Link-Local Addresses; Ipv4-Compatible Ipv6 Addresses - Cisco Nexus 7000 Series Configuration Manual

Chapter 3 Configuring IPv6
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m .
If no IEEE 802 interface types are in the router, link-local IPv6 addresses are generated on the interfaces
in the router in the following sequence:
1.
2.
3.

Link-Local Addresses

A link-local address is an IPv6 unicast address that can be automatically configured on any interface
using the link-local prefix FE80::/10 (1111 1110 10) and the interface identifier in the modified EUI-64
format. Link-local addresses are used in the neighbor discovery protocol and the stateless
autoconfiguration process. Nodes on a local link can use link-local addresses to communicate; the nodes
do not need globally unique addresses to communicate.
address.
IPv6 routers cannot forward packets that have link-local source or destination addresses to other links.
Figure 3-2
1111 1110 10
FE80::/10

IPv4-Compatible IPv6 Addresses

An IPv4-compatible IPv6 address is an IPv6 unicast address that has zeros in the high-order 96 bits of
the address and an IPv4 address in the low-order 32 bits of the address. The format of an IPv4-compatible
IPv6 address is 0:0:0:0:0:0:A.B.C.D or ::A.B.C.D. The entire 128-bit IPv4-compatible IPv6 address is
used as the IPv6 address of a node and the IPv4 address embedded in the low-order 32 bits is used as the
IPv4 address of the node. IPv4-compatible IPv6 addresses are assigned to nodes that support both the
IPv4 and IPv6 protocol stacks and are used in automatic tunnels.
IPv4-compatible IPv6 address and a few acceptable formats for the address.
OL-20002-02
The router is queried for MAC addresses (from the pool of MAC addresses in the router).
If no MAC addresses are available in the router, the serial number of the router is used to form the
link-local addresses.
If the serial number of the router cannot be used to form the link-local addresses, the router uses a
Message Digest 5 (MD5) hash to determine the MAC address of the router from the hostname of the
router.
Link-Local Address Format
0
10 bits
Cisco Nexus 7000 Series NX-OS Unicast Routing Configuration Guide, Release 4.x
Figure 3-2
128 bits
Interface ID
Information About IPv6
shows the structure of a link-local
Figure 3-3 shows the structure of an
3-5