ipv6 address auto link-local

Function

The ipv6 address auto link-local command configures an interface to automatically generate a link-local address.

The undo ipv6 address auto link-local command deletes the automatically generated link-local address on a specified interface.

By default, no link-local address is automatically generated on an interface.

Format

ipv6 address auto link-local

undo ipv6 address auto link-local

Parameters

None

Views

Interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

Link-local addresses are used for communications between link-local nodes in either the neighbor discovery or stateless auto-configuration process. A packet with a link-local address set to a source or destination address will not be forwarded to another link. That is, link-local addresses are valid only on local links.

After the ipv6 address auto link-local command is run, a device uses the link-local address prefix FE80::/10 (1111 1110 10) and IEEE EUI-64 interface identifier go generate a link-local address for an interface. An IEEE EUI-64 interface identifier is converted from an interface link layer address, for example a MAC address.

The hexadecimal number FFFE (1111 1111 1111 1110 in binary) is inserted in the middle of a MAC address.
The U/L bit (the leftmost seventh bit) is set to 1.
The interface ID in EUI-64 format then is obtained.

After an interface automatically obtains a link-local address, it can implement neighbor discovery and automatically configure a global unicast address or a unique local address.

Prerequisites

Before running this command, run the ipv6 enable command in the interface view to enable the IPv6 function.

Precautions

Only a single link-local address can be assigned to each interface. If an automatically allocated link-local address has already been configured on an interface, running the ipv6 address link-local command will overwrite the existing link-local address.

The undo ipv6 address auto link-local command can only delete a link-local address that is automatically generated by an interface. To delete a manually configured link-local address, run the undo ipv6 address link-local command.

Example

# Configure VLANIF2 to automatically generate a link-local address.

<HUAWEI> system-view
[HUAWEI] ipv6
[HUAWEI] interface vlanif 2
[HUAWEI-Vlanif2] ipv6 enable
[HUAWEI-Vlanif2] ipv6 address auto link-local

# Configure GE0/0/1 to automatically generate a link-local address.

<HUAWEI> system-view
[HUAWEI] ipv6
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] ipv6 enable
[HUAWEI-GigabitEthernet0/0/1] ipv6 address auto link-local