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- Table of Contents
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- 02-Layer 2 Configuration Guide
- 00-Preface
- 01-Ethernet Interface Configuration
- 02-Loopback and Null Interface Configuration
- 03-MAC Address Table Configuration
- 04-Ethernet Link Aggregation Configuration
- 05-Port Isolation Configuration
- 06-Spanning Tree Configuration
- 07-VLAN Configuration
- 08-GVRP Configuration
- 09-LLDP Configuration
- Related Documents
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| Title | Size | Download |
|---|---|---|
| 02-Loopback and Null Interface Configuration | 65.28 KB |
Contents
Loopback and null interface configuration
Configuring a loopback interface
Introduction to the loopback interface
Configuring the null interface
Introduction to the null interface
Displaying and maintaining loopback and null interfaces
This chapter includes these sections:
· Configuring a loopback interface
· Configuring the null interface
· Displaying and maintaining loopback and null interfaces
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NOTE: · The term "switch" or "device" in this chapter refers to the switching engine on a WX3000E wireless switch. · The WX3000E series comprises WX3024E and WX3010E wireless switches. · The port numbers in this chapter are for illustration only. |
Configuring a loopback interface
Introduction to the loopback interface
A loopback interface is a software-only virtual interface. It delivers the following benefits.
· The physical layer state and link layer protocols of a loopback interface are always up unless the loopback interface is manually shut down.
· You can assign a loopback interface an IP address with an all-F mask to save the IP address resources. When you assign an IPv4 address whose mask is not 32-bit, the system automatically changes the mask into a 32-bit mask. When you assign an IPv6 address whose mask is not 128-bit, the system automatically changes the mask into a 128-bit mask.
· You can enable routing protocols on a loopback interface, and a loopback interface can send and receive routing protocol packets.
Because of the benefits mentioned above, loopback interfaces are widely used in the following scenarios. You can configure a loopback interface address as the source address of the IP packets that the device generates. Because loopback interface addresses are stable unicast addresses, they are usually used as device identifications. Therefore, when you configure a rule on an authentication or security server to permit or deny packets generated by a device, you can simplify the rule by configuring it to permit or deny packets carrying the loopback interface address identifying the device. Note that, when you use a loopback interface address as the source address of IP packets, make sure that the route from the loopback interface to the peer is reachable by performing routing configuration. All data packets sent to the loopback interface are considered as packets sent to the device itself, so the device does not forward these packets.
Configuration procedure
Follow these steps to configure a loopback interface:
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To do… |
Use the command… |
Remarks |
|
Enter system view |
system-view |
— |
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Create a loopback interface and enter loopback interface view |
interface loopback interface-number |
— |
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Set the interface description |
description text |
Optional By default, the description of a loopback interface is interface name Interface. |
|
Shut down the loopback interface |
shutdown |
Optional By default, a loopback interface is up. |
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NOTE: You can configure settings such as IP addresses and IP routes on loopback interfaces. For more information, see Layer 3 Configuration Guide. |
Configuring the null interface
Introduction to the null interface
A null interface is a completely software-based logical interface, and is always up. However, you cannot use it to forward data packets or configure an IP address or link layer protocol on it. With a null interface specified as the next hop of a static route to a specific network segment, any packets routed to the network segment are dropped. The null interface provides a simpler way to filter packets than ACL. You can filter uninteresting traffic by transmitting it to a null interface instead of applying an ACL.
For example, by executing the ip route-static 92.101.0.0 255.255.0.0 null 0 command (which configures a static route leading to null interface 0), you can have all the packets destined to the network segment 92.101.0.0/16 discarded.
Only one null interface, interface Null 0, is supported on your device. You cannot remove or create a null interface.
Configuration procedure
Follow these steps to enter null interface view:
|
To do… |
Use the command… |
Remarks |
|
Enter system view |
system-view |
— |
|
Enter null interface view |
interface null 0 |
Required The Null 0 interface is the default null interface on your device. It cannot be manually created or removed. |
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Set the interface description |
description text |
Optional By default, the description of a null interface is interface name Interface. |
Displaying and maintaining loopback and null interfaces
|
To do… |
Use the command… |
Remarks |
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Display information about loopback interfaces |
display interface loopback [ brief [ down ] ] [ | { begin | exclude | include } regular-expression ] display interface loopback interface-number [ brief ] [ | { begin | exclude | include } regular-expression ] |
Available in any view |
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Display information about the null interface |
display interface null [ brief [ down ] ] [ | { begin | exclude | include } regular-expression ] display interface null 0 [ brief ] [ | { begin | exclude | include } regular-expression ] |
Available in any view |
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Clear the statistics on a loopback interface |
reset counters interface [ loopback [ interface-number ] ] |
Available in user view |
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Clear the statistics on the null interface |
reset counters interface [ null [ 0 ] ] |
Available in user view |
