Quick Reference Guide

Link Aggregation | 165

Link Aggregation

This chapter contains the following major sections:

• Link Aggregation—IEEE 802.3

• Link Aggregation Group (LAG) Commands on page 168

• Configuring a LAG on page 170

• Link Aggregation Control Protocol (LACP) on page 174

• Displaying LAGs (Port Channels) on page 176

Link Aggregation—IEEE 802.3

A Link Aggregation Group (LAG), also called a Port Channel or port trunking, conforms to IEEE 802.3

(802.3ad), enabling MAC interfaces to be grouped logically to appear as one physical link. A LAG enables

you to treat multiple physical links between two end-points as a single logical link, providing automatic

redundancy between two devices. A LAG is often used to directly connect two switches when the traffic

between them requires high bandwidth and reliability, or to provide a higher bandwidth connection to a

public network.

You can configure LAGs as either dynamic or static (SFTOS configures dynamic LAGs by default.):

• Dynamic configuration uses the IEEE 802.3ad standard, which provides for the periodic exchanges of

LACP PDUs (Link Aggregation Control Protocol Protocol Data Units).

• Static configuration is used when connecting the switch to an external switch that does not support the

exchange of LACP PDUs.

Note: SFTOS 2.5.1 introduces the Interface Port Channel Config mode (see Interface Port

Channel Config mode commands on page 168), which contains new commands and some

commands that are versions of previous commands used for configuring Port Channels,

generically called Link Aggregation Groups (LAGs). Some of the previous commands are

deprecated, while some remain, providing alternative ways to accomplish a task.

Starting with SFTOS 2.5.1, static LAGs and dynamic LAGs — through Link Aggregation Control

Protocol (LACP) — can coexist in the same configuration. Up to 48 LAGs can be configured in a

stack, up to six of them dynamic LAGs.

SFTOS 2.5.1 discontinues the logical interface identifier (0/1/xx) for a LAG (Port Channel).

Instead, the ID is an integer, as exemplified in Figure 11-131 on page 173.

Configuration migration: Range values of some commands used to configure your system with

SFTOS versions previous to SFTOS 2.5.1 might need to be adjusted to the range values in SFTOS

2.5.1 and above.