Link Aggregation | 16511Link AggregationThis 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 176Link Aggregation—IEEE 802.3A 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 enablesyou to treat multiple physical links between two end-points as a single logical link, providing automaticredundancy between two devices. A LAG is often used to directly connect two switches when the trafficbetween them requires high bandwidth and reliability, or to provide a higher bandwidth connection to apublic 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 ofLACP PDUs (Link Aggregation Control Protocol Protocol Data Units).• Static configuration is used when connecting the switch to an external switch that does not support theexchange of LACP PDUs.Note: SFTOS 2.5.1 introduces the Interface Port Channel Config mode (see Interface PortChannel Config mode commands on page 168), which contains new commands and somecommands that are versions of previous commands used for configuring Port Channels,generically called Link Aggregation Groups (LAGs). Some of the previous commands aredeprecated, while some remain, providing alternative ways to accomplish a task.Starting with SFTOS 2.5.1, static LAGs and dynamic LAGs — through Link Aggregation ControlProtocol (LACP) — can coexist in the same configuration. Up to 48 LAGs can be configured in astack, 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 withSFTOS versions previous to SFTOS 2.5.1 might need to be adjusted to the range values in SFTOS2.5.1 and above.
