Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 668)

IPv6 Introduction
Software Reference for x310 Series Switches
26.2 AlliedWare Plus TM Operating System - Version 5.4.4C C613-50046-01 REV A
Introduction
This chapter describes the main features of IPv6, the switch’s implementation of IPv6 and
how to configure and operate IPv6 on the switch.
This chapter describes the following IPv6 features:
■ linking together networks that run IPv6.
■ allowing address autoconfiguration of hosts connected to the switch.
Overview
IPv6 is the next generation of the Internet Protocol (IP). It has primarily been developed to
solve the problem of the eventual exhaustion of the IPv4 address space, but also offers
other enhancements. IPv6 addresses are 16 bytes long, in contrast to IPv4’s 4 byte
addresses. Other features of IPv6 include:
■ Address structure improvements:
« globally unique addresses with more levels of addressing hierarchy to reduce the
size of routing tables
« autoconfiguration of addresses by hosts
« improved scalability of multicast routing by adding a “scope” field to multicast
addresses
« a new type of address, the “anycast address”, which sends packets to any one of a
group of devices
■ Removes the need for packet fragmentation en-route, by dynamic determination of
the largest packet size that is supported by every link in the path. A link’s MTU
(Maximum Transmission Unit) must be at least 1280 bytes, compared with 576 bytes
for IPv4.
■ Includes a Traffic Class that allow packets to be labeled with an appropriate priority. If
the network becomes congested, the lowest priority packets are dropped.
■ Includes Flow labels that indicate to intermediate switches and routers that packets
are part of a flow, and that a particular flow requires a particular type of service. This
feature enables, for example, real-time processing of data streams. It also increases
routing speed because the forwarding router or switch needs only to check the flow
label, not the rest of the header. The handling indicated by the flow label can be done
by the IPv6 Hop-by-Hop header, or by a separate protocol such as RSVP.
■ Mandatory authentication and data integrity protocols through IPsec. IPsec is
optional in IPv4.