实例一:
无论如何配置，就是不能将端口有trunk改为access
后面发现这样配置，就可以将端口更改：
用下面两条命令就可以更改端口类型
[Huawei-GigabitEthernet0/0/1]undo port trunk allow-pass vlan all //取消trunk 口上面允许通过的所有vlan
[Huawei-GigabitEthernet0/0/1]port trunk allow-pass vlan 1 //将trunk端口重新允许默认的vlan1通过
实例二:
[S9306-GigabitEthernet2/0/42]dis this
#
interface GigabitEthernet2/0/42 原先的为trunk，
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
interface GigabitEthernet2/0/42 现在改为access
undo port trunk allow-pass vlan all
port trunk allow-pass vlan 1
port link-type access
port default vlan 10
使用undo port trunk allow-pass vlan all命令时会将默认的Vlan 1也会undo掉，
所以必须再执行一次port trunk allow-pass vlan 1
或者使用下面的命令也可以：
interface GigabitEthernet0/0/26 原先的为trunk
port link-type trunk
port trunk allow-pass vlan 2 to 4094
#
undo port trunk allow-pass vlan 2 to 4094 先undo掉2-4094
undo port link-type 再undo掉trunk
port link-type access 设置为access
port default vlan 10 设置默认VLAN