EtherChannels
EtherChannel is a way of combining several physical links between switches
into one logical connection. Normally, Spanning Tree blocks redundant
links; EtherChannel gets around that and allows load balancing across those
links. Load is balancing on the basis of such things as source or destination
MAC address or IP address. The Etherchannel load-balancing method is
configured at global configuration mode.
(config)#port-channel load-balance type
A logical interface—the Port Channel interface—is created. Configuration
can be applied to both the logical and physical interfaces.
Some guidelines for EtherChannels are as follows:
■ Interfaces in the channel do not have to be physically next to each
other or on the same module.
■ All ports must be the same speed and duplex.
■ All ports in the bundle should be enabled.
■ None of the bundle ports can be a SPAN port.
■ Assign an IP address to the logical Port Channel interface, not the
physical ones.
■ Put all bundle ports in the same VLAN, or make them all trunks. If
they are trunks, they must all carry the same VLANs and use the same
trunking mode.
■ Configuration you apply to the Port Channel interface affects the entire
EtherChannel. Configuration you apply to a physical interface only
affects that interface.