Bob,
For LACP, you have the option of active and passive and one side of the connection must be active.
LACP supports the automatic creation of EtherChannels by exchanging LACP packets between LAN
ports. LACP packets are exchanged only between ports in passive and active modes.
The protocol learns the capabilities of LAN port groups dynamically and informs the other LAN ports.
Once LACP identifies correctly matched Ethernet links, it facilitates grouping the links into an
EtherChannel. The EtherChannel is then added to the spanning tree as a single bridge port.
Both the passive and active modes allow LACP to negotiate between LAN ports to determine if they can
form an EtherChannel, based on criteria such as port speed and trunking state. Layer 2 EtherChannels
also use VLAN numbers.
LAN ports can form an EtherChannel when they are in different LACP modes as long as the modes are
compatible. For example:
• A LAN port in active mode can form an EtherChannel successfully with another LAN port that is
in active mode.
• A LAN port in active mode can form an EtherChannel with another LAN port in passive mode.
• A LAN port in passive mode cannot form an EtherChannel with another LAN port that is also in
passive mode, because neither port will initiate negotiation.
HTH
Reza
