This has come up on a couple of projects I have been involved in lately. It seems that this is becoming frequently used as a redundancy configuration for Linux-based Oracle Server applications on the network.
In Cisco lingo this is called an EtherChannel. In Linux-speak it's called Bonding. The protocol used - as required by the Linux software - is LACP (Link Aggregation Control Protocol).
I focused on mode 4 since that provides link aggregation - makes all the ports on the server look like one logical connection to the network, thus providing higher bandwidth. The nice thing about this setup is that if anyone port fails, the traffic continues to flow uninterrupted through the other ports.
This example goes a step further, and also adds Tagging (allowing traffic for multiple VLANs to be transported across the link. That's called"trunking" in Cisco lingo as shown below.
This is a working configuration from a port in a production environment:
***Note proprietary information has been changed to generic information
