真机开机都是desirable switchport mode
access+trunk报错,限制连接
port           mode          encap      stat           native
F0/23        desirable      n-isl        trunking       1
                                     n表示negotiate
关闭自动协商:
Switch(config-if)#switchport nonegotiate
Command rejected: Conflict between 'nonegotiate' and 'dynamic' status.
Switch(config-if)#switchport mode ?

  access  Set trunking mode to ACCESS unconditionally

  dynamic  Set trunking mode to dynamically negotiate access or trunk mode

  trunk    Set trunking mode to TRUNK unconditionally


改变交换机接口模式:switchport mode dynamic auto

Switch(config-if)#switchport mode dynamic ?

  auto      Set trunking mode dynamic negotiation parameter to AUTO

  desirable  Set trunking mode dynamic negotiation parameter to DESIRABLE