"OSPFv3 requires functional extension beyond what can readily be done with the fixed-format Link State Advertisement (LSA) as described in RFC 5340. Without LSA extension@ attributes associated with OSPFv3 links and advertised IPv6 prefixes must be advertised in separate LSAs and correlated to the fixed-format LSAs. This document extends the LSA format by encoding the existing OSPFv3 LSA information in Type-Length-Value (TLV) tuples and allowing advertisement of additional information with additional TLVs. Backward-compatibility mechanisms are also described. This document updates RFC 5340@ ""OSPF for IPv6""@ and RFC 5838@ ""Support of Address Families in OSPFv3""@ by providing TLV-based encodings for the base OSPFv3 unicast support and OSPFv3 address family support."