With IPv6, both the address shortage and the complicated conguration should be a
thing of the past. The following sections tell more about the improvements and benets
brought by IPv6 and about the transition from the old protocol to the new one.
13.2.1 Advantages
The most important and most visible improvement brought by the new protocol is the
enormous expansion of the available address space. An IPv6 address is made up of 128
bit values instead of the traditional 32 bits. This provides for as many as several
quadrillion IP addresses.
However, IPv6 addresses are not only different from their predecessors with regard to
their length. They also have a different internal structure that may contain more specic
information about the systems and the networks to which they belong. More details
about this are found in Section 13.2.2, “Address Types and Structure” (page 232).
The following is a list of some other advantages of the new protocol:
Autoconguration
IPv6 makes the network “plug and play” capable, which means that a newly set up
system integrates into the (local) network without any manual conguration. The
new host uses its automatic conguration mechanism to derive its own address
from the information made available by the neighboring routers, relying on a pro-
tocol called the neighbor discovery (ND) protocol. This method does not require
any intervention on the administrator's part and there is no need to maintain a central
server for address allocation—an additional advantage over IPv4, where automatic
address allocation requires a DHCP server or the usage of ARP and 169.254.0.0/16
addresses.
Nevertheless if a router is connected to a switch, the router should send periodic
advertisements with ags telling the hosts of a network how they should interact
with each other. For more information, see RFC 2462 and the radvd.conf(5)
manpage, and RFC 3315.
Mobility
IPv6 makes it possible to assign several addresses to one network interface at the
same time. This allows users to access several networks easily, something that
could be compared with the international roaming services offered by mobile phone
companies: when you take your mobile phone abroad, the phone automatically
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