Enable Null Vlan As The Default Vlan - Dell Force10 MXL Blade Configuration Manual

To configure a port so that it can be a member of an untagged and tagged VLANs, follow these steps:
Step Task
1 Remove any Layer 2 or Layer 3 configurations from the interface.
2 Configure the interface for hybrid mode.
3 Configure the interface for switchport mode.
4 Add the interface to a tagged or untagged VLAN.
Note: You cannot configure an existing switchport or port channel interface for Native VLAN. Interfaces
must have no other Layer 2 or Layer 3 configurations when entering the command portmode hybrid or a
message similar to
Message 1 Native VLAN Error
% Error: Port is in Layer-2 mode Tengig 5/6.

Enable Null VLAN as the Default VLAN

In a Carrier Ethernet for Metro Service environment, service providers who perform frequent
reconfigurations for customers with changing requirements occasionally enable multiple interfaces, each
connected to a different customer, before the interfaces are fully configured. This presents a vulnerability
because both interfaces are initially placed in the native VLAN (VLAN 1) and for that period customers
are able to access each other's networks. FTOS has a null VLAN to eliminate this vulnerability.
When you enable the null VLAN, all ports are placed into by it default, so that even if you activate the
physical ports of multiple customers, no traffic is allowed to traverse the links until each port is place in
another VLAN.
To disable the default VLAN, use the following command:
Task
Disable the default VLAN, so that all ports belong to
the Null VLAN until configured as a member of another
VLAN.
Message 1 is displayed.
Command
portmode hybrid
switchport
[tagged | untagged]
Command Syntax
default-vlan disable
Default: the default VLAN is enabled
( ).
no default-vlan disable
Command Mode
INTERFACE
INTERFACE
INTERFACE
VLAN INTERFACE
Command Mode
CONFIGURATION
Virtual LANs (VLAN) | 631