Cisco 500 Series, Configuration Manual

Page: 1043 / 1140

D-9
Cisco Security Appliance Command Line Configuration Guide
OL-12172-03
Appendix D Addresses, Protocols, and Ports
IPv6 Addresses
Figure D-1 IPv6 Multicast Address Format
IPv6 nodes (hosts and routers) are required to join the following multicast groups:
• The All Nodes multicast addresses:
–
FF01:: (interface-local)
– FF02:: (link-local)
•
The Solicited-Node Address for each IPv6 unicast and anycast address on the node:
FF02:0:0:0:0:1:FFXX:XXXX/104, where XX:XXXX is the low-order 24-bits of the unicast or
anycast address.
Note
Solicited-Node addresses are used in Neighbor Solicitation messages.
IPv6 routers are required to join the following multicast groups:
• FF01::2 (interface-local)
•
FF02::2 (link-local)
•
FF05::2 (site-local)
Multicast address should not be used as source addresses in IPv6 packets.
Note
There are no broadcast addresses in IPv6. IPv6 multicast addresses are used instead of broadcast
addresses.
Anycast Address
The IPv6 anycast address is a unicast address that is assigned to more than one interface (typically
belonging to different nodes). A packet that is routed to an anycast address is routed to the nearest
interface having that address, the nearness being determined by the routing protocol in effect.
Anycast addresses are allocated from the unicast address space. An anycast address is simply a unicast
address that has been assigned to more than one interface, and the interfaces must be configured to
recognize the address as an anycast address.
The following restrictions apply to anycast addresses:
•
An anycast address cannot be used as the source address for an IPv6 packet.
92617
128 bits
4 bits 4 bits
0 if permanent
1 if temporary
Interface ID 0
1111 1111
8 bits 8 bits
F F Flag Scope
Flag =
Scope =
1 = node
2 = link
4 = admin
5 = site
8 = organization
E = global