Training Learning IPv6 Routing Protocol from SPOTO.

The Internet connects everyone in the world. In Internet communication, IP addresses are the most important ones. Today, SPOTO talks about IPv6 routing protocols, understands Internet communication protocol knowledge, and has a deeper understanding of the entire Internet.

The initial unreasonable IP address planning in IPv4 makes the network very complicated and has a large number of routing table entries. Although this problem has been alleviated to some extent by subnetting and route aggregation, this problem still exists. Therefore, at the beginning of IPv6 design, the address was changed from user ownership to carrier ownership. On this basis, some changes have been made to the routing policy. In addition, the length of the IPv6 address has changed, so the routing protocol has changed accordingly.

Like IPv4, IPv6 routing protocols are also divided into Interior Gateway Protocol (IGP) and External Gateway Protocol (EGP). IGP includes RIPng changed by RIP, OSPFv3 changed by OSPF and IS-IS protocol changes. IS-ISv6. EGP is mainly BGP4+ from BGP.

First, RIPng

The next-generation RIP protocol (RIPng) is an extension of the original RIPv2. Most RIP concepts can be used for RIPng. In order to be applied in an IPv6 network, RIPng modified the original RIP protocol:

UDP port number: Send and receive routing information using port 521 of UDP.

Multicast address: Use FF02::9 as the multicast address of the RIPng router in the link-local range.

Route prefix: Use a 128-bit IPv6 address as the route prefix.

Next hop address: Use a 128-bit IPv6 address.

Second, OSPFv3

RFC 2740 defines OSPFv3 to support IPv6. The main differences between OSPFv3 and OSPFv2 are as follows:

1. Modified the type and format of the LSA to support the release of IPv6 routing information.

2. Modified some of the protocol processes. The main modifications include using Router-LD to identify neighbors, using link-local addresses to discover neighbors, etc., so that the network topology itself is independent of the network protocol for future expansion.

3. Further, rationalize the relationship between topology and routing. OSPFv3 separates the topology from the routing information in the LSA. The first- and second-class LSAs do not carry routing information, but only the topology description information. In addition, eight or nine types of LSAs are added, combined with the original three or five. Seven types of LSAs are used to advertise routing prefix information.

4. Improved protocol adaptability. By introducing the concept of LSA diffusion range, the processing flow of the unknown LSA is further clarified, so that the protocol can be properly processed according to the needs without identifying the LSA, and the scalability of the protocol is improved.

Third, BGP 4+

Traditional BGP 4 can only manage IPv4 routing information. For applications that use other network layer protocols (such as IPv6), it will be restricted when it is transmitted across autonomous systems. In order to provide support for multiple network layer protocols, the RFC2858 document released by the IETF has extended multi-protocol to BGP 4 to form BGP4+.

In order to support the IPv6 protocol, BGP 4+ must reflect the information of the IPv6 network layer protocol to the NLR1 (Network Layer Reachable Information) and Next Hop attributes. To this end, the following two NLRI attributes have been introduced in BGP4+.

MP_REACH_NLRI: Multi-protocol reachable NLRI for publishing reachable routes and next hop information.

MP_UNREACH_NLRI: Multi-protocol unreachable NLRI, used to revoke unreachable routes.

The Next Hop attribute in BGP 4+ is represented by an IPv6 address, which can be an IPv6 global unicast address or a link-local address of the next hop. The original messaging mechanism and routing mechanism of BGP 4 have not changed.

Fourth, the ICMPv6 agreement

The ICMPv6 protocol is used to report error messages that occur during IPv6 node processing and to implement simple network diagnostics. The newly added neighbor discovery function of ICMPv6 replaces the function of the ARP protocol, so there is no ARP protocol in the IPv6 architecture. In addition to supporting the IPv6 address format, ICMPv6 adds some new packet types to support route optimization, IP multicast, and mobile IP in IPv6.