RFC 2080 describes changes to RIP to support IPv6 networks, called Routing Information Protocol next generation (RIPng). RIP mechanisms remain the same. RIPng still has a 15-hop limit, counting to infinity, and split horizon with poison reverse. Instead of using User Datagram Protocol (UDP) port 520, as RIPv2 does, RIPng uses UDP port 521. RIPng supports IPv6 addresses and prefixes. Cisco IOS software currently supports RIPng. RIPng uses multicast group FF02::9 for RIP updates to all RIP routers.
EIGRP for IPv6
Cisco has developed EIGRP support for IPv6 networks to route IPv6 prefixes. EIGRP for IPv6 is configured and managed separately from EIGRP for IPv4; no network statements are used. EIGRP for IPv6 retains all the characteristics (network discovery, DUAL, modules) and functions of EIGRP for IPv4. EIGRP uses multicast group FF02::A for EIGRP updates.
OSPFv3
RFC 5340 describes OSPFv3 to support IPv6 networks. OSPF algorithms and mechanisms (flooding, designated router [DR] election, areas, and shortest-path first [SPF] calculations) remain the same. Changes are made for OSPF to support IPv6 addresses, address hierarchy, and IPv6 for transport. Cisco IOS software currently supports OSPFv3.
OSPFv3 uses multicast group FF02::5 for all OSPF routers and FF02::6 for all DRs.
IS-IS for IPv6
Specifications for routing IPv6 with integrated IS-IS are described in RFC 5308: Routing IPv6 with IS-IS. The draft specifies new type, length, and value (TLV) objects, reachability TLVs, and an interface address TLV to forward IPv6 information in the network. IOS supports IS-IS for IPv6, as currently described in the draft standard. Multi-topologies for IS-IS are described in RFC 5120: M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs). M-ISIS allows for creating independent IP topologies within a single IS-IS domain. IPv4, IPv6, or IPv4/IPv6 may be configured on the interface for either Level 1, Level 2, or Level 1/2. But if IPv4 and IPv6 are configured on the same interface, they must be running the same IS-IS level. If IPv4 and IPv6 are sharing the same topologies with the same router levels, there is no need for multi-topology nor transition features.
BGP4 Multiprotocol Extensions (MP-BGP) for IPv6
RFC 2545 specifies the use of BGP attributes for passing on IPv6 route information. Multiprotocol BGP (MP-BGP) is also referred to as BGP4+. The MP_REACH_NLRI (multiprotocol-reachable) attribute describes reachable destinations. It includes the next-hop address and a list of Network Layer Reachability Information (NLRI) prefixes of reachable networks. The MP_UNREACH_NLRI (multiprotocol-unreachable) attribute conveys unreachable networks. IOS currently supports these BGP4 multiprotocol attributes to communicate reachability information for IPv6 networks.