Configuring the Prefix Information Included in Neighbor Discovery Advertisements
Router advertisement messages carry prefixes and information about them. A prefix is onlink when it is assigned to an interface on a specified link. The prefixes specify whether they are onlink or not onlink. A node considers a prefix to be onlink if it is represented by one of the link’s prefixes, a neighboring router specifies the address as the target of a redirect message, a neighbor advertisement message is received for the (target) address, or any neighbor discovery message is received from the address. These prefixes are also used for address autoconfiguration. The information about the prefixes specifies the lifetime of the prefixes, whether the prefix is autonomous, and whether the prefix is onlink.
You can perform the following tasks when configuring the prefix information:
Setting the Prefix for Onlink Determination
You can specify prefixes in the router advertisement messages as onlink. When set as onlink, the prefixes are used for onlink determination. By default, prefixes are onlink.
To explicitly set prefixes as onlink, include the on-link statement:
To set prefixes as not onlink, include the no-on-link statement:
For a list of hierarchy levels at which you can include these statements, see the statement summary sections for these statements.
Setting the Prefix for Stateless Address Autoconfiguration
You can specify prefixes in the router advertisement messages as autonomous. When set as autonomous, the prefixes are used for stateless address autoconfiguration. By default, prefixes are autonomous.
To explicitly specify prefixes as autonomous, include the autonomous statement:
To specify prefixes as not autonomous, include the no-autonomous statement:
For a list of hierarchy levels at which you can include these statements, see the statement summary sections for these statements.
Configuring the Preferred Lifetime
The preferred lifetime for the prefixes in the router advertisement messages specifies how long the prefix generated by stateless autoconfiguration remains preferred. By default, the preferred lifetime is set to 604,800 seconds.
To configure the preferred lifetime, include the preferred-lifetime statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
If you set the preferred lifetime to 0xffffffff, the lifetime is infinite.
The preferred lifetime value must never exceed the valid lifetime value.
Configuring the Valid Lifetime
The valid lifetime for the prefixes in the router advertisement messages specifies how long the prefix remains valid for onlink determination. By default, the valid lifetime is set to 2,592,000 seconds.
To configure the valid lifetime, include the valid-lifetime statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
If you set the valid lifetime to 0xffffffff, the lifetime is infinite.
The valid lifetime value must never be smaller than the preferred lifetime value.
