Detailed introduction of IPV6 protocol

IPV6 is an innovation for IPv4, although most IPV6 routing protocols need to be redesigned or developed, IPV6 routing protocols have only a small change in relative IPv4. At present, various common unicast routing protocols (IGP, EGP) and multicast protocols have been supported by IPV6.

1 IPV6 Unicast routing protocol

IPV6 Unicast routing protocol implementations are similar to those in IPv4, some are simply extended on the original protocol (e.g., ISISV6, bgp4+), and some are entirely new (e.g., RIPng, OSPFv3).

1.1 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 for ripng.

In order to be applied in IPv6 network, the original RIP protocol is modified by RIPng:

UDP port number: Send and receive routing information using UDP's 521 port

Multicast address: Using Ff02::9 as a RIPng router multicast address in link-local scope

Routing prefix: using a 128-bit IPV6 address as the route prefix

Next hop Address: Use a 128-bit IPV6 address

1.2 OSPFv3

OSPFv3 is the OSPF version 3 abbreviation, mainly provides support for IPV6, followed by the standard RFC2740 (OSPF for IPV6). Compared with OSPFV2, OSPFv3 not only provide support for IPV6, but also fully consider the network independence and scalability of the Protocol, further rationalize the relationship between topology and routing, make the protocol logic of OSPF more simple and clear, and greatly improve the scalability of OSPF.

The main differences between OSPFv3 and OSPFv2 are:

Modified the type and format of the LSA to enable it to support publishing IPV6 routing information

Modify part of the protocol process to make it independent of the network protocol, greatly improving scalability

The main modifications include using Router-id to identify neighbors, using link-local (link-local) addresses to discover neighbors, making the topology itself independent of network protocols and facilitating future expansion.

Further straighten out the relationship between topology and routing

OSPFv3 the topology with the routing information in the LSA, the one or two-class LSA no longer carries routing information, but simply describes the topology information, and uses the new eight or nine-class LSA in conjunction with the original three-, five or seven-class LSA to publish the routing prefix information.

Improved protocol adaptability

By introducing the concept of LSA diffusion scope, the processing of the unknown LSA is further clarified, so that the protocol can deal with the need according to the requirement without the LSA, and greatly improve the adaptability of the Protocol to the future extension.

1.3 IS-ISV6

Is-is is a dynamic routing protocol CLNP released by ISO for its connectionless network protocol. Like BGP, Is-is can host routing information for both IPV4 and IPV6.

To enable the Is-is support IPV4,IETF to extend the Is-is protocol in RFC1195, it is named Integrated Is-is (integrated Is-is) or dual Is-is (Dual is-is). This new Is-is protocol can be applied simultaneously in both TCP/IP and OSI environments. On this basis, in order to effectively support the IPV6,IETF in the Draft-ietf-isis-ipv6-05.txt to further expand the Is-is, mainly is the new support IPV6 routing information Two TLV (Type-length-values) and a new NLP ID (Networklayer Protocol Identifier).

The TLV is a variable-length structure in the LSP (Link state PDUs), with the addition of two TLV, respectively:

IPv6 reachability (TLV type 236):

The type value is 236 (0xEC), which describes the accessibility of the network by defining information such as the prefix of the routing information, measures, and so on.

IPV6 Interface Address (TLV type 232):

The type value is 232 (0XE8), which corresponds to the "IP Interface address" TLV in IPv4, except that the original 32-bit IPV4 address is changed to 128-bit IPv6.

The NLP ID is a 8-bit field that identifies what network layer protocol the Is-is supports, and IPv6 corresponds to the Nlpid value (0x8E). If the Is-is router supports IPV6, it must carry the value in the hello message to the neighbor to advertise its support for IPV6.