This document defines enhancements to the OSPF protocol to support a new class of link state advertisements (LSAs) called Opaque LSAs. Opaque LSAs provide a generalized mechanism to allow for the future extensibility of OSPF. Opaque LSAs consist of a standard LSA header followed by application-specific information. The information field may be used directly by OSPF or by other applications. Standard OSPF link-state database flooding mechanisms are used to distribute Opaque LSAs to all or some limited portion of the OSPF topology. This document replaces RFC 2370 and adds to it a mechanism to enable an OSPF router to validate Autonomous System (AS)-scope Opaque LSAs originated outside of the router's OSPF area. [STANDARDS-TRACK]