LACP

LACP (Link Aggregation Control Protocol) combines multiple physical network links between two devices into a single logical link, adding bandwidth and providing redundancy. Two 10Gbps links become one 20Gbps logical connection that survives a single cable failure.

When one uplink between two switches isn't enough — either for bandwidth or redundancy — LACP lets you bond multiple physical ports into a single logical port channel. Both sides negotiate the aggregation automatically using the LACP protocol; the result is a link that appears as a single higher-bandwidth connection.

Common uses: uplinks between access and distribution switches, server connections to a switch (often called NIC teaming or bonding on the server side), and storage connections where both throughput and availability matter.

Traffic distribution across member links is handled by a hashing algorithm based on source/destination MAC addresses, IP addresses, or port numbers. This means a single flow (one TCP connection) still travels on one link — you won't see a single download speed double. The aggregate bandwidth benefits concurrent flows from multiple sources, not a single stream.

Key requirements: all member ports must be the same speed and duplex. A 1Gbps and a 10Gbps port cannot be in the same LAG. The same is true on both ends — both switches must have identical port speeds for the bundled interfaces.

LACP is a vendor-neutral standard supported by virtually all modern equipment — prefer it over any vendor-specific equivalent for interoperability between mixed hardware.