How Monitor Link Works; Configuring Monitor Link - H3C S3100 Series Operation Manual

How Monitor Link Works

Figure 2-2 Network diagram for a Monitor Link group implementation
Eth1/0/11
Switch C
Eth1/0/1
Eth1/0/2
Eth1/0/3
Eth1/0/1
Eth1/0/2
Switch A
As shown in Figure
Switch C is configured with a Monitor Link group, where Ethernet1/0/1 is the uplink port, while
Ethernet1/0/2 and Ethernet1/0/3 are the downlink ports. Switch A is configured with a Smart Link group,
where Ethernet1/0/1 is the master port and Ethernet1/0/2 is the slave port.
If Switch C is not configured with Monitor Link group, when the link for the uplink port Ethernet1/0/1
on Switch C fails, the links in the Smart Link group are not switched because the link for the master
port Ethernet1/0/1 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 Ethernet1/0/1.
If Switch C is configured with Monitor Link group and Monitor Link group detects that the link for the
uplink port Ethernet1/0/1 fails, all the downlink ports in the group are shut down; therefore,
Ethernet1/0/3 on Switch C is blocked. Now, Smart Link group configured on Switch A detects that a
link fault occurs on the master port Ethernet1/0/1. Then, Smart Link immediately activates the slave
port Ethernet1/0/2 so that traffic is switched to the backup link.
Currently, member ports of a Monitor Link group cannot be dynamic link aggregation groups.
If the uplink or downlink port in the Monitor Link group is a link aggregation group, you cannot
directly delete this aggregation group or change this aggregation group into a dynamic aggregation
group. To delete this aggregation group, you must first unbind this aggregation group from the
Monitor Link.

Configuring Monitor Link

Eth1/0/12
Switch E
Switch D
Eth1/0/1
Eth1/0/2
BLOCK
Switch B
2-2, the devices Switch C and Switch D are connected to the uplink device Switch E.
2-2