Objective

Link Aggregation Control Protocol (LACP) bundles individual links into a single logical link to provide a much higher bandwidth. It is used to prioritize ports on a Link aggregation (LAG). A dynamic LAG can have up to 16 ports of the same type but only 8 ports can be active at one time. When a LAG has more than 8 ports, the device uses LACP system priority and LACP port priority to determine which ports become active.

LACP system priority is used to determine if the local device or the remote device has priority. The device with the lower priority value controls the port selection in the LAG. If the devices have the same LACP system priority the MAC addresses are compared. The device with the lowest MAC address is given control. LACP port priority is used to determine which 8 ports of the higher priority device are active in the LAG. Ports with the lowest priority values are active.

This article explains how to configure LACP on the Sx500 Series Stackable Switches.

Applicable Devices

• Sx500 Series Stackable Switches

Software Version

• v1.2.7.76

LACP Configuration

Step 1. Log in to the web configuration utility and choose Port Management > Link Aggregation > LACP. The LACP page opens:

Step 2. Enter a value for the LACP system priority in the LACP System Priority field. The LACP system priority is used to determine which switch makes the decision of ports that are going to actively participate in the LAG.

Step 3. Click Apply.

Step 4. Click the radio button of the port you want to modify and click Edit.

Step 5. (Optional) From the Unit/Slot and Port drop-down lists choose the port to configure.

Step 6. Enter a value for the port priority in the LACP Port Priority field. The lower the value, the higher the priority the port has on the LAG.

Step 7. Click the radio button that corresponds to the desired LACP timeout. This determines the interval between the send and receive times of LACP protocol data units (PDUs).

• Long — Uses a long interval between the send and receive times of consecutive LACP PDUs. This is recommended so that the PDUs are not exchanged very frequently which can overwhelm the switch's CPU.

• Short — Uses a short interval between the send and receive times of consecutive LACP PDUs. The PDUs are sent very frequently.

Step 8. Click Apply.