Native VLAN support breaks this barrier so that you can connect a port to both VLAN-aware and VLAN-unaware stations. Such ports arereferred to as hybrid ports. Physical and port-channel interfaces may be hybrid ports.Native VLAN is useful in deployments where a Layer 2 port can receive both tagged and untagged traffic on the same physical port. Theclassic example is connecting a voice-over-IP (VOIP) phone and a PC to the same port of the switch. The VOIP phone is configured togenerate tagged packets (with VLAN = VOICE VLAN) and the attached PC generates untagged packets.NOTE: When a hybrid port is untagged in a VLAN but it receives tagged traffic, all traffic isaccepted.NOTE: You cannot configure an existing switchport or port channel interface for Native VLAN. Interfaces must have no otherLayer 2 or Layer 3 configurations when using the portmode hybrid command or a message similar to this displays: % Error:Port is in Layer-2 mode Gi 5/6.To configure a port so that it can be a member of an untagged and tagged VLANs, use the following commands.1 Remove any Layer 2 or Layer 3 configurations from the interface.INTERFACE mode2 Configure the interface for Hybrid mode.INTERFACE modeportmode hybrid3 Configure the interface for Switchport mode.INTERFACE modeswitchport4 Add the interface to a tagged or untagged VLAN.VLAN INTERFACE mode[tagged | untagged]Enabling Null VLAN as the Default VLANIn a Carrier Ethernet for Metro Service environment, service providers who perform frequent reconfigurations for customers with changingrequirements 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 ableto access each other's networks. Dell Networking OS has a Null VLAN to eliminate this vulnerability. When you enable the Null VLAN, allports are placed into it by default, so even if you activate the physical ports of multiple customers, no traffic is allowed to traverse the linksuntil each port is place in another VLAN.To enable Null VLAN, use the following command.• Disable the default VLAN, so that all ports belong to the Null VLAN until configured as a member of another VLAN.CONFIGURATION modedefault-vlan disableDefault: the default VLAN is enabled (no default-vlan disable).Virtual LANs (VLANs) 975
