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What Is Link Aggregation (NIC Teaming / Port Bonding)?

Combining several physical network ports into one logical connection can boost bandwidth and add redundancy -- here is how link aggregation actually works.

What link aggregation is

Link aggregation logically combines multiple physical network ports on a server, NAS, or switch into what behaves like a single connection. It is also commonly called NIC teaming or port bonding.

Why you would bond ports: throughput and redundancy

There are two main goals: spreading traffic from multiple clients across several ports to raise total throughput, and redundancy, so the connection stays up if one port fails. Depending on the distribution algorithm used, a single device's individual connection speed usually does not simply double, though.

The LACP standard

LACP (Link Aggregation Control Protocol) is the standard protocol that lets both ends of a connection automatically negotiate and manage which ports belong to the same group, which keeps equipment from different manufacturers working together reliably.

The switch has to support it too

Link aggregation is not something you can configure on just the server or NAS side -- the switch on the other end of the cables also needs to support the same standard and have those ports grouped together for it to work correctly.

Where it actually helps: NAS and file servers

On a NAS or file server that many clients connect to at once, bonding two or more ports together can produce a real, noticeable improvement in total throughput when multiple users are connected simultaneously.

Why home internet rarely benefits much

In a typical home, the internet connection itself is usually the bottleneck, and most distribution algorithms will not push a single device's session above the speed of one port anyway. That combination means home router setups usually see little practical benefit from link aggregation.

It multiplies aggregate throughput, not per-session speed

The most common misconception is expecting a single file transfer between two specific devices to run at double speed after bonding two ports. In most setups, the distribution algorithm assigns an entire session to one physical port based on the pair of endpoints involved, so the real benefit shows up when many different clients are connecting at once, not in a single one-to-one transfer.

Where you are likely to actually run into this feature

Link aggregation is common on business-grade NAS units, virtualization hosts, and managed network switches, where administrators use it to build both extra bandwidth and a fallback path in case one cable or port fails. It is much less common, and much less useful, on typical consumer routers.

Frequently Asked Questions

If I bond two ports, does a single transfer to one device get twice as fast?

Usually not. Most distribution algorithms choose which port to use based on the specific pair of communicating devices, so a single session with one other device is often still capped at the speed of one port. The gain typically shows up when several clients connect at the same time.

Do home routers support link aggregation?

Some higher-end routers and NAS devices include port bonding, but since the home internet connection itself is usually the actual bottleneck, the real-world improvement tends to be limited in a typical home setup.