Internet Protocol version 6 (IPv6) is a network layer for packet-switched internetworks. It is designated as the successor of IPv4, the current version of the Internet Protocol, for general use on the Internet. The benefits of IPv6 include: 1) Increased IP Address Size, 2) Increased Addressing Hierarchy Support, 3) Simplified Host Addressing (unified addressing: global, site, local), 4) Simplified Autoconfiguration of Addresses (easier readdressing, DHCPv6), 5) Improved Scalability of Multicast Routing, 7) The Anycast Address, 8) Streamlined Header, 9) Better Mobility (home agent, care-of address, routing extension header), 10) Better Performance (aggregation, Neighbor Discovery instead of ARP broadcasts, no fragmentation, no header checksum, flow ,priority, integrated QoS), 1. The main change brought by IPv6 is a much larger address space that allows greater flexibility in assigning addresses. It was not the intention of IPv6 designers, however, to give permanent unique addresses to every individual and every computer. It is common to see examples that attempt to show that the IPv6 address space is extremely large. For example, IPv6 supports 2128 (about 3.4 - 1038) addresses or approximately 5- 1028 addresses for each of the roughly 6.5 billion people alive today. 2. The large number of addresses allows a hierarchical allocation of addresses that may make routing and renumbering simpler. As we learned earlier in the chapter, IPv6 addressing has restructured the means by which address blocks are delegated. IPv4 first used the classfull IP assignment rules, then began to assign based on the principles of Classless Inter-Domain Rouing (CIDR). IPv6 corrects the deaggregation problems associated with each of these by splitting the IPv6 address into a set of definite scopes, or bound-aries, by which IPv6 addresses are delegated. 3. Simplified Host Addressing As we studied earlier, the IPv6 model defines 128 bits of address space. The first 64 bits are used for network numbering, and the last 64 bits are used for host numbering. We also remember that the last 64 bits of the host ID are obtained from the MAC address of the host's Network Interface. 4. Simpler Autoconfiguration of Addresses One of IPv6's best perks for administrators is that not only is the Host ID determined prior to configuring an IPv6 speaking machine, but the network on which it resides can be deduced as well, making it possible for autoconfiguration to take place. Ex A multicast address can be simultaneously assigned to more than one machine. It differs from an anycast address in that anycast packets are routed to the closest destination (one of the set of machines with the same address), while multicast packets are routed to all machines that are assigned that address. This is fundamentally different than a Globally Routable Unicast address in that more than one host can be numbered with the same address, so the address that a given host is assigned need not necessarily be unique for the scope on which the multicast address is acting. 5. The Anycast Address IPv6 defines a new type of address, known as the anycast address. Although this form of address is deployed in a limited fashion in IPv4, IPv6 integrates this address type into its operations, which improves routing efficiency. An anycast address is an IPv6 address that is assigned to a group of one or more hosts, all of which serve a common purpose or function. When packets are sent to the IPv6 anycast address, routing will dictate which member of the group receives the packet via the machine closest to the source, as determined by the IGP of the network in question. (IGP is the Interior Gateway Protocol) 6. Security
1. Introduction to IPv6 Architecture Chapter 2 http://www.syngres.com/ pages 35, 41 - 53. 2. Could IPv6 Improve Network Security? And, If So, at What Cost? http://www.is-journal.org/ V02I02/2ISJLP231-Rowe%20and%20Gallaher.pdf pages 1,3. 3. IPv6-The Road Ahead http://www.ist-ipv6.org/pdf/ISTClusterbooklet2005.pdf pages 18. 4. IPv6- IPv4 Threat Comparison v1.0. http://www.cisco.com/security_services/ciag/documents/v6-v4-threats.pdf pages 6,16,25.
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