VLAN

VLAN

1. VLAN segmentation

   • General description of VLANs
     • VLAN definitions
       • Within a switched network, VLANs provide segmentation and organizational flexibility. VLANs provide a way to group devices within a LAN.
     • Benefits of VLAN networks
       • The productivity of the users and the adaptability of the network are important for the growth and success of the companies. VLANs facilitate the design of a network to support the objectives of an organization.
     • Types of VLANs
       • There are different types of VLANs, which are used in modern networks. Some types of VLANs are defined according to traffic classes. Other types of VLANs are defined according to the specific function they fulfill.
     • Voice VLAN
       • Guaranteed bandwidth to ensure voice quality Priority of transmission over network traffic types
   • VLAN networks in a multiple switched environment
     • VLAN trunk links
       • A trunk is a point-to-point link between two network devices that carries more than one VLAN. A VLAN trunk extends the VLANs across the entire network.
     • Control of broadcast domains with VLANs
       • Under normal operating conditions, when a switch receives a broadcast frame on one of its ports, it forwards the frame to all other ports, except the port where it received the broadcast.
     • Labeling of Ethernet frames for VLAN identification
       • The Catalyst 2960 series switches are layer 2 devices. They use the information in the Ethernet frame header to forward packets.
     • Native VLANs and tagged 802.1Q
       • Frames tagged in the native VLAN Some devices that support trunk links add a VLAN tag to native VLAN traffic.
     • Voice VLAN tagging
       • a VLAN for voice traffic and another VLAN for data traffic from a device connected to the telephone.

2. VLAN implementations

   • VLAN network assignment
     • VLAN ranges in Catalyst switches
       • Different Cisco Catalyst switches support varying amounts of VLANs. The amount of VLANs they support is sufficient to meet the needs of most organizations.
     • Creating a VLAN
       • When configuring normal-range VLANs, the configuration details are stored in the flash memory of the switch in a file called vlan.dat. Flash memory is persistent and does not require the copy running-config startup-config command.
     • Assigning ports to VLANs
       • to define a port as an access port and assign it to a VLAN. The switchport mode access command is optional, but is recommended as a security best practice.
     • Changing port membership of a VLAN
       • to change the membership of a switch port in VLAN 1 with the no switchport access vlan command in the interface configuration mode.
     • Removing VLANs
       • the global configuration mode command not vlan vlan-id is used to remove VLAN 20 from the switch. Switch S1 had a minimum configuration with all ports in VLAN 1 and one VLAN 20
     • Verifying VLAN information
       • The show vlan name student command produces a result that is not easily interpreted. The show vlan summary command shows the count of all configured VLANs.