networking for n+ student

8/9/2019 Networking for n+ Student

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CHAPTER 1

NETWORKING BASICS


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What is a Network?

A network consists of two or more computers that are linked in order to share

resources (such as printers and CD-ROMs), exchange files, or allow electronic

communications. The computers on a network may be linked through cables,

telephone lines, radio waves, satellites, or infrared light beams.


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1. LAN (LOCAL AREA NETWORK)

2. CAN (CAMPUS AREA NETWORK)

3. MAN (METROPOLITAN AREA NETWORK)

4. WAN (WIDE AREA NETWORK)

TYPES OF NETWORK


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CABLES AND STANDARDS USED FOR LAN NETWORK

CAT 3, 4 AND 5

IBM TYPE 1-9 CABLING STANDARDS

EIA568A AND 568B

ETHERNET CABLING STANDARDS: IEEE 802.3 (10base5),

IEEE 802.3a(10base2)

IEEE 802.3i(10baset)

UNSHEILDED TWISTED PAIR (UTP)

SHIELDED TWISTED PAIR (STP)

CONNECTORS: RJ-45, RJ-11, RS-232, BNC


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HARDWARE DEVICES USED IN LAN

NICs (NETWORK INTERFACE CARDS)

REPEATERS

ETHERNET HUBS

TOKEN RING

BRIDGES

BROUTERS

ROUTERS

GATEWAYS

PRINT SERVERS

FILE SERVERS

SWITCHES


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PEER to PEER NETWORK

Peer-to-peer network operating systems allow users to share resources and files

located on their computers and to access shared resources found on other computers.However, they do not have a file server or a centralized management source (See the

figure below). In a peer-to-peer network, all computers are considered equal; they all

have the same abilities to use the resources available on the network. Peer-to-peer

networks are designed primarily for small to medium local area networks.


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Client/Server

Client/server network operating systems allow the network to centralize functions andapplications in one or more dedicated file servers (See the figure below). The file

servers become the heart of the system, providing access to resources and providing

security. Individual workstations (clients) have access to the resources available on the

file servers. The network operating system provides the mechanism to integrate all the

components of the network and allow multiple users to simultaneously share the same

resources irrespective of physical location


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CAMPUS AREA NETWORK

Campus Area Network or CAN is a network spread over a limited geographical area

such as an university. Cables as the communication medium, and a device that can

interface various patches of LANs across the campus. Once such device is the LAN

extender.

Cable 1: Power adapter

Cable 2: RJ45 Ethernet port. You could either connect the LAN extender directly to a

PC using a cross-over cable, or connect it to an Ethernet hub or switch using a straight

through cable.

Cable 3: Console port. Initial configuration of the LAN Extender is done by connecting

it to a free COM port on your PC using a RS232 cable.

Cable 4: RJ11 Telephone cable. A plain two-wire telephone cable serves as the WAN

link between the two LAN Extenders.


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MAN (METROPOLITAN AREA NETWORK)

METROPOLITAN AREA NETWORKS (MAN) ARE NETWORKS THAT

CONNECT LANS TOGETHER WITHIN A CITY.

THE PROTOCOLS USED FOR MAN ARE :-

RS-232, V-35

X.25 (56KBPS), PACKET ASSEMBLETS AND DISSEMBLERS

FRAME RELAY

ASYNCHRONOUS TRANSFER MODE (ATM)

ISDN (INTEGRATED SERVICES DIGITAL NETWORK)


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A typical use of MANs to provide shared access

to a wide area network is shown in thefigure below:


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WAN (WIDE AREA NETWORK)

Wide Area Networks (WANs) connect larger geographic areas, such as Florida, the

United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be

used to connect this type of network.

Using a WAN, schools in Florida can communicate with places like Tokyo in a matter

of minutes, without paying enormous phone bills. A WAN is complicated. It uses

multiplexers to connect local and metropolitan networks to global communicationsnetworks like the Internet. To users, however, a WAN will not appear to be much

different than a LAN or a MAN.


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OSI REFERENCE MODEL

When computers were first linked together into networks, moving information betweendifferent types of computers was a very difficult task.

In the early 1970s, the International Organization of Standards (ISO) recognized the

need for a standard network model. This would help vendors to create interpretable

network devices. The Open Systems Interconnection (OSI) reference model, released in

1984, addressed this need.

The OSI model describes how information makes its way from application programs

through a network medium to another application program in another computer. It

divides this one big problem into seven smaller problems.

Each of these seven problems is reasonably self-contained and therefore more easily

solved without excessive reliance on external information. Each problem is addressedby one of the seven layers of the OSI model.


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The Seven Layers of the OSI model

Application

Presentation

Session

Transport

Network

Data-link

Physical

The lower two OSI model layers are implemented with hardware and software.


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OSI Model


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Data Encapsulation


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APPLICATION LAYER

The application layer of the OSI model is the layer that is closest to the user. Instead of

providing services to other OSI layers, it provides services to application programs

outside the scope of the OSI model. It's services are often part of the application

process. Main functions are:-

identifies and establishes the availability of the intended communication partner.

synchronizes the sending and receiving applications.

establishes agreement on procedures for error recovery and control of data integrity. determines whether sufficient resources for the intended communications exist.

Devices :-

Browsers

Search engines E-mail programs

Newsgroup and chat programs

Transaction services

Audio/video conferencing

Telnet

SNMP


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The presentation layer

It ensures that information sent by the application layer of one system will be readableby the application layer of another system. It provides a common format for

transmitting data across various systems, so that data can be understood, regardless of

the types of machines involved.

The presentation layer concerns itself not only with the format and representation of

actual user data, but also with data structure used by programs. Therefore, the

presentation layer negotiates data transfer syntax for the application layer.

Devices:-

Encryption

EBCDIC and ASCII GIF & JPEG


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The Session LayerThe main function of the OSI model's session layer is to control "sessions", which are

logical connections between network devices. A session consists of a dialog, or data

communications conversation, between two presentation entities. Dialogs can be

simplex (one-way)

half-duplex (alternate)

full-duplex (bi-directional)

Simplex conversations are rare on networks. Half-duplex conversations require a good

deal of session layer control, because the start and end of each transmission need to be

monitored.Most networks are of course capable of full-duplex transmission, but in fact many

conversations are in practice half-duplex.

Devices:-

Some examples of session layer protocols and interfaces are:

Network File System (NFS)

Concurrent database access X-Windows System

Remote Procedure Call (RPC)

SQL

NetBIOS Names

AppleTalk Session Protocol (ASP)

Digital Network Architecture


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The Transport Layer

You can think of the transport layer of the OSI model as a boundary between the upper

and lower protocols. The transport layer provides a data transport service that shields

the upper layers from transport implementation issues such as the reliability of a

connection.

The transport layer provides mechanisms for:-

multiplexing upper layer applications the establishment, maintenance, and orderly termination of virtual circuits

information flow control

transport fault detection and recovery

Devices:-

TCP, UDP, SPX and Sliding Windows.


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The Network LayerLayer three of the OSI model is the network layer.

The network layer sends packets from source network to destination network.

It provides consistent end-to-end packet delivery services to its user, the transport

layer.

In wide area networking a substantial geographic distance and many networks can

separate two end systems that wish to communicate. Between the two end systems the

data may have to be passed through a series of widely distributed intermediary nodes.

These intermediary nodes are normally routers.

Routers are special stations on a network, capable of making complex routing decisions. The network layer is the domain of routing.

Routing protocols select optimal paths through the series of interconnected networks.

Network layer protocols then move information along these paths.

One of the functions of the network layer is "path determination".

Path determination enables the router to evaluate all available paths to a destination and

determine which to use. It can also establish the preferred way to handle a packet.After the router determines which path to use it can proceed with switching the packet.

It takes the packet it has accepted on one interface and forwards it to another interface

or port that reflects the best path to the packet's destination.

Devices:-

IP, IPX, Routers, Routing Protocols (RIP, IGRP, OSPF, BGP etc), ARP, RARP, ICMP.


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The Data-Link Layer

Layer two of the OSI reference model is the data-link layer. This layer is responsible forproviding reliable transit of data across a physical link. The data-link layer is concerned

with

physical addressing; Bridges, Transparent Bridges, Layer 2 Switches

network topology; CDP

line discipline (how end systems will use the network link)

error notification ordered delivery of frames

flow control

Frame Relay, PPP, SDLC, X.25, 802.3, 802.3, 802.5/Token Ring, FDDI.


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The Physical LayerLayer one of the OSI model is the physical layer. The physical layer is concerned with

the interface to the transmission medium. At the physical layer, data is transmitted onto

the medium (e.g. coaxial cable or optical fiber) as a stream of bits.So, the physical layer is concerned, not with networking protocols, but with the

transmission media on the network.

The physical layer defines the electrical, mechanical, procedural, and functional

specifications for activating, maintaining, and deactivating the physical link between

end systems. This layer puts 1's & 0's onto the wire.

Characteristics specified by the physical layer include

voltage levels

timing of voltage changes

physical data rates

maximum transmission distances

physical connectors

Devices:-

Hubs, FDDI Hardware, Fast Ethernet, Token Ring Hardware.


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CHAPTER 2

NETWORK TOPOLOGIES


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CHAPTER 2

NETWORK TOPOLOGIES

What is a Topology?

The physical topology of a network refers to the configuration of cables, computers,

and other peripherals. Physical topology should not be confused with logical topology

which is the method used to pass information between workstations. Logical topologywill be discussed in the Protocol Chapter.


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Main Types of Physical Topologies

The following sections discuss the physical topologies used in networks and otherrelated topics.

Linear Bus

Star

Ring

TreeConsiderations When Choosing a Topology

Summary Chart


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Linear BusA linear bus topology consists of a main run of cable with a terminatorat each end (See

fig. 1). All nodes (file server, workstations, and peripherals) are connected to the linear

cable. Ethernet and LocalTalknetworks use a linear bus topology.

Advantages of a Linear Bus Topology

Easy to connect a computer or peripheral to a linear bus.Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

Entire network shuts down if there is a break in the main cable.

Terminators are required at both ends of the backbone cable.

Difficult to identify the problem if the entire network shuts down.

Not meant to be used as a stand-alone solution in a large building


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StarA star topology is designed with each node (file server, workstations, and peripherals)

connected directly to a central networkhub orconcentrator(See fig. 2).Data on a star network passes through the hub or concentrator before continuing to its

destination. The hub or concentrator manages and controls all functions of the network.

It also acts as a repeaterfor the data flow. This configuration is common with twisted

pair cable; however, it can also be used with coaxial cable orfiber optic cable.

Advantages of a Star TopologyEasy to install and wire.

No disruptions to the network then connecting or removing devices.

Easy to detect faults and to remove parts.

Disadvantages of a Star Topology

Requires more cable length than a linear topology.

If the hub or concentrator fails, nodes attached are disabled.More expensive than linear bus topologies because of the cost of the concentrators.

The protocols used with star configurations are usually Ethernet orLocalTalk. Token

Ring uses a similar topology, called the star-wired ring.


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Ring Topology

A star-wired ring topology may appear (externally) to be the same as a star topology.Internally, the MAU (multistation access unit) of a star-wired ring contains wiring that

allows information to pass from one device to another in a circle or ring. The Token

Ringprotocol uses a star-wired ring topology.


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TreeA tree topology combines characteristics of linear bus and star topologies. It consists of

groups of star-configured workstations connected to a linear bus backbone cable. Tree

topologies allow for the expansion of an existing network, and enable schools toconfigure a network to meet their needs.

Advantages of a Tree Topology

Point-to-point wiring for individual segments.

Supported by several hardware and software venders.

Disadvantages of a Tree Topology

Overall length of each segment is limited by the typeof cabling used.

If the backbone line breaks, the entire segment goes down.

More difficult to configure and wire than other topologies


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MESH TOPOLOGY


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Hierarchical Topology


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Physical

Topology

Common Cable Common Protocol

Linear Bus Twisted PairCoaxialFiber

EthernetLocalTalk

Star Twisted PairFiber

EthernetLocalTalk

Star-Wired

Ring

Twisted Pair Token Ring

Tree Twisted PairCoaxialFiber

Ethernet

Summary Chart:


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CHAPTER 3

NETWORK TECHNOLOGY


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ETHERNET

The termEthernetrefers to the family of local-area network (LAN) products covered

by the IEEE 802.3 standard that defines what is commonly known as the CSMA/CD

protocol. Three data rates are currently defined for operation over optical fiber and

twisted-pair cables:

10 Mbps10Base-T Ethernet

100 MbpsFast Ethernet

1000 MbpsGigabit Ethernet

10-Gigabit Ethernet is under development and will likely be published as the IEEE

802.3ae supplement to the IEEE 802.3 base standard in late 2001 or early 2002.

Other technologies and protocols have been touted as likely replacements, but the

market has spoken. Ethernet has survived as the major LAN technology (it is currently

used for approximately 85 percent of the world's LAN-connected PCs and

workstations) because its protocol has the following characteristics: Is easy to understand, implement, manage, and maintain

Allows low-cost network implementations

Provides extensive topological flexibility for network installation

Guarantees successful interconnection and operation of standards-compliant products,

regardless of manufacturer


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EthernetABriefHistory

The original Ethernet was developed as an experimental coaxial cable network in the

1970s by Xerox Corporation to operate with a data rate of 3 Mbps using a carrier sensemultiple access collision detect (CSMA/CD) protocol for LANs with sporadic but

occasionally heavy traffic requirements. Success with that project attracted early

attention and led to the 1980 joint development of the 10-Mbps Ethernet Version 1.0

specification by the three-company consortium: Digital Equipment Corporation, Intel

Corporation, and Xerox Corporation.

The original IEEE 802.3 standard was based on, and was very similar to, the EthernetVersion 1.0 specification. The draft standard was approved by the 802.3 working group

in 1983 and was subsequently published as an official standard in 1985 (ANSI/IEEE

Std. 802.3-1985). Since then, a number of supplements to the standard have been

defined to take advantage of improvements in the technologies and to support additional

network media and higher data rate capabilities, plus several new optional network

access control features.Throughout the rest of this chapter, the termsEthernetand 802.3 will refer exclusively

to network implementations compatible with the IEEE 802.3 standard.


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Ethernet Network Elements

Ethernet LANs consist of network nodes and interconnecting media. The network nodes

fall into two major classes: Data terminal equipment (DTE)Devices that are either the source or the

destination of data frames. DTEs are typically devices such as PCs, workstations, file

servers, or print servers that, as a group, are all often referred to as end stations.

Data communication equipment (DCE)Intermediate network devices that receive

and forward frames across the network. DCEs may be either standalone devices such as

repeaters, network switches, and routers, or communications interface units such as

interface cards and modems.

Throughout this chapter, standalone intermediate network devices will be referred to as

eitherintermediate nodes orDCEs. Network interface cards will be referred to asNICs.

The current Ethernet media options include two general types of copper cable:

unshielded twisted-pair (UTP) and shielded twisted-pair (STP), plus several types ofoptical fiber cable


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802.3 (Ethernet)

This standard specifies a network that uses a bus topology, base band signaling, and a

CSMA/CD network access method. This standard was developed to match the Digital,

Intel, and Xerox (DIX) Ethernet networking technology. So many people implemented

the 802.3 standard, which resembles the DIX Ethernet, that people just started calling it

Ethernet. It is the most widely implemented of all the 802 standards because of itssimplicity and low cost.

EthernetSpeeds - 10, 100, or 1000 Mbps

Access - CSMA/CD

Topologies - Logical bus

Media - Coaxial or UTP


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10BASE-T

Speeds - 10Mbps

Signal type - base band

Length - 100 meters between the node and

hub (100 meters per segment)

- no more than 1024 nodes per hub

Topology - physica

lstar,

logica

lbus

Cable type - UTP

- one of the most popular networking

cabling schemes


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100BASE-TX

Speeds - 100 Mbps

Cable type - UTP/STP

Length - 100 meters per segment

- Two pairs of category 5 UTP or

Type 1 STP

- Physically resembles 10BASE-T


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10 Base 2

Can be used I many of the same instances as 10BASE5, but it is much easier to

install and much less expensive. 10BASE2 uses RG-58 coaxial cable with BNC

connectors.

Cables in the 10BASE2 systems connect with BNC connectors. The network

interface card in a computer requires a T-connector where you can two cables to

adjacent computers. Any unused connection must have a 50-ohm terminator.

Speeds - 10 Mbps

signal

type - base band (single signa

lon the cab

le)

length - no longer than 185 meters

- no more than 30 nodes per segment ,

nodes must be spaced at least 0.5 Meters apart

Known as - thin Ethernet, thinnet, and sometimes

cheapernet

cable type - coax


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10BASE5

Speeds - 10 Mbpssignal type - base bandlength - 500 meters per segment

- no more than 100 nodes per segment- nodes must be placed at 2.5 meter intervals

(cable is marked every 2.5 Meters forease of installation)

Color - typically yellow in color but its not standard

know as - thick Ethernet or thicknetcable type - coax

- uses vampire taps to connect devices to cable


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100BASE-FX

Speeds - 100Mbps (Ethernet over fiber

optic implementation)

Connectors - SC or ST

Cable type - fiber optic

Length - 2000 meters


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Gigabit Ethernet

1000BASESX

Cable type - Multimode fiber optic

Speeds - 1000Mbps

Length - 260 meters

Connectors - SC fiber

1000BASETX

Cable type - Cat 5 UTP

Speeds - 1000Mbps

Length - 100 meters

Connectors - same as 10BASE-T (RJ-45)


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The IEEE 802.3 Logical Relationship to the ISO Reference Model

Figure below shows the IEEE 802.3 logical layers and their relationship to the OSI

reference model. As with all IEEE 802 protocols, the ISO data link layer is divided into

two IEEE 802 sublayers, the Media Access Control (MAC) sublayer and the MAC-

client sublayer. The IEEE 802.3 physical layer corresponds to the ISO physical layer.


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The MAC-client sublayer may be one of the following:

Logical Link Control (LLC), if the unit is a DTE. This sublayer provides the interface

between the Ethernet MAC and the upper layers in the protocol stack of the end station.The LLC sublayer is defined by IEEE 802.2 standards.

Bridge entity, if the unit is a DCE. Bridge entities provide LAN-to-LAN interfaces

between LANs that use the same protocol (for example, Ethernet to Ethernet) and also

between different protocols (for example, Ethernet to Token Ring). Bridge entities are

defined by IEEE 802.1 standards.

Because specifications for LLC and bridge entities are common for all IEEE 802 LAN

protocols, network compatibility becomes the primary responsibility of the particular

network protocol. Figure shows different compatibility requirements imposed by the

MAC and physical levels for basic data communication over an Ethernet link.


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The Basic Ethernet Frame FormatThe IEEE 802.3 standard defines a basic data frame format that is required for all MAC

implementations, plus several additional optional formats that are used to extend the

protocol's basic capability. The basic data frame format contains the seven fields shown

in Figure. Preamble (PRE)Consists of 7 bytes. The PRE is an alternating pattern of ones and

zeros that tells receiving stations that a frame is coming, and that provides a means to

synchronize the frame-reception portions of receiving physical layers with the incoming

bit stream.

Start-of-frame delimiter (SOF)Consists of 1 byte. The SOF is an alternating

pattern of ones and zeros, ending with two consecutive 1-bits indicating that the next bit

is the left-most bit in the left-most byte of the destination address.

Destination address (DA)Consists of 6 bytes. The DA field identifies which

station(s) should receive the frame. The left-most bit in the DA field indicates whether

the address is an individual address (indicated by a 0) or a group address (indicated by a

1). The second bit from the left indicates whether the DA is globally administered(indicated by a 0) or locally administered (indicated by a 1). The remaining 46 bits are a

uniquely assigned value that identifies a single station, a defined group of stations, or all

stations on the network.

Source addresses (SA)Consists of 6 bytes. The SA field identifies the sending

station. The SA is always an individual address and the left-most bit in the SA field is

always 0.


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Length/TypeConsists of 2 bytes. This field indicates either the number of MAC-

client data bytes that are contained in the data field of the frame, or the frame type ID if

the frame is assembled using an optional format. If the Length/Type field value is less

than or equal to 1500, the number of LLC bytes in the Data field is equal to the

Length/Type field value. If the Length/Type field value is greater than 1536, the frameis an optional type frame, and the Length/Type field value identifies the particular type

of frame being sent or received.

DataIs a sequence ofnbytes of any value, where n is less than or equal to 1500. If

the length of the Data field is less than 46, the Data field must be extended by adding a

filler (a pad) sufficient to bring the Data field length to 46 bytes.

Frame check sequence (FCS)Consists of 4 bytes. This sequence contains a 32-bitcyclic redundancy check (CRC) value, which is created by the sending MAC and is

recalculated by the receiving MAC to check for damaged frames. The FCS is generated

over the DA, SA, Length/Type, and Data fields.


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Frame TransmissionWhenever an end station MAC receives a transmit-frame request with the

accompanying address and data information from the LLC sublayer, the MAC begins

the transmission sequence by transferring the LLC information into the MAC frame

buffer.

The preamble and start-of-frame delimiter are inserted in the PRE and SOF fields.

The destination and source addresses are inserted into the address fields.

The LLC data bytes are counted, and the number of bytes is inserted into the

Length/Type field. The LLC data bytes are inserted into the Data field. If the number of LLC data bytes is

less than 46, a pad is added to bring the Data field length up to 46.

An FCS value is generated over the DA, SA, Length/Type, and Data fields and is

appended to the end of the Data field.

After the frame is assembled, actual frame transmission will depend on whether the

MAC is operating in half-duplex or full-duplex mode.The IEEE 802.3 standard currently requires that all Ethernet MACs support half-duplex

operation, in which the MAC can be either transmitting or receiving a frame, but it

cannot be doing both simultaneously. Full-duplex operation is an optional MAC

capability that allows the MAC to transmit and receive frames simultaneously.


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Half-Duplex TransmissionThe CSMA/CDAccess Method

The CSMA/CD access rules are summarized by the

protocol's acronym:Carrier senseEach station continuously listens for

traffic on the medium to determine when

gaps between frame transmissions occur.

Multiple accessStations may begin transmitting any

time they detect that the network is quiet

(there is no traffic).Collision detectIf two or more stations in the same

CSMA/CD network (collision domain)

begin transmitting at approximately the

same time, the bit streams from the

transmitting stations will interfere

(collide) with each other, and both

transmissions will be unreadable. If

that happens, each transmitting station

must be capable of detecting that a

collision has occurred before it

has finished sending its frame.


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FullDuplex Operation

Full-duplex operation is an optional MAC capability that allows simultaneous

two-way transmission over point-to-point links. Full duplex transmission is

functionally much simpler than half-duplex transmission because it involves no

media contention, no collisions, no need to schedule retransmissions, and no need

for extension bits on the end of short frames. The result is not only more time

available for transmission, but also an effective doubling of the link bandwidth

because each link can now support full-rate, simultaneous, two-way

transmission.Transmission can usually begin as soon as frames are ready to send. The only

restriction is that there must be a minimum-length inter-frame gap between

successive frames, as shown in Figure, and each frame must conform to Ethernet

frame format standards


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10-Mbps Ethernet10Base-T

10Base-T provides Manchester-encoded 10-Mbps bit-serial communication over two

unshielded twisted-pair cables. Although the standard was designed to supporttransmission over common telephone cable, the more typical link configuration is to use

two pair of a four-pair Category 3 or 5 cable, terminated at each NIC with an 8-pin RJ-

45 connector (the MDI). Figure below is he 10Base-T Link A Four-Pair UTP cable in

which Two Pairs are not used.


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100 MbpsFast EthernetIncreasing the Ethernet transmission rate by a factor of ten over 10Base-T was not a

simple task, and the effort resulted in the development of three separate physical layer

standards for 100 Mbps over UTP cable: 100Base-TX and 100Base-T4 in 1995, and100Base-T2 in 1997. Each was defined with different encoding requirements and a

different set of media-dependent sublayers, even though there is some overlap in the

link cabling. Table compares the physical layer characteristics of 10Base-T to the

various 100Base versions.

Ethernet

Version

Transmit

Symbol Rate1Encodi

ngCabling

Full-Duplex

Operation

10Base-T 10 MBps Manch

ester

Two pairs of UTP Category -3

or better

Supported

100Base-

TX

125 MBps 4B/5B Two pairs of UTP Category -5

or Type 1 ST

P

Supported

100Base-

T4

33 MBps 8B/6T Four pairs of UTP Category -3

or better

Not supported

100Base-

T2

25 MBps PAM5x

5

Two pairs of UTP Category -3

or better

Supported


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The 100Base-T4 Frame Transmission Sequence


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1000 MbpsGigabit Ethernet

The Gigabit Ethernet standards development resulted in two primary specifications:

1000Base-T for UTP copper cable and 1000Base-X STP copper cable, as well as singleand multimode optical fiber (see Figure).


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1000Base-T

1000Base-T Ethernet provides full-duplex transmission over four-pair Category 5 or

better UTP cable. 1000Base-T is based largely on the findings and design approachesthat led to the development of the Fast Ethernet physical layer implementations:

100Base-TX proved that binary symbol streams could be successfully transmitted

over Category 5 UTP cable at 125 MBps.

100Base-T4 provided a basic understanding of the problems related to sending

multilevel signals over four wire pairs.

100Base-T2 proved that PAM5 encoding, coupled with digital signal processing,could handle both simultaneous two-way data streams and potential crosstalk problems

resulting from alien signals on adjacent wire pairs.


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1000Base-X

All three 1000Base-X versions support full-duplex binary transmission at 1250 Mbps

over two strands of optical fiber or two STP copper wire-pairs, as shown in Figure.Transmission coding is based on the ANSI Fibre Channel 8B/10B encoding scheme.

Each 8-bit data byte is mapped into a 10-bit code-group for bit-serial transmission. Like

earlier Ethernet versions, each data frame is encapsulated at the physical layer before

transmission, and link synchronization is maintained by sending a continuous stream of

IDLE code-groups during interframe gaps. All 1000Base-X physical layers support both

half-duplex and full-duplex


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Network Cabling Link Crossover Requirements


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CHAPTER 4

NETWORK CABLING


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What is NetworkCabling?

Cable is the medium through which information usually moves from one networkdevice to another. There are several types of cable which are commonly used with

LANs. In some cases, a network will utilize only one type of cable, other networks will

use a variety of cable types. The type of cable chosen for a network is related to the

network's topology, protocol, and size. Understanding the characteristics of different

types of cable and how they relate to other aspects of a network is necessary for the

development of a successful network.

The types of cables used in networks

Unshielded Twisted Pair (UTP) Cable

Shielded Twisted Pair (STP) Cable

Coaxial Cable

Fiber Optic Cable

Wireless LANs


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Unshielded twisted pair (UTP) is the most popular and is generally the best option for

school networks

The quality of UTP may vary from telephone-grade wire to extremely high-speed cable.

The cable has four pairs of wires inside the jacket. Each pair is twisted with a different

number of twists per inch to help eliminate interference from adjacent pairs and other

electrical devices. The tighter the twisting, the higher the supported transmission rate

and the greater the cost per foot. The EIA/TIA (Electronic Industry

Association/Telecommunication Industry Association) has established standards of UTP

and rated five categories of wire.


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Unshielded Twisted Pair Connector

The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This

is a plastic co

nnecto

r that loo

ks like a large telepho

ne-style co

nnecto

r.A

slo

t allo

ws theRJ-45 to be inserted only one way. RJ stands for Registered Jack, implying that the

connector follows a standard borrowed from the telephone industry. This standard

designates which wire goes with each pin inside the connector.


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Shielded Twisted Pair (STP) Cable

A disadvantage of UTP is that it may be susceptible to radio and electrical frequency

interference. Shielded twisted pair (STP) is suitable for environments with electricalinterference; however, the extra shielding can make the cables quite bulky. Shielded

twisted pair is often used on networks using Token Ring topology.


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Coaxial Cable

Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation

between the center conductor and a braided metal shield The metal shield helps to block any

outside interference from fluorescent lights, motors, and other computers.

Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In

addition, it can support greater cable lengths between network devices than twisted pair cable.The two types of coaxial cabling are thick coaxial and thin coaxial.

Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the specifications for thin

coaxial cable carrying Ethernet signals. The 2 refers to the approximate maximum segment

length being 200 meters. In actual fact the maximum segment length is 185 meters. Thin coaxial

cable is popular in school networks, especially linear bus networks.

Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the specifications for thick

coaxial cable carrying Ethernet signals. The 5 refers to the maximum segment length being 500meters. Thick coaxial cable has an extra protective plastic cover that helps keep moisture away

from the center conductor. This makes thick coaxial a great choice when running longer lengths

in a linear bus network. One disadvantage of thick coaxial is that it does not bend easily and is

difficult to install.


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CoaxialCable Connectors

The most common type of connector used with coaxial cables is theBayone-Neill-Concelman (BNC) connector. Different types of adapters

are available for BNC connectors, including a T-connector, barrel

connector, and terminator. Connectors on the cable are the weakest

points in any network. To help avoid problems with your network,

always use the BNC connectors that crimp, rather than screw, onto thecable.

FiberOptic Cable


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FiberOptic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of

protective materials. It transmits light rather than electronic signals eliminating the

problem of electrical interference. This makes it ideal for certain environments thatcontain a large amount of electrical interference. It has also made it the standard for

connecting networks between buildings, due to its immunity to the effects of moisture

and lighting.

Fiber optic cable has the ability to transmit signals over much longer distances than

coaxial and twisted pair. It also has the capability to carry information at vastly greater

speeds. This capacity broadens communication possibilities to include services such as

video conferencing and interactive services. The cost of fiber optic cabling is

comparable to copper cabling; however, it is more difficult to install and modify.

10BaseF refers to the specifications for fiber optic cable carrying Ethernet signals.


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FiberOptic Connector

The most common connector used with fiber optic cable is an ST connector. It is barrel

shaped, similar to a BNC connector. A newer connector, the SC, is becoming more

popular. It has a squared face and is easier to connect in a confined space.


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Ethernet Cable Summary

10BaseT Unshielded Twisted Pair 100 meters

10Base2 Thin Coaxial 185 meters

10Base5 Thick Coaxial l500 meters

10BaseF Fiber Optic 2000 meters

100BaseT Unshielded Twisted Pair 100 meters

100BaseTX Unshielded Twisted Pair 220 meters

Wireless LANs


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Wireless LANs

Not all networks are connected with cabling; some networks are wireless. WirelessLANs use high frequency radio signals, infrared light beams, or lasers to communicate

between the workstations and the file server or hubs. Each workstation and file server

on a wireless network has some sort of transceiver/antenna to send and receive the data.

Information is relayed between transceivers as if they were physically connected. For

longer distance, wireless communications can also take place through cellular telephone

technology, microwave transmission, or by satellite.

Wireless networks are great for allowing laptop computers or remote computers to

connect to the LAN. Wireless networks are also beneficial in older buildings where it

may be difficult or impossible to install cables.


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Installing Cable - Some Guidelines

When running cable, it is best to follow a few simple rules:

Always use more cable than you need. Leave plenty of slack.Test every part of a network as you install it. Even if it is brand new, it may have

problems that will be difficult to isolate later.

Stay at least 3 feet away from fluorescent light boxes and other sources of electrical

interference.

If it is necessary to run cable across the floor, cover the cable with cable protectors.

Label both ends of each cable.Use cable ties (not tape) to keep cables in the same location together.


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CHAPTER 5

NETWORKING BASICS

Hubs


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Hubs

The term hub is sometimes used to refer to any piece of network equipment that

connects PCs together, but it actually refers to a multi-port repeater. This type of device

simply passes on (repeats) all the information it receives, so that all devices connected

to its ports receive that information.

Hubs repeat everything they receive and can be used to extend the network. However,

this can result in a lot of unnecessary traffic being sent to all devices on the network.

Hubs pass on traffic to the network regardless of the intended destination; the PCs to

which the packets are sent use the address information in each packet to work out which

packets are meant for them. In a small network repeating is not a problem but for a

larger, more heavily used network, another piece of networking equipment (such as a

switch) may be required to help reduce the amount of unnecessary traffic being

generated.


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StandAloneHub


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StackableHub


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ModularHub

Hubs function on Layer 1, have a single collision domain, and do not segment network

traffic.

ROUTER


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ROUTER

A router is a computer networking device that forwards data packets toward their

destinations through a process known as routing. Routing occurs at layer 3 of the OSI

seven-layer model.


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Router Responsibilities

1. Optimizing the Routing Paths.

2. Switching


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Router Features

Use dynamic routingOperate at the protocollevel

Remote administration

Support complex networks

The more filtering done, the lower the performance

Provides security

Segment networks logically

Broadcast storms can be isolated

Often provide bridge functions also

More complex routing protocols used [such as RIP, IGRP,

OSPF]

Bridges


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g

A data-linkbridge is a device that connects two similar networks or divides one

network into two. It takes frames from one network and puts them on the other,

and vice versa.As it does this, it regenerates the signal strength of the frames,

allowing data to travel further. In this sense, a data-link bridge incorporates thefunctionality of a repeater, which also regenerates frames to extend a LAN. But a

bridge does more than a repeater.A bridge is more intelligent than a repeater. It

can look at each frame and decide on which of the two networks it belongs.

Repeaters simply forward every frame from one network to the other, without

looking at them.

A bridge looks at each frame as it passes, checking the source and destination

addresses. If a frame coming from Station 1 on LANA is destined for Station 5 on

LAN B, the bridge willpass the frame onto LAN B. If a frame coming from

Station 1 on LANA is destined for Station 3 on LAN A, the bridge will not forward

it; that is, it will filter it.

Bridges know which frames belong where by looking at the source and destination

addresses in the MediumAccess Control (MAC) layer information carried in the

frame. The MAClayer, which is part of the second layer ofOSI Model, defines

how frames get on the network without bumping into each other. It also contains

information about where the frame came from and where it should go. Because

bridges use this level of information, they have several advantages over other

forms of interconnecting LANs.


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Types of Bridges


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Bridges can be grouped into categories based on various product characteristics. Using

one popular classification scheme, bridges are either local or remote. Localbridges

provide a direct connection between multiple LAN segments in the same area.Remotebridges connect multiple LAN segments in different areas, usually over

telecommunications lines.

Figure Local and Remote Bridges Connect LAN Segments in SpecificAreas

AMAC-Layer Bridge Connects the IEEE 802.3


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and IEEE 802.5 Networks

Advantages of Bridges


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Increase the number of attached workstations and

network segments

Since bridges buffer frames, it is possible to interconnect

different segments which use different MACprotocols

Since bridges work at the MAClayer, they are

transparent to higher levelprotocols

By subdividing the LAN into smaller segments,

overall reliability is increased and the network becomes

easier to maintain

Used for non routable protocols like NetBEUI

which must be bridged

Advantages of Bridges

Disadvantages of Bridges


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The buffering of frames introduces network delays

Bridges may overload during periods of high traffic

Bridges combine different MACprotocols,require

the frames to be modified before transmission onto

the new segment. This causes delays

In complex networks, data may be sent over redundant

paths, and the shortest path is not always taken

Bridges pass on broadcasts, giving rise to broadcast

storms on the network

Disadvantages of Bridges

Bridge Features


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Operate at the MAClayer (layer 2 of the OSI model)

Can reduce traffic on other segments

Broadcasts are forwarded to every segment

Most allow remote access and configuration

Small delays introduced

Fault tolerant by isolating fault segments and

reconfiguring paths in the event of failure

Not efficient with complex networks

Redundant paths to other networks are not used (would

be useful if the major path being used was overloaded)

Shortest path is not always chosen by spanning tree

algorithm

Bridge Features

SWITCHES


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Switches are smart hubs that send data directly to the destination rather than

everywhere within a network. Switches also allow components of different

speeds to communicate.

Switches divide the network into smaller collision domains [a collision domain is a

group of workstations that contend for the same bandwidth]. Each segment

into the switch has its own collision domain (where the bandwidth is competed

for by workstations in that segment).As packets arrive at the switch, it looks at the

MAC address in the header, and decides which segment to forward the packet

to.Higher protocols like IPX and TCP/IP are buried deep inside the packet, so

are

invisible to the switch. Once the destination segment has been determined, the

packet is forwarded without delay.

Different forwarding techniques:-

1. Cut-through Switches

2. Store-Forward Switches

LAN Switch


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LAN switches are used to interconnect multiple LAN segments. LAN switching

provides dedicated, collision-free communication between network devices, with

support for multiple simultaneous conversations. LAN switches are designed to switchdata frames at high speeds. Figure 4-4 illustrates a simple network in which a LAN

switch interconnects a 10-Mbps and a 100-Mbps Ethernet LAN.

LAN Switch Can Link 10-Mbps and 100-Mbps Ethernet Segments

ATM Switch


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ATM Switch

Asynchronous Transfer Mode (ATM) switches provide high-speed switching and

scalable bandwidths in the workgroup, the enterprise network backbone, and the wide

area. ATM switches support voice, video, and data applications, and are designed to

switch fixed-size information units called cells, which are used in ATM

communications. Figure 4-3 illustrates an enterprise network comprised of multiple

LANs interconnected across an ATM backbone.

Multi-LAN Networks Can Use an ATM-Based Backbone When Switching Cells

Switch Benefits


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Switch Benefits

Isolates traffic, relieving congestion

Separates collision domains, reducing collisionsSegments, restarting distance and repeater rules

Switch Costs

Price: currently 3 to 5 times the price of a hubPacket processing time is longer than in a hub

Monitoring the network is more complicated

The two main impacts of switching will be faster

network connection to the server(s) and the isolation ofnon-relevant traffic from each segment.

Distinguishing between Bridges and Routers


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Both bridges and routers

Forward packets between networksSend data across WAN links

ABridge

Recognizes the address of EACH computer on it's segment and forwards packets onthe basis of the destination address

ARouter


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Works at the NETWORK layer and thus takes more information into account when

determining what to forward and where to forward it to.


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A router can connect networks that use

Different architectures

Different media access control methods

-- for example, they can connect an Ethernet segment

to a Token-Ring segment

MODEM


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The word "modem" stands for "modulator-demodulator".

A modem's purpose is to convert digital information to analog signals (modulation),

and to convert analog signals back into useful digital information (demodulation).

Wireless network means that each computer can communicate directly with every


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Wireless network means that each computer can communicate directly with every

other computer on the network. But some wireless networks are client/server.

They have an access point, which is a wired controller that receives and transmits

data to the wireless adapters installed in each computer.A gateway is a network point that acts as an entrance to another network.

In the network for an enterprise, a computer server acting as a gateway

node is often also acting as a proxy server and a firewall server


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A channel service unit/digital service unit (CSU/DSU) is a digital-interface

device used to connect a router to a digital circuit like a T1.


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RJ-45 CONNECTOR


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AUI

B t N il C l B iti h N l C t


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Bayonet Neil-Concelman or British NavelConnector


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SC


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SC


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CHAPTER 6

IEEE STANDARS


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IEEE STANDARDS

Fast Ethernet specification (IEEE 802.3u) is known as

100BASE-T. This new LAN standard has raised the

Ethernet speed limit from 10 Megabits per second to

100 Megabits per second with only minimal changes

to the existing cable structure

The Fast Ethernet specification calls for three types of transmission schemes

The first is 100BASE-TX

The second variation is 100Base-FX

The third variation is 100BASE-T4.

Types of Repeaters


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Class I Repeater: The Class 1 repeater operates by

translating line signals on the incoming port to adigital signal.

Class II Repeater: The Class II repeater immediately

repeats the signal on an incoming port to all the ports

on the repeater.


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The Fiber Distributed Data Interface (FDDI) specifies a 100-Mbps token passing dual-


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The Fiber Distributed Data Interface (FDDI) specifies a 100-Mbps token passing, dual-

ring LAN using fiber-optic cable. FDDI is frequently used as high-speed

backbone technology because of its support for high bandwidth and greater distances

than copper.


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FDDI Transmission Media

FDDI defines two types of optical fiber: single-modeand multimode. A mode is a ray of light that enters thefiber at a particular angle.Multimode fiber uses LED asthe light-generating device, while single-mode fibergenerally uses lasers.

Light Sources Differ for Single-Mode and Multimode Fibers


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Light Sources Differ for Single Mode and Multimode Fibers


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FDDI's four specifications are

Media Access Control (MAC)

Physical Layer Protocol (PHY),

Physical-Medium Dependent (PMD)

Station Management (SMT)


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FDDI Station-Attachment Types

FDDI defines four types of devices:

Single-Attachment Station (SAS)

Dual-Attachment Station (DAS)

Single-Attached Concentrator (SAC)Dual-Attached Concentrator (DAC).


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FDDI DAS PortsAttach to the Primary and Secondary Rings

AConcentratorAttaches to Both the Primary and


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y

Secondary Rings

A Ring Recovers from a Station Failure by Wrapping


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ARing also Wraps to Withstand a Cable Failure


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ADual-Homed Configuration Guarantees Operation


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The FDDI Frame Is Similar to That of a Token Ring Frame


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802.11b wireless network adapter can operate in two modes,

Ad-Hoc and Infrastructure.

In infrastructure mode, all your traffic passes through a

wireless access point.

InAd-hoc mode your computers talk directly to each other

and do not need an access point at all.


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Access point varieties

Access points come in three varieties

Bridge

NAT router

NAT router+bridge.

A bridge type connects a wireless network to a wired

network transparently. Communication is possible

between both networks in both directions

A NAT router type routes traffic from your wireless

network to an Ethernet wired network, but it will notroute traffic back. This type can be used to share

an Internet connection


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Hybrid NAT router + Bridge devices that bridge your

wired and wireless networks, then route them both to theinternet using a single IP address. This is good for sharing

an Internet connection when you have both wired and

wireless computers in your home. These are often

called Cable/DSL routers with wireless.

Bridging a wireless 802.11b network with a

i d Eth t t k


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wired Ethernet network.

Wireless access point (802.11b) of the router variety


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Cable/DSL Router with Wireless Ethernet


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IEEE 802.2 LLC - Logical LinkControl Layer

SAPs are Service Access Ports. A SAP is a port(l i l li k) t th N t k l t l If


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(logical link) to the Network layer protocol. If we wereoperating a multi protocol LAN, each Network Layer

protocol would have its own SAP.

Types of LLC Operation

Type 1: ConnectionlessType 2: Connection Oriented


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Type 1: Connectionless

Connectionless service for data communications is verysimilar to sending mail through the postal system(hand delivered mail): the data is sent and we hope itarrives at its destination.

Connection Oriented


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Connection Oriented

Connection Oriented service for data communications isvery similar to having a phone conversation


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Connection-Oriented operation for the LLC

layer provides these 4 services:

Connection establishment

Confirmation and acknowledgement that data has

been received.

Error recovery by requesting received bad data to

be resent.

Sliding Windows


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CHAPTER 7

MAC ADDRESS

MACAddress


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MAC addresses are also known as hardware addresses or physical addresses. They

uniquely identify an adapter on a LAN.

Short for Media Access Control address. This is OSI layer 2 hardware address defined

by IEEE standard and is used to deliver packets in the local network. It is sequence of

six two-digits hexadecimal numbers separated by colons, exempli gratia:

00:2f:21:c1:11:0a

MM:MM:MM:SS:SS:SSMM-MM-MM-SS-SS-SS

The first half of a MAC address contains the ID number of the adapter manufacturer.

These IDs are regulated by an Internet standards body. The second half of a MAC

address represents the serial number assigned to the adapter by the manufacturer


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IP networks maintain a mapping between the IP address of a device and its MAC

address This mapping is known as the ARP cache or ARP table


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address. This mapping is known as the ARP cache or ARP table

How to find your MAC address in Windows XP


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CHAPTER 8

IP ADDRESS

IPAddressing

IPAddress Requirements


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IPAddress Requirements

What is an IPAddress?

Network IDs and Host IDsIPAddressing Rules

Classfull IPAddressing

Address Classes

ClassAAddresses

Class BAddresses

Class CAddressesClass D & EAddresses

Address Class Summary

IP Addressing Requirements

Each Device that uses TCP/IP needs at least one!


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Computer/Host (each Network Interface Card)

Routers (each port or connection)

Other Devices

Each Device needs a Unique IP Address

An Example:

206.77.105.9Configured in TCP/IP Software

What is an IP Address?

32-bit Binary Number (Address)


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11000000101010000111000100010011

Divided into 4, 8-bit Octets

11000000.10101000.01110001.00010011

Converted to Decimal Numbers

See: Binary Math

192.168.113.19

Decimal range of an Octet: 0-255

It contains the devices:

Network ID and Host ID

Network ID and Host ID

Network ID

Sh d C t ll t th h i l t


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Shared or Common to all computers on the same physical segment

Unique on the Entire Network

Area Code

Host ID

Identifies a specific device (Host) within a physical segment

Unique on the physical segment

Phone Number

192.176.11.201

IP Addressing Rules

Each Device (Host) Needs at Least One Unique IP Address


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All Devices on the Same Physical Segment Share a Common Network ID (Subnet

Mask)

Each Physical Segment Has a Unique Network ID (Subnet Mask)

Classfull IP Addressing

Traditional Manner of Addressing

Class A


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Class A

Class B

Class C

Address Classes Specify Which Octets of the IP Address are the Network-ID and

Which are the Host-ID

Address Classes Specify Network Sizes (Number of Hosts)

Address Classes

ClassA

Network . Host . Host . Host

Class B

Network . Network . Host . Host

Class CNetwork . Network . Network . Host

Class D & E

Class A Networks:

The Definition

Per Specification:


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Per Specification:

1st Octet is the Network ID

2nd, 3rd, 4th Octets are the Host ID

In Binary

Any address that starts with a 0 in the first bit!

First Class A Network Address:

00000001.00000000.0000000.00000000 (Binary)

1.0.0.0 (Decimal)

Last Class A Network Address:

01111111.00000000.00000000.00000000 (Binary)

127.0.0.0 (Decimal) (Loopback Address)

Class A Networks:

Network IDs

1 t O t t i th N t k ID


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0.0.0.0 (Invalid)

1.0.0.0

2.0.0.0

3.0.0.0

~~~~

127.0.0.0 (Loop back)

2nd, 3rd, 4th Octets are the Host IDs

An Assigned Class A Network Address:

33.0.0.0 (Specifies the Network)


Specified by Network Administrators

Class A Networks:

The Number of Networks



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1-126 = 126 Possible Class A Network IDs


Each of the three Octets has a possible 256 Host IDs

Number of Host IDs from three Octets:

256 * 256 * 256 = 16,777,216 (minus 2) = 16,777,214

Always Subtract 2 from the number of Host IDs

Host IDs cannot be all 1s (reserved for broadcast address)

Host IDs cannot be all 0s (reserved for this network only address)

Class A Networks:

Host ID Addresses

33 0 0 0 (A A i d Cl AAdd )


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33.0.0.0 (An Assigned Class A Address)

All devices would share the 33 network ID.The Administrator would number the IP devices:

33.0.0.1 33.0.0.255 (255 Addresses)

33.0.1.0 33.0.1.255 (256 Addresses)

~~~~

33.0.255.0 -- 33.0.255.255 (256 Addresses)

(A Total of 65,535 Addresses)33.1.0.0 -- 33.1.255.255 (65,536 Addresses)

33.2.0.0 -- 33.2.255.255 (65,536 Addresses)

~~~~

33.255.0.0 -- 33.255.255.254 (65,535 Addresses)

( Total Addresses: 16.7 Million)

Class B Networks:

The Definition Per Specification:


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1st and 2nd Octets are the Network ID

3rd, 4th Octets are the Host IDs

In Binary

Any address that starts with a 10 in the first two bits of the first octet!

First Class B Network Address:

10000000.00000000.0000000.00000000 (Binary)

128.0.0.0 (Decimal)

Last Class B Network Address:

10111111.11111111.00000000.00000000 (Binary)

191.255.0.0 (Decimal)

Class B Networks:

Network IDs

1st and 2nd Octets are the Network IDs


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128.0.0.0

128.1.0.0

~~~~

128.255.0.0

129.0.0.0

129.1.0.0

~~~~

191.255.0.0


An Assigned Class B Network Addresses 153.11.0.0


Specified by Network Administrators

Class B Networks:




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1st Octet 128 -- 191 = 64 Possible Network IDs

2nd Octet 0 255 = 256 Possible Network IDs

Total Class B Network IDs 64 * 256 = 16,384


Each of the Two Octets has a possible 256 Host IDs

Number of Host IDs from Two Octets:256 * 256 = 65,536 (minus 2) = 65,534


Host ID cannot be all 1s (reserved for broadcast address)

Host ID cannot be all 0s (reserved for this network only address)

Class B Networks:

Host ID Addresses

An Assigned Class B Address 153 11 0 0


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An Assigned Class B Address 153.11.0.0

All devices would share the 153.11 Network ID.

The Administrator would number the IP devices:153.11.0.1 -- 153.11.0.255 (255 Addresses)

153.11.1.0 -- 153.11.1.255 (256 Addresses)

153.11.2.0 -- 153.11.2.255 (256 Addresses)

~~~~

153.11.255.0 -- 153.11.255.254 (255 Addresses)

Total Addresses: 65,534

Class C Networks:

The DefinitionPer Specification:

1st 2nd 3rd Octets are the Network ID


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1st, 2nd, 3rd Octets are the Network ID

4th Octet is the Host ID

In Binary

Any address that starts with a 110 in the first three bits of the first octet!

First Class C Network Address:

11000000.00000000.0000000.00000000 (Binary)

192.0.0.0 (Decimal)

Last Class C Network Address:

11011111.11111111.11111111.00000000 (Binary)

223.255.255.0 (Decimal)

Class C Networks:

Network IDs

1st 2nd 3rd Octets are the Network IDs


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1st, 2nd, 3rd Octets are the Network IDs

192.0.0.0 192.0.255. 0

192.1.0.0 192.1.255.0

~~~~

192.255.0.0 192.255.255.0

193.0.0.0 193.255.255.0

~~~~

223.0.0.0 223.255.255.04th Octet is the Host IDs

An Assigned Class C Network Address

201.11.206.0

4th Octet is the Host IDsSpecified by Network Administrators

Class C Networks:


1st 2nd 3rd Octets are the Network IDs


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1st, 2nd, 3rd Octets are the Network IDs

1st Octet 192 -- 223 = 31 Possible IDs

2nd Octet 0 255 = 256 Possible IDs

3nd Octet 0 255 = 256 Possible IDs

Total Class C Network IDs 32 * 256 *256 = 2,097,152

4th Octet is the Host ID

An Octet has a possible 256 IDs

Number of Host IDs an Octet:

256 (minus 2) = 254


Host ID cannot be all 1s (reserved for broadcast address)

Host ID cannot be all 0s (reserved for this network only address)

Class C Networks:

Host ID Addresses

An Assigned Class C Address


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An Assigned Class C Address

201.11.206.0

All devices would share the 201.11.206.0 Network ID.

The Administrator would number the IP devices:

201.11.206.1, 201.11.206.2, ~~~~ 201.11.206.254

Class D & E

Class D

Used by Multicast Applications


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Used by Multicast Applications

Shared Addresses

224.0.0.0 239.255.255.255

Class EExperimental

240.0.0.0 +

Address Classes:

Network IDs and Host IDs


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Class A (1st Octet 1-127)

Network.Host.Host.Host

Class B (1st Octet 128-191)

Network.Network.Host.Host

Class C (1st Octet 192-223)

Network.Network.Network.Host

Address Class Summary

1st Networks Hosts IDs

Octet IDs /Network


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Class A 1-127 126 16,777,214

Class B 128-191 16,384 65,534

Class C 192-223 2,097,152 254

Subnetting and Creating Custom Subnet Masks

Introduction: Why Custom Subnet Masks? What are Subnet IDs?


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Step 1 Design the Physical Network

Step 2 Choose a Custom Subnet Mask

Step 3 Determining the Subnet IDs

Step 4 Determining the Host IDs

Quick Review:

What is a Subnet Mask?


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An Address the accompanies an IP address that indicates which portion of the IP

address is the Network ID and which portion of the IP address is the Host ID.

152.107.102.7 (IP Address)

255.255.255.0 (Subnet Mask)

The IP Address and Subnet Mask (SNM) are interrelated and each only has meaning in

the context of the other!

IP Address and SNM are the minimum IP addressing requirements.

What Makes up a Subnet Mask (SNM)?

In Binary:

1s represent what portion of the IP address is the Network ID


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p p

0s represent what portion of the IP address is the Host ID

ForExample:

207.23.106.99 (Class CAddress)

Net . Net . Net . Host

11111111 . 11111111 . 11111111 . 00000000 (SNM in Binary)

255.255.255.0 (SNM in Decimal)

Default Subnet Masks (SNM)

ClassA (Net.Host.Host.Host)

11111111.00000000.00000000.00000000

255.0.0.0

Class B (Net.Net.Host.Host)

11111111.11111111.00000000.00000000255.255.0.0

Class C (Net.Net.Net.Host)

11111111.11111111.11111111.00000000

255.255.255.0

Why Custom Subnet Masks?

Default Subnet Masks

Class A (1 Network 16.7M Hosts)


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Class A (1 Network 16.7M Hosts)

Class B (1 Network 65K Hosts)

Class C (1 Network 254 Hosts)

Addressing an IP Network

Assigned an IP Network Address 152.77.0.0 (IP Address)

255.255.0.0 (Subnet Mask)

All Devices/Hosts on the Same Physical Segment Must have the Same Network ID

One Network ID Supports Only One Physical Segment!

What are Subnets?

A Subnet is a portion or subdivision of the IP Addresses that are associated with an

assigned Network ID.The Range of IP Addresses included in a subnet is determined by


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g g y

the Subnet Mask. Subnets must be meticulously numbered for network communication

to be successful.

Custom Subnetting:

The Steps


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Design Physical Network

Determine the Number of Physical Segments

Determine the Maximum Number of Hosts per Physical Segment

Choose a Subnet Mask that creates the number of:

Subnet-IDs >= Physical Segments

Host-IDs/Subnet-ID >= Hosts/Physical Segment

Determine and Number Subnet IDs (SN ID)

Determine and Number Host IDs

Subnet IDs

Portions of the Assigned Network ID are Defined by Subnet IDs 152.77.0.0

(Network IP Address) 255.255.0.0 (Default Subnet Mask)


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Network . Network . Host . Host (Default SNM)Network . Network . SN-ID . Host (Custom SNM)

All Device/Hosts Share the Assigned Network ID (All Physical Segments)

Each Physical Segment of the Network has a Unique Subnet-ID and the Subnet ID is

Common to All Hosts on a Physical Segment

Each Host on the Network has a Host ID Unique to its Subnet ID

Domain Naming System

DNS as a Service


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Domain Name Structure

DNS Software

Configuring DNS

How DNS Works

DNS as a Service

IP Address needed by programs


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y p g

100.109.23.144

The DNS Service Provides IP Name Resolution

DNS is a distributed database of Domain Names and their corresponding IP Addresses

Domain Naming System

A hierarchical naming system used to give each server on the Internet a unique name.

www.learntosubnet.com (URL or FQDN)


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( Q )

HostName.Domain.TLD HostName and the Domain Name = Fully Qualified Domain

Name (FQDN)

DNS keeps a complete listing of all FQDNs and their associated IP address

Domain Name Structure (Organizational Structure)

R t


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Root

NET COM GOV Org, us, ca, etc

IIHT COMPAQ SEC

DNS Software

Resolver


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Built into Client TCP/IP Software

Ask Designated Name Server for IP Address When Client Enters FQDN (URL)

Name Server

DNS Server (Available with Most OSs)

Retrieves IP Addresses for Clients

Supplies IP Address to other Name Servers

Provided by the Internet, ISP, or business

How DNS Works (The Two Key Functions)

Root Level DNS Server


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CLIENT

FQDN IP Address

TLD (com DNS Server)

SEC DNS Server

IP address

www.iiht.com

PROBLEMS

Scenario 1

Required Number of Physical Segments: 5


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Maximum Number of Hosts/Physical Segment: 5000Network Address:152.77.0.0

Scenario 2


Maximum Number of Hosts/Physical Segment: 350

Network Address: 177.133.0.0

Scenario 3


Maximum Number of Hosts/Physical Segment: 88,000

Network Address:39.0.0.0

PROBLEMS

Scenario 4



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Maximum Number of Hosts/Physical Segment: 1,500,000Network Address: 120.0.0.0

Scenario 5




Scenario 6





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CHAPTER 9

COMMUNICATION PROTOCOLS


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Internet Protocol Suite

The Internet Protocol suite, usually referred to as "TCP/IP," is a full set of

internetworking protocols that operate in the network layer, the transport layer, and the

application layer. While TCP/IP refers to two separate protocols called TCP and IP,


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pp y p p ,

Internet Protocol suite refers to the entire set of protocols developed by the Internetcommunity. Still, most people just say "TCP/IP" when they are referring to the Internet

Protocol suite.

The global Internet is a success because of TCP/IP. It is hard to believe that there ever

was a "protocol war," but during the 1980s and early 1990s, many organizations wereindecisive about which protocols to use. TCP/IP was popular in academic, military, and

scientific communities, but many businesses had installed LANs using Novell SPX/IPX

and Microsoft's NetBEUI/NetBIOS, or were tied to legacy protocols such as IBM SNA.

The Internet protocols have been universally accepted because they support scalable

internetworking, for which the global Internet is the best example.

LAYERS IN THE TCP/IP SUITE

APPLICATION LAYER


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TRANSPORT LAYER

INTERNETWORK LAYER

NETWORK ACCESS LAYER

Network Access Layer

The design of TCP/IP hides the function of this layer from usersit is concerned with

getting data across a specific type of physical network (such as Ethernet, Token Ring,


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g g p yp p y ( g

etc.). This design reduces the need to rewrite higher levels of a TCP/IP stack when newphysical network technologies are introduced (such as ATM and Frame Relay).

The functions performed at this level include encapsulating the IP datagrams into

frames that are transmitted by the network. It also maps the IP addresses to the physical

addresses used by the network. One of the strengths of TCP/IP is its addressing scheme,

which uniquely identifies every computer on the network. This IP address must be

converted into whatever address is appropriate for the physical network over which thedatagram is transmitted.

Data to be transmitted is received from the internetwork layer. The network access layer

is responsible for routing and must add its routing information to the data. The network

access layer information is added in the form of a header, which is appended to the

beginning of the data.

Internetwork Layer

The best known TCP/IP protocol at the internetwork layer is the Internet Protocol (IP),

which provides the basic packet delivery service for all TCP/IP networks. In addition to

the physical node addresses used at the network access layer the IP protocol


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the physical node addresses used at the network access layer, the IP protocol

implements a system of logical host addresses called IP addresses. The IP addresses areused by the internetwork and higher layers to identify devices and to perform

internetwork routing. The Address Resolution Protocol (ARP) enables IP to identify the

physical address that matches a given IP address.

IP is used by all protocols in the layers above and below it to deliver data, which means

all TCP/IP data flows through IP when it is sent and received, regardless of its final

destination.

Host-to-Host Transport Layer

The protocol layer just above the internetwork layer is the host-to-host layer. It is

responsible for end-to-end data integrity. The two most important protocols employed at

this layer are the Transmission Control Protocol (TCP) and User Datagram Protocol


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this layer are the Transmission Control Protocol (TCP) and User Datagram Protocol

(UDP).TCP provides reliable, full-duplex connections and reliable service by ensuring that data

is resubmitted when transmission results in an error (end-to-end error detection and

correction). Also, TCP enables hosts to maintain multiple, simultaneous connections.

When error correction is not required, UDP provides unreliable datagram service

(connectionless) that enhances network throughput at the host-to-host transport layer.

Both protocols deliver data between the application layer and the internetwork layer.Applications programmers can choose the service that is most appropriate for their

specific applications.

Application Layer

The most widely known and implemented TCP/IP application layer protocols are listed

below:

File Transfer Protocol (FTP)


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File Transfer Protocol (FTP).

Telnet.Simple Mail Transfer Protocol (SMTP).

HyperText Transfer Protocol (HTTP).

Domain Name Service (DNS).

Routing Information Protocol (RIP).

Simple Network Management Protocol (SNMP).

Network File System (NFS).

HTTP

Protocol used by web browsers to request information from web servers

A Web Browser sends an HTTP Get packet to request a web page or other data

A Web Server sends the web page to the client in a HTTP Response packet.


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The HTTP Post packet allows end-users to send data to web servers (data entryforms)

Can transfer any type of data (resources)

HTML (Web pages)

Files (data, graphics, multimedia,etc.)

Packet format includes data like:

Request Method Get, Post, etc.

Location URL of Web site being accessed

Referrer URL of of last client access


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Referrer URL of of last client access

User-Agent Version information about the accessing web browser Data

Data-link header IP header TCP header HTTP Data link CRC

Hyper Text Markup Language (HTML)

A page description (formatting) language used to create Web sites

Uses tags and attributes to define the layout of a web page

Specify fonts, font sizes and colors of text

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networking for n+ student

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