ip address unnumbered (interface view)

Function

The ip address unnumbered command enables an interface to borrow an IP address from another interface.

The undo ip address unnumbered command disables an interface from borrowing an IP address from another interface.

By default, an interface is disabled from borrowing an IP address from another interface.

Format

ip address unnumbered interface { interface-name | interface-type interface-number }

undo ip address unnumbered

Parameters

Parameter	Description	Value
interface interface-name	Specifies the name of an interface whose IP address is borrowed.	The value is a string of 1 to 63 case-sensitive characters, spaces not supported.
interface interface-type interface-number	Specifies the type and number of an interface whose IP address is borrowed.	-

Parameter

Description

Value

interface interface-name

Specifies the name of an interface whose IP address is borrowed.

The value is a string of 1 to 63 case-sensitive characters, spaces not supported.

interface interface-type interface-number

Specifies the type and number of an interface whose IP address is borrowed.

Views

100ge sub-interface view, 100GE interface view, 10GE sub-interface view, 10GE interface view, 200GE sub-interface view, 25GE sub-interface view, 25GE interface view, 400GE sub-interface view, 400GE interface view, 40GE sub-interface view, 40GE interface view, 50GE sub-interface view, 50GE interface view, Eth-Trunk sub-interface view, FlexE sub-interface view, FlexE interface view, Physical FlexE subInterface view, GE optical interface view, GE sub-interface view, GE interface view, GE electrical interface view, Global VE sub-interface view, LMP interface view, Tunnel interface view, VE sub-interface view, VLANIF interface view, Management interface view, Virtual template view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
interface-mgr	write

Usage Guidelines

Usage Scenario

To save IP address resources, run the ip address unnumbered command to configure an interface to borrow an IP address from another interface. If an interface is only occasionally used, it is unnecessary to configure an IP address for the interface. Instead, configure the interface to borrow an IP address from another interface.

The following interfaces support IP borrowing from other interfaces such as Ethernet and loopback interfaces:

Interfaces encapsulated with PPP
Tunnel interfaces
Global-VE sub-interfaces and VE sub-interfaces
Ethernet interfaces and GE sub-interfaces
Vlanif interfaces
Eth-Trunk sub-interfaces

Prerequisites

The numbered interface has been configured with an IP address using the ip address command or has obtained an IP address through negotiation.

Configuration Impact

After an unnumbered interface borrows an IP address, the interface can use this IP address to communicate with other devices. The display interface command displays the borrowed IP address and its subnet mask.
If an interface is configured to borrow the IP address of another interface, the interface sends ICMP reply packets to the CPU for processing even if the ICMP fast reply function is enabled.

Precautions

Because an interface with a borrowed IP address does not have its own IP address, the system cannot generate any device for the interface. Therefore, you need to manually configure the device to implement interconnection between devices.

When configuring IP address unnumbered on an interface, note the following:

The IP address of the numbered interface cannot be a borrowed IP address.
The IP address of the numbered interface can be lent to multiple interfaces.
If the numbered interface has multiple IP addresses, only the primary IP address can be lent.
If the numbered interface is not configured with any IP address, the IP address 0.0.0.0 is borrowed.
The IP address of the virtual loopback interface can be lent to other interfaces, but the virtual loopback interface cannot borrow an IP address from another interface.
If a tunnel interface is not configured to borrow IP addresses of other interfaces, the tunnel interface does not have an IP address by default.

Example

# Configure Tunnel 10 to borrow the IP address of LoopBack0.

<HUAWEI> system-view
[~HUAWEI] interface LoopBack 0
[*HUAWEI-LoopBack0] ip address 1.1.1.1 24
[*HUAWEI-LoopBack0] quit
[*HUAWEI] interface Tunnel 10
[*HUAWEI-Tunnel10] ip address unnumbered interface loopback 0