ECS3510-26P_Management Guide R02

C HAPTER 40 | IP Interface Commands
Interface Address Configuration and Utilities
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DEFAULT SETTING
No IPv6 addresses are defined
COMMAND MODE
Interface Configuration (VLAN)
COMMAND USAGE
◆ 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.
◆ 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 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.