14-11-2012, 01:11 PM
A REPORT ON Virtual LAN
Virtual LAN.docx (Size: 82.5 KB / Downloads: 32)
Abstract
A VLAN is a group of network services not restricted to a physical segment or LAN switch. Configuration or reconfiguration of VLANs is done through software which makes it unnecessary to physically connect or move cables and equipment. VLANs address scalability, security, and network management. Routers in VLAN topologies provide broadcast filtering, security, and traffic flow management. Traffic should only be routed between VLANs. Switches may not bridge any traffic as this would violate the integrity of the VLAN broadcast domain. The primary benefit of VLANs is that they permit the network administrator to organize the LAN logically instead of physically. This includes the ability to move workstations on the LAN, add workstations to the LAN, change the LAN configuration, control network traffic, and improve security. A VLAN is a broadcast domain created by one or more switches. VLANs are used to create broadcast domains in order to improve the overall performance of the network. The switch then checks the destination so a forwarding decision can be made. For learning and forwarding the search is made against the address table for that VLAN only.There are three basic VLAN memberships for determining and controlling how a packet gets assigned., They include port-based VLANs, MAC address based VLANs, and protocol based VLANs. Packet tagging provides a mechanism for controlling the flow of broadcasts and applications while not interfering with the network and applications. Each VLAN must have a unique Layer 3 network address assigned. This enables routers to switch packets between VLANs. VLANs can exist either as end-to-end networks or they can exist inside of geographic boundaries. An end-to-end VLAN network groups users into VLANs based on group or job function. All users in a VLAN should have the same 80/20 traffic flow patterns. VLAN membership does not change for a user as they physically move locations. Each VLAN has a common set of security requirements for all members. Static VLANs are ports on a switch that are manually assigned to a VLAN by using a VLAN management application or by working directly within the switch. These ports maintain their assigned VLAN configuration until they are changed manually. Dynamic VLANs do not rely on ports assigned to a specific VLAN. Use the show vlan, show vlan brief, or show vlan id id_number commands to verify VLAN configuration.