The ipv6 nd nud reachable-time command configures the neighbor reachable time.
The undo ipv6 nd nud reachable-time command restores the default neighbor reachable time.
By default, the neighbor reachable time is 30000 milliseconds.
| Parameter | Description | Value |
|---|---|---|
| value | Specifies the neighbor reachable time. | It is an integer ranging from 1 to 3600000 milliseconds. By default, it is 30000 milliseconds. |
Ethernet interface view, Eth-Trunk interface view, Tunnel interface view, VLANIF interface view, BDIF interface view
Usage Scenario
Setting the IPv6 neighbor reachable time helps to:
Control the aging time of ND entries on a router.
Enable a host to automatically configure the neighbor reachable time.
Each RA message sent by a router carries the neighbor reachable time. This allows all nodes along the same link to use the same neighbor reachable time.
Prerequisites
The ipv6 enable command has been run in the interface view to enable IPv6.
Configuration Impact
A shorter neighbor reachable time set on a router enables the router to detect neighbor reachability more quickly. This, however, consumes more network bandwidth and CPU resources. Therefore, setting a short neighbor reachable time is not recommended on an IPv6 network. The default value (30000 ms) is recommended.
If the ipv6 nd nud reachable-time command is run more than once, the latest configuration overrides the previous one.
Precautions
The neighbor reachable time set on a router is the same as that carried in an RA message. In the following cases, however, the neighbor reachable time set on a router is the default value 30000 ms, whereas the neighbor reachable time carried in an RA message is 0 ms.
After a host receives an RA message in which the neighbor reachable time is 0 ms, the host sets the neighbor reachable time to 30000 ms, the same as that on the device.