In regard to VMware vSphere, combining multiple network links can be done with the IEEE 802.3ad standard. IEEE 802.3ad can be configured to support static and dynamic link aggregation.
No cause information.
Does VMware 3.x - 5.0 support 802.3ad Dynamic?
Not until VMware ESXi 5.1 is 802.3ad Dynamic supported, and then only on a vShere Distributed Switch (vDS) which is explained in this VMware KB article: (1010270)
Background Information:
IEEE 802.3ad static: (Supported on on VMware ESX/ESXi 3.x - 5.x on vSwitches and vDS). Static link aggregation is configured individually on hosts or switches and no automatic negotiations happen between the two end points. Static link aggregation does not detect cabling or configuration issues and any switch port failures that do not result in a loss of link status.
Does enabling Route based on IP hash without 802.ad aggregation or vise-versa disrupt networking?
Yes, if you must enable 802.ad Static mode ON and configure the vSwitch to route based on IP Hash, configure route based on IP hash inside ESX/ESXi first, then enable the LAG on the physical network. You will loose connectivity to the ESX/ESXi host temporarily until you configure the phyical side.
Does VMware support any other algorithm other than IP HASH when using EtherChannel?
No, only route based on IP hash is supported when configuring based on EtherChannel.
How many EtherChannels exist per vSwitch or vSphere Distributed Switch (vDS)?
One and only one EtherChannel per vSwitch or vDS.
Can I use beacon probing with IP Hash load balancing?
No. Beacon probing with IP Hash load balancing is not supported. Beacon probing is most useful in detecting networking failures which do not result in a link down condition. This could be a misconfiguration resulting in link that is still up, but not operating as expected.
See http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf for more information.
Can I configure standby or unused uplinks while using IP Hash?
No. Do not configure standby or unused uplinks with IP Hash. IEEE 802.3ad dynamic: Only supported in ESXi 5.1 vDS. See VMware KB article "ESX/ESXi host requirements for link aggregation" (1001938) for more information.
Pior to ESXi 5.1 VMware only supported static link aggregation. With ESXi 5.1 Dynamic LACP is supported only vSphere Distributed Switches (vDS). Static LAG are still supported on vSwithes and vDS. Dynamic LACP provides additional support for Plug and Play automatic configuration and negotiation between host and physical switch. Dynamic LACP will detect link failures and cabling errors and automatically reconfigure the links.
What is the difference between Active and Passive Mode for LACP configuration?
Active - The port will actively negotiate the link state by initiating negotiation and send LACP frames.
Passive - The port is passive state and will respond to LACP fames sent during LACP negotiation.
References:
http://www.vmware.com/files/pdf/techpaper/Whats-New-VMware-vSphere-51-Network-Technical-Whitepaper.pdf
http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/gigeth.html
See Sample configuration of EtherChannel / LACP with ESXi/ESX (1004048) and Enabling or disabling LACP on a Uplink Port Group using vSphere Web Client (2034277)