Chapter 11
IPv6 Multicast Configuration
Table of Contents
11.1 IPv6 Multicast Overview
Introduction to Multicast
As a replacement of IPv4, IPv6 uses 128–bit address structure to solve the problem of IP
address shortage. Meanwhile, IPv6 optimizes some characteristics. IPv4 multicast solves
the problem of single-point sending and multi-point receiving, and it realizes high-efficiency
point-to-multipoint data transmission. It saves a lot of network bandwidths and reduces
network load. Therefore, multicast is applied and enhanced in IPv6.
The most obvious difference between IPv6 multicast and IPv4 multicast is that IPv6
multicast address mechanism is improved. The group member management, multicast
packet forwarding and multicast path establishment of IPv6 are similar to those of IPv4.
Multicast Address
An IPv6 address is of 128–bit long, divided by colons into eight bytes with four hex numbers
in each byte, such as FEDC:BA98:7654:3210:FEDC:BA98:7654:3210. An IPv6 multicast
address identifies a group of interfaces that belong to different nodes. A node can belong
to 0 or several multicast groups. A packet sent to a multicast address is received by all
interfaces identified by the multicast address.
According to RFC 4291, some IPv6 multicast addresses have been allocated permanently,
as described in
Table 11-1 IPv6 Multicast Address Allocation
Name
Address
Description
Reserved multicast address
FF0x::
Not allocated to any multicast
address
All node multicast addresses
FF01::1 (node-local)
FF02::1 (link-local)
-
All router multicast addresses
FF01::2 (node-local)
FF02::2 (link-local)
FF05::2 (site-local)
-
11-1
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