Configuring Neighbor Discovery
Context
IPv6 NDP provides address resolution, neighbor unreachability detection, DAD, router/prefix discovery, address autoconfiguration, and redirection.
After the IPv6 function is enabled on the switch, the switch automatically implements address resolution, DAD, and redirection. Neighbor unreachability detection, router/prefix discovery, and address autoconfiguration need to be manually configured. You can also configure the switch to send RA packets to enable router/prefix discovery and address autoconfiguration, and enable the automatic detection of ND entries to check whether neighbors are reachable.
After the automatic detection of ND entries is enabled on the switch, the switch can send NS packets to check whether neighbors are reachable before aging ND entries. If neighbors are reachable, the switch updates ND entries; otherwise, the switch ages ND entries.
You can enable the switch to send RA packets. After receiving the RA packets, network nodes perform address autoconfiguration and router/prefix discovery based on the prefix and other configuration information contained in RA packets.
After the preceding configurations are complete, NDP functions work properly. You can also adjust ND parameters based on service requirements.
Procedure
- Enable NDP functions to work properly.
Run system-view
The system view is displayed.
Run ipv6
IPv6 packet forwarding is enabled.
By default, IPv6 packet forwarding is disabled.
Run interface interface-type interface-number
The specified interface view is displayed.
(Optional) On an Ethernet interface, run undo portswitch
The interface is switched to Layer 3 mode.
By default, an Ethernet interface works in Layer 2 mode.
Only the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S support switching between Layer 2 and Layer 3 modes.
Run ipv6 enable
The IPv6 function is enabled.
By default, the IPv6 function is disabled on an interface.
Run undo ipv6 nd ra halt
The system is enabled to send RA packets.
By default, the system is disabled from sending RA packets.
- (Optional) Adjust ND parameters to meet service requirements.
Run the following commands in the system view.
Run quit
Return to the system view.
In the system view, run ipv6 nd hop-limit limit
The hop limit for IPv6 unicast packets initially sent by a device is set.
By default, the IPv6 unicast packets initially sent by a device can travel a maximum of 64 hops.
In the system view, run ipv6 nd stale-timeout timeout-value
The aging time of ND entries in STALE state is set.
By default, the aging time of ND entries in STALE state is 1200 seconds.
In the system view, run ipv6 nd learning strict
IPv6 ND strict learning is enabled.
By default, IPv6 ND strict learning is disabled.
Run the following commands on the interface.
Run interface interface-type interface-number
The specified interface view is displayed.
Run ipv6 nd stale-timeout seconds
The aging time of ND entries in STALE state is set.
By default, the aging time of ND entries in STALE state is 1200 seconds.
Run ipv6 nd learning strict { force-disable | force-enable | trust }
IPv6 ND strict learning is enabled.
By default, IPv6 ND strict learning is disabled.
Run ipv6 nd ra hop-limit limit
The hop limit for RA packets is set.
By default, the hop limit for RA packets is 64.
If the ipv6 nd ra hop-limit command is executed on an interface, the hop limit for RA packets is determined by the interface configuration.
If the ipv6 nd ra hop-limit command is not executed on an interface, the hop limit for RA packets is determined by the hop limit configured using the ipv6 nd hop-limit command.
Run ipv6 nd ns retrans-timer interval
The interval for sending NS packets is set.
By default, the interval for sending NS packets is 1000 ms.
Run ipv6 nd ra { max-interval maximum-interval | min-interval minimum-interval }
The interval for sending RA packets is set.
By default, the maximum interval is 600s and the minimum interval is 200s.
Run ipv6 nd ra prefix { ipv6-address prefix-length | ipv6-address/prefix-length } valid-lifetime preferred-lifetime [ no-autoconfig ] [ off-link ] or ipv6 nd ra prefix default no-advertise
Prefix information in RA packets is configured.
By default, an RA packet carries only the address prefix configured using the ipv6 address command.
Prefixes configured using the ipv6 nd ra prefix command take precedence over the default prefix generated based on the interface IPv6 address. An RA packet can carry a maximum of 10 prefixes. If exactly 10 prefixes are configured manually, the default prefix is not used.
Run ipv6 nd autoconfig managed-address-flag
The managed address configuration flag (M flag) for stateful autoconfiguration in RA packets is set.
By default, the M flag in an RA packet is not set.
Run ipv6 nd autoconfig other-flag
The other configuration flag (O flag) for stateful autoconfiguration in RA packets is set.
By default, the O flag in an RA packet is not set.
Run ipv6 nd nud reachable-time value
The IPv6 neighbor reachable time is set.
By default, the IPv6 neighbor reachable time is 30000 ms.
Run ipv6 nd ra router-lifetime ra-lifetime
The time to live (TTL) is set for RA packets.
By default, the TTL of RA packets is 1800s.
Run ipv6 nd dad attempts value
The number of times NS packets are sent when the system performs DAD is set.
By default, the number of times NS packets are sent when the system performs DAD is 1.
Run ipv6 nd neighbor-limit limit-number
The maximum number of dynamic neighbor entries that can be learned by an interface is set.
By default, the maximum of dynamic neighbor entries that an interface can learn is 1000 for the S2720-EI, S5720-LI, and S5720S-LI, 1024 for the S5735-L, S5735S-L, and S5735S-L-M, 2048 for the S5720I-SI, S5720-SI, and S5720S-SI, 3072 for the S5735-S, S5735-S-I, and S5735S-S, 8192 for the S5720-EI, S5731-S, S5731S-S, S6720-LI, and S6720S-LI, 64000 for the S5720-HI, 65536 for the S5731S-H, S5730-HI and S5731-H, 10240 for the S5730-SI, S5730S-EI, S6720-SI, and S6720S-SI, 49152 for the S6720-EI and S6720S-EI, and 32768 for the S5732-H, S6720-HI, S6730-S, S6730-H, S6730S-H, and S6730S-S.
- (Optional) Configure the default router priority and route information.
Run the following commands on the interface. If the current view is system view, run the interface interface-type interface-number command to enter interface view.
Run ipv6 nd ra preference { high | medium | low }
The default router priority is configured in RA packets.
By default, the router preference of RA packets is medium.
Run ipv6 nd ra route-information ipv6-address prefix-length lifetime route-lifetime [ preference { high | medium | low } ]
Route information is configured in RA packets.
By default, there is no route information in RA packets.