Reference Guide

Stateless autoconguration uses three mechanisms for IPv6 address conguration:
Prex advertisement Routers use router advertisement messages to announce the network prex. Hosts use their interface-identier
MAC address to generate a valid IPv6 address.
Duplicate address
detection
An IPv6 host node device checks whether that address is used anywhere on the network duplicate address
detection (DAD) before conguring its IPv6 address.
Prex renumbering Transparent renumbering of hosts in the network when an organization changes its service provider.
As an alternative to stateless autoconguration, network hosts can obtain their IPv6 addresses using DHCP servers via stateful
autoconguration.
IPv6 provides the exibility to add prexes on router advertisements (RA) to advertise responses to router solicitations (RS). RA response
messages are sent when an RS message is received by default. The system manipulation of IPv6 stateless autoconguration supports the
router side only. Neighbor discovery (ND) messages advertise so the neighbor can use this information to auto-congure its address.
Received ND messages are not used to create an IPv6 address.
Inconsistencies in router advertisement values between routers are logged. The values checked for consistency include:
• Current hop limit
• M and O ags
• Reachable time
• Retransmission timer
• MTU options
• Preferred and valid lifetime values for the same prex
The router redirect functionality in the NDP is similar to IPv4 router redirect messages. NDP uses ICMPv6 redirect messages (Type 137) to
inform nodes that a better router exists on the link.
DHCP address assignment
DHCPv6 enables DHCP servers to pass conguration parameters (such as IPv6 network addresses) to IPv6 clients. The address
assignment feature manages non-duplicate address assignment in the correct prex based on the network where the host is connected.
Assigned IPv6 addresses can be from one or multiple prex pools. Additional options, such as default domain and DNS name-server
address, can be passed back to the client. Address pools can be assigned for use on a specic interface, on multiple interfaces, or the
server can automatically nd the appropriate pool.
Static routing
Static routes are manually congured and dene an explicit route between two networking devices. Static routes are useful for smaller
networks with only one path to an outside network or to provide security for certain types of trac in a larger network.
IPv6 addresses
IPv6 128-bit addresses are represented as a series of eight 16-bit hexadecimal elds separated by colons in the format: n:n:n:n:n:n:n:n. This
is an example of an IPv6 address:
2001:0db8:0000:0000:0000:0000:1428:57a
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Layer 3