LAG Ports

Link Aggregation Overview

Link aggregation (also known as load sharing) lets you increase bandwidth and availability by using a group of ports to carry traffic in parallel between switches.

A Link Aggregation Group (LAG) allows multiple physical switch ports to be aggregated into one logical port, which provides the advantages of:

Increased bandwidth when the egress bandwidth of traffic exceeds the capacity of a single link.
Multiple links (link redundancy) for the purpose of network resiliency.

In both situations, the aggregation of separate physical links into a single logical link multiplies the total link bandwidth, in addition to providing resiliency against individual link failures.

Note

All ports in a LAG must run at the same speed and duplex setting.

If a port in a LAG fails, traffic is redistributed to the remaining ports in the LAG. If the failed port becomes active again, traffic is redistributed to include that port.

Note

Load sharing must be enabled on both ends of the link, or a network loop may result.

How LAGs Work with ExtremeCloud

As an administrator, you can configure a LAG port on a switch. 1-N ports can be selected. N is a function of the switch. All ports assigned to a LAG must have the same function (AP port, uplink port, host port, or other port).

LAG configuration does not create a new port. Instead, one port is assigned as the master port and receives all of the configuration, and the configuration applies to all of the LAG members. Adding a port to a LAG deletes out its previous configuration, and the port will inherit the LAG configuration.

If the port function of the LAG is access point (AP), you cannot assign more than two ports to the LAG.

Important

When configuring a LAG port for use by an ExtremeCloud-enabled access point, enable link aggregation on the access point first. If you do not do this, the AP can become isolated from the network. If the AP becomes isolated by the switch LAG port configuration, disable link aggregation on the switch ports used by the AP to allow the AP to join the network again. LAG can then be enabled on the AP, which takes one minute to update the configuration. Approximately two minutes later, LAG can be enabled on the corresponding switch ports.

If you want to configure a port differently than the LAG or assign it to a different LAG, you must remove the port from the existing LAG.

LAG Ports

Link Aggregation Overview

How LAGs Work with ExtremeCloud

More Information