How port-channel works in cisco switches

Port-channel is a feature to aggregate 2 links in an interconnection to another switch. It is very usefull in the following cenarios: - Increasing the throughput by adding another link. For example, in a port-channel of 2 Gbps, if you need more throughput, you just have to add aother link to the port-channel. There is no downtime altough the hashing of the port-channel will change. - Very efecient for link upgrade cenario as you will not have STP rotation.

Things you should know about port-channel that are not very clear in documentation: - The maximum flow in a port-channel is the maximum link throught that you have. This is beacause the best Cisco equipments can do is IP Hashing. This means, that each IP will be associated to only one port. This means that any flow from any to that IP behing it will always have 1Gbps throughput. - Aggregation protocols are very important such as LACP. It will add keeplive checks up to the port-channel to garantee that it is still up. LACP fast can detect a failure really fast. - High CPU can bring down aggregation protocols, which could end in link down catastrophic cenarios.