System information

Command Line Interface
4-232
4
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 switch’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
id) and the rest of the address, resulting in a modified EUI-64 interface
identifier of 2A-9F-18-FF-FE-1C-82-35.
• This host addressing method allows the same interface identifier to be used
on multiple IP interfaces of a single device, as long as those interfaces are
attached to different subnets.