Addressing
Compared to IPv4, the most obvious advantage of IPv6 is its larger address space. IPv4 addresses are 32 bits long and number about 4.3×109 (4.3 billion). IPv6 addresses are 128 bits long and number about 3.4×1038 (340 Undecillion). IPv6's addresses are deemed enough for the foreseeable future.
IPv6 addresses are written in eight groups of four hexadecimal digits separated by colons, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334. IPv6 unicast addresses other than those that start with binary 000 are logically divided into two parts: a 64-bit (sub-)network prefix, and a 64-bit interface identifier.
For stateless address autoconfiguration (SLAAC) to work, subnets require a /64 address block, as defined in RFC 4291 section 2.5.1. Local Internet registries get assigned at least /32 blocks, which they divide among ISPs. The obsolete RFC 3177 recommended the assignment of a /48 to end-consumer sites. This was replaced by RFC 6177, which "recommends giving home sites significantly more than a single /64, but does not recommend that every home site be given a /48 either". /56s are specifically considered. It remains to be seen if ISPs will honor this recommendation; for example, during initial trials, Comcast customers were given a single /64 network.
IPv6 addresses are classified by three types of networking methodologies: unicast addresses identify each network interface, anycast addresses identify a group of interfaces, usually at different locations of which the nearest one is automatically selected, and multicast addresses are used to deliver one packet to many interfaces. The broadcast method is not implemented in IPv6. Each IPv6 address has a scope, which specifies in which part of the network it is valid and unique. Some addresses are unique only on the local (sub-)network. Others are globally unique.
Some IPv6 addresses are reserved for special purposes, such as loopback, 6to4 tunneling, and Teredo tunneling. See RFC 5156. Also, some address ranges are considered special, such as link-local addresses for use on the local link only, Unique Local addresses (ULA) as described in RFC 4193, and solicited-node multicast addresses used in the Neighbor Discovery Protocol.
Read more about this topic: IPv6
Famous quotes containing the word addressing:
“A writer who writes, “I am alone” ... can be considered rather comical. It is comical for a man to recognize his solitude by addressing a reader and by using methods that prevent the individual from being alone. The word alone is just as general as the word bread. To pronounce it is to summon to oneself the presence of everything the word excludes.”
—Maurice Blanchot (b. 1907)
“He took up his pen, which seemed to parch like a martyr in his hand. He began to write, nevertheless, addressing the nine-and-ninety lies of the moment he hoped with for a night of saloperie at the side of the twisted strumpet, Fiction, who lasciviously rolled her eyes at him, hiked up her skirt, and beckoned him on.”
—Alexander Theroux (b. 1940)
“But what is quackery? It is commonly an attempt to cure the diseases of a man by addressing his body alone. There is need of a physician who shall minister to both soul and body at once, that is, to man. Now he falls between two stools.”
—Henry David Thoreau (1817–1862)