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  • Lynne Hunter thinks this is interesting:

Specifically, you should avoid using the on state because it hard-codes the links into a bundle and disables PAgP’s capability to intelligently monitor the bundle. For example, all STP BPDUs are sent over a single link of the EtherChannel. If this one link fails, the entire bundle can be declared down if PAgP is not running in the auto or desirable states.

From

Cover of Cisco LAN Switching

Note

Is this still true on modern (2016) software images?