Configuring DAD

Syntax:

ipv6 nd dad-attempts <0-255>

This command is executed at the global config level, and configures the number of neighbor solicitations to send when performing duplicate address detection for a unicast address configured on a VLAN interface.

<0-255> : The number of consecutive neighbor solicitation messages sent for DAD inquiries on an interface. Setting this value to 0 disables DAD on the interface, which bypasses checks for uniqueness on newly configured addresses. If a reboot is performed while DAD is disabled, the duplicate address check is not performed on any IPv6 addresses configured on the switch.

Default: 3 (enabled); Range: 0–255 (0 = disabled)

The no form of the command restores the default setting (3).

Syntax:

ipv6 nd NS-interval <milliseconds>

Used on VLAN interfaces to reconfigure the ND time in milliseconds between DAD neighbor solicitations sent for an unresolved destination, or between duplicate address detection neighbor solicitation requests. Increasing this setting is indicated where neighbor solicitation retries or failures are occurring, or in a "slow" (WAN) network.

This value can be configured in an RA to help ensure that all hosts on a VLAN are using the same retransmit interval for ND. See Setting or changing the hop-limit for host-generated packets.

To view the current setting, use show ipv6 nd.

Default: 1000 ms; Range: 1000–4294967295 ms

Syntax:

ipv6 nd reachable-time <milliseconds>

Used on VLAN interfaces to configure the length of time in milliseconds a neighbor is considered reachable after the Neighbor Unreachability Detection algorithm has confirmed it to be reachable. When the switch operates in host mode, this setting can be overridden by a reachable time received in an RA.

This value can be configured in an RA to help ensure that all hosts on a VLAN are using the same reachable time in their neighbor cache.

To view the current setting, use show ipv6 nd.

Default: 30,000 ms; Range: 1000–3600000 ms