Overview of Link Aggregation
Definition
Ethernet link aggregation, also called Eth-Trunk, bundles multiple physical links into a logical link to increase link bandwidth. The bundled links back up each other, increasing reliability.
Purpose
As networks grow in scale, users require Ethernet backbone networks to provide higher bandwidth and reliability. In the past, to increase the bandwidth, users had to replace legacy devices with devices supporting high-speed LPUs or replace LPUs on legacy devices with high-speed ones. This solution, however, is costly and inflexible.
Link aggregation helps increase bandwidth by bundling a group of physical interfaces into a single logical interface, without having to upgrade hardware. In addition, link aggregation provides link backup mechanisms, greatly improving link reliability.
Link aggregation has the following advantages:
Increased bandwidth
The bandwidth of the link aggregation interface is the sum of the bandwidth of member interfaces.
Higher reliability
When an active link fails, traffic on this active link moves to another active link, improving reliability of the link aggregation interface.
Load balancing
In a link aggregation group (LAG), traffic is load balanced among active link members.