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| 6.5 |  | Multiarea OSPF Operation |
| 6.5.7 |  | Opaque LSAs |

Opaque LSAs provide a means to allow for the future extensibility of OSPF. The information contained in opaque LSAs may be used directly by OSPF or indirectly by applications wishing to distribute information throughout an OSPF domain. For example, the OSPF opaque LSA may be used for traffic engineering with MPLS.

Opaque LSAs are Types 9, 10, and 11 link-state advertisements. Opaque LSAs consist of a standard LSA header followed by a 32-bit aligned application specific information field. Like any other LSA, the opaque LSA uses the link-state database distribution mechanism for flooding this information throughout the topology. The link-state type field of the opaque LSA identifies the topological distribution range of LSA. This range is referred to as the flooding scope.

The flooding scope associated with each opaque link-state type is defined as follows:

- Link-state Type 9 denotes a link-local scope. Type 9 opaque LSAs are not flooded beyond the local network or subnetwork.
- Link-state Type 10 denotes an area-local scope. Type 10 opaque LSAs are only flooded within their associated area.
- Link-state Type 11 denotes that the LSA is flooded throughout the entire Autonomous System (AS). The flooding scope of Type 11 LSAs is equivalent to the flooding scope of AS-external, Type 5, LSAs.