How Monitor Link Works - H3C S3100-52P Operation Manual

Operation Manual – Smart Link-Monitor Link
H3C S3100-52P Ethernet Switch

2.1.1 How Monitor Link Works

Switch C
Eth1/0/3
Eth1/0/1
Switch A
Figure 2-2 Network diagram for a Monitor Link group implementation
As shown in
device Switch E. Switch C is configured with a Monitor Link group, where Ethernet 1/0/1
is the uplink port, while Ethernet 1/0/2 and Ethernet 1/0/3 are the downlink ports. Switch
A is configured with a Smart Link group, where Ethernet 1/0/1 is the master port and
Ethernet 1/0/2 is the slave port.
If Switch C is not configured with Monitor Link group, when the link for the uplink
port Ethernet 1/0/1 on Switch C fails, the links in the Smart Link group are not
switched because the link for the master port Ethernet 1/0/1 of Switch A
configured with Smart Link group operates normally. Actually, however, the traffic
on Switch A cannot be up-linked to Switch E through the link of Ethernet 1/0/1.
If Switch C is configured with Monitor Link group and Monitor Link group detects
that the link for the uplink port Ethernet 1/0/1 fails, all the downlink ports in the
group are shut down; therefore, Ethernet 1/0/3 on Switch C is blocked. Now,
Smart Link group configured on Switch A detects that a link fault occurs on the
master port Ethernet 1/0/1. Then, Smart Link immediately activates the slave port
Ethernet 1/0/2 so that traffic is switched to the backup link.
Eth1/0/12
Eth1/0/11
Switch E
Eth1/0/1
Eth1/0/1
Eth1/0/2 Eth1/0/2
BLOCK
Eth1/0/2
Figure 2-2, the devices Switch C and Switch D are connected to the uplink
Chapter 2 Monitor Link Configuration
Switch D
Switch B
2-2