7.6.2 Link aggregation forwarding

If the link aggregation that connects to multiple member switches is the forwarding destination, the port of the received member switch is given priority for forwarding. The stack link bandwidth can be effectively utilized by assigning a priority to the port of the member switch that received the frame. In addition, if other member switches in the stack fail, they will not be affected by communications. For effective use of priority distribution, it is recommended that you configure multiple member switches when using link aggregation on the stack.

On the other hand, if you prefer to forward ports on a received member switch, traffic might be concentrated on the ports on a specific member switch. In such cases, you can set the configuration command system port-channel load-balance-all-port to assign ports to all member switches that belong to link aggregation.

For details about selecting a forwarding port when there are multiple ports to be sorted in each forwarding operation, see 21.1.5 Port sorting during frame transmission.

<Structure of this section>

(1) Transfer operation during normal operation

(a) To prioritize the port of the received member switch

If the link aggregation that connects to multiple member switches is the forwarding destination, the port of the received member switch is given priority for forwarding. The following figure shows the normal transfer operation when the port of the member switch received in link aggregation is given priority.

Figure 7-12: Normal transfer operation when the port of the received member switch is given priority (link aggregation)

(b) When the ports of all member switches are to be sorted

If the link aggregation to which multiple member switches are connected is the destination, the link aggregation is selected from the ports of all member switches belonging to the link aggregation and forwarded. The following figure shows the normal transfer operation when link aggregation is used to distribute all member switch ports.

Figure 7-13: Normal transfer operation when ports on all member switches are subject to distribution (link aggregation)

One of the following is selected for forwarding: a route forwarded directly from a port on the backup switch and a route forwarded from a port on the master switch via the stack link.

(2) Transfer operation at the time of port failure at the transfer source

If a member switch that is received due to a fault in the source port during link aggregation is changed, the port on the received member switch is prioritized for forwarding. The following figure shows the transfer operation in the event of a port failure at the transfer source in link aggregation.

Figure 7-14: Transfer operation when a transfer source port fails (link aggregation)

If you want all member switch ports to be sorted, select the ports and forward them in the same way as they normally would if the member switches were changed.

(3) Forwarding Operation in Case of Port Failure at Forwarding Destination

If link aggregation fails on the destination port and no port is forwarded to the received member switch, the port is forwarded through the stack link to the port of the other member switch. The following figure shows the transfer operation in the event of a transfer destination port failure during link aggregation.

Figure 7-15: Transfer operation when a transfer destination port fails (link aggregation)

If you want all member switch ports to be redirected, select and forward non-failed ports from all member switch ports that belong to link aggregation.