H3C Technologies H3C S12500 Series Switches - Manual (Page 131)

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Configuring Monitor Link
Overview
Monitor Link is a port collaboration function. Monitor Link usually works together with Layer 2 topology
protocols. The idea is to monitor the states of uplink ports and adapt the up/down state of downlink ports
to the up/down state of uplink ports, triggering link switchover on the downstream switch in time, as
shown in Figure 26 .
Figure 26 Monitor Link application scenario
Terminology
Monitor link group
A monitor link group is a set of uplink and downlink ports. A port can belong to only one monitor link
group. As shown in
Figure 26 , ports GigabitEthernet 3/0/1 and GigabitEthernet 3/0/2 of Device B
and those of Device D each form a monitor link group. GigabitEthernet 3/0/1 on both switches are
uplink ports, and GigabitEthernet 3/0/2 on both switches are downlink ports.
Uplink/Downlink ports
Uplink port and downlink port are two port roles in monitor link groups:
• Uplink ports refer to the monitored ports. The state of a monitor link group adapts to that of its
member uplink ports. When a monitor link group contains no uplink port or all the uplink ports are
down, the monitor link group becomes down; as long as one member uplink port is up, the monitor
link group stays up.