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41
IP Interface Commands
ipv6 address eui-64
This command configures an IPv6 address for an interface using an EUI-64
interface ID in the low order 64 bits and enables IPv6 on the interface. Use the no
form without any arguments to remove all manually configured IPv6 addresses from
the interface. Use the no form with a specific address to remove it from the interface.
Syntax
ipv6 address ipv6-prefix/prefix-length eui-64
no ipv6 address [ipv6-prefix/prefix-length eui-64]
• ipv6-prefix - The IPv6 network portion of the address assigned to the
interface. The prefix must be formatted according to RFC 2373 "IPv6
Addressing Architecture," using 8 colon-separated 16-bit hexadecimal
values. One double colon may be used in the address to indicate the
appropriate number of zeros required to fill the undefined fields.
• prefix-length - A decimal value indicating how many contiguous bits (from
the left) of the address comprise the prefix (i.e., the network portion of the
address).
Default Setting
No IPv6 addresses are defined
Command Mode
Interface Configuration (VLAN)
Command Usage
• If a link local address has not yet been assigned to this interface, this
command will dynamically generate a global unicast address and a link-local
address for this interface. (The link-local address is made with an address
prefix of FE80 and a host portion based the router's MAC address in modified
EUI-64 format.)
• Note that the value specified in the ipv6-prefix may include some of the
high-order host bits if the specified prefix length is less than 64 bits. If the
specified prefix length exceeds 64 bits, then the network portion of the
address will take precedence over the interface identifier.
• If a duplicate address is detected, a warning message is sent to the console.
• IPv6 addresses are 16 bytes long, of which the bottom 8 bytes typically form
a unique host identifier based on the device's MAC address. The EUI-64
specification is designed for devices that use an extended 8-byte MAC
address. For devices that still use a 6-byte MAC address (also known as
EUI-48 format), it must be converted into EUI-64 format by inverting the
universal/local bit in the address and inserting the hexadecimal number FFFE
between the upper and lower three bytes of the of the MAC address.
For example, if a device had an EUI-48 address of 28-9F-18-1C-82-35, the
global/local bit must first be inverted to meet EUI-64 requirements (i.e., 1 for
globally defined addresses and 0 for locally defined addresses), changing 28
to 2A. Then the two bytes FFFE are inserted between the OUI (i.e., company
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