is the IP interface address of the DR.
• Type 3: Summary LSA (OSPFv2), Inter-Area-Prefix LSA (OSPFv3) — An ABR takes information it has learned on one of its attached areas and can summarize it before sending it out on other areas it is connected to. The link-state ID of the Type 3 LSA is the destination network number.
• Type 4: AS Border Router Summary LSA (OSPFv2), Inter-Area-Router LSA (OSPFv3) — In some cases, Type 5 External LSAs are flooded to areas where the detailed next-hop information may not be available. An ABR floods the information for the router (for example, the ASBR where the Type 5 advertisement originated. The link-state ID for Type 4 LSAs is the router ID of the described ASBR).
• Type 5: LSA — These LSAs contain information imported into OSPF from other routing processes. They are flooded to all areas, except stub areas. The link-state ID of the Type 5 LSA is the external network number.
• Type 7: External LSA — Routers in an NSSA do not receive external LSAs from ABRs, but are allowed to send external routing information for redistribution. They use Type 7 LSAs to tell the ABRs about these external routes, which the ABR then translates to Type 5 external LSAs and floods as normal to the rest of the OSPF network.
• Type 8: Link LSA (OSPFv3) — This LSA carries the IPv6 address information of the local links.
• Type 9: Link Local LSA (OSPFv2), Intra-Area-Prefix LSA (OSPFv3) — For OSPFv2, this is a link-local "opaque" LSA as defined by RFC2370. For OSPFv3, this LSA carries the IPv6 prefixes of the router and network links.
• Type 11 - Grace LSA (OSPFv3) — For OSPFv3 only, this LSA is a link-local “opaque” LSA sent by a restarting OSPFv3 router during a graceful restart.

For all LSA types, there are 20-byte LSA headers. One of the fields of the LSA header is the link-state ID.

Each router link is defined as one of four types: type 1, 2, 3, or 4. The LSA includes a link ID field that identifies, by the network number and mask, the object this link connects to.