I am puzzled about silent & nonsilent when configuring PAgP. What is the difference, please?
"desirable" & "desirable non-silent"
"auto" & "auto non-silent"
I have looked up several stuff/guides, but still not clearly understand it.
I agree it's a bit confusing, but my understanding is that when silent mode is used, it allows PAgP to operate when the neighbor device isn't PAgP capable.
If you have non-silent setting, it will send PAgP packets and it won't form the etherchannel until it receives a reply from the neighbor device.
As for using mode on, Yes - this should be the ideal mode for link partners that do not support PAgP nor LACP.