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Configuring IPv6 IPv6 Overview
OmniSwitch 6600 Family Network Configuration Guide April 2006 page 15-5
IPv6 Addressing
One of the main differences between IPv6 and IPv4 is that the address size increased from 32 bits to 128
bits. Going to a 128-bit address also increases the size of the address space to the point where running out
of IPv6 addresses is not a concern.
The following types of IPv6 addresses are supported:
Unicast—Standard unicast addresses, similar to IPv4.
Multicast—Addresses that represent a group of devices. Traffic sent to a multicast address is delivered to
all members of the multicast group.
Anycast—Traffic that is sent to this type of address is delivered to one member of the anycast group. The
device that receives the traffic is usually the one that is easiest to reach as determined by the active rout-
ing protocol.
Note. IPv6 does not support the use of broadcast addresses. This functionality is replaced using improved
multicast addressing capabilities.
IPv6 address types are identified by the high-order bits of the address, as shown in the following table:
Note that anycast addresses are unicast addresses that are not identifiable by a known prefix.
IPv6 Address Notation
IPv4 addresses are expressed using dotted decimal notation and consist of four eight-bit octets. If this
same method was used for IPv6 addresses, the address would contain 16 such octets, thus making it diffi-
cult to manage. IPv6 addresses are expressed using colon hexidecimal notation and consist of eight 16-bit
words, as shown in the following example:
1234:000F:531F:4567:0000:0000:BCD2:F34A
Note that any field may contain all zeros or all ones. In addition, it is possible to shorten IPv6 addresses by
suppressing leading zeros. For example:
1234:F:531F:4567:0:0:BCD2:F34A
Another method for shortening IPv6 addresses, is known as zero compression. When an address contains
contiguous words that consist of all zeros, a double colon (::) is used to identify these words. For exam-
ple, using zero compression the address 0:0:0:0:1234:531F:BCD2:F34A is expressed as follows:
::1234:531F:BCD2:F34A
Address Type Binary Prefix IPv6 Notation
Unspecified 00...0 (128 bits) ::/128
Loopback 00...1 (128 bits) ::1/128
Multicast 11111111 FF00::/8
Link-local unicast 1111111010 FE80::/10
Site-local unicast 1111111011 FEC0::/10
Global unicast everything else