Table of Contents

1 Monitor Link Configuration· 1-1

Overview· 1-1

Terminology· 1-1

How Monitor Link Works· 1-1

Configuring Monitor Link· 1-2

Configuration Prerequisites· 1-2

Configuration Procedure· 1-2

Monitor Link Configuration Example· 1-2

Displaying and Maintaining Monitor Link· 1-3

Monitor Link Configuration Example· 1-3

When configuring monitor link, go to these sections for information you are interested in:

l          Overview

l          Configuring Monitor Link

l          Displaying and Maintaining Monitor Link

l          Monitor Link Configuration Example

Overview

Monitor link is a port collaboration function. Monitor link is usually used in conjunction with Layer 2 topology protocols. The idea is to adapt the up/down state of downlink ports to the up/down state of uplink ports, triggering link switchover on the downlink device in time.

Terminology

Monitor link group

A monitor link group is a set of uplink ports and downlink ports. For the purpose of monitor link, uplink ports refer to the monitored ports while downlink ports refer to the ports adapted to the up/down state of the monitored ports. A port can be assigned to only one monitor link group. Both Layer 2 Ethernet ports and Layer 2 aggregate interfaces can be assigned to a monitor link group.

Uplink

The uplink is the link monitored by the monitor link group. The monitor link group is down when the group has no uplink ports or all uplink ports are down. The monitor link group is up when any uplink port is up.

Downlink

The downlink is the state-adaptive link in the monitor link group. The state of the downlink ports is always consistent with the up/down state of the monitor link group.

How Monitor Link Works

A monitor link group works independently of other monitor link groups. When a monitor link group contains no uplink ports or all its uplink ports go down, the monitor link group goes down and forces all downlink ports down at the same time. When any uplink port goes up, the monitor link group goes up and brings up all the downlink ports.

Configuring Monitor Link

Configuration Prerequisites

Before assigning a port to a monitor link group, make sure the port is not the member port of any aggregation group.

Configuration Procedure

Follow these steps to configure monitor link:

Monitor Link Configuration Example

Network requirements

GigabitEthernet1/0/1 and GigabitEthernet1/0/2 of a device are up. Configure GigabitEthernet1/0/2 to change its up/down state as GigabitEthernet1/0/1.

Configuration procedure

<Sysname> system-view

[Sysname] monitor-link group 1

[Sysname-mtlk-group1] port gigabitethernet 1/0/1 uplink

[Sysname-mtlk-group1] port gigabitethernet 1/0/2 downlink

Displaying and Maintaining Monitor Link

Monitor Link Configuration Example

Network requirements

As shown in Figure 1-1:

l          Device C is dually uplinked to Device A through a smart link group.

l          It is required that when GigabitEthernet1/0/1 or GigabitEthernet1/0/2 of Device A fails, Device C can sense the link failure and perform link switchover in the smart link group.

Figure 1-1 Network diagram for smart link in combination with monitor link configuration

Configuration procedure

1)        Configuration on Device C

# Disable STP on GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2.

<DeviceC> system-view

[DeviceC] interface gigabitethernet 1/0/1

[DeviceC-GigabitEthernet1/0/1] undo stp enable

[DeviceC-GigabitEthernet1/0/1] quit

[DeviceC] interface gigabitethernet 1/0/2

[DeviceC-GigabitEthernet1/0/2] undo stp enable

[DeviceC-GigabitEthernet1/0/2] quit

# Create smart link group 1 and configure the smart link group to protect all the VLANs mapped to MSTIs 0 through 15.

[DeviceC] smart-link group 1

[DeviceC-smlk-group1] protected-vlan reference-instance 0 to 15

# Configure GigabitEthernet 1/0/1 as the master port and GigabitEthernet 1/0/2 as the slave port.

[DeviceC-smlk-group1] port gigabitethernet 1/0/1 master

[DeviceC-smlk-group1] port gigabitethernet 1/0/2 slave

# Enable the smart link group to transmit flush messages in VLAN 1.

[DeviceC-smlk-group1] flush enable

2)        Configuration on Device A

# Configure VLAN 1 as the control VLAN for receiving flush messages on GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2.

<DeviceA> system-view

[DeviceA] interface gigabitethernet 1/0/1

[DeviceA-GigabitEthernet1/0/1] smart-link flush enable

[DeviceA-GigabitEthernet1/0/1] quit

[DeviceA] interface gigabitethernet 1/0/2

[DeviceA-GigabitEthernet1/0/2] smart-link flush enable

3)        Configuration on Device B

# Create monitor link group 1.

<DeviceB> system-view

[DeviceB] monitor-link group 1

# Configure GigabitEthernet 1/0/1 as an uplink port and GigabitEthernet 1/0/2 as a downlink port.

[DeviceB-mtlk-group1] port gigabitethernet 1/0/1 uplink

[DeviceB-mtlk-group1] port gigabitethernet 1/0/2 downlink

# Configure VLAN 1 as the control VLAN for receiving flush messages on GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2.

[DeviceB-mtlk-group-1] quit

[DeviceB] interface gigabitethernet 1/0/1

[DeviceB-GigabitEthernet1/0/1] smart-link flush enable

[DeviceB-GigabitEthernet1/0/1] quit

[DeviceB] interface gigabitethernet 1/0/2

[DeviceB-GigabitEthernet1/0/2] smart-link flush enable

4)        Configuration on Device D

# Create monitor link group 1.

<DeviceD> system-view

[DeviceD] monitor-link group 1

# Configure GigabitEthernet 1/0/1 as the uplink port and GigabitEthernet 1/0/2 as the downlink port.

[DeviceD-mtlk-group1] port gigabitethernet 1/0/1 uplink

[DeviceD-mtlk-group1] port gigabitethernet 1/0/2 downlink

# Configure VLAN 1 as the control VLAN for receiving flush messages on GigabitEthernet 1/0/1 and GigabitEthernet 1/0/2.

[DeviceD-mtlk-group1] quit

[DeviceD] interface gigabitethernet 1/0/1

[DeviceD-GigabitEthernet1/0/1] smart-link flush enable

[DeviceD-GigabitEthernet1/0/1] quit

[DeviceD] interface gigabitethernet 1/0/2

[DeviceD-GigabitEthernet1/0/2] smart-link flush enable