Configuring Interface Characteristics
Interface Types
Port-Based VLANs
A VLAN is a switched network that is logically segmented by function, team, or application, without regard to the physical location of the users. Packets received on a port are forwarded only to ports that belong to the same VLAN as the receiving port. Network devices in different VLANs cannot communicate with one another without a Layer 3 device to route traffic between the VLANs.
VLAN partitions provide hard firewalls for traffic in the VLAN, and each VLAN has its own MAC address table. A VLAN comes into existence when a local port is configured to be associated with the VLAN, when the VLAN Trunking Protocol (VTP) learns of its existence from a neighbor on a trunk, or when a user creates a VLAN. VLANs can be formed with ports across the stack.
To configure VLANs, use the vlan
In a switch stack, the VLAN database is downloaded to all switches in a stack, and all switches in the stack build the same VLAN database. The running configuration and the saved configuration are the same for all switches in a stack.
Add ports to a VLAN by using the switchport interface configuration commands:
•Identify the interface.
•For a trunk port, set trunk characteristics, and, if desired, define the VLANs to which it can belong.
•For an access port, set and define the VLAN to which it belongs.
Switch Ports
Switch ports are Layer
Configure switch ports by using the switchport interface configuration commands.
Access Ports
An access port belongs to and carries the traffic of only one VLAN (unless it is configured as a voice VLAN port). Traffic is received and sent in native formats with no VLAN tagging. Traffic arriving on an access port is assumed to belong to the VLAN assigned to the port. If an access port receives a tagged packet
Two types of access ports are supported:
•Static access ports are manually assigned to a VLAN (or through a RADIUS server for use with IEEE 802.1x.
•VLAN membership of dynamic access ports is learned through incoming packets. By default, a dynamic access port is not a member of any VLAN, and forwarding to and from the port is enabled only when
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