3com WX3000 Manuel D’Utilisation

2-2

How Monitor Link Works

Figure 2-2 Network diagram for a Monitor Link group implementation

BLOCK

Switch A

Switch B

GE 1/0 /1

GE1 /0/2

Switch C

Switch D

Switch E

GE1 /0/1

GE1 /0/2

GE 1/0 /3

GE 1/0/1

GE 1/0/2

GE1/0/3

GE 1/0/11

GE 1/0/12

As shown in

, the devices Switch C and Switch D are connected to the uplink device Switch E.

Switch C is configured with a Monitor Link group, where GigabitEthernet 1/0/1 is the uplink port, while

GigabitEthernet 1/0/2 and GigabitEthernet 1/0/3 are the downlink ports. Switch A is configured with a

Smart Link group, where GigabitEthernet 1/0/1 is the master port and GigabitEthernet 1/0/2 is the slave

port.

If Switch C is not configured with Monitor Link group, when the link for the uplink port

GigabitEthernet 1/0/1 on Switch C fails, the links in the Smart Link group are not switched because

the link for the master port GigabitEthernet 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 GigabitEthernet 1/0/1.

If Switch C is configured with Monitor Link group and Monitor Link group detects that the link for the

uplink port GigabitEthernet 1/0/1 fails, all the downlink ports in the group are shut down; therefore,

GigabitEthernet 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 GigabitEthernet 1/0/1. Then, Smart Link

immediately activates the slave port GigabitEthernet 1/0/2 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.