In the figure, traffic coming from several links (usually 100 or 1000 Mb/s) aggregates on the access switch and must be sent to distribution switches. Because of the traffic aggregation, links with higher bandwidth must be available between the access and distribution switches.

It may be possible to use faster links, such as 10 Gb/s, on the aggregated link between the access and distribution layer switches. However, adding faster links is expensive. Additionally, as the speed increases on the access links, even the fastest possible port on the aggregated link is no longer fast enough to aggregate the traffic coming from all access links.

It is also possible to multiply the number of physical links between the switches to increase the overall speed of switch-to-switch communication. However, by default, STP is enabled on switch devices. STP will block redundant links to prevent routing loops.

For these reasons, the best solution is to implement an EtherChannel configuration.