Lan & vlan

BSNL

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LAN & VLAN

Presented By:-RAMAKANT TYAGI

BSNLBASIC OF NETWORKING

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• There are 7 layer in networking

• Out Of the 7 layers, we are concerned with the bottom 3 layers.

• The top 4 layers are used more on host machines to support TCP/UDP, HTTP, other applications

Application Layer (Layer 7)

Presentation Layer (Layer 6)

Session Layer (Layer 5)

Transport Layer (Layer 4)

Network Layer (Layer 3)

Data Link Layer (Layer 2)

Physical Layer (Layer 1)

BSNLNetwork Devices

• There are 5 general devices:RepeaterHubBridgeSwitchRouter


BSNLRepeater

A Layer 1 deviceAn electronic device to receive a signal

on a port and retransmits it at a higher level or higher power

Used when you need to go farther distances than the cabling will allow

Usually has 2 ports (IN/OUT)


BSNL Hub

A Layer 1 deviceA device that contains multiple portsHas no logic or “brain”Simply passes data out all other portsIn simple terms, it is a multi-port repeater


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Bridge

A Layer 2 deviceConnects multiple Layer 2 segmentsHas logic or “brain”Learns what Layer 2 MAC addresses are

associated with each portReceives frames destined for a particular

MAC address and only sends the data out the correct port


BSNLSwitch

A layer 2 deviceBasically a multi-port bridgeLearns MAC Addresses to Port

mappingsDoesn’t flood data out every port unless

the MAC address hasn’t been learned


BSNLRouter

A Layer 3 deviceConnects multiple Layer 3 networksUses Layer 3 addressing (IP addressing)Allows communication between

different Layer 2 segmentsBreaks up broadcast domains


BSNLIntroduction

•Definition: A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.

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http://compnetworking.about.com/library/glossary/bldef-wan.htm

BSNL Diagrammatic representation

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Local Area Network (LAN)

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BSNLLAN OVERVIEW

• A LAN is a computer network that covers a small area (home, office, building, campus)– a few kilometers

• LANs have higher data rates (10Mbps to 40Gbps) as compared to WANs

• LANs (usually) do not involve leased lines; cabling and equipments belong to the LAN owner

• A LAN consists of– Shared transmission medium• now so valid today due to switched LANs (for wired LANs), but

still valid for wireless LANs– regulations for orderly access to the medium– set of hardware and software for the interfacing devices

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BSNLLAN Topologies

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BSNLBus Topology

• Stations attach to linear medium (bus)– Via a tap - allows for transmission

and reception• Transmission propagates in

medium in both directions • Received by all other stations

– Not addressed stations ignore• Need to identify target station

– Each station has unique address – Destination address included in

frame header• Terminator absorbs frames at the

end of medium 14

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Bus Topology

• Need to regulate transmission– To avoid collisions

• If two stations attempt to transmit at same time, signals will overlap and become garbage

– To avoid continuous transmission from a single station. If one station transmits continuously, access is blocked for others• Solution: Transmit Data in small blocks – frames

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BSNLRing Topology

• Repeaters joined by point-to-point links in closed loop– Links are unidirectional– Receive data on one link and retransmit on another– Stations attach to repeaters

• Data transmitted in frames– Frame passes all stations in a circular manner– Destination recognizes address and copies frame– Frame circulates back to source where it is removed

• Medium access control is needed to determine when station can insert frameALTTC LAN & VLAN 16

BSNLRing Topology

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BSNLStar Topology

• Each station connected directly to central node– using a full-duplex

(bi-directional) link• Central node can broadcast (hub)

– Physical star, but logically like bus due to broadcast medium

– Only one station can transmit at a time; otherwise, collision occurs

• Central node can act as frame switch– retransmits only to destination– today’s technology

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BSNLSummary Of Network Topology

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Topology/structure Advantages Disadvantages

Bus structure -easy to install-simply expandable-short cable lengths

-net expansion limits-complicated access methods

Ring structure -large net expansion -complex error tracing-high wiring expenditure-when disturbances net failure

Star structure -simple cross-linking-simple extension-high reliability

-high wiring expenditure-net failure in case of failure or overloading of the hubs

BSNLADVANTAGES OF LAN

• Expensive hardware can be shared e.g. laser printer.

• Users can access the same files.• Messages can be sent between users.• A single Internet connection can be shared

among many users.• Network software is cheaper than buying

individual packages.

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BSNLDISADVANTAGES OF LAN

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Disadvantages of connecting computers in a LAN:• Special security measures are needed to stop users from using programs and data that they should not have access to.• Networks are difficult to set up and need to be maintained by skilled technicians.• If the file server develops a serious fault, all the users are affected, rather than just one user in the case of a stand-alone machine.• Wired and therefore more difficult to setup. Drilling holes in wall, running cables in lofts etc, fitting sockets and redecorating. More expensive to set up. More time consuming to set up. Not as flexible, can only use where there is a socket - cannot use outside for example.• Wired systems cannot be used in listed buildings

BSNLVLAN Introduction

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BSNLIntroduction

In simple terms, a VLAN is a set of workstations within a LAN that can communicate with each other as though they were on a single, isolated LAN.

What does it mean to say that they “communicate with each other as though they were on a single, isolated LAN”?

Among other things, it means that: broadcast packets sent by one of the workstations

will reach all the others in the VLANALTTC LAN & VLAN 23

BSNL Introduction

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Broadcasts sent by one of the workstations in the VLAN will never reach any workstations that are not in the VLAN

The workstations can all communicate with each other without needing to go through a gateway. For example, IP connections would be established by AR Ping for the destination

IP and sending packets directly to the destination workstation—there would be no need to send packets to the IP gateway to be forwarded on.

The workstations can communicate with each other using non-routable protocols

BSNLVLAN-based LAN

• As we earlier discussed ,By utilizing VLANs, the same users can be spread out over various geographical locations and still remain in their same IP subnet (broadcast domain).

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BSNLVLAN OVERVIEW

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• A VLAN allows a network administrator to create groups of logically networked devices that act as if they are on their own independent network, even if they share a common infrastructure with other VLANs.

• Using VLANs, you can logically segment switched networks based on functions, departments, or project teams.

• You can also use a VLAN to geographically structure your network to support the growing reliance of companies on home-based workers.

• These VLANs allow the network administrator to implement access and security policies to particular groups of users.

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OVERVIEW

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BSNLHOW VLAN WORKS ?

• VLANs are identified by a number– Valid ranges 1-4094

• On a VLAN-capable switch, you assign ports with the appropriate VLAN number

• The switch then only allows data to be sent between ports with the same VLAN

• Since almost every network is larger than a single switch, there needs to be a way to have traffic sent between two different switchesALTTC LAN & VLAN 28


• One way to do it is to assign a port on each switch with a VLAN and run a cable between the switches– Not very feasible or cost effective • For example, if there were 6 hosts on each switch on 6

different vlans, you would need 6 ports on each switch to connect the switches together. This would mean that if you had 24 different vlans you could only have 24 hosts on a 48 port switch

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• There was a standard develop to make it so that a single connection between two switches could be used to send traffic for all vlans

• 802.1q – Provides a VLAN tag in front of the Layer 2 frame

• We enable 802.1q tagging (trunking) on the ports between the switches

• The switch receives the frame with the 802.1q header and strips it off & It determines what VLAN and sends the data to the appropriate port

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BSNLTypes of VLAN

• Three basic VLAN memberships for determining and controlling how a packet entering a switch gets assigned to a VLAN.

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BSNLPort driven VLANs

• Most common configuration method

• User assigned by port association

• Easily administered through GUIs

• Maximizes security between VLANs

• Packets do not “leak” into other domainsALTTC LAN & VLAN 32

BSNLPort driven VLANs cont’d.

• User assigned port association ???

• For example, in a bridge with four ports, ports 1, 2, and 4 belong to

VLAN 1 and port 3 belongs to VLAN 2

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Port VLAN1 12 13 24 1

Assignment of ports to different VLAN's.

Disadvantage: •Does not allow for user mobility

BSNLMAC address driven VLANs

• User assigned based on MAC addresses

• Offers flexibility• For Example:Since MAC addresses form a part

of the workstation's network interface card, when a workstation is moved, no reconfiguration is needed to allow the workstation to remain in the same VLAN

• Impacts performance, scability, and administration

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BSNLMAC address driven VLANs cont’d

• Disadvantage• VLAN membership must be assigned initially. • In networks with thousands of users. Also, in environments

where notebook PC's are used, the MAC address is associated with the docking station and not with the notebook PC. Consequently, when a notebook PC is moved to a different docking station, its VLAN membership must be reconfigured.

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MAC Address VLAN1212354145121 12389234873743 23045834758445 25483579475843 1Assignment of IP subnet addresses to different VLAN's

BSNLNetwork address driven VLANs

• The network IP subnet address can be used to classify VLAN membership

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IP Subnet VLAN

23.2.24 1

26.21.35 2

Assignment of IP subnet addresses to different VLAN's

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Network address driven VLANs cont’d

• IP addresses are used only as a mapping to determine membership in VLAN's.

• In Layer 3 VLAN's, users can move their workstations without reconfiguring their network addresses. The only problem is that it generally takes longer to forward packets using Layer 3 information than using MAC addresses.

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BSNLBenefits of VLAN

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BSNLBenefits of VLAN

• VLANs allow network administrators to organize LANs logically instead of physically.

• Easily move workstations on the LAN • Easily add workstations to the LAN • Easily change the LAN configuration • Easily control network traffic • Improve security VLAN can also be used to control broadcast domains

Set up firewalls

Restrict access

Inform the network manager of an intrusion

• Eliminate the need for expensive routersALTTC LAN & VLAN

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BSNLDisadvantages Of Vlan

*Management is complex*Possible problems in interoperability*A VLAN cannot forward traffic to another VLAN(need a router to communicate between VLANs)

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BSNLLAN V/S VLAN

• VLAN requires lesser cost by eliminating use of expensive routers unlike LAN.

• Data transmission is safe on VLAN as compared to LAN.

• VLAN delivers better performance when compared to traditional LANs.

• VLAN also helps in reducing traffic

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BSNL

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Thank You

Lan & vlan

Engineering

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