Port Management
Link Aggregation
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4
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Static and Dynamic LAG Workflow
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Link Aggregation Overview
Link Aggregation Control Protocol (LACP) is part of the IEEE specification (802.3az) that
enables you to bundle several physical ports together to form a single logical channel (LAG).
LAGs multiply the bandwidth, increase port flexibility, and provide link redundancy between
two devices.
Two types of LAGs are supported:
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Static
—The ports in the LAG are manually configured. A LAG is static if LACP is
disabled on it. The group of ports assigned to a static LAG are always active
members. After a LAG is manually created, the LACP option cannot be added or
removed, until the LAG is edited and a member is removed (which can be added back
prior to applying); the LACP button then become available for editing.
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Dynamic
—A LAG is dynamic if LACP is enabled on it. The group of ports assigned
to dynamic LAG are candidate ports. LACP determines which candidate ports are
active member ports. The non-active candidate ports are
standby
ports ready to replace
any failing active member ports.
Load Balancing
Traffic forwarded to a LAG is load-balanced across the active member ports, thus achieving an
effective bandwidth close to the aggregate bandwidth of all the active member ports of the
LAG.
Traffic load balancing over the active member ports of a LAG is managed by a hash-based
distribution function that distributes Unicast and Multicast traffic based on Layer 2 or Layer 3
packet header information.
The device supports two modes of load balancing:
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By MAC Addresses
—Based on the destination and source MAC addresses of all
packets.
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By IP and MAC Addresses
—Based on the destination and source IP addresses for IP
packets, and destination and source MAC addresses for non-IP packets.
