# Configuring an IPv6 discovery prefix

Use this procedure to determine the source of an IPv6 address or set of IPv6 addresses. The discovery prefix also permits other tables to share the information through a pointer rather than by copying. For example, when the node configures both a unicast and anycast address for a prefix, the ipAddressPrefix objects for those addresses point to a single row in the table.

## Procedure steps

1. From the navigation tree, double-click IPv6.

2. Double-click IPv6.

3. Click the Discovery Prefix tab.

4. Click Insert.

5. In the IfIndex box, click Port or VLAN, and select a port number or VLAN.

6. Edit the remaining fields.

7. Click Insert.

8. Click Apply.

## Variable definitions

The following table describes the fields of the Discovery Prefix tab.

Variable | Value
--- | ---
IfIndex | Specifies a read-only value indicating the unique value to identify an IPv6 interface.
Prefix | Configures the prefix to create an IPv6 address in the IPv6 interface table.
PrefixLen | Configures the mask to create an IPv6 prefix entry as either advertised or suppressed.
VlanId | Specifies the VLAN ID of the IPv6 interface.
UseDefaultVal | Select one of the values to set its value to default value. This is a bitmask field, setting all the bits means that all the options will be reverted to default values.
ValidLife | Configures the valid lifetime in seconds that indicates the length of time this prefix is advertised. The default is 2592000.
PreferredLife | Configures the preferred lifetime in seconds that indicates the length of time this prefix is advertised. The default value is 604800.
Infinite | Configures the prefix valid lifetime so it never expires. The default is false.
OnLinkFlag | Configures the prefix for use when determining if a node is onlink. This value is placed in the L-bit field in the prefix information option. It is a 1-bit flag. The default is true.
AutoFlag | Configures the prefix for use as the autonomous address configuration. This value is placed in the autoflag field in the prefix information option. It is a 1-bit flag. The default is true.
AddressEui | Configures the EUI address. Use an EUI-64 interface ID in the low-order 64-bits of the address when the ID is not specified in the address field. If enabled, use EUI, or use EUI-64 and the complement Universal/Local (U/L) bit. This operation provides for both global and link-local addresses. After you create the entry, you cannot modify this value. This value is valid for use only when the PrefixLength is 64 or less. The default is eui-not-used.
NoAdvertise | Select true to not include the prefix in the neighbor advertisement. The default is false.