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Types of VLAN

A Local Area Network (LAN) was originally defined as a network of computers located within the same area. Today, Local Area Networks are defined as a single broadcast domain. This means that if a user broadcasts information on his/her LAN, the broadcast will be received by every other user on the LAN. Broadcasts are prevented from leaving a LAN by using a router. The disadvantage of this method is routers usually take more time to process incoming data compared to a bridge or a switch. More importantly, the formation of broadcast domains depends on the physical connection of the devices in the network. Virtual Local Area Networks (VLAN's) were developed as an alternative solution to using routers to contain broadcast traffic. In a traditional LAN, workstations are connected to each other by means of a hub or a repeater. These devices propagate any incoming data throughout the network. However, if two people attempt to send information at the same time, a collision will occur and all the transmitted data will be lost. Once the collision has occurred, it will continue to be propagated throughout the network by hubs and repeaters. The original information will therefore need to be resent after waiting for the collision to be resolved, thereby incurring a significant wastage of time and resources. To prevent collisions from traveling through all the workstations in the network, a bridge or a switch can be used. These devices will not forward collisions, but will allow broadcasts (to every user in the network) and multicasts (to a pre -specified group of users) to pass through. A router may be used to prevent broadcasts and multicasts from travelling through the network. The workstations, hubs, and repeaters together form a LAN segment. A LAN segment is also known as a collision domain since collisions remain within the segment. The area within which broadcasts

in a bridge with four ports. VLAN's also allow broadcast domains to be defined without using routers. it does not allow for user mobility. when a workstation is moved. its VLAN membership must be reconfigured. switches. 2. For example. Also. membership in a VLAN is based on the MAC address of the workstation. In networks with thousands of users. MAC address.and multicasts are confined is called a broadcast domain or LAN. Types of VLAN's: VLAN membership can be classified by port. 1) Layer 1 VLAN: Membership by Port Membership in a VLAN can be defined based on the ports that belong to the VLAN. Thus a LAN can consist of one or more LAN segments. Defining broadcast and collision domains in a LAN depends on how the workstations. VLAN's allow a network manager to logically segment a LAN into different broadcast domains. MAC Address VLAN 1212354145121 1 2389234873743 2 3045834758445 2 5483573475843 1 The main problem with this method is that. when a notebook PC is moved to a different docking station. Users on different floors of the same building. Routers would only have to be used to communicate between two VLAN's. Port VLAN 1 2 3 4 1 1 2 1 The main disadvantage of this method is that. hubs. VLAN membership must be assigned initially. 3) Layer 2 VLAN: Membership by Protocol Type VLAN membership for Layer 2 VLAN's can also be based on the protocol type field found in the Layer 2 header. ports 1. This is unlike Layer 1 VLAN's where membership tables must be reconfigured. or even in different buildings can now belong to the same LAN. in environments where notebook PC's are used. Protocol VLAN . no reconfiguration is needed to allow the workstation to remain in the same VLAN. This means that everyone on a LAN must be located in the same area. If a user moves to a different location away from the assigned bridge. and 4 belong to VLAN 1 and port 3 belongs to VLAN 2. Consequently. the network manager must reconfigure the VLAN. and protocol type. Since this is a logical segmentation and not a physical one. Bridging software is used instead to define which workstations are to be included in the broadcast domain. and routers are physically connected together. 2) Layer 2 VLAN: Membership by MAC Address Here. The switch tracks the MAC addresses which belong to each VLAN. this is no easy task. workstations do not have to be physically located together. the MAC address is associated with the docking station and not with the notebook PC. Since MAC addresses form a part of the workstation's network interface card.

htm DX -5726GT: https://www. 5) Higher Layer VLAN's It is also possible to define VLAN membership based on applications or The 802. file transfer protocol (FTP) applications can be executed on one VLAN and telnet applications on another DX -5744GS: https://www. Protocol type based VLAN's and higher layer VLAN's have been allowed Dax BTI -0524T/0548T/ 0548T -D-L3: https://www.htm DX -508MS: https://www.htm Dax BTI -T5C-24GT / Dax BTI-0524G: https://www. this has nothing to do with network routing and should not be confused with router IPX 1 2 4) Layer 3 VLAN: Membership by IP Subnet Address Membership is based on the Layer 3 header.daxnetworks.daxnetworks.htm DX -5018MG: The only problem is that. IP addresses are used only as a mapping to determine membership in VLAN's.htm DX -5016VS: https://www. users can move their workstations without reconfiguring their network DX -5044GS: https://www.daxnetworks. these VLAN's will remain proprietary. but are not defined in this standard.htm Dax Megastack: Dax Product Offering: Some of the Dax products that support various types of VLAN are listed below: DX -5016es: https://www. In Layer 3 VLAN's.daxnetworks.htm DX -5024eS: https://www.daxnetworks. As a result.daxnetworks. it generally takes longer to forward packets using Layer 3 information than using MAC addresses. For example. The network IP subnet address can be used to classify VLAN membership.24 In this method.htm DX -5008AG: https://www.1Q draft standard defines Layer 1 and Layer 2 VLAN's only.htm DX -5016AG: . No other processing of IP addresses is or any combination Dax BTI -0530 RN -L3: https://www.daxnetworks.htm DX -5024VS: https://www.daxnetworks.daxnetworks.htm DX -5026MF: https://www.35 1 2 Although VLAN membership is based on Layer 3 information. IP Subnet VLAN DX -5026MG: https://www.

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