BigIron RX Series Configuration Guide 105953-1001986-01Chapter42IPv6 AddressingThis chapter includes overview information about the following topics:• IPv6 addressing.• The IPv6 stateless autoconfiguration feature, which enables a host on a local link toautomatically configure its interfaces with new and globally unique IPv6 addresses associatedwith its location.IPv6 addressingA limitation of IPv4 is its 32-bit addressing format, which is unable to satisfy potential increases inthe number of users, geographical needs, and emerging applications. To address this limitation,IPv6 introduces a new 128-bit addressing format.An IPv6 address is composed of 8 fields of 16-bit hexadecimal values separated by colons (:).Figure 138 shows the IPv6 address format.FIGURE 138 IPv6 address formatAs shown in Figure 138, HHHH is a 16-bit hexadecimal value, while H is a 4-bit hexadecimal value.The following is an example of an IPv6 address.2001:0000:0000:0200:002D:D0FF:FE48:4672Note that the sample IPv6 address includes hexadecimal fields of zeros. To make the address lesscumbersome, you can do the following:• Omit the leading zeros; for example, 2001:0:0:200:2D:D0FF:FE48:4672.• Compress the successive groups of zeros at the beginning, middle, or end of an IPv6 addressto two colons (::) once per address; for example, 2001::200:2D:D0FF:FE48:4672.When specifying an IPv6 address in a command syntax, keep the following in mind:• You can use the two colons (::) once in the address to represent the longest successivehexadecimal fields of zeros.• The hexadecimal letters in the IPv6 addresses are not case-sensitive.As shown in Figure 138, the IPv6 network prefix is composed of the left-most bits of the address.As with an IPv4 address, you can specify the IPv6 prefix using the <prefix>/<prefix-length> format,where the following applies.Network Prefix Interface IDHHHH = Hex Value 0000 – FFFF128 BitsHHHH HHHH HHHH HHHH HHHH HHHH HHHH HHHH
