Technical Improvement of IPv4.

At present, the Internet is developing rapidly, and various technologies are constantly being updated and upgraded. As one of the new routing protocols, IPv6 routing plays an important role in it. IPv6 is an innovative solution for IPv4. Although most IPv6 routing protocols need to be re-designed or developed, IPv6 routing protocols have only a small change compared with IPv4. Currently, various common unicast routing protocols IGP and EGP have been supported by IPv6.

IPv6 Routing Protocol

The implementation of the IPv6 routing protocol is similar to that of IPv4. Some of them are simple extensions of the original routing protocol, such as ISISv6 and BGP4 +), and some are completely new versions, such, RIPng, OSPFv3 ).

RIPng

The next-generation RIP Protocol (RIPng) is an extension of the RIP-2 protocol in the original IPv4 network. Most RIP concepts can be used in RIPng. For IPv6 application, RIPng modifies the original RIP Protocol: UDP port: Use UDP port 521 to send and receive route information multicast address: Use FF02 :: 9 As the routing prefix of the RIPng vro multicast address in the local range of the link: Use a 128-bit IPv6 address as the routing prefix, And the next hop address: Use a 128-bit IPv6 address

OSPFv3

OSPFv3 is short for OSPF version 3. It mainly supports IPv6 and follows the RFC2740OSPF for IPv6 standard ). Compared with OSPFv2, OSPFv3 not only provides IPv6 support, but also fully considers Protocol Network independence and scalability to further streamline the relationship between topology and routing, this makes the IPv6 Routing Protocol logic simpler and clearer, and greatly improves the scalability of OSPF.

The differences between OSPFv3 and OSPFv2 include: modifying the LSA type and format, enabling it to publish IPv6 routing information, modifying some protocol flows, and making it independent from the network protocol, this greatly improves scalability. The main changes include the use of Router-ID to identify neighbors and the use of Link local Link-local) addresses to discover neighbors, so that the topology itself is independent of the network protocol, and facilitate future expansion. The relationship between the topology and the route is further streamlined. OSPFv3 separates the Topology from the route information in LSA. The first and second types of LSA do not carry the route information, but simply describe the topology information, in addition, the routing prefix information is published using the newly added Class 8 and 9 LSA combined with the original Class 3, 5, and 7 LSA.

Improved protocol Adaptability

By introducing the concept of LSA diffusion range, the processing of unknown LSA is further clarified, so that the IPv6 routing protocol can be properly handled as needed without recognizing LSA, this greatly improves the adaptability of the protocol to future expansion.

IS-ISv6

IS-IS an IPv6 Routing Protocol released by ISO for its connectionless network protocol CLNP. Like BGP, IS-IS can carry both IPv4 and IPv6 routing information. To enable IS-IS to support IPv4, IETF has extended the IS-IS protocol in RFC1195 and named it integrated IS-ISIntegrated IS-IS) or DUIs-ISDual IS-IS ). This new IS-IS protocol can be applied in both TCP/IP and OSI environments. In order to effectively support IPv6, IETF further expands IS-IS in draft-ietf-isis-ipv6-05.txt, two new TLVType-Length-Values that support IPv6 routing information and a new NLP IDNetwork Layer Protocol Identifier are added ). TLV is a variable-length structure in the LSPLink State PDUs. The two new TLVs are:

IPv6 reachabilitytlvtype 236 ):

The type value is 2360xEC). The network accessibility is described by defining the prefix and measurement value of the route information.

IPv6 Interface AddressTLV type 232 ):

Type value: 2320xE8), which is equivalent to "IP Interface Address" TLV in IPv4, but changes the original 32-bit IPv4 Address to 128-bit IPv6 Address. Nlp id is an 8-bit field that identifies which network layer IPv6 routing protocol IS supported by IS-IS, and the nlp id value corresponding to IPv6 IS 1420x8E ). If the IS-IS router supports IPv6, it must carry this value in the Hello message to inform the neighbor that it supports IPv6.