EtherChannel, Port Channel, Trunking, Port trunking, Link aggregation

Po1, which stands for the interface "port-channel1". This is the logical interface created when an Etherchannel is built. We are now using both physical paths between the two switches at one time!
http://ezinearticles.com/?Cisco-CCNA-/-CCNP-Certification:-How-And-Why-To-Build-An-Etherchannel&id=93114

Etherchannel/port-channel
On different Cisco switches it is possible to create logical connections that are made-up off different fysical interface. It is needed that these interface do have the same speed.

Cisco switch show command’s

· show interfaces port-channel [channel-group-number]

· show etherchannel [channel-group-number] summary

http://www.edgenetworks.nl/etherchannel.html

 EtherChannel between a switch and a server.

EtherChannel is a port trunking (link aggregation being the general term) technology or port-channel architecture used primarily on Cisco switches. It allows grouping several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers. An EtherChannel can be created from between two and eight active Fast Ethernet, Gigabit Ethernet or 10-Gigabit Ethernet ports, with an additional one to eight inactive (failover) ports which become active as the other active ports fail. EtherChannel is primarily used in the backbone network, but can also be used to connect end user machines.
http://en.wikipedia.org/wiki/EtherChannel

Trunking
In modern communications, trunking is a concept by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of this include telephone systems and the VHF radios commonly used by police agencies. More recently port trunking has been applied in computer networking as well.
http://en.wikipedia.org/wiki/Trunking

Link Aggregation between a switch and a server

Link aggregation/Port trunking
Link aggregation or IEEE 802.1AX-2008 is a computer networking term which describes using multiple network cables/ports in parallel to increase the link speed beyond the limits of any one single cable or port, and to increase the redundancy for higher availability.
http://en.wikipedia.org/wiki/Link_aggregation
http://en.wikipedia.org/wiki/Port_trunking