Reference Guide
Stateless autoconguration of IPv6 addresses is performed using:
Prex advertisement Routers use router advertisement messages to advertise the network prex. Hosts append their interface-identier
MAC address to generate a valid IPv6 address.
Duplicate address
detection
An IPv6 host node checks whether that address is used anywhere on the network using this mechanism before
conguring its IPv6 address.
Prex renumbering Transparent renumbering of hosts in the network when an organization changes its service provider.
IPv6 provides the exibility to add prexes on router advertisements in response to a router solicitation (RS). By default, RA response
messages are sent when an RS message is received. The system manipulation of IPv6 stateless autoconguration supports the router side
only. Neighbor Discovery (ND) messages advertise so the neighbor can use the information to auto-congure 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 prex
The router redirect functionality in the Neighbor Discovery protocol (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.
Neighbor discovery
The IPv6 Neighbor Discovery protocol (NDP) determines if neighboring IPv6 devices are reachable and receives the IPv6 addresses of
IPv6 devices on local links. Using the link-layer and global prexes of neighbor addresses, OS10 performs stateless autoconguration of
IPv6 addresses on interfaces.
ICMPv6 Router Advertisement messages advertise the IPv6 addresses of IPv6-enabled interfaces and allow a router to learn of any
address changes in IPv6 neighbors. By default, router advertisements are disabled on an interface.
Prerequisites
To enable RA messages, the switch must be in Router mode with IPv6 forwarding enabled and stateless autoconguration disabled (no
ipv6 address autoconfig
command).
Enable router advertisement messages
1 Enable IPv6 neighbor discovery and sending ICMPv6 RA messages in Interface mode.
ipv6 nd send-ra
2 (Optional) Congure IPv6 neighbor discovery options in Interface mode.
• ipv6 nd hop-limit hops — (Optional) Sets the hop limit advertised in RA messages and included in IPv6 data packets
sent by the router (0 to 255; default 64). 0 indicates that no hop limit is specied by the router.
• ipv6 nd managed-config-flag — (Optional) Sent in RA messages to tell hosts to use stateful address autoconguration,
such as DHCPv6, to obtain IPv6 addresses.
• ipv6 nd max-ra-interval seconds — (Optional) Sets the maximum time interval for sending RA messages (4 to 1800
seconds; default 600).
• ipv6 nd mtu number — (Optional) Sets the maximum transmission unit (MTU) used in RA messages on the link (1280 to
65535 bytes; default 1500). By default, no MTU setting is included in RA messages.
• ipv6 nd other-config-flag — (Optional) Tells hosts to use stateful autoconguration to obtain nonaddress-related
information.
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