OS10 Enterprise Edition User Guide Release 10.4.0E(R3)

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Stateless autoconfiguration

When an interface comes up, OS10 uses stateless autoconfiguration to generate a unique link-local IPv6 address with a FE80::/64 prefix and an interface ID generated from the MAC address. To use stateless autoconfiguration to assign a globally unique address using a prefix received in router advertisements, enter the ipv6 address autoconfig command.

Stateless autoconfiguration sets an interface in host mode, and allows the interface connected to an IPv6 network to autoconfigure IPv6 addresses and communicate with other IPv6 devices on local links. A DHCP server is not required for automatic IPv6 interface configuration. IPv6 devices on a local link send router advertisement (RA) messages in response to solicitation messages received at startup.

Stateless autoconfiguration of IPv6 addresses is performed using:

Prefix advertisement
Routers use router advertisement messages to advertise the network prefix. Hosts append their interface-identifier 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 configuring its IPv6 address.
Prefix renumbering
Transparent renumbering of hosts in the network when an organization changes its service provider.

IPv6 provides the flexibility to add prefixes 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 autoconfiguration supports the router side only. Neighbor Discovery (ND) messages advertise so the neighbor can use the information to auto-configure 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 flags
  • Reachable time
  • Retransmission timer
  • MTU options
  • Preferred and valid lifetime values for the same prefix

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.


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