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VLAN | 1107
To configure a port so that it has a native VLAN:
Change the Default VLAN ID
By default, VLAN 1 is the Default VLAN. You can make another VLAN the default (which then enables
you to configure VLAN 1).
Set the 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.
Step Task Command Command Mode
1 Remove any Layer 2 or Layer 3 configurations from the interface. INTERFACE
If the port has any configurations on it when you enter the command portmode hybrid, FTOS rejects
the configuration, citing the following message: % Error: Port is in Layer-2 mode <slot/port>.
2 Configure the interface for hybrid mode. portmode hybrid INTERFACE
3 Configure the interface for switchport mode.
switchport
INTERFACE
4 Add the interface as a member of one or more VLANs. [
tagged | untagged] VLAN INTERFACE
Task Command Syntax Command Mode
Make a VLAN other than VLAN 1 the default VLAN.
default vlan-id
CONFIGURATION
Task Command Syntax Command Mode
Disable the default VLAN, so that all ports belong to
the Null VLAN until configured as a member of another
VLAN.
default-vlan disable
Default: the default VLAN is enabled
(no default-vlan disable).
CONFIGURATION