command in the interface configuration mode. To disable the Standalone mode and revert to the default use the port-channel standalone disable command in the interface configuration mode. Link Aggregation Control Protocol and Link Redundancy LACP port-channel operation, bandwidth availability, and link redundancy can be further refined with the LACP port-channel min-links and the LACP max-bundle features. The LACP port-channel min-links feature: • Configures the minimum number of ports that must be linked up and bundled in the LACP port channel. • Prevents a low-bandwidth LACP port channel from becoming active.
• Causes an LACP port channel to become inactive if there are too few active members ports to supply the required minimum bandwidth. The LACP max-bundle feature: • Defines an upper limit on the number of bundled ports in an LACP port channel. • Allows hot-standby ports with fewer bundled ports. For example, in an LACP port channel with five ports, you can specify a max-bundle of three, and the two remaining ports are designated as hot-standby ports. Link Aggregation Control Protocol Interaction with Other Features The DTP and the CDP send and receive packets over the physical ports in the EtherChannel. Trunk ports send and receive LACP PDUs on the lowest numbered VLAN.
In Layer 2 EtherChannels, the first port in the channel that comes up provides its MAC address to the EtherChannel. If this port is removed from the bundle, one of the remaining ports in the bundle provides its MAC address to the EtherChannel. For Layer 3 EtherChannels, the MAC address is allocated by the active device as soon as the interface is created through the interface port-channel global configuration command. LACP sends and receives LACP PDUs only from ports that are up and have LACP enabled for the active or passive mode.
Link Aggregation Control Protocol Interaction with Other Features 1:1 Redundancy The LACP 1:1 Redundancy feature supports an EtherChannel configuration with one active link, and fast switchover to a hot-standby link. The link that is connected to the port with the lower port priority number (and therefore, of a higher priority) will be the active link, and the other link will be in a hot-standby state. If the active link goes down, LACP performs a fast switchover to the hot-standby link to keep the EtherChannel up. When the failed link becomes operational again, LACP performs another fast switchover to revert to the original active link.
To allow the higher priority port to stabilize when it becomes active again after a higher-priority to lower-priority switchover, the LACP 1:1 Hot Standby Dampening feature configures a timer that delays switchover back to the higher priority port after higher priority port becomes active. EtherChannel On Mode EtherChannel on mode can be used to manually configure an EtherChannel. The on mode forces a port to join an EtherChannel without negotiations. The on mode can be useful if the remote device does not support Configuring EtherChannels Link Aggregation Control Protocol and Link Redundancy Configuring EtherChannels 7