API Guide

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, use 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.
Perform stateless autoconfiguration of IPv6 addresses 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 RAs 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 RA 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 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 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 prefixes of neighbor addresses, OS10 performs stateless autoconfiguration of IPv6
addresses on interfaces.
ICMPv6 RA messages advertise the IPv6 addresses of IPv6-enabled interfaces and allow a router to learn of any address
changes in IPv6 neighbors. By default, RAs are disabled on an interface.
Prerequisites
To enable RA messages, the switch must be in Router mode with IPv6 forwarding enabled and stateless autoconfiguration
disabled using the 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) Configure 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, from 0 to 255; default 64. 0 indicates that no hop limit is specified by the router.
● ipv6 nd managed-config-flag — (Optional) Sent in RA messages to tell hosts to use stateful address
autoconfiguration, such as DHCPv6, to obtain IPv6 addresses.
● ipv6 nd max-ra-interval seconds — (Optional) Sets the maximum time interval for sending RA messages,
from 4 to 1800 seconds; default 600.
670
Layer 3