
IPv6 ◾ 105
e global routing prefix is 45 bits long, and the subnet ID is 16 bits long. e
remaining 64 bits are allocated to the interface ID and have the form of the EUI-
64 format.
Interface Identity
In all the ULAs, the lowest 64 bits of the IPv6 address field have been allocated as
the interface identity. is identity address field is allocated in several ways.
Using the 48-bit MAC, the interface ID can be auto-configured and expanded
to the required EUI-64 format. is ID can also be assigned using DHCPv6, or
manually configured or automatically generated using a pseudo-random format.
is helps in reducing the ease of interface ID piracy. e I ...