31 switchport mode trunk allow-null, 31 switchport mode trunk allow-null -67 – PLANET XGS3-24042 User Manual
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receive the data, the deal way is same, but the deal way is different in sending the data. Because
Hybrid ports can allow the packets of multiple VLANs to send with no tag, however, Trunk ports can
only allow the packets of the default VLAN to send with no tag. The attribute of ports can not directly
convert between Hybrid and Trunk, it must configure to be access at first, then configure to be
Hybrid or Trunk. When the Trunk or Hybrid attribute is cancelled, the port attribute restores the
default (access) attribute and belongs to vlan1.
Example:
Set port 5 to trunk mode and port 8 to access mode, port 10 to hybrid mode.
Switch(config)#interface ethernet 1/0/5
Switch(Config-If-Ethernet1/0/5)#switchport mode trunk
Switch(Config-If-Ethernet1/0/5)#exit
Switch(config)#interface ethernet 1/0/8
Switch(Config-If-Ethernet1/0/8)#switchport mode access
Switch(Config-If-Ethernet1/0/8)#exit
Switch(config)#interface ethernet 1/0/10
Switch(Config-If-Ethernet1/0/10)#switchport mode hybrid
Switch(Config-If-Ethernet1/0/10)#exit
12.1.31 switchport mode trunk allow-null
Command:
switchport mode trunk allow-null
Function:
Add a port as trunk mode. When enabling GVRP, the mode that adds the ports with trunk mode to
all VLANs is not appropriate. Therefore, add a port as trunk port and does not join any VLANs by
default for enabling GVRP on trunk port is appropriate. It is recommended to configure a port as
trunk with this command before enabling GVRP. This command can also be used when a port has
been configured as trunk already, which equals to clearing allow-list and quits all VLANs.
Command mode:
Port Mode.
Default:
access mode.
Usage Guide:
Configure the port as trunk, enable it to leave all VLANs and clear allow-list.
Example:
Switch(config-if-ethernet1/0/1)#switchport mode trunk allow-null