Port Channel Modes – Cisco Port Channels and vPCs

Port Channel Modes

Individual interfaces in port channels are configured with channel modes. When you run static port channels with no aggregation protocol, the channel mode is always set to on. When you run LACP as the aggregation protocol, you must first enable the LACP feature. By default, LACP is disabled. The system automatically takes a checkpoint before disabling the feature, and you can roll back to this checkpoint. You cannot disable LACP while any LACP configurations are present. After you enable LACP globally on the device, you enable LACP for each channel by setting the channel mode for each interface to either active or passive. You can configure channel mode for individual links in the LACP channel group when you are adding the links to the channel group. When you delete the port channel, the software automatically deletes the associated channel group. All member interfaces revert to their original configuration.

Table 4-1 describes the channel modes.

  

Table 4-1 Channel Modes

Channel Mode	Description
Passive	The LACP is enabled on this port channel, and the ports are in a passive negotiating state. Ports respond to the LACP packets they receive but do not initiate LACP negotiation.
Active	The LACP is enabled on this port channel, and the ports are in an active negotiating state. Ports initiate negotiations with other ports by sending LACP packets.
On	The LACP is disabled on this port channel, and the ports are in a non-negotiating state. The “on” state of the port channel represents the static mode. The port will not verify or negotiate port channel memberships. When an LACP attempts to negotiate with an interface in the on state, it does not receive any LACP packets and becomes an individual link with that interface. The link with the on state configured does not join the LACP channel group. The on state is the default port channel mode.

Both the passive and active modes allow LACP to negotiate between ports to determine if they can form a port channel based on criteria such as the port speed and the trunking state. The passive mode is useful when you do not know whether the remote system, or partner, supports LACP.

Two devices can form an LACP port channel, even when their ports are in different LACP modes, if the modes are compatible.

Table 4-2 shows various compatible channel modes for port channels.

Table 4-2 Channel Modes Compatibility

Device 1 > Port-1	Device 2 > Port-2	Result
Active	Active	Can form a port channel.
Active	Passive	Can form a port channel.
Passive	Passive	Cannot form a port channel because no ports can initiate negotiation.
On	Active	Cannot form a port channel because LACP is enabled only on one side.
On	Passive	Cannot form a port channel because LACP is not enabled.