A retail bank port-channel between two Nexus switches never bundles. One side is channel mode active and the other side is mode on. Why does the bundle fail to form?
Select an answer to reveal the explanation.
Short Explanation
One side is speaking a negotiation language, and the other side has the radio off. You set mode on, which bundles only as a static channel and does not run LACP toward the active peer. Spanning tree does not have to be removed for a port-channel to form.
Full Explanation
NX-OS channel mode active sends LACP packets and expects a peer that also runs LACP. Mode on brings a link into a static port-channel and does not speak LACP at all. The bank therefore has one side negotiating and the other side silent, so no bundle forms. Both ends need the same kind of channel: LACP on both, or static mode on on both. Rapid PVST+ is the spanning-tree mode. Port-channels form while spanning tree is running, and removing it is not a requirement for LACP. The vPC peer-keepalive is a separate liveness link between vPC peers. It is not supposed to ride the member ports of a data port-channel, and this failure is an LACP mode mismatch, not a keepalive path. HSRP version selects the virtual MAC format and the group range for a gateway. It has no role in whether two Ethernet links bundle. Caveat: if the static side comes up as an individual link while the LACP side suspends, you can pass traffic in one unexpected way, so fix the mode before you chase spanning tree. Operational check: set both sides to active or both sides to on, then confirm the members are bundled and neither side is suspended for an LACP mismatch.