EtherChannel support

EtherChannel aggregates multiple network interfaces so that they appear as a single interface. The IP/NIC, IPMultiNIC/MultiNICA, and IPMultiNICB/MultiNICB agents support EtherChannel use with VCS. For example you can combine en0 and en1 into an EtherChannel and call the combined interface en2. You then use the NIC (or MultiNICA or MultiNICB) agent to monitor this en2 interface. You use the IP (or IPMultiNIC or IPMultiNICB) agent to configure and monitor an IP address on the en2 interface. Note that you use the en2 interface configured through EtherChannel for the Device attribute. EtherChannel is responsible for providing local adapter swapping, which is outside of VCS control. EtherChannel backup and active-active modes are supported.