3Com H3C S3100 16C SI User manual

H3C Loopback Detection Feature Manual

Release 2107 Table of Contents

Table of Contents

Chapter 1 Loopback Detection Configuration............................................................................ 1-1

1.1 Loopback Detection Configuration.....................................................................................1-1

1.1.1 Loopback Detection Overview ................................................................................1-1

1.1.2 Configuring Loopback Detection for Ethernet Port(s).............................................1-2

Chapter 2 Loopback Detection Configuration Commands.......................................................2-1

2.1 Loopback Detection Configuration Commands.................................................................2-1

2.1.1 loopback-detection control enable ..........................................................................2-1

2.1.2 loopback-detection enable......................................................................................2-2

2.1.3 loopback-detection interface-list enable..................................................................2-4

2.1.4 loopback-detection interval-time .............................................................................2-5

2.1.5 loopback-detection per-vlan enable........................................................................2-5

2.1.6 loopback-detection shutdown enable......................................................................2-6

H3C Loopback Detection Feature Manual

Release 2107 Chapter 1 Loopback Detection Configuration

1-1

Chapter 1 Loopback Detection Configuration

Note:

Two functions are added to release 2107: configuring loopback detection for a list of

ports in bulk, and enabling auto-shutdown of loopback ports.

1.1 Loopback Detection Configuration

1.1.1 Loopback Detection Overview

Loopback detection is used to monitor if a port of a switch is looped back.

After you enable loopback detection on Ethernet ports, the switch can monitor if an

external loopback occurs on them. If there is a loopback port found, the switch will deal

with the loopback port according to your configuration.

1) If a loop is found on an access port, the system will set the port to the block state

(ports in this state cannot forward data packets), send log messages to the

terminal, and remove the corresponding MAC forwarding entry.

zIf you have additionally enabled the loopback port auto-shutdown function on the

port, the system will shut down the port, and send log messages to the terminal.

After the loop is removed, you need touse the undo shutdown command to bring

up the port.

zIf you have not enabled the loopback port auto-shutdown function on the port, the

port will automatically resume the normal forwarding state after the loop is

removed.

2) If a loop is found on a trunk or hybrid port, the system sends log messages to the

terminal. If you have additionally enabled the loopback port control function or the

loopback port auto-shutdown function, the system will deal with the port

accordingly:

zIf the loopback port control function is enabled on the port, the system will set the

port to the block state (ports in this state cannot forward data packets), send log

messages to the terminal, and remove the corresponding MAC forwarding entry.

After the loop is removed, the port will automatically resume the normal forwarding

state.

H3C Loopback Detection Feature Manual

Release 2107 Chapter 1 Loopback Detection Configuration

1-2

zIf the loopback port auto-shutdown function is enabled on the port, the system will

shut down the port and send log messages to the terminal. After the loop is

removed, you need to use the undo shutdown command to bring up the port.

Note:

You cannot enable both the loopback port control function and the loopback port

auto-shutdown function on a port. If you do so, the function configured later will take

effect.

1.1.2 Configuring Loopback Detection for Ethernet Port(s)

Table 1-1 Configure loopback detection for Ethernet port(s)

Operation Command Remarks

Enter system view system-view —

Enable loopback

detection globally loopback-detection

enable

Optional

By default, the global loopback

detection function is enabled if

the device boots with the default

configuration file (config.def); if

the device boots with null

configuration, this function is

disabled.

Enable loopback

detection on the

specified ports in

bulk

loopback-detection

interface-list enable

Optional

By default, the loopback

detection function is enabled on

ports if the device boots with the

default configuration file

(config.def); if the device boots

with null configuration, this

function is disabled.

At present, you can configure the

loopback detection for ports in

bulk on the S3100-EI series

(except the S3100-EPON-EI

series) switches and the E126A

switch only. These switches are

all shipped with a default

configuration file (config.def).

Set the interval for

performing port

loopback detection

loopback-detection

interval-time time Optional

The default is 30 seconds.

Enter Ethernet port

view interface interface-type

interface-number —

H3C Loopback Detection Feature Manual

Release 2107 Chapter 1 Loopback Detection Configuration

1-3

Operation Command Remarks

Enable loopback

detection on a

specified port

loopback-detection

enable

Optional

By default, the loopback

detection function is enabled on

ports if the device boots with the

default configuration file

(config.def); if the device boots

with null configuration, this

function is disabled.

Enable loopback

port control on the

trunk or hybrid port

loopback-detection

control enable

Optional

By default, the loopback port

control function is enabled on

ports if the device boots with the

default configuration file

(config.def); if the device boots

with null configuration, this

function is disabled.

Enable the loopback

port auto-shutdown

function

loopback-detection

shutdown enable

Optional

By default, the loopback port

auto-shutdown function is

enabled on ports if the device

boots with the default

configuration file (config.def); if

the device boots with null

configuration, this function is

disabled.

Configure the

system to run

loopback detection

on all VLANs of the

current trunk or

hybrid port

loopback-detection

per-vlan enable

Optional

By default, the system runs

loopback detection only on the

default VLAN of the current trunk

or hybrid port.

Caution:

zTo enable loopback detection on a specific port, you must use the

loopback-detection enable command in both system view and the specific port

view.

zAfter you use the undo loopback-detection enable command in system view,

loopback detection will be disabled on all ports.

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-1

Chapter 2 Loopback Detection Configuration

Commands

Note:

Two functions are added to release 2107: configuring loopback detection for a list of

ports in bulk, and enabling auto-shutdown of loopback ports. For detailed description of

the two functions, refer to loopback-detection interface-list enable and

loopback-detection shutdown enable.

2.1 Loopback Detection Configuration Commands

2.1.1 loopback-detection control enable

Syntax

loopback-detection control enable

undo loopback-detection control enable

View

Ethernet port view

Parameter

None

Description

Use the loopback-detection control enable command to enable the loopback port

control function on the current trunk or hybrid port.

Use the undo loopback-detection control enable command to disable the loopback

port control function on the trunk or hybrid port.

The loopback port control function works in conjunction with the loopback detection

function (refer to loopback-detection enable). If a loop is found on a VLAN of the trunk

or hybrid port:

zWith the function enabled on the trunk or hybridport, the system will set the port to

the block state (ports in this state cannot forward data packets), send log

messages to the terminal, and remove the corresponding MAC forwarding entry.

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-2

After the loop is removed, the port will automatically resume the normal forwarding

state.

zWith the function disabled on the trunk or hybrid port, the system will only send log

messages to the terminal, and the port is still in the normal forwarding state.

By default, the loopback port control function is enabled on ports if the device boots with

the default configuration file (config.def); if the device boots with null configuration, this

function is disabled.

Note that this command is invalid for an access port.

Related command: loopback-detection enable.

Example

# Enable the loopback port control function on Ethernet 1/0/1.

<H3C> system-view

System View: return to User View with Ctrl+Z.

[H3C] interface ethernet 1/0/1

[H3C-Ethernet1/0/1] port link-type trunk

[H3C-Ethernet1/0/1] loopback-detection control enable

2.1.2 loopback-detection enable

Syntax

loopback-detection enable

undo loopback-detection enable

View

System view or Ethernet port view

Parameter

None

Description

Use the loopback-detection enable command to enable the loopback detection

function on the current port to detect whether an external loopback occurs on the port.

Use the undo loopback-detection enable command to disable the loopback

detection function on the port.

1) If a loop is found on an access port, the system will set the port to the block state

(ports in this state cannot forward data packets), send log messages to the

terminal, and remove the corresponding MAC forwarding entry.

zIf you have enabled the loopback port auto-shutdown function (with the

loopback-detection shutdown enable command) on the access port, the system

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-3

will shut down the port, and send log messages to the terminal. After the loop is

removed, you need to use the undo shutdown command to bring up the port.

zIf you have not enabled the loopback port auto-shutdown function on the access

port, the port will automatically resume the normal forwarding state after the loop is

removed.

2) If a loop is found on a trunk or hybrid port, the system sends log messages to the

terminal. If you have additionally enabled the loopback port control function or the

loopback port auto-shutdown function, the system will deal with the port

accordingly:

zIf the loopback port control function is enabled on the port (with the

loopback-detection control enable command), the system will set the port to the

block state (ports in this state cannot forward data packets), send log messages

to the terminal, and remove the corresponding MAC forwarding entry. After the

loop is removed, the port will automatically resume the normal forwarding state.

zIf the loopback port auto-shutdown function is enabled on the port (with the

loopback-detection shutdown enable command), the system will shut down the

port and send log messages to the terminal. After the loop is removed, you need to

use the undo shutdown command to bring up the port.

Note:

The loopback detection function on a specific port can take effect only after you enable

the loopback detection function globally (in system view) and on the port (in the

specified port view).

By default, the loopback detection function is enabled globally and onports if the device

boots with the default configuration file (config.def); if the device boots with null

configuration, this function is disabled.

Related command: loopback-detection control enable, loopback-detection

shutdown enable.

Example

# Enable the loopback detection function on Ethernet 1/0/1.

<H3C> system-view

System View: return to User View with Ctrl+Z.

[H3C] loopback-detection enable

[H3C] interface ethernet 1/0/1

[H3C-Ethernet1/0/1] loopback-detection enable

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-4

2.1.3 loopback-detection interface-list enable

Syntax

loopback-detection interface-list enable

undo loopback-detection interface-list enable

View

System view

Parameter

interface-list: Ethernet port list, in the form of interface-list = { interface-type

interface-number [ to interface-type interface-number ] } &<1-10>, where

zinterface-type is the port type, and interface-number is the port number.

zKeyword to is used to specify a range of ports. The port number after to must be

equal to or greater than that before to.

z&<1-10> means that you can specify up to 10 ports or port ranges.

Description

Use the loopback-detection interface-list enable command to enable the loopback

detection function on a range of ports.

Use the undo loopback-detection interface-list enable command to disable the

loopback detection function on a range of ports.

By default, the loopback detection function is enabled on ports if the device boots with

the default configuration file (config.def); if the device boots with null configuration, this

function is disabled.

At present, you can configure the loopback detection for ports in bulk on the S3100-EI

series (except the S3100-EPON-EI series) switches and the E126Aswitch only. These

switches are all shipped with a default configuration file (config.def).

Example

# Enable the loopback detection function on ports Ethernet 1/0/1 through Ethernet

1/0/4.

<H3C> system-view

System View: return to User View with Ctrl+Z.

[H3C] loopback-detection enable

[H3C] loopback-detection Ethernet 1/0/1 to Ethernet 1/0/4 enable

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-5

2.1.4 loopback-detection interval-time

Syntax

loopback-detection interval-time time

undo loopback-detection interval-time

View

System view

Parameter

time: Time interval for loopback detection, in the range of 5 to 300 (in seconds). It is 30

seconds by default.

Description

Use the loopback-detection interval-time command to set time interval for loopback

detection.

Use the undo loopback-detection interval-time command to restore the default time

interval.

Example

# Set time interval for loopback detection to 10 seconds.

<H3C> system-view

System View: return to User View with Ctrl+Z.

[H3C] loopback-detection interval-time 10

2.1.5 loopback-detection per-vlan enable

Syntax

loopback-detection per-vlan enable

undo loopback-detection per-vlan enable

View

Ethernet port view

Parameter

None

Description

Use the loopback-detection per-vlan enable command to configure the system to

run loopback detection on all VLANs of the current trunk or hybrid port.

H3C Loopback Detection Feature Manual

Release 2107 Chapter 2 Loopback Detection Configuration

Commands

2-6

Use the undo loopback-detection per-vlan enable command to restore the default

setting.

By default, the system runs loopback detection only on the default VLAN of the trunk or

hybrid port.

Note that the command is invalid for any access port.

Example

# Configure the system to run loopback detection on all VLANs of the trunk port

Ethernet1/0/1.

<H3C> system-view

System View: return to User View with Ctrl+Z.

[H3C] interface ethernet 1/0/1

[H3C-Ethernet1/0/1] port link-type trunk

[H3C-Ethernet1/0/1] loopback-detection per-vlan enable

2.1.6 loopback-detection shutdown enable

Syntax

loopback-detection shutdown enable

undo loopback-detection shutdown enable

View

Ethernet port view

Parameter

None

Description

Use the loopback-detection shutdown enable command to enable the loopback port

auto-shutdown function.

Use the undo loopback-detection shutdown enable command to disable the

function.

The loopback port auto-shutdown function works in conjunction with the loopback

detection function (refer to loopback-detection enable). If a loop is found at a port:

zWith the function enabled on the port, the system willshut down the port, and send

log messages to the terminal. After the loop isremoved, you need to use the undo

shutdown command to bring up the port.

zWith the function disabled on the port, the system will only send log messages to

the terminal, and the port is still in the normal forwarding state.

This manual suits for next models

Table of contents

Other 3Com Network Hardware manuals

3Com

3Com 3C421600A User manual

3Com

3Com DUAL SPEED HUB/PS HUB CASCADE CONVERTER User manual

3Com

3Com 3CNJPSE24 User manual

3Com

3Com AccessBuilder 4000 User manual

3Com

3Com AirProtect Enterprise Engine 6100 User manual

3Com

3Com NETBuilder II User manual

3Com

3Com 486 User manual

3Com

3Com 3CR10551A-US - Asterisk IP Communications... User manual

3Com

3Com 3C433279A Instruction Manual

3Com

3Com 3C421600A User manual

3Com

3Com OfficeConnect User manual

3Com

3Com 3CRWE90096A - Wireless Access Point User manual

3Com

3Com 3C421600A Programming manual

3Com

3Com WL-560 User manual

3Com

3Com 3CR870-95-US - OfficeConnect VPN Firewall User manual

3Com

3Com ETHERLINK III User manual

3Com

3Com 3CRWEASYG73 - 11g Wireless LAN Outdoor User manual

3Com

3Com IntelliJack NJ200 User manual

3Com

3Com 3CRWE725075 User manual

3Com

3Com 3C16630A User manual

3Com

3Com SuperStack 3870 User manual

3Com

3Com OfficeConnect WX4400 User manual

3Com

3Com 3C17203 - SuperStack 3 Switch 4400 User manual

3Com

3Com Oven How to use

Popular Network Hardware manuals by other brands

Matrix Switch Corporation

Matrix Switch Corporation MSC-HD161DEL product manual

B&B Electronics

B&B Electronics ZXT9-IO-222R2 product manual

Yudor

Yudor YDS-16 user manual

D-Link

D-Link ShareCenter DNS-320L datasheet

Samsung

Samsung ES1642dc Hardware user manual

Honeywell Home

Honeywell Home LTEM-PV Installation and setup guide

evertz

evertz 7700 Series manual

D-Link

D-Link ShareCenter DNS-343 Quick installation guide

Asante

Asante AsanteBridge 1012 user guide

FireBrick

FireBrick FB2700 user manual

Audiovox Electronics

Audiovox Electronics ARWH2T user manual

ADC

ADC DSX-1 Operational Procedures Guide

NetComm

NetComm NF2 user guide

Alcatel-Lucent

Alcatel-Lucent 5620 user guide

Dell EMC

Dell EMC XC6420 Series Solution guide

Lanner

Lanner NCA-1020A user manual

Allied Telesis

Allied Telesis AT-TN121-A Specifications

Arista

Arista CCA-ETM-Q12 quick start guide