Virtual Local Area Network Bounds, Taylor Fowler, Tucker Pantoja, Erica Sedys, Martynas Kartawinata, Andrew

Content Definition How do VLANs work? LAN vs VLANs Advantages of VLAN VLAN Limitations Different types of VLANs

Definition A Virtual LAN is logical subgroup within a local area network that is created via software rather than manually moving cables in the wiring closet. A VLAN is an independent LAN network A VLAN allows student and faculty PCs to be separated although they share the same infrastructure A VLAN can be named for easier identification Virtual LANs (VLANs) are an abstraction to permit a single physical network to emulate the functionality of multiple parallel physical networks. This is handy because there may be situations where you need the functionality of multiple parallel physical networks but you'd rather not spend the money on buying parallel hardware

Sounds kinda like subnetting….. Nope

VLAN and Subnetting Subnetting Hardware - mask applied at router to determine the network address VLAN Software - Ports on a network are grouped together into a VLAN to segregate traffic. No masking needed After VLAN is set up traffic between VLANs or between VLAN and larger network must be done with a router.

How do VLANs work? Devices in different physical locations, not going back to the same router, can be on the same network The limitation of subnetting a network with a router is that all devices on that subnet must be connected to the same switch and that switch must be connected to a port on the router

Advantages of VLANs Ease of administration Confinement of broadcast domains Reduce broadcast traffic Enforcement of security policies Increased performance Switched networks by nature will increase performance over shared devices in use today by reducing collisions. Grouping users into logical networks will also increase performance by limiting broadcast traffic to users performing similar functions within workgroups. Additionally, less traffic will need to be routed, and the latency added to routers will be reduced. Improved manageability VLANs provide an easy, flexible, less costly way to modify logical groups in changing environments. VLANs make large networks more manageable by allowing centralized configuration of devices located in assorted locations. Simplification of software configurations VLANs will allow LAN administrators to "fine tune" their networks by grouping users. Software configurations can be made the same across machines with the consolidation of a department's resources into a single subnet. IP addresses and subnet masks will be more consistent across the entire VLAN. These services can be more effectively deployed when they can span buildings within a VLAN. Increased security options VLANs have the ability to provide additional security not available in a shared network environment. A switched network delivers packets only to the intended recipients and packets only to other members of the VLAN. This allows the network administrator to segment users requiring access to sensitive information into separate VLANs from the rest of the general users regardless of physical location.

VLAN Limitations Device Limitations - VLAN can only support about 500 ethernet address per device. Port Constraints - All ports on the hub/switch must be connected to VLAN. This is a distribution of about 20 devices per port on a 25 port switch. In an ideal network situation, there is one device per port, for example, a printer, a workstation, and voice IP phone will require 3 ports. If you wanted to have one VLAN assignment for each port, then the maximum VLANs will equal 25.

LAN vs VLANs VLAN provide better performance when compared to LAN. There is no need for physical administration for VLAN. VLAN can handle more traffic by using less router compare to LAN. The transmission of sensitive information on VLAN is much safer when compared to LAN.

When do I need a VLAN? Consider using VLAN’s in any of the following situations: Have more than 200 devices on your LAN Have a lot of broadcast traffic on your LAN Groups of users need more security or are being slowed down by too many broadcast? Groups of users need to be on the same broadcast domain because they are running the same applications. Make a single switch into multiple virtual switches.

Different types of VLANs Cell-based VLANs Used in ATM switched networks with LAN Emulation (LANE) Allows hosts on traditional LAN segments to communicate using ATM networks without special hardware or software modifications Frame-based VLANs Used in Ethernet networks with frame tagging (primarily, IEEE 802.10 and ISL- Inter Switch Link) IEEE 802.10 standard allows the use of VLANs with Ethernet, Token-Ring, and FDDI

VLAN Modes VLAN can be configured in three different ways: VLAN switching mode. VLAN translation mode. VLAN routing mode.

VLAN Switching Mode The VLAN forms a switching bridge in which frames are forwarded unmodified.

VLAN Translation Mode Used when the packet needs to pass into a traditional or native interface that is not configured in a VLAN. The packet VLAN frame is removed during this translation mode.

VLAN Routing Mode Used when a packet needs to go from one VLAN to another VLAN. Packet is modified by a router Router places its MAC address into a packet as the source. Changes packet’s VLAN ID.

Different VLAN definitions Cisco VLAN HP VLAN

References Difference Between VLAN and LAN retrieved from http://www.differencebetween.net/technology/internet/difference-between-vlan-and-lan/ VLAN retrieved from http://www.tech-faq.com/vlan.html Virtual LAN - Benefits and Limitations retrieved from http://www.people.eku.edu/mahaneyb/CISStudentClub/1007/index.htm

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