Monitor Link Configuration; Overview; Terminology; How Monitor Link Works - 3Com 4210G Series Configuration Manual

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Monitor Link Configuration

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

Overview

Configuring Monitor Link
Displaying and Maintaining Monitor Link
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.
Do not manually shut down or bring up the downlink ports in a monitor link group.
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