HP-UX IPv6 Transport Administrator's Guide for TOUR 2.0 (April 2004, rev 2)

IPv6 Addressing and Concepts
Stateless Address Autoconfiguration
Chapter 6 61
Link-Local Address Assigned Automatically
A link-local address is formed by prepending the well-known link-local
prefix FE80::/10 to the interface identifier which is typically 64 bits long
and based on EUI-64 identifiers. Link-local addresses are sufficient for
allowing communication among IPv6 hosts attached to the same link.
Figure 6-3 shows the Primary Interface Autoconfiguration steps
performed after using the ifconfig command, which is as follows:
ifconfig lan0 inet6 up
Figure 6-3 Primary Interface Address Autoconfiguration
If you mark an interface “up” without assigning a primary address, the
system derives a link-local address by performing the following 4 steps:
1. Taking the LAN card’s 48-bit link-level address (“MAC address”
8:0:9:78:f3:39)
0000 1000 0000 0000 0000 1001 0111 1000 1111 0011 0011 1001
and putting it into an EUI-64 identifier by:
2. Putting two bytes (0xffee) into the middle (bit 24) of the 48-bit
link-level address 8:0:9:ff:fe:78:f3:39;
0000 1000 0000 0000 0000 1001 1111 1111 1111 1110 0111 1000 1111 0011 0011 1001
and flipping the Universal/local bit (as described in RFC 2373) to
form a 64-bit EIU-64 interface identifier a:0:9:ff:fe:78:f3:39
0000 1010 0000 0000 0000 1001 1111 1111 1111 1110 0111 1000 1111 0011 0011 1001
3. Prepending the well-known prefix fe80::/10
lan0
MAC Address
8:0:9:78:f3:39
Prefix
fe80::/10 =
lan0
Primary Link-Local
Address:
fe80::a00:9ff:fe78:f339
octets
0xfffe
+
0xfffe
into middle (bit 24) of
MAC address
1.
2.
3.
4.