Chapter 05 LAN Connectivity Devices

Chapter 05Chapter 05

LAN Connectivity LAN Connectivity DevicesDevices

11

Connectivity DevicesConnectivity Devices

Objectives:Objectives:

Basic LAN devicesBasic LAN devices The Evolution of Network Devices:The Evolution of Network Devices:

Network Devices that operate at each Network Devices that operate at each layer.layer.

Basics of Data Flow Through LANsBasics of Data Flow Through LANs

(Encapsulation Process)(Encapsulation Process) How to Build a LANHow to Build a LAN

Local-Area NetworksLocal-Area NetworksIntroduction:Introduction: Understanding of:Understanding of:

the OSI Modelthe OSI Model What happens to the packets as they travel through What happens to the packets as they travel through

the layers.the layers.

LANs Devices LANs Devices

Network DevicesNetwork Devices

As Organizations grow, so do their networksAs Organizations grow, so do their networks Growth in number of usersGrowth in number of users Geographical GrowthGeographical Growth

Network Devices :Network Devices : Are products used to expand or connect networks.Are products used to expand or connect networks. Can control the amount of traffic on a network.Can control the amount of traffic on a network. Can speed up the flow of data over a network.Can speed up the flow of data over a network.

Networking DevicesNetworking Devices

Device: Equipment that connects directly to Device: Equipment that connects directly to a network segment.a network segment.

End user devices or hostsEnd user devices or hosts Hosts are devices that connect directly to a Hosts are devices that connect directly to a

network segment. It includes: Computers network segment. It includes: Computers (Client / Servers), Printers, Scanners, etc.(Client / Servers), Printers, Scanners, etc.

Network Devices:Network Devices: Include all devices that connect the end-user Include all devices that connect the end-user

devices to allow them communicate.devices to allow them communicate.

End-user devices or HostsEnd-user devices or Hosts

Allows users to share, create and obtain Allows users to share, create and obtain informationinformation

Can exist without a networkCan exist without a network

Are physically connected to the network Are physically connected to the network media using a Network Interface Card.media using a Network Interface Card.

Network Interface Card (NIC)Network Interface Card (NIC)

Physical link between machine & Physical link between machine & networknetwork

Connection between machine & Connection between machine & mediummedium

The NIC controls the host’s access to the The NIC controls the host’s access to the medium.medium.

Translates parallel signals produced by the Translates parallel signals produced by the computer into serial format that is sent over the computer into serial format that is sent over the network.network.

The MAC address is hard coded onto the NIC.The MAC address is hard coded onto the NIC.

Network Interface Card - NICNetwork Interface Card - NIC

Transceiver:Transceiver: Send and receive signalsSend and receive signals Convert one type of signal (or connector) into Convert one type of signal (or connector) into

another. another. Internal and / or External Internal and / or External Layer 1 device. It looks only at bits and not at Layer 1 device. It looks only at bits and not at

any address information or higher level any address information or higher level protocolsprotocols

Network Interface CardNetwork Interface Card

From Parallel to Serial, and From Parallel to Serial, and Vice VersaVice Versa

Selecting a Network CardSelecting a Network Card

Consider the following factorsConsider the following factors Network Architecture or LAN Technology: Network Architecture or LAN Technology:

Ethernet, Token Ring, FDDI, etc.Ethernet, Token Ring, FDDI, etc. Type of Media: Thinnet or 10Base2, Thicknet or Type of Media: Thinnet or 10Base2, Thicknet or

10Base5, 10BaseT, Fiber Optic)10Base5, 10BaseT, Fiber Optic) Data Transfer SpeedData Transfer Speed Type of System Bus: Type of System Bus:

ISA, EISA, Microchanel, PCI, PCIMCA)ISA, EISA, Microchanel, PCI, PCIMCA) Some NICs connect through SCSI busSome NICs connect through SCSI bus Some NICs use USB Some NICs use USB Integrated on the MotherboardIntegrated on the Motherboard

An Ethernet NICAn Ethernet NIC

Type of System BusType of System Bus

ISA (Industrial Standard Architecture)ISA (Industrial Standard Architecture)

EISA (Enhanced ISA)EISA (Enhanced ISA)

MCA (Micro Channel Architecture)MCA (Micro Channel Architecture)

PCI (Peripheral Component Interconnect)PCI (Peripheral Component Interconnect)

Primary Bus Architectures Primary Bus Architectures

Network DevicesNetwork Devices

Provide transport for the data that needs to Provide transport for the data that needs to be transferred between end-user devices.be transferred between end-user devices.

Extend cable connectionsExtend cable connections Concentrate connectionsConcentrate connections Convert Data FormatsConvert Data Formats Manage data transferManage data transfer

Connectivity DevicesConnectivity Devices Each topology and network architecture has Each topology and network architecture has

its limits.its limits.

Beyond a point networks networks can not be Beyond a point networks networks can not be expanded by simple adding more servers or expanded by simple adding more servers or cablingcabling

Connectivity devicesConnectivity devices are the basic building are the basic building blocks of network expansionblocks of network expansion

Connectivity DevicesConnectivity Devices

Are used to connect separate segments of Are used to connect separate segments of the network or inter-networkthe network or inter-network

A segment is a portion of the network A segment is a portion of the network transmission media that is assigned a transmission media that is assigned a network address.network address.

Creating Larger NetworksCreating Larger Networks

Physically expand the networkPhysically expand the network

Segment network to filter trafficSegment network to filter traffic

Extend network to connect separateExtend network to connect separate LANsLANs

Connect two separate computer Connect two separate computer environmentsenvironments

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Devices to Expand the NetworkDevices to Expand the Network

Repeaters Repeaters BridgesBridgesSwitchesSwitchesRoutersRoutersGatewayGateway

11

Network Connectivity DevicesNetwork Connectivity Devices

Repeaters Repeaters HubsHubs BridgesBridges SwitchesSwitches

Internetwork Connectivity DevicesInternetwork Connectivity Devices

RoutersRouters GatewaysGateways

RepeatersRepeaters

A repeater can be used to increase the length of A repeater can be used to increase the length of your network by eliminating the effect of your network by eliminating the effect of attenuation on the signal.attenuation on the signal.

It connects two segments of the same network, It connects two segments of the same network, overcoming the distance limitations of the overcoming the distance limitations of the transmission media.transmission media.

Some repeaters also serve as transmission media Some repeaters also serve as transmission media adapters, connecting two different types of media.adapters, connecting two different types of media.

RepeatersRepeaters

Repeaters can connect segments that have the Repeaters can connect segments that have the same access method. (CSMA/CD, Token Passing, same access method. (CSMA/CD, Token Passing, Polling, etc.)Polling, etc.)

DisadvantagesDisadvantages Repeaters do not filter data Repeaters do not filter data Its use is inappropriate when there is a heavy network Its use is inappropriate when there is a heavy network

traffic.traffic.

RepeatersRepeatersFigure 11-5Figure 11-5

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RepeatersRepeatersFigure11-6Figure11-6

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HubsHubs

A hub is used as a central point of connection A hub is used as a central point of connection among media segments.among media segments.

Cables from network devices plug in to the Cables from network devices plug in to the ports on the hub.ports on the hub.

Hubs are referred as Concentrators or multi-Hubs are referred as Concentrators or multi-port repeaterport repeater

Hubs receive signals from connected devices Hubs receive signals from connected devices and transmit them to the other connected and transmit them to the other connected devicesdevices

HubsHubs

Regenerate and repeat signalsRegenerate and repeat signals Propagate signals through the networkPropagate signals through the network Can not filter network trafficCan not filter network traffic Can not determine the best pathCan not determine the best path Are used as network concentration points.Are used as network concentration points.

HubsHubs

HubsHubs

HubsHubs

Figure 6-3a Shared Media LAN ArchitectureFigure 6-3a Shared Media LAN Architecture

GOLDMAN: DATACOMM FIG. 06-03

serversclient workstations

Shared Media Hubshared, single 10Mbps LAN

segment

only one 10Mbps connection at a

time

Shared Media LAN Architecture

10 Mbps

"10 Mbps for ALL"

Switching Hubmultiple dedicated

10Mbps LAN segments

Workgroup with shared connection

Workgroup with shared connection

servers with dedicated connections

shared media hub

shared media hub

Workstations with dedicated connections

Multiple, simultaneous

10Mbps connections

All connections at 10Mbps

switching matrix

Switch-Based LAN Architecture

"10 Mbps for EACH"

Types of HubsTypes of Hubs

Passive HubsPassive Hubs

Active HubsActive Hubs

Intelligent Hubs (Switches)Intelligent Hubs (Switches)

Passive HubPassive Hub

It functions only as a connection point for It functions only as a connection point for the signals the signals

The signal pass through a passive hub The signal pass through a passive hub without regeneration or amplification.without regeneration or amplification.

Active HubActive Hub

It regenerates or amplifies the signal before It regenerates or amplifies the signal before they are retransmitted. they are retransmitted.

Drawback:Drawback: The noise is also regenerated The noise is also regenerated

BridgesBridgesLayer 2 (Data Link Layer) device.Layer 2 (Data Link Layer) device.

Divide a network into segments and filter traffic. EachDivide a network into segments and filter traffic. Each

segment is a segment is a collision domain.collision domain.

Limit or filter traffic keeping local traffic local yet allowLimit or filter traffic keeping local traffic local yet allow

connectivity to other parts (segments)connectivity to other parts (segments)

Make decision based on the MAC address list Make decision based on the MAC address list Connect different architectures and Forward packetsConnect different architectures and Forward packets

between architectures: between architectures: Ethernet & Token-Ring.Ethernet & Token-Ring.

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BridgesBridges

GOLDMAN: DATACOMM FIG. 09-01

20% of LAN traffic travels

between LANs

80% of LAN traffic stays on local LAN

bridge LAN B

Segmentation

Micro-Segmentation

LAN switch

FDDI modules (100 Mbps)

backbone network router

backbone network router

10BaseT module (10Mbps)

10BaseT module (10Mbps)

LAN A

Server Isolation

LAN switch or router

hub hub

Hierarchical Networking

10BaseT hub 10BaseT hub

BridgesBridgesRead network addresses at the MAC Read network addresses at the MAC

(Media Access Control) sub-layer(Media Access Control) sub-layer

Decide which segment address is onDecide which segment address is on

Decide whether or not to forward packetDecide whether or not to forward packet

Drawback:Drawback:Broadcast packages are passed across bridges.Broadcast packages are passed across bridges.

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BridgesBridges11

SwitchesSwitchesA high speed multiport bridgeA high speed multiport bridge

Replacing repeaters & hubs in UTPReplacing repeaters & hubs in UTP

Switches maintains a switching tableSwitches maintains a switching table

Dedicated bandwidth to each port, making data Dedicated bandwidth to each port, making data

transmission more efficient.transmission more efficient.

Each port can use full 10/100/1000 Mbps.Each port can use full 10/100/1000 Mbps.

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SwitchesSwitches

GOLDMAN: DATACOMM FIG. 06-03

serversclient workstations

Shared Media Hubshared, single 10Mbps LAN

segment

only one 10Mbps connection at a

time

Shared Media LAN Architecture

10 Mbps

"10 Mbps for ALL"

Switching Hubmultiple dedicated

10Mbps LAN segments

Workgroup with shared connection

Workgroup with shared connection

servers with dedicated connections

shared media hub

shared media hub

Workstations with dedicated connections

Multiple, simultaneous

10Mbps connections

All connections at 10Mbps

switching matrix

Switch-Based LAN Architecture

"10 Mbps for EACH"

SwitchesSwitches

GOLDMAN: DATACOMM FIG. 11-03

broadcast source

LAN switch

B

B

B

broadcast source

LAN switch

LAN Switch

broadcast traffic

Broadcasts to all ports on LAN switch.

Single Switch Virtual LANs

Broadcasts only to members of Virtual LAN.

broadcast traffic

A

Virtual LAN assignments

Virtual LAN "A" is a multi-switch Virtual LAN

B

B

B

broadcast source

LAN switch

Multi-Switch Virtual LANs

A

C

C

LAN switch

C

C

Proprietary switch-to-switch communications

high-speed backbone network

A

A

A

A

A

A

A

SwitchesSwitches

GOLDMAN: DATACOMM FIG. 11-03

broadcast source

LAN switch

B

B

B

broadcast source

LAN switch

LAN Switch

broadcast traffic

Broadcasts to all ports on LAN switch.

Single Switch Virtual LANs

Broadcasts only to members of Virtual LAN.

broadcast traffic

A

Virtual LAN assignments

Virtual LAN "A" is a multi-switch Virtual LAN

B

B

B

broadcast source

LAN switch

Multi-Switch Virtual LANs

A

C

C

LAN switch

C

C

Proprietary switch-to-switch communications

high-speed backbone network

A

A

A

A

A

A

A

Figure 6-4 Figure 6-4 Implementation Implementation Scenarios for Switched Scenarios for Switched LAN ArchitecturesLAN Architectures

GOLDMAN: DATACOMM FIG. 06-04

shared media hub

LAN Switch LAN Switch

shared media hub

Stand-Alone Workgroup/Departmental LAN Switches

Dedicated switched connections for all clients and servers.

Dedicated switched connections for servers, shared switched connections for clients.

Standard Server front-end variation

LAN Switch

Backbone-Attached Workgroup/Departmental LAN Switches

100Mbps backbone connection to backbone network.

10Mbps local switched connections

Backbone/Data Center Switches

Corporate shared servers

Corporate backbone network

Backbone/data center switch

Ba

ckb

on

e n

etw

ork

Backbone attached workgroup/departmental LAN switches with locally attached clients and servers.

Figure 6-4a Implementation Scenarios for Switched LAN Figure 6-4a Implementation Scenarios for Switched LAN Architectures: Stand-Alone WorkgroupArchitectures: Stand-Alone Workgroup

GOLDMAN: DATACOMM FIG. 06-04

shared media hub

LAN Switch LAN Switch

shared media hub

Stand-Alone Workgroup/Departmental LAN Switches

Dedicated switched connections for all clients and servers.

Dedicated switched connections for servers, shared switched connections for clients.

Standard Server front-end variation

LAN Switch

Backbone-Attached Workgroup/Departmental LAN Switches

100Mbps backbone connection to backbone network.

10Mbps local switched connections

Backbone/Data Center Switches

Corporate shared servers

Corporate backbone network

Backbone/data center switch

Ba

ckb

on

e n

etw

ork

Backbone attached workgroup/departmental LAN switches with locally attached clients and servers.

SwitchesSwitches

Selection Issues:Selection Issues: Need for 10 Mbps, 100 Mbps, or 1 Gbps on media.Need for 10 Mbps, 100 Mbps, or 1 Gbps on media. Need for trunking and internet-switch linksNeed for trunking and internet-switch links Workgroup segmentation (VLAns)Workgroup segmentation (VLAns) Port Density needs: 12, 16, 24 ports.Port Density needs: 12, 16, 24 ports. Different User Interfaces.Different User Interfaces.

Type of SwitchesType of Switches

Store and Forward SwitchesStore and Forward Switches Cut Through SwitchesCut Through Switches SymetricSymetric Switches Switches Asymetric SwicthesAsymetric Swicthes

RoutersRouters

Layer 3 (Network Layer) deviceLayer 3 (Network Layer) device

Connect networks with multiple paths between Connect networks with multiple paths between network segments (subnets)network segments (subnets)

Make decisions based on the network address.Make decisions based on the network address.

Network segment – Network addressNetwork segment – Network address

Connect different layer 2 technologies (ethernet, Connect different layer 2 technologies (ethernet, Token Ring, FDDI, etc.)Token Ring, FDDI, etc.)

Have become the backbone for the Internet, running Have become the backbone for the Internet, running the IP protocol. the IP protocol.

RoutersRouters

Its purpose is to:Its purpose is to: examine incoming messages (layer 3 data),examine incoming messages (layer 3 data), choose the best path for them through the choose the best path for them through the

network, and network, and switch them to the proper outgoing port.switch them to the proper outgoing port.

They don’t allow bad data or broadcast They don’t allow bad data or broadcast storm to be passed on the networkstorm to be passed on the network

They can connect networks using the same They can connect networks using the same protocol but different network architecture.protocol but different network architecture.

Routers Routers Figure 11-7Figure 11-7

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Routers Routers vsvs Bridges Bridges

SegmentationSegmentation

Collision DomainsCollision Domains Broadcast DomainsBroadcast Domains Segmentation with BridgesSegmentation with Bridges Segmentation with SwitchesSegmentation with Switches Segmentation with RoutersSegmentation with Routers

Phase 1: The Traditional Routed NetworkPhase 1: The Traditional Routed NetworkTraditional LAN routers that segment the network Traditional LAN routers that segment the network will not be able to keep up with the performance as will not be able to keep up with the performance as

network communications demands grow.network communications demands grow.

Phase 2: Switched NetworksPhase 2: Switched Networks

The standard switched network The standard switched network provides a fast, simple and cost-provides a fast, simple and cost-effective alternative, but ….effective alternative, but ….

are becoming harder to control are becoming harder to control and …….and …….

vulnerable to broadcast storms vulnerable to broadcast storms and redundant traffic.and redundant traffic.

Phase 3: The Layer 3 SolutionPhase 3: The Layer 3 Solution

By integrating router functionality into the silicon By integrating router functionality into the silicon within a switch, Layer 3 Switching offers high-within a switch, Layer 3 Switching offers high-speed LAN routing in affordable solution.speed LAN routing in affordable solution.

CloudsClouds

Its symbol suggests another network or Its symbol suggests another network or perhaps the entire Internet.perhaps the entire Internet.

It represents a collection of devices that It represents a collection of devices that operate at all levels of the OSI model.operate at all levels of the OSI model.

Network SegmentsNetwork Segments

Different definitionsDifferent definitions Its correct definition depend on the situation Its correct definition depend on the situation

in which is used.in which is used. A segment identifies the Layer 1 media that A segment identifies the Layer 1 media that

is the common path for data transmission.is the common path for data transmission. There is a maximum length for each media There is a maximum length for each media

transmission (Coaxial, UTP, Fiber Optic)transmission (Coaxial, UTP, Fiber Optic)

A definition used by Cisco:A definition used by Cisco: A segment is a collision domain.A segment is a collision domain.

Other definition:Other definition: A segment is the Packet Data Unit at the A segment is the Packet Data Unit at the

transport layer.transport layer.

Evolution of Network DevicesEvolution of Network Devices

1940’s – Huge computers – Electromechanical devices.1940’s – Huge computers – Electromechanical devices. 1947 – The invention of semiconductor – Smaller and 1947 – The invention of semiconductor – Smaller and

more reliable computersmore reliable computers 1950’s – Mainframes – Punched-card programs – Large 1950’s – Mainframes – Punched-card programs – Large

institutionsinstitutions Late of 1950’s – Integrated Circuit was invented – Millions Late of 1950’s – Integrated Circuit was invented – Millions

of transistors on one small piece of semiconductor.of transistors on one small piece of semiconductor. 1960’s Mainframes with terminals – Commonplace1960’s Mainframes with terminals – Commonplace 1960s and 1970s – Smaller computers – middle range 1960s and 1970s – Smaller computers – middle range

computers – came into existence.computers – came into existence. 1978 – Apple computer introduced – Personal Computer1978 – Apple computer introduced – Personal Computer 1981 – IBM – Introduced the open-architecture personal 1981 – IBM – Introduced the open-architecture personal

computercomputer

Encapsulation ProcessEncapsulation Process

Top three layers prepare data for transmission by Top three layers prepare data for transmission by creating a common format for transmissioncreating a common format for transmission

Transport layer – Segments, Sequence NumberTransport layer – Segments, Sequence Number Network layer – Encapsulates the segment Network layer – Encapsulates the segment

creating a data packet or datagram adding creating a data packet or datagram adding headers about source and destination network.headers about source and destination network.

Data Link encapsulates datgrams into frames and Data Link encapsulates datgrams into frames and transmit bits to physical layer mediatransmit bits to physical layer media

Physical layer media - signalsPhysical layer media - signals

Network DevicesNetwork Devices Physical Layer Devices (Work with bits)Physical Layer Devices (Work with bits)

Passive: Plugs, connectors, jacks, patch panels, Passive: Plugs, connectors, jacks, patch panels, physical media.physical media.

Active: Active: Repeaters and hubsRepeaters and hubs Transceivers Transceivers

Connector adapters: RJ45- AUI portConnector adapters: RJ45- AUI port Media converters: RJ-45 – ST Optical) Media converters: RJ-45 – ST Optical)

Data Link Layer Devices: NIC, Bridges, SwitchesData Link Layer Devices: NIC, Bridges, Switches Network Layer Devices:Network Layer Devices:

Layer 1: Bits from the media to the router interfaceLayer 1: Bits from the media to the router interface Layer 2: Frames Switched from one Interface to Layer 2: Frames Switched from one Interface to

anotheranother Layer 3: Routing decisionsLayer 3: Routing decisions

SummarySummary

LAN devices: Routers, Switches and HubsLAN devices: Routers, Switches and Hubs Evolution of networking devicesEvolution of networking devices Basics of Data FlowBasics of Data Flow Basics related to build networks.Basics related to build networks.

Voice, DSL, Cable Modem, Voice, DSL, Cable Modem, and Optical Devicesand Optical Devices Demand of new devices due to integration of Demand of new devices due to integration of

voice and data networksvoice and data networks Fast Data TransmissionFast Data Transmission Network BackbonesNetwork Backbones

Voice GatewaysVoice Gateways Handling converged packetized voice and data Handling converged packetized voice and data

traffic.traffic. Convert information from one protocol stack to Convert information from one protocol stack to

another.another.

Digital Subscriber Line Access Multiplexer (DSLAM)Digital Subscriber Line Access Multiplexer (DSLAM) Used at ISP central office for concentrating DSL Used at ISP central office for concentrating DSL

modem connections from hundreds of homes.modem connections from hundreds of homes.

Cable Modem Termination System (CMTS)Cable Modem Termination System (CMTS) Used at cable operator’s headend or central location Used at cable operator’s headend or central location

to concentrate connections from many cable to concentrate connections from many cable subscribers.subscribers.

Optical PlatformsOptical Platforms For sending and receiving data over fiber-optic cable, For sending and receiving data over fiber-optic cable,

providing high-speed connectionsproviding high-speed connections

Security DevicesSecurity Devices

Increased Internet and extranet connectionsIncreased Internet and extranet connections More telecommutersMore telecommuters Mobile usersMobile users Security Devices:Security Devices:

Firewalls:Firewalls: Software or HardwareSoftware or Hardware Only valid traffic can enter or leave the networkOnly valid traffic can enter or leave the network

AAA ServersAAA Servers Authentication, Authorization, and Accounting ServersAuthentication, Authorization, and Accounting Servers

VPN ConcentratorsVPN Concentrators Remote access and site-to site VPN capablitiesRemote access and site-to site VPN capablities

Wireless DevicesWireless Devices

Wireless NICsWireless NICs Provide wireless connectivity Provide wireless connectivity PCMCIA and PCI cards to provide PCMCIA and PCI cards to provide

Wireless Access PointsWireless Access Points It is a wireless LAN tranceiver It is a wireless LAN tranceiver Acts as a hub or as a bridgeActs as a hub or as a bridge Multiple Access Points – Roaming FunctionalityMultiple Access Points – Roaming Functionality

Wireless BridgesWireless Bridges Provide long-range connectivity – 25 milesProvide long-range connectivity – 25 miles Line of sight wirelessLine of sight wireless

Wireless LAN TopologyWireless LAN Topology

Wireless Bridges Wireless Bridges Extended LAN (ELAN)Extended LAN (ELAN)