n etworking h ardware ( networking devices ). o bjectives identify major hardware devices in a...

NETWORKING HARDWARE (NETWORKING

DEVICES)

OBJECTIVES Identify major hardware devices in a computer

network Describe the factors involved in choosing a

network adapter, hub, switch, or router Describe the functions of repeaters, hubs,

bridges, switches, and gateways Identify problems associated with connectivity

hardware

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NETWORKING DEVICES Device: Equipment that connects directly to a network

segment.End user devices or hosts

Hosts are devices that connect directly to a network segment. It includes: Computers (Client / Servers), Printers, Scanners, etc.

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

allow them communicate.

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NETWORK ADAPTERS Also called network interface cards (NICs) Connectivity devices enabling a workstation, server,

printer, or other node to receive and transmit data over the network media

In most modern network devices, network adapters contain the data transceiver.

The NIC controls the host’s access to the medium. Translates parallel signals produced by the computer

into serial format that is sent over the network. The MAC address is hard coded onto the NIC.

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NETWORK INTERFACE CARD - NIC Transceiver:

Send and receive signalsConvert one type of signal (or connector)

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

at any address information or higher level protocols

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NETWORK INTERFACE CARD

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FROM PARALLEL TO SERIAL, AND VICE VERSA

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SELECTING A NETWORK CARD Consider the following factors

Network Architecture or LAN Technology: Ethernet, Token Ring, FDDI, etc.

Type of Media: Thinnet or 10Base2, Thicknet or 10Base5, 10BaseT, Fiber Optic)

Data Transfer SpeedType of System Bus:

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

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AN ETHERNET NIC

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TYPES OF NETWORK ADAPTERS

PCMIADeveloped in early 1990s to provide standard interface for

connecting any type of device to a portable computerMore commonly known as PC Cards

USB (universal serial bus) portStandard external bus that can be used to connect multiple

types of peripherals A parallel port network adapter Wireless network adapters A variety of Ethernet network adapters

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TYPES OF NETWORK ADAPTERS

PCMIADeveloped in early 1990s to provide standard interface for

connecting any type of device to a portable computerMore commonly known as PC Cards

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TYPES OF NETWORK ADAPTERS

USB (universal serial bus) portStandard external

bus that can be used to connect multiple types of peripherals

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TYPES OF NETWORK ADAPTERS

A parallel port network adapter 13

TYPES OF NETWORK ADAPTERS

Wireless network adapters

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TYPES OF NETWORK ADAPTERS

Ethernet network adapters for printers

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NETWORK DEVICES

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

Extend cable connections Concentrate connections Convert Data Formats Manage data transfer

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CONNECTIVITY DEVICES Each topology and network architecture has its

limits. Beyond a point networks networks can not be

expanded by simple adding more servers or cabling

Connectivity devices are the basic building blocks of network expansion

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

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

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CREATING LARGER NETWORKS

Physically expand the network

Segment network to filter traffic

Extend network to connect separate LANs

Connect two separate computer environments

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DEVICES TO EXPAND NETWORKS

Repeaters BridgesSwitchesRoutersGateway

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INTERNETWORK CONNECTIVITY DEVICES

Routers Gateways

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

A repeater contains one input port and one output port, so it is capable only of receiving and repeating a data stream.

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

Repeaters are suited only to bus topology. Some repeaters also serve as transmission media adapters,

connecting two different types of media.

REPEATERS

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Repeaters repeat signalsClean and boost digital transmissionAnalog networks use amplifiers to boost signal

Repeaters only work with the physical signalCannot reformat, resize, or manipulate the data

Physical layer (layer 1) device.

REPEATERS

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REPEATERS

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REPEATERS

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A hub is referred as a concentrator or a multiport repeater containing multiple ports to interconnect multiple devices

A hub accepts signals from a transmitting node and repeats those signals to all other connected nodes in a broadcast fashion.

All devices connected to a hub share the same amount of bandwidth and the same collision domain.

Regenerate and repeat signals Propagate signals through the network Can not filter network traffic Can not determine the best path 25

HUB

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HUB

ADVANTAGES AND DISADVANTAGES OF REPEATERS AND HUBS Advantages of using repeaters

Extend network physical distanceDo not seriously affect network performanceSpecial repeaters connect different media

Copper to fiber Disadvantages of using repeaters

Cannot connect different network architecturesToken Ring and Ethernet

Cannot reduce network traffic27

Disadvantages of using repeaters Do not segment the network

Repeat everything without discriminationNumber of repeaters must be limited

Repeaters are part of a collision domain

ADVANTAGES AND DISADVANTAGES OF REPEATERS AND HUBS

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Layer 2 (Data Link Layer) device.Divide a network into segments and filter traffic. Each segment is a collision domain.Limit or filter traffic keeping local traffic local yet allow connectivity to other parts (segments)Forward or drop framesCannot filter broadcastsMAC to segment # tableMAC to segment # table initial developmentMake decision based on the MAC address listConnect different architectures and Forward packets between architectures: Ethernet & Token-Ring.

BRIDGES

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Addresses are 6 bytes long Generally written in hexadecimal Globally unique (unicast)

00.0C.12.34.AB.CD - legal FF.FF.FF.FF.FF.FF - legal 00.00.01.10.45.G2 - illegal

To ensure a unique MAC address, the Ethernet card manufacturers encode the MAC address onto the card, usually in a ROM chip. The first half of the address identifies the manufacturer of the card. This code, which is assigned to each manufacturer by the IEEE, is called the organizationally unique identifier (OUI). Each manufacturer assigns a MAC address with its own OUI as the first half of the address, with the second half of the address being assigned a number that this manufacturer has never used on another card

MAC ADDRESS

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BRIDGES

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Creating a Forwarding Table• Based on the addresses of the sending computers• New addresses are added if they are not in the table

Add01

Add03

Add02

S 01 D 02

Forwarding tableSeg 1 Seg 2

01

02Stop

S 02 D 01

BRIDGES

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BRIDGES

Transparent bridges are also called learning bridges. Build a table of MAC addresses as frames arrive Ethernet networks use transparent bridges. Token Ring networks use source-routing bridges. Translation bridges Connect networks with different

network architecture, example: Token ring connecting to Ethernet.

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BRIDGES

ADVANTAGES AND DISADVANTAGES OF BRIDGES

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Subdivide a network into smaller logical pieces. Switches operate at the Data Link layer (layer 2) of the OSI

model. Can interpret address information. Switches resemble bridges and can be considered as a high

speed multiport bridge. Replacing repeaters & hubs in UTP Switches maintain a switching table. Dedicated bandwidth to each port, making data transmission

more efficient. Each port can use full 10/100/1000 Mbps. 36

SWITCHES

As a multiport device, it can better use limited bandwidth and prove more cost-effective than bridge.

Switches divide a network into several isolated channels. Packets sending from 1 channel will not go to another if

not specified. Each channel has its own capacity and need not be shared

with other channels. Switch is combination

of hub and bridge.

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SWITCHES

Switch is combination of hub and bridge. Workstations that connect to hub are on shared segment. Workstations that connect to switch are on switched

segment.

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SWITCHES

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SWITCHES

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SWITCHES

Full duplex switch allows for simultaneous transmission and reception of data to and from workstation.

Full duplex connection helps to eliminate collisions. To support full duplex connection to switch, two sets

of wires are necessary - one for receive operation and one for transmit operation.

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SWITCHES

TYPES OF SWITCHES – CUT THROUGH SWITCH

Read only address information in MAC layer head before beginning processing.

After reading destination address, switch consults an address look up table to determine which port on switch this frame should be forwarded to.

Once address look up is completed, point-to-point connection is created and frame is immediately forwarded.

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Preamble Des. Add Sour. Add Length Data FCS

7 Bytes

2/6 Bytes

2/6 Bytes

2 Bytes

46 - 1500 Bytes 4 Bytes

1 Byte

TYPES OF SWITCHES- STORE AND FORWARD

Store and Forward switches – read entire frame into shared memory area in switch.

Contents of transmitted Frame Check Sequence (FCS) field is read and compared to locally recalculated frame check sequence.

If results match, switch consults address look up table, builds appropriate point-to-point connection, and forwards frame.

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TYPES OF SWITCHES- ERROR FREE CUT THROUGH

SWITCHES Error free cut through switches – read both addresses

and frame check sequences for every frame. Frames are forwarded immediately to destination nodes

in an identical fashion to cut through switches. Should bad frames be forwarded, error free cut through

switch is able to reconfigure those individual ports producing bad frames to use store and forward switching.

As errors diminish to preset thresholds, port is set back to cut through switching for higher performance throughput.

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USING SWITCHES TO CREATE VLANS

Virtual local area networks (VLANs)Network within a network that is logically defined by

grouping its devices’ switch ports in the same broadcast domain.

Switches can logically group together some ports to form a virtual local area network (VLAN)

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Switches can be configured to communicate only within the devices in the group

HubHub

Hub

SW1

SW2

SW3

VLAN1 VLAN2

USING SWITCHES TO CREATE VLANS

HIGHER-LAYER SWITCHES

Switch capable of interpreting Layer 3 data is called a Layer 3 switch

Switch capable of interpreting Layer 4 data is called a Layer 4 switch

These higher-layer switches may also be called routing switches or application switches

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Advantages of switchesIncrease available network bandwidthReduced workload, computers only receive packets

intended for them specificallyIncrease network performanceSmaller collision domains

SWITCHES

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Disadvantages of switchesMore expensive than hubs and bridgesDifficult to trace network connectivity problems

through a switchDoes not filter broadcast traffic

SWITCHES

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SWITCHES

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ROUTERS

Multiport connectivity device Can integrate LANs and WANs running at different

transmission speeds and using a variety of protocols Routers operate at the Network layer (Layer 3) of the OSI

Model. Connect networks with multiple paths between network

segments (subnets) Make decisions based on the network address. Connect different layer 2 technologies (ethernet, Token

Ring, FDDI, etc.) Have become the backbone for the Internet, running the

IP protocol. 51

ROUTERS

Its purpose is to:examine incoming messages (layer 3 data), choose the best path for them through the network, and switch them to the proper outgoing port.

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

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

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ROUTERS Calculates the optimal path to a particular network

Reroute packets if a path is not available Routing tables stored in the router list all known addresses

and possible paths. Consist of hardware and software

Hardware Network server, separate computer, special black box Physical interface for various networks

Software Operating system and Routing protocol

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ROUTER FEATURES AND FUNCTIONS

Filter out broadcast transmission to alleviate network congestion

Support simultaneous local and remote activity Provide high network fault tolerance through redundant

components. Monitor network traffic and report statistics to a MIB Diagnose internal or other connectivity problems and trigger

alarms. Routers often incorporate firewall functions. A router accepts an outgoing packet, removes any LAN

headers and trailers, and encapsulates the necessary WAN headers and trailers

Because a router has to make wide area network routing decisions, the router has to dig down into the network layer of the packet to retrieve the network destination address

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Static routingTechnique in which a network administrator programs a

router to use a specified paths between nodes Dynamic routing

Automatically calculates best path between nodes and accumulates this information in a routing table

HopTerm used in networking to describe each trip data take

from one connectivity device to another

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ROUTER FEATURES AND FUNCTIONS

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Static Routers Dynamic Routers

Manual configurationof routes

Manual configuration of the firstroute. Automatic discovery of newroutes

Always use the sameroute

Can select the best route

More secure Need manual configuration toimprove security

ROUTER FEATURES AND FUNCTIONS

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ROUTER FEATURES AND FUNCTIONS

ROUTING PROTOCOLS

To determine the best path, routers communicate with each other through routing protocols

In addition to its ability to find the best path, a routing protocol can be characterized according to its convergence time and bandwidth overheadConvergence time

The time it takes for a router to recognize a best path in the event of a change or outage

Bandwidth overheadBurden placed on an underlying network to support the

routing protocol58

ROUTING PROTOCOLS

The four most common routing protocols:RIP (Routing Information Protocol) for IP and IPXOSPF (Open Shortest Path First) for IPEIGRP (Enhanced Interior Gateway Routing Protocol)

for IP, IPX, and AppleTalkBGP (Border Gateway Protocol) for IP

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BROUTERS AND ROUTING SWITCHES

Bridge routerAlso called a brouterIndustry term used to describe routers that take on

some characteristics of bridges Routing switch

Router hybrid that combines a router and a switch.Another name to switch layer 3.

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PHYSICAL VERSUS LOGICAL ADDRESSES

MAC addressesData Link layer applicationUsed by switches, bridges, and routersUsed for directly connected devices

Logical addressesNetwork and transport protocols dictate the format of

the logical network layer addressTCP/IP, IPX/SPXIP addresses are assigned manually or by software

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ADVANTAGES AND DISADVANTAGES OF

ROUTERS

Advantages of routers Can connect networks of different architecture

Token Ring to Ethernet Choose best path through or to a network Create smaller collision domains Create smaller broadcast domains

Disadvantages of routers Only work with routable protocols More expensive than hubs, bridges, and switches Routing table updates consume bandwidth Increase latency due to a greater degree of packet

filtering and/or analyzing62

ROUTERS

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BROUTERS

Hybrid device Functions as a router for routable

protocols Functions as a bridge for non-routable

protocols Operates at Data Link and Network layers

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GATEWAYS

Combination of networking hardware and software that connects two dissimilar kinds of networks

Translate between different protocol suites Operates on all 7 layers of the OSI model Most negative on network performance

Latency Popular types of gateways include:

E-mail gatewaysIBM host gatewaysInternet gatewaysLAN gateways

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