Which of the following statements concerning OSPFv3 is false?

The statement that NSSA (Not-So-Stubby Area) is not supported in OSPFv3 is false. OSPFv3 provides full support for NSSAs, which function similarly to their OSPFv2 counterparts. An NSSA allows an OSPF area to import external routes via a new LSA type (Type-7 LSA) while still blocking external routes (Type-5 LSAs) from other areas. This functionality is crucial for network designs that require controlled distribution of external routing information into stub areas. The NSSA feature in OSPFv3 is explicitly defined in its governing standard, RFC 5340.

A. MD5 Authentication is not supported. This statement is true. OSPFv3 removes the protocol-specific authentication fields found in OSPFv2 and instead relies on the underlying IPv6 protocol's security mechanisms, specifically IPsec (AH and ESP), for authentication and integrity.
B. Router LSAs do not carry IPv6 prefix information. This statement is true. OSPFv3 decouples topology information from address prefix information. Router LSAs (Type 1) and Network LSAs (Type 2) describe the network topology, while new LSA types, such as the Intra-Area Prefix LSA (Type 9), are used to advertise IPv6 prefixes.
D. OSPFv3 uses a 32-bit router ID. This statement is true. Despite being designed for IPv6, OSPFv3 retains the same 32-bit router ID format as OSPFv2. This ID must be unique within the OSPF domain and is typically represented in dotted-decimal notation.

1. IETF RFC 5340: OSPF for IPv6.

Correct Answer (C): Section 2.5, "NSSA areas," explicitly details the operation and support for Not-So-Stubby Areas in OSPFv3, including the use of Type-7 LSAs.

Incorrect Option (A): Section 2.3, "Differences from OSPFv2," states, "The OSPF packet authentication has been removed. The IPv6 Authentication Header [RFC4302] or IPv6 Encapsulating Security Payload Header [RFC4303] should be used to ensure integrity and authentication..."

Incorrect Option (B): Section 4.4.3.2, "Router-LSAs," describes the contents of the Type 1 LSA, which does not include address prefixes. Prefix information is detailed in Section 4.4.3.9, "Intra-Area-Prefix-LSAs."

Incorrect Option (D): Section 2.2, "The OSPFv3 protocol," specifies, "Each router in an OSPF routing domain is identified by a 32-bit Router ID."

2. Nokia 7750 SR OS Services, Routing, and MPLS Guide, Release 22.10.R1.

Correct Answer (C): In the "OSPFv3" chapter, under the "OSPFv3 Areas" section, the documentation confirms, "OSPFv3 supports the following area types: Standard areas, Stub areas, Not-So-Stubby-Areas (NSSAs)." This directly contradicts the claim in option C.

Incorrect Option (D): The "OSPFv3" chapter states, "OSPFv3 uses a 32-bit router ID to identify the originating router."