Modes used for channel
V active     Enable LACP unconditionally
C auto       Enable PAgP only if a PAgP device is detected
C desirable  Enable PAgP unconditionally
  on         Enable Etherchannel only
V passive    Enable LACP only if a LACP device is detected

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configuration

interface Port-channel 1
 switchport mode trunk

switchport mode trunk
switchport nonegotiate
channel-group 1 mode desirable