Concept Guide

NOTE: You cannot assign an IP address to the Default VLAN (VLAN 1). To assign another VLAN ID to the Default VLAN, use the
default vlan-id vlan-id command.
You can place VLANs and other logical interfaces in Layer 3 mode to receive and send routed trac. For more information, refer to Bulk
Conguration.
To assign an IP address, use the following command.
• Congure an IP address and mask on the interface.
INTERFACE mode
ip address ip-address mask [secondary]
– ip-address mask — Enter an address in dotted-decimal format (A.B.C.D) and the mask must be in slash format (/24).
– secondary — This is the interface’s backup IP address. You can congure up to eight secondary IP addresses.
Conguring Native VLANs
Traditionally, ports can be either untagged for membership to one VLAN or tagged for membership to multiple VLANs.
You must connect an untagged port to a VLAN-unaware station (one that does not understand VLAN tags), and you must connect a
tagged port to a VLAN-aware station (one that generates and understands VLAN tags).
Native VLAN support breaks this barrier so that you can connect a port to both VLAN-aware and VLAN-unaware stations. Such ports are
referred 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 trac on the same physical port. The
classic example is connecting a voice-over-IP (VOIP) phone and a PC to the same port of the switch. The VOIP phone is congured to
generate 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 trac, all trac is accepted.
NOTE: You cannot congure an existing switchport or port channel interface for Native VLAN. Interfaces must have no other
Layer 2 or Layer 3 congurations when using the portmode hybrid command or a message similar to this displays: % Error:
Port is in Layer-2 mode Te 5/6.
To congure 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 congurations from the interface.
INTERFACE mode
2 Congure the interface for Hybrid mode.
INTERFACE mode
portmode hybrid
3 Congure the interface for Switchport mode.
INTERFACE mode
switchport
4 Add the interface to a tagged or untagged VLAN.
VLAN INTERFACE mode
[tagged | untagged]
Virtual LANs (VLANs)
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