3i infotech

Network Support Group (Rajasthan)Network Support Group (Rajasthan)

Saturday, September 27 2008Saturday, September 27 2008

Welcome to 3i Infotech

“3i Infotech is an agile and fast growing global organization that drives customer success through innovative and flexible IT

solutions.

Large enough to depend on. Agile enough to perform”

Brief about 3i Infotech

• Founded in 1999. Revenue run rate of US$ 750m• Global provider of entire value chain solutions, in the area of

Banking, Financial Services and Insurance Capital Markets Mutual funds Enterprise Resource Planning and Management Government Software Services and IT Outsourcing BPO Services

• Powered by a multicultural team of 5000 technical and functional specialists• Physical presence in 11 countries• 500 customers in over 50 countries across 5 continents• Listed on NSE and BSE in India

Log on to www.3i-infotech.com for more details

http://www.3i-infotech.com/

• Maintain a formal dress code

• Always keep a smiling face

• Gents, come with clean shaven beard and shoes neatly polished

Your appearance

• Pick up the phone within three rings.

• Greet the user appropriately

• Understand the problem that the customer has logged

in at the help desk

• Treat each call /caller as ‘Important’

• Be courteous while talking to the customer on phone.

• Try to analyze and provide a solution if the problem is

simple, over phone.

Telephone etiquette

Introduction to OSI ModelIntroduction to OSI Model

Introduction to OSI Layer Introduction to OSI Layer When computers were first linked together into networks, moving information between different types of computers was a very difficult task.

In the early 1980s, the International Standards Organization (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, to addressed these needs. It divides the different functions and services provided by network hardware and software in 7 layers. This facilitates modular engineering, simplifies teaching and learning network technologies, helps to isolate problems and allows vendors to focus on just the layer(s) in which their hardware or software is implemented and be able to create products that are compatible, standardized and interoperable.

Introduction to OSI Layer Introduction to OSI Layer

The diagram below shows the 7 layers of the OSI Model, to remember them in the correct order a common mnemonic is often used: All People Seem To Need Data Processing

Introduction to OSI Layer Introduction to OSI Layer The Application, Presentation and Session layer are known as

the Upper Layer and are implemented in software.

The Transport and Network layer are mainly concerned with protocols for delivery and routing of packets to a destination and are implemented in software as well.

The Data Link is implemented in hard- and software and the Physical layer is implemented in hardware only, hence its name.

ApplicationApplication The Application layer provides network services

directly to the user's application such as a web browser, email software and Windows Explorer. This layer is said to be "closest to the user".Protocols that operate on this layer include: TELNET, HTTP, FTP, TFTP, SMTP, NTP, SNMP,

PresentationPresentation

This layer 'represents' the data in a particular format to the Application layer (masks the difference of data format between two dissimilar systems). It also defines encryption, compression, conversion and other coding functions.Specifications defined at this layer include: GIF, TIFF, JPEG, MPEG, MIME, and ASCII.

SessionSession

Establishes, maintains and terminates end-to-end connections (sessions) between two applications on two network nodes. It controls the dialogue between the source and destination node, which node can send when and how long. Also provides error reporting for the Application, Presentation and Session layer.

Protocols/API's that operate on this layer include: RPC, SQL, NETBIOS.

TransportTransport

This layer converts the data received from the upper layers into segments. The Transport layer is responsible for end-to-end (also called source-to-destination) delivery of entire messages. Provides end-to-end connectivity, it allows data to be transferred reliably and sequencing to guarantee that it will be delivered in the same order that it was sent. Provides services such as error checking and flow control (software).

Protocols that operate on this layer: TCP, UDP, NETBEUI.

Transport Transport Cont…Cont…

These protocols are either connectionless or connection-oriented:

Connection-oriented means that a connection (a virtual link) must be established before data can be exchanged. This can guarantee that data will arrive, and in the same order it was sent. It guarantees delivery by sending acknowledgements back to the source when messages are received. TCP is an example of an connection-oriented transport protocol.

A common example of connection-oriented communication is a telephone call: you call, the 'destination' picks up the phone and acknowledges and you start talking (sending data). When a message or a piece of it doesn't arrive, you say: "What!?" and the sender will retransmit the data.

Connectionless is the opposite of connection-oriented; the sender does not establish a connection before it sends data, it just sends without guaranteeing delivery. UDP is an example of an connectionless transport protocol.

A common example of connectionless communication is a Radio City, News paper, Television

NetworkNetwork This layer converts the segments from the Transport layer into

packets and is responsible for path determination, routing, and the delivery of these individual packets across multiple networks without guaranteed delivery. The network layer treats these packets independently, without recognizing any relationship between those packets, it relies on upper layers for reliable delivery and sequencing and also this layer is responsible for logical addressing (also known as network addressing or Layer 3 addressing) for example IP addresses

Examples of protocols defined at this layer: IP, IPX, AppleTalk, ICMP, RIP, OSPF, BGP, IGRP, EIGRP

Devices that operate on this layer: Routers, Layer 3 Switches.

Data LinkData Link The Data Links provides transparent network services to the

Network layer so the Network layer can be ignorant about the physical network topology and provides access to the physical networking media. Responsible for reassembling bits taken of the wire by the Physical layer to frames, makes sure they are in the correct order and requests retransmission of frames in case an error occurs. Provides error checking by adding a CRC to the frame, and flow control.

Examples of devices that operate on this layer are switches, bridges

Data Link layer has two sub layers: the LLC and the MAC sub layer.

Data LinkData Link Cont…Cont…

LLC sublayer :

The Logical Link Control is the upper sublayer of the Data Link layer. LLC masks the underlying network technology by hiding their differences hence providing a single interface to the network layer. This layer is also responsible for frames sequencing and acknowledgements.

MAC sublayer :

The Media Access Control layer takes care of physical addressing and allows upper layers access to the physical media, handles frame addressing, error checking. This layer controls and communicates directly with the physical network media through the network interface card. It converts the frames into bits to pass them on to the Physical layer who puts them on the wire (and vice versa)

PhysicalPhysical This layer communicates directly with the physical media, it is

responsible for activating, maintaining and deactivating the physical link. It handles a raw bits stream and places it on the wire to be picked up by the Physical layer at the receiving node. It defines electrical and optical signaling, voltage levels, data transmission rates and distances as well as mechanical specifications such as cable lengths and connectors, the amount of pins and their function.

Devices that operate on this layer: HUB, repeaters and WAN interfaces such as RS-232,, BRI, V.24, V.35, X.25 and Frame Relay.

SummarySummaryWhat basically happens when data passes from Host A to Host B:

1. Application, Presentation and Session layer take user input and converts it into data,

2. Transport layer adds a segment header converting the data into segments,

3. Network layer adds a network header and converts the segments into packets ,

4. Data Link layer adds a frame header converting the packets into frames,

5. MAC sub layer converts the frames into a bits which the Physical layer can put on the wire.

The steps are known as the 5 steps of data encapsulation. When the bits stream

arrives at the destination, the Physical layer takes it of the wire and converts it

into frames, each layer will remove their corresponding header while the data

flows up the OSI model until it is converted back to data and presented to the

user, this is known as de-capsulation.

TCP/IP Protocol

Introduction to TCP/IP The TCP/IP Suite defines a set of rules to enable

computers to communicate over a network. TCP/IP provides end-to-end connectivity specifying how data should be formatted, addressed, shipped, routed and delivered to the right destination .

http://en.wikipedia.org/wiki/Internet_protocol_suite

http://en.wikipedia.org/wiki/Computer_network

http://en.wikipedia.org/wiki/Routing

Application Layer Handles high-level protocols, issues of

representation, encoding, and dialog control.

Transport LayerFive basic services:• Segmenting upper-layer application data• Establishing end-to-end operations• Sending segments from one end host to another end

host• Ensuring data reliability• Providing flow control

Internet LayerBest path determination and packet switching

IP as a Routed Protocol

IP is a connectionless, unreliable, best-effort delivery protocol.

As information flows down the layers of the OSI model; the data is processed at each layer.

IP accepts whatever data is passed down to it from the upper layers.

Packet Propagation and Switching Within a Router

Network Access Layer The network access layer is concerned with all of the issues that an

IP packet requires to actually make a physical link to the network media. It includes the LAN and WAN technology details, and all the details contained in the OSI physical and data link layers.

Types of cables

Coaxial Cable:• widely used for radio frequency applications• not susceptible to the effects of

– RFI– EMI

• Ethernet originally used coaxial cables• longer distances & higher transmission rates

– 10base2 - 200m (185m), 10 Mbps– 10base5 - 500m, 10 Mbps

• Ethernet/802.3 coax - 50, ARCNET coax 93

Types of cables cont…

Coaxial – cont…• Advantages:

– higher speeds than UTP– supports broad band (multi channel) LANs

• Disadvantages:

– easily damaged– difficult to work with– expensive than UTP– for different LANs specific coax types needed


Twisted Pair• The type depends on:

– no. of pairs– no. of twists per unit length– gauge of the wire– type of insulation

• Shielded Twisted Pair (STP):– expensive– higher data rate– easy to work with

Unshielded Twisted Pair (UTP)

• Grouped into categories based on quality

• Generally used in LAN

• Cat 5 cable• RJ45

connector


• Un-shielded Twisted Pair (UTP):– low cost– lower data rate– limited length– easy installation– flexible configuration (when star wired)– supports many LANs and voice communication in the

same cable type– easy fault isolation

Unshielded Twisted Pair (UTP)

• Adv– Does not require grounding like STP, easier to add

connectors– Thinner, more flexible to install– Same data speeds as other copper media

• Disadv– More susceptible to electrical noise and interference– Shorter cabling distance (100m when used for

Ethernet LANs)


• UTP Categories:– category 3

• Up to 16 Mbps

• used for 10baseT Ethernet & 4 Mbps Token Ring

– category 4• Up to 20 Mbps

• used for 16 Mbps Token Ring

– category 5• Up to 100 Mbps

• 100baseT Ethernet

Fiber Optic Cable

Fiber Optic Cable

• Thin wire (usually very pure glass or plastic) surrounded by a reflective cladding that is used to transmit optical signals (light)

• Copper wire cables transmit signals electrically, whereas fiber-optic cables transmit signals by means of light

• More expensive than copper wires, more skill to install

Fiber Optic Cable

• Not susceptible to lightning, electromagnetic interference (EMI), or radio frequency interference (RFI), and does not generate EMI or RFI

• Much greater bandwidth• Greater transmission distances• Excellent signal quality

Fiber Optic Cable

• More secure (difficult to tap)

• Thin, requires little space in a conduit

• Lightweight, easy to install

• Better resistance to environment factors, e.g. water

• Generally used to link LANs, WANs, or as backbone of large networks


• Fibre Optics• Advantages:

– no susceptibility to electrical & magnetic interference– allows electrical isolation between LAN segments– difficult to tap– very high data rates– longer cabling distances

• Disadvantages:– expensive– difficult to install– easy to damage


Fibre Optics cont..• backbone cables typically contain 12 or 24 fibres

– multi-mode and single mode types– diameters:

• Multimode– 62.5 m or 50 m core, 125 m cladding (human hair – 100 m)

• single mode– 8 – 10 m core, 125 m cladding

– multi mode:• signal jitter at far end can occur• easy coupling of the light source to the cable


• bandwidth:• expressed as MHz-km

– e.g.: 200 MHz-km 200 MHz, 1 km, or 100 MHz, 2 km

• connectors:• ST (straight tip) – for 10 BASE FL• SC (subscriber connector) – for 100 BASE FX and

1000 BASE FX• MT-RJ – for 1000 BASE FX – more compact

Cable splicing and fibre termination should be done by specialized people – requires skilled personnel and proper equipment

Fiber Optic Cable

• Fiber Optics Types:– Multi-mode cable

• Less expensive• Less expensive LED transmitters are used• Larger core, multiple angles of entry

– Single-mode cable• More expensive• More expensive laser transmitters are used• Significant longer cabling distances• Skinny core, only one angle of entry

Fiber Optic Cable


Other LAN Media• Infrared

• modulated infrared signals passed through open space

• laser beam• modulated laser beams passed through open space

• Microwave• high frequency radio waves passed by line of sight

transceivers

• Radio• earlier low speeds (9.6 - 230 kbps) - now 2-10 Mbps• used for mobile LAN stations when cabling is not possible

Cabling Topologies

• Linear topology– uses terminators

• Star topology– uses a hub (concentrator or Multi-station

Access Unit (MAU))• star wired bus

– signals passed to all stations as in a bus

• star wired ring– signals passed from one station to the other by the hub

Connectors

• UTP:• RJ-11 (6 pins)• RJ-45 (8 pins)

– pin-outs will differ according to LAN type

• Thin Coaxial(10base2):• BNC (BayoNet Connector)• Terminator 50

• Thick Ethernet (10base5)• Transceiver• Attachment Unit Interface(AUI) < 50

Interfaces

• AUI – Attachment Unit InterfaceMedium independent attachment for 10 Mbps media systems

• MAU – Medium Attachment Unit• MDI – Medium Dependent Interface• MII – Medium Independent Interface• GMII – Gigabit Medium Independent Interface• TBI – Gigabit Ten-Bit Interface

To accommodate 8B/10B signal encoding in Gigabit Ethernet if 1000 BASE X is used

• GBIC – Gigabit Interface ConverterHot swappableMedia signaling components are contained

Interfaces cont…

Hub

DTE

10BASET internal transceiver (MAU)

MDI connector (RJ 45)

DTE

External transceiver (MAU)

AUI cable

Ethernet interface

AUI connector MII (15 pin)

DTE

40 pin MII connector for 100 BASE T

GBIC

2 SC connectors to fibre optic 20 pin connector to

Ethernet port

Cable Types• UTP – 10 BASE T

– Voice grade cabling– RJ-45 jack used– 100m maximum– 300mV signal squelch level (to eliminate cross talk signals)

• but after 100m, due to attenuation, data signals also will go below this

– 100 impedance (in some implementations 120 )0 high

-1 V DC offset

-2 V low

300 mV

300 mV

Cable Types cont…

• 100 BASE T– unshielded or shielded (for Token Ring)

twisted pair– 100m, 100, RJ-45 jack– 40 pin MII connector also may be used with

an external transceiver (not commonly used)– data is scrambled to eliminate electro-

magnetic effects

Cable Types cont…

• 100 BASE FX– 40 pin MII may be used– if transceiver is built-in, fibre optic can be directly

connected– Non-Return-to-Zero, Invert-on-Ones (NRZI) encoding

is used– Peek optical transmission power is 200-400 W for

62.5/125 m fibre– No data scrambling needed– Two strands of multi-mode fibre optics are used for Tx

and Rx

Cable Types cont…

• 1000 BASE T– Gigabit Ethernet twisted pair – defined by 802.3ab– UTP all 4 pairs are used – requires CAT-5 or higher quality cables

• All patch panels also should be of high quality

– Each pair has Tx and Rx wires (total of four Tx and four Rx wires in a cable)• hence total of 8bit at a time• 125 Mbaud achieves 1000 Mbps

– A combination of signaling and encoding is used to achieve the speed– No external transceivers or MIIs available – requires a built in transceiver– Digital Signal Processing (DSP) is used to handle cross talk

• echo cancellation• near end cross talk (NEXT) cancellation• far end cross talk (FEXT) cancellation• signal equalization for distortion compensation

– Auto negotiation possible (10/100/1000 Mbps) if the interface supports that

Cable Types cont…

• 1000 BASE X– Gigabit Ethernet for fibre optic– SX – Short Wave Length

• Most widely used• Less expensive• Short distance• Inside buildings

– LX – Long Wave Length• 500 m• long haul version – 10 km• extended reach version – 70-100 km

– CX – Short Copper Jumper• 25 m maximum• used for linking equipment in computer rooms, racks etc.

Structured Cabling– TIA

• Telecommunications Industry Association

– EIA• Electronics Industries Association

– TIA/EIA 568 A• Commercial Building Telecommunications Cabling Standard

– Aim• To provide a generic vendor independent cabling system to

support both voice and data

– Similar international standard• ISO/IEC 11801:1995

• Generic cabling for customer premises

• (IEC: International Electrotechnical Commission)

What TIA/EIA 568 A specifies

– horizontal cables– backbone cables– interconnection equipment– telecommunication closets (place where hubs,

switches, connectors, etc. are placed)– equipment rooms– cable pathways– uniform administration schemes– grounding practices

Elements of Structured Cabling

Building Entrance Facilities – Cables– surge protection equipment– connecting hardware for linking the cables

inside the building

Elements of Structured Cabling cont…

Equipment Rooms– More complex equipment– Major cable terminations– Grounding equipment


Building Backbone Cabling– Using star topology– Provides connections between

• Telecommunication closets• Equipment rooms• Entrance facilities


Telecommunications Closets– Also called wiring closets– Provides a location for the termination of the

horizontal cabling on a given floor of a building– Mechanical cable terminations and cross connects for

the horizontal and backbone cabling system– Interconnection equipment (Ethernet hubs and

switches etc.)


Horizontal Cabling– Extends from the telecommunications closets

to the communications outlets located in the work area

– Work area outlets and patch panels (used for cable termination) are also included

– Patch cables


Work Area– An office space– Computers and other equipment are located– Telephones and other devices connecting to

the communications outlet on the wall

Structured Cabling Topology

Structured cabling described in TIA/EIA 568 is based on star topology

• Within a building no more than two levels of hierarchy– i.e. the cable should not go through more than one

“Intermediate Cross Connect” (IC) device between the “Main Cross Connect” (MC) and “Horizontal Cross Connect” (HC)

Some Terms

• ER – Equipment Room• HC – Horizontal Cross Connect – located in a

wiring closet. Should be less than 90 m (patch panel cables should be less than 6m)

• IC – Intermediate Cross Connect• MC – Main Cross Connect – terminated in an

equipment room• TC – Telecommunications Closet• WA – Work Area

Advantages of Structured Cabling

• Central wiring hubs make it easy to manage moving, adding, changing, etc.

• Central cabling points provide faster trouble shooting

• Independent point to point links prevent cable problems – does not affect other links

• Easier migration to newer technologies – no or less re-cabling required if hubs, switches, routers etc. upgraded in most cases

• Physical security for central equipment room

Cables used for EIA/TIA 568

• Category 5 – 100 UTP– Up to 100 MHz

• Category 5e (Enhanced category 5)– With enhanced testing– For gigabit Ethernet

• Fibre optic

LAN UTP Cabling Standards

Category

Purpose Comments

1 Telephones Not suitable for data

2 Token Ring Supports 4Mbps Token Ring

3 Telephones and 10BASE-T

4 Token Ring Supports 16Mbps Token Ring

5 Ethernet 10BASE-T and 100BASE-T

5e Ethernet Supports Gigabit Ethernet

6 Ehernet Officially supports 1Gbps, working for 10Gbps support

Ethernet LAN Media and Connectors

Ethernet Types Media Max Segment Length

Connector

10BASE2 50-ohm coax(Thinnet)

185m BNC

10BASE5 50-ohm coax

(Thicknet)

500m Attachment unit interface (AUI)

10BASE-T Cat 3,4,5 UTP

100m RJ45

100BASE-TX Cat 5 UTP 100m RJ45

100BASE-FX 62.5/125 micron multimode fiber

400m Duplex media interface connector (MIC), ST, or SC

1000BASE-T Cat 5 UTP 100m RJ45

UTP Cable Pinouts

• Key concepts– Ethernet devices (at 10 and 100Mbps Ethenet) use

one pair of wires to transmit data– Ethernet devices (at 10 and 100Mbps Ethenet) use

another pair of wires to receive data– Two pairs of wires are required

• Types– Straight-Through Cable– Crossover Cable– Console Connection and Rollover Cable

Straight-Through Cable

• To connect an end-user device and a LAN hub or switch

• PC’s NIC uses– Pin 1, 2 to transmit– Pin 3, 6 to receive

• LAN hubs, switches (the other end)– Pin 3, 6 to transmit– Pin 1, 2 to receive

Straight-Through Cable• TIA/EIA-T568-B or A on BOTH ends of the cable

TIA/EIA 568-A

Crossover Cable

• To connect two devices that both want to send on the same pins (two devices of similar ‘type’, e.g. two PCs)

• BOTH sides use– Pin 1, 2 to transmit– Pin 3, 6 to receive

Crossover Cable• One side is T568-A and T568-B one the other (10BaseT,

100BaseT)• Special arrangement for 1000BaseT

How to create Console cable

• Preparation We should prepare the following two, as well as a Cisco and a

console-terminal.

RJ45-DSub9Pin Cable Changer (In=RJ45 Female, Out=DSub9Pin Female)

• How to connect them

D Sub9 Pin Female

123456789

12345678

RJ 45 Female

How to choose?

• Two groups of devices– PC, router, server, AP (use pins 1 and 2 to transmit)– Switch, hub, bridge, repeater (use pins 3 and 6 to transmit)

• When connecting two devices that are similar in regard to which pins they use to transmit, use a crossover cable– e.g. Switch to Switch, Switch to Hub, Hub to Hub, Router

to Router, PC to PC, Router to PC• When connecting two devices that differ in regard to

which pins they use to transmit, use a straight-through cable– e.g Switch to Router, Switch to PC, Hub to PC

Network Topologies

• The physical or logical arrangement of computers of computers, transmission media, and other components

• Types of network topologies– Bus topology– Ring topology– Star topology– Hybrid topology

Bus Topology

• All nodes are connected in sequence on a single cable

• Used most often on peer-to-peer networks

• Networked computers communicate with each other

• One computer transmits data at a time– Access methods avoid data

collisions– Data is transmitted in

“packets”

Ring Topology

• Nodes are laid out in a ring

• Token (data packet) flows in one direction from device to device

Star Topology

• Nodes connect to a central communications device (switch)

• A node sends a signal to the switch, which retransmits it to the other nodes

• A node accepts only signal addressed to it

LAN Equipment

• Repeaters/Hubs:– At Physical layer– Ethernet can be extended using repeaters– 10baseT concentrator is a multi port repeater– amplifies the signal and increase the overall distance –

restores the amplitude of the signal– restores signal symmetry– re-timing can be done– can be used for dissimilar media– 7 hops maximum– different LANs cannot be converted – no protocol conversion

LAN Equipment cont…

• Bridges/Switches:– Operates at Data-link layer or MAC layer– Multiple LANs can be connected– Can connect similar LANs with dissimilar media– Can link LANs of different speeds– Passes Packets to the other segment only if

addressed to a node in that segment– Builds an address data base dynamically (a table with port –

address combinations) and use this to filter traffic– Hence collision domains are extended only if required

– Management software could be used to manage the switches

LAN Equipment cont…

• Routers:– At Network layer– Can connect dissimilar LANs on the same protocol– Some routers have support for may protocols and

protocol conversion– Can build large complex networks with complex traffic

routing– Limits the flow of broadcasts– Load sharing and balancing can be done– Complex features as Network Address Translation

(NAT), authentication, firewalling, etc. possible

Classifications of Networks• Local area network (LAN):

– Nodes are within a small geographic region:• Homes• Schools• Small businesses

• Wide area network (WAN):– LANs connected over long distances:

• Computers linked over large geographic locations (few miles to thousands of miles

• Use telecommunications lines

• Metropolitan area network (MAN)– Metropolitan area network– Computers linked together within a city or county

• Personal area network (PAN)– Wireless devices connected in close proximity to each other

• Intranet– Private corporate network, not accessible to non-employees– Protected by a firewall

Introduction to WAN

• Connect devices separated by wide geographical areas

• Use services or RBOCs (Regional Bell Operation Co.), Sprint,MCI, etc.

• Uses various types of serial connections

• Companies use a WAN to connect sites so that information can be exchanged between distant offices.

WAN devices• routers – provides WAN interface ports

• switches - provide connectivity for voice, data, and video communication

• modems - interface voice-grade services – CSU/DSUs that interface T1/E1 services– TA/NT1s (ISDN modem) that interface ISDN services

• communication servers – dial-in and dial-out user communication– manages the dial-up– log-on authentication

Routers in a WAN• Computers have four basic components:

– CPU

– Memory

– Interfaces

– Bus

• A router also has these components;

therefore it can be referred to as a computer• Routers need the Internetworking Operating

Software (IOS) to run configuration files just like a computer needs an OS to run software applications

Router components

RAM• RAM, or dynamic RAM (DRAM) is usually

logically divided into main processor memory and shared input/output (I/O) memory– Stores routing tables – Holds ARP cache – Holds fast-switching cache – Performs packet buffering (shared I/O memory)– Maintains packet-hold queues – Provides temporary memory for the configuration file

of the router while the router is powered on – Loses content when router is powered down – Can be upgraded by adding Dual In-Line Memory

Modules (DIMMs)

NVRAM and Flash• NVRAM

– Store backup/startup config file– Retains contents when powered down or restarted.

• Flash– Erasable programmable ROM (EPROM)– Upgraded with Single In-Line Memory Modules

(SIMMs) or Flash Cards (PCMCIA) without removing chips on board

– Multiple versions of IOS can be stored in the flash– Contents remain when powered down – In most routers the IOS is transferred to RAM during

the boot process. In others the IOS may be run directly from flash

ROM and Interfaces

• ROM– Maintains instructions for POST– Stores bootstrap program and basic IOS.– Software upgrades in ROM require replacing chips on

the CPU– Stores a scaled down version of the IOS

• Interfaces – Network connections through which packets enter

and exit– Located on motherboard or on a separate module

Bus

• Buses – Most routers contain a system bus and a CPU bus. – The system bus transfers packets between

the CPU and interfaces. – The CPU bus transfers instructions and data

between the CPU and specified memory addresses

Segmentation with Routers

• Can be used to segments LANs, but generally used as a WAN device

• Routers have both LAN and WAN interfaces• Routers are the backbone devices of large

intranets and of the Internet • A correctly configured internetwork

provides: – Consistent end-to-end addressing – Addresses that represent network topologies – Best path selection – Dynamic or static routing – Switching

Router role in a WAN

• WANs operate at the Physical and Data Link layers

• The standards and protocols used in WANs at Layer 1 and 2 are different from those used in LANs at the same layers

• Data link layer protocols describe how frames are carried between systems on a single data link

• Physical layer describes the interface between the DTE and the DCE

WAN Layer 1 and 2 Protocols

HDLC, PPP, Frame Relay, SDLC, SLIP, X.25, ATM, LAPB, LAPD, LAPF

EIA/TIA-232, EIA/TIA-449, V.24, V.35, X.21, G.703, EIA-530, ISDN, T1, T3, E1, E3, xDSL, SONET (OC-3, OC-12, OC-48, OC-192)

Lab Setup• Unlike the lab setup, the serial cables in the

real world are not connected back to back• In the lab, devices that make up the WAN

cloud are simulated by the connection between the back-to-back DTE-DCE cables.

Ports• 3 types of interfaces

– LAN-• Ethernet,Token Ring or FDDI

– WAN-• Serial, ISDN, and integrated Channel Service Unit

(CSU)

– Management-• Console and Aux port

• EIA-232 asynchronous serial ports connects to the computers COM port

• Computers must use a terminal emulation program that provides a text-based session with the router

• DB9-RJ45 connector and a rollover cable

• not designed as networking ports

Management port connections

•Recommended for initial configuration •Displays router startup, debugging, and error messages by default •Used for password recovery procedures

Connecting Console Interfaces

1. Configure terminal emulation software on the PC for: – The appropriate com port – 9600 baud – 8 data bits – No parity – 1 stop bit – No flow control

2. Connect the RJ-45 connector of the rollover cable to the router console port.

3. Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter.

4. Attach the female DB-9 adapter to a PC

Connecting LAN interfaces

• A router is a host that communicates with the LAN via a hub or a switch using a straight through cable

• The router is connected to the LAN using an Ethernet or Fast Ethernet interface

• A 10/100BaseTX router interface requires UTP, Cat 5 or better cable

Connecting WAN interfaces

• The customer premises equipment (CPE) is often a router and is the data terminal equipment (DTE)

• The DTE is connected to the service provider using a data circuit-terminating equipment (DCE) device, commonly a modem or channel service unit/data service unit (CSU/DSU).

• The DCE is used to convert the data from the DTE into a form acceptable to the WAN service provider.

Connecting WAN interfaces

IP Addressing

IPv4 Addressing Overview

Internet address’s architecture Classes of IP addresses Subnet mask

IP Address

An IP address is a 32-bit sequence of 1s and 0s.To make the IP address easier to use, the address is usually

written as four decimal numbers separated by periods. This way of writing the address is called the dotted decimal

format.

IP Address

Every IP address has two parts: NetworkHost

The Class D address class was created to enable multicasting.

IETF reserves Class E addresses for its own research.

Address Classes(32 Bit Address 232 = 4.2 billion possible addresses)

• There are 5 different address classes.

• Only 3 are in commercial use at this time.

• You can determine the class of the address by looking at the first 4 bits of the IP address:

– Class A begin with 0xxx, or 1 to 126 decimal– Class B begin with 10xx, or 128 to 191 decimal– Class C begin with 110x, or 192 to 223 decimal– Class D begin with 1110, or 224 to 239 decimal– Class E begin with 1111, or 240 to 254 decimal

IP Address

Reserved IP AddressesCertain host addresses

are reserved and cannot be assigned to devices on a network.

An IP address that has binary 0s in all host bit positions is reserved for the network address.

An IP address that has binary 1s in all host bit positions is reserved for the broadcast address.

IP Private AddressesNo two machines that connect to a public

network can have the same IP address because public IP addresses are global and standardized

Private IP addresses are a solution to the problem of the exhaustion of public IP addresses. Addresses that fall within these ranges are not routed on the Internet backbone:• Connecting a network using private addresses to the Internet requires the usage of NAT

Subnet Mask Address

A subnet mask allows you to identify which part of an IP address is reserved for the network, and which part is available for host are.

In summary, knowing the subnet mask can allow you to easily calculate whether IP addresses are on the same subnet, or not using bitwise AND gate (A Boolean operator that returns a value of TRUE if both its operands are TRUE, and FALSE otherwise)

.

Default Subnet Masks

Class A - 255.0.0.011111111.00000000.00000000.00000000

Class B - 255.255.0.011111111.11111111.00000000.00000000

Class C - 255.255.255.011111111.11111111.11111111.00000000

Establishing the Subnet Mask Address

To determine the number of bits to be used, the network designer needs to calculate how many hosts the largest subnetwork requires and the number of subnetworks needed.

Subnetting

• Subnetting an IP network can be done for various reasons including:

– Organization– Use of different physical media– Preservation of address space– Security– Control network traffic

Subnetting

• Subnetting is a way of taking an existing class license and breaking it down to create more Network Addresses.

• This will always reduce the number of host addresses for a given network.

• Subnetting makes more efficient use of the address or addresses assigned to you.

How Does Subnetting Work?

• Additional bits can be added (changed from 0 to 1) to the subnet mask to further subnet, or breakdown, a network.

• When the logical AND is done by the computer, the result will give it a new Network (or Subnet) Address.

• Remember, an address of all “0”s or all “1”s cannot be used in the last octet (or host portion). All “0”s signify the Network Address and all “1”s signify the broadcast address

Network Security

• Authentication– User ID and password used to access the network

• Access privileges– Enable access to certain network systems

• Physical protection measures– Restrict physical access to sensitive network

equipment– Magnetic card readers– Biometric access devices

• Firewalls– Prevent access to the network by unauthorized users– Composed of software and/or hardware– Screen and validate data packets– Bastion host/proxy server

Network Firewall Layout

Computer Threats

• Cyber-crimes are criminal acts conducted through the use of computers by Cyber-criminals.

• Cyber criminals are individuals who use computers, networks, and the Internet to perpetrate crime.

• The existence of cyber crime means that computer users must take precautions to protect themselves

Hackers • Anyone who unlawfully accesses a computer system• Types of hackers:

– White-hat, hackers who break into systems just for the challenge of it

– Black-hat, hackers who use their knowledge to destroy information or for illegal gain

– Script kiddies use tools created by skilled hackers

What Hackers Do

• Steal information from computers:– Credit card numbers– Bank account numbers

• Internet packet sniffing• Commit identity theft

Denial of Service Attacks

• Backdoor programs – Trojan horse, allow hackers to take almost complete

control of your computer without your knowledge– Zombies

• Denial of service attacks (DoS)

How Hackers Gain Access

• Direct access:– Hacking software

• Indirect access:– Internet connection– Logical ports

Computer Safeguards Firewalls

• Software programs or hardware designed to close logical ports to invaders– A firewall is built into Windows XP– More robust firewalls are available from other

vendors.– Firewalls are critical if you

have an always-on broadband connection.

Computer Threat - Viruses

• A program that attaches itself to another program and spreads itself to other computers

• Viruses are hidden within the code of a host program

• Replicate themselves:– Slow down networks

• Secondary objectives:– Annoying messages– Delete files on the hard drive– Change computer settings

How Does a Computer Catch a Virus

• Viruses copy themselves • Infect a file on your computer• Viruses spread by sharing disks• E-mail attachments are the most likely source of a virus

Types of Viruses

• Boot-sector viruses:– Replicate themselves in the boot sector of the hard drive

• Logic bombs:– Activate when certain conditions are met

• Time bombs:– are viruses that are triggered by the passage of time or

on a certain date.

• Worms:– Travel between systems through networks

Types of Viruses

• Script viruses:– Hidden on Web pages– Mini programs

• Macro viruses:– Attached to documents– Series of commands

• Trojan horses:– Backdoor programs– Control remote computers

Virus Classifications

• Polymorphic viruses:– Periodically rewrite themselves to avoid

detection

• Multipartite viruses:– Infect multiple file types

• Stealth viruses:– Erase their code from the hard drive and

reside in the active memory

Antivirus Software

• Programs designed to detect viruses:– Scan files looking for virus signatures (unique code)– Provides options for deleting or fixing infected files

• Detect known viruses• Antivirus programs need to be updated frequently

Lease Line Looping System

NIC JaipurDDF,Jaipur

NTR, Jaipur

District NICMODEM

NTR, DistrictExchangeMODEM

District NICRouter

BSNLExchange

District NICSwitch

FIBER COPPERFIBER

V 35 Blue Cable

COPPER

Video Conferencing

VC Over IP Network

Distance < 100mSwitch Switch

IP Address: 172.16.1.2/16Gateway: 172.16.1.1

IP Address: 172.16.2.2/16Gateway: 172.16.1.1

NIC VC over Lease Line Network

NIC – (District Centres) Kota, Bikaner, etc.

MCU

NIC, Delhi

NIC Jaipur

Switch

Users

NIC , Jaipur

NIC-District Router Router

Lease LineLease Line

Lease Line

ISDN BRI Line

Switch

NTU/V.35NTU/V.35

E1/G.703 E1/G.703

NT1

NT1

ISDN PRI Line

BSNL Network

ISDN VC Network

Jaipur

ISDNNetwrok

ISDN BRI Line

NT1 NT1

ISDN BRI Line

ISDN BRI Line

NT1

Jodhpur

Kota

Features Phone

Features Phone

Troubleshooting of VC

PING

VC Set Top Box IP

VC Gateway

NICNET Gateway Status of Switch/ Router/ MODEM BSNL NICNET iNOC


Cables

Audio Video Cable (Color Coding)

LAN Cable

UTP Cable (Rx & Tx Pair)

Straight & Cross Cable

ISDN Cable (Rx & Tx Pair) MIC


POWER Supply

220 VC

N. E. L.

N-E Voltage: 2 Volt Voltage of ISDN line will be 96 Volt DC. Voltage of PSTN line will be 48 Volt DC.


• ISDN problems.Check the power of NT box, voltage of ISDN line it will be 96 Volt DC. If both are ok then contact to BSNL.

• In case of Audio problems, check the volume level in TV as well as VC system and Mic.

• In case of Video problems, check the AV selection in the TV, ISDN line.

System Maintenance and Troubleshooting

Network Troubleshooting

Troubleshooting Windows Startup

Problems

Repairing Internet Explorer 6

Troubleshooting MS Outlook

Network Troubleshooting

We will learn how to troubleshoot basic network related problems

UN IT

ONE

Troubleshooting Windows Networks

Determine the TCP/IP Settings: In XP, open the Network

Connections folder, right click the LAN connection, and click

Status | Support | Details.


Description of TCP/IP Settings:

Here are the TCP/IP settings that are used in network

troubleshooting:

IP Address:

Unique address assigned to a network adapter. A computer with multiple network adapters has an IP address for each one, and each one must be in a different subnet.

Subnet Mask:

Used in conjunction with the IP address to determine which subnet an adapter belongs to. At the simplest level, communication is only possible between two network adapters when they’re in the same subnet.


Default Gateway:

IP address of a computer or router, on one of this computer’s local area networks, that knows how to communicate with subnets not present on this computer. For an Internet connection, the default gateway is a router belonging to your Internet service provider, and all access to sites on the Internet goes through it. For an ICS client, the default gateway is the ICS host. If you use a hardware router, it serves as the default gateway.

DHCP Server:

If an adapter is configured to obtain an IP address automatically, this is the address of the server that provides it. It could be your ISP, an ICS host, or a hardware router.

DNS Servers – IP address of one or more Domain Name Server computers. DNS servers translate Internet names (like 3i-infotech.com) to their IP addresses (like 63.146.109.227).

Pinging:

Troubleshooting Windows NetworksTroubleshooting Windows Networks


The ping command is the basic tool for testing TCP/IP connectivity. It sends a special packet (called ICMP Echo) to a particular IP address and looks for a reply. If everything is working right, the reply comes back. If not, the ping times out in a few seconds. By default, the ping command repeats the process four times. Here’s an example of an ICS client computer pinging a Windows XP Home Edition ICS host, using the host’s IP address and its computer name.


When ping fails, you’ll see one of these error messages:

Request timed out :

The IP address is valid, but there’s no reply from it. If the IP

address is on a local area network, the most likely cause is a

firewall program blocking the ping.

Unknown host <name> or Ping request could not find host <name>:

The computer name doesn’t exist on the local area network. Make

sure that NetBIOS over TCP/IP is enabled.

Destination host unreachable:

The IP address isn’t on a local area network, and the default

gateway can’t access it. Either there’s no default gateway, its

address is wrong, or it isn’t functioning.

http://www.practicallynetworked.com/sharing/troubleshoot/netbt.htm


Command Target What Ping Failure Indicates

ping 127.0.0.1 Loopback address

Corrupted TCP/IP installation

ping localhost Loopback name Corrupted TCP/IP installation

ping 192.168.1.101

This computer’s IP address


ping winxp This computer’s name


ping 192.168.1.123

Another computer’s IP address

Bad hardware or NIC driver

Series of ping commands to use in finding where a problem occurs on a local area network

Troubleshooting Windows NetworksCommand Target What Ping

Failure Indicates

ping w.x.y.z Default Gateway

Default Gateway down

ping w.x.y.z DNS Server DNS Server down

ping w.x.y.z Web site IP address

Internet service provider or web site down

ping www.something.com

Web site name

DNS Server down or web site down

Network troubleshooting methodology

OSI model

The basis of each of troubleshooting approaches is the

Seven-Layer OSI Reference Model:

Layer 1: Physical

Layer 2: Data Link

Layer 3: Network

Layer 4: Transport

Layer 5: Session

Layer 6: Presentation

Layer 7: Application

http://techrepublic.com.com/5100-1035_11-1039788.html

Network troubleshooting methodologyBottom-up Approach:

The bottom-up approach as the name implies, start at the

bottom—Layer 1, the physical layer—and work your way up to

the top layer (application). The physical layer includes the network

cable and the network interface card. So if you encounter a

broken or disconnected network cable, there's probably no need

to do anymore troubleshooting. You must resolve any physical

layer problems before moving on. After fixing the problem, check

to see if the trouble still exists. If so, move on to troubleshooting

the data link layer

Network troubleshooting methodology

Top-down

Once again, the name of this methodology implies the approach.

With the top-down method, start at the top of the OSI model (i.e.,

the application layer) and work your way down to the bottom

layer (i.e., physical).

Divide and conquer

This approach involves a little more intuition. With the divide and

conquer method, start at whichever layer you best feel is the root

cause of the problem. From there, you can go either up or down

through the layers.

Network troubleshooting methodologyChoosing an approach

Which approach you decide to use may depend on where you

believe the problem lies. For example, if a user is unable to

browse the Web and you think most users have a lot of problems

with spyware and Internet Explorer settings, then you may want to

start with the top-down approach. On the other hand, if the user

mentions that he or she just connected a laptop to the network and

can't browse the Web, you might want to use the bottom-up

method since there's a good chance the user has a disconnected

cable or similar problem.

Troubleshooting Startup Problems

We will learn how to resolve common startup problems associated with booting Windows XP and Windows Server 2003 systems.


Windows may fail to start for a variety of reasons, and generally

speaking in order of decreasing likelihood here they are:

Hardware failure Bad driver Corrupt file or volume System misconfiguration Virus infection


Common error Messages & Probable Causes:

Symptom Probable Cause

"Invalid Partition Table"

"Missing Operating System"

Master boot record is corrupt due to hard disk errors or virus infection

“NTLDR is missing"

"A disk read error occurred"

System hangs after BIOS POST finishes

Boot sector is corrupt due to hard disk errors or virus infection

“Windows could not start because of a computer”

“disk hardware configuration problem"

"Could not read from selected boot disk"

"Check boot path and disk hardware “

Boot.ini file is corrupt, missing, or needs updating

"Windows could not start because the following file is missing or corrupt”

Boot volume is corrupt or the referenced system file is missing.


In addition to these error messages, a variety of other startup

problems can occur including:

Blue screens:

These are typically caused by hardware failure or driver problems

but can also be due to virus infection.

Hung system:

These are typically caused by buggy drivers or by registry

corruption but can also be due to virus infection.

Dialog box saying "One or more services failed to start”:

This is typically caused by misconfiguration or registry corruption

but can also be caused by application incompatibility of some

form.


How to resolve startup problems:

Last known good Configuration Option:

Restores the HKLM\System\CurrentControlSet portion of the

registry its version during the last successful logon to the system.

Safe mode: Starts Windows with a minimal set of drivers and

creates a record of which drivers load in %windir%\Ntbtlog.txt.

System Restore: Windows XP only feature to restore system to

previously saved configuration.

Recovery Console: Boots to a command line that allows you to

run various commands.

Troubleshooting Startup ProblemsHow to resolve startup problems:

Automated System Recovery (ASR):

Restores the boot volume from backup.

Repair:

Run Windows Setup from your product CD and select the option to

try and repair your installation


Problem Resolution Table:

Problem/Symptom Tool's) to Use

Corrupt master boot record

Corrupt boot sector

Recovery Console (fixmbr)

Corrupt or missing boot.ini Recovery Console (bootcfg /rebuild)

Corrupt system file Recovery Console (chkdsk)Restore from ASR backupPerform a Repair install

Corrupt registry Recovery Console (chkdsk)System Restore (XP only)Restore system state from backupPerform a Repair install


Problem Resolution Table:

Problem/Symptom Tool's) to Use

Blue screen Last known goodSystem Restore (XP only)Safe mode (roll back suspect driver using Device Manager)

Hung system Last known goodSystem Restore (XP only)Safe mode (roll back suspect driver using Device Manager)

"One or more services failed to start" Don't logon! Reboot and select last known good, log on, undo the last configuration steps you performed.Safe mode (undo last configuration steps you performed)

Repairing Internet Explorer 6

We will learn how to reinstall or to repair Internet Explorer 6 in Windows XP, We may have to do this if we have problems with Internet Explorer because of damaged files or missing registration information. In some cases, the steps to reinstall or to repair Internet Explorer 6 will also resolve problems in Microsoft Outlook Express

UN IT

THREE

Repairing Internet Explorer 6Methods to follow:

Method 1: Install Internet Explorer 7:

We may be able to resolve problems with Internet Explorer 6 if

we install Internet Explorer 7. Installing Internet Explorer 7

probably will not resolve problems with Outlook Express.

Method 2: Install Windows XP Service Pack 2:

If you do not want to install Internet Explorer 7, or for some reason

cannot do so, you may be able to resolve problems with Internet

Explorer 6 by installing Windows XP Service Pack 2. Additionally,

installing Windows XP Service Pack 2 may help resolve issues

with-Outlook-Express.


Method 3: Repair Internet Explorer 6 by using the System File

Checker in Windows XP:

If you already have Windows XP Service Pack 2 installed, and you

do not want to install Internet Explorer 7, you may be able to

resolve problems with Internet Explorer 6 by running the System

File Checker.

To run the System File Checker, follow these steps:

1.Click Start, click Run type sfc /scannow, and then press ENTER

2.Follow the prompts throughout the System File Checker process.

3.Restart the computer when System File Checker process is complete


Method 4: Reinstall Internet Explorer 6 by using the ie.inf file:

If you already have Windows XP Service Pack 2 installed, and you

do not want to install Internet Explorer 7, you may be able to

resolve problems with Internet Explorer 6 by using the ie.inf file to

reinstall Internet Explorer 6. To do this, follow these steps:

1.Click Start, click Run, type %systemroot%\inf, and then press Enter.

2.Find the Ie.inf file that is located in Windows\Inf folder.

3.Right-click the ie.inf file, and then click Install.

4.Restart the computer when the file copy process is complete.

Repairing Internet Explorer 6Method to follow if you have Internet Explorer 7:

If you have Internet Explorer 7, you can repair damaged files

or missing registration information in Internet Explorer 7. To

do this, follow these steps:

1.Start Internet Explorer 7.

2.On the Tools menu, click Internet Options.

3.On the Advanced tab, click Reset.

4.In the Rest Internet Explorer Settings dialog box,

click Reset to confirm.

Troubleshooting Ms Outlook Express

We will learn how to troubleshoot error messages when we send and receive e-mails.

We may receive an error message that is similar to one of the

following: “ No connection could be made because the target machine actively refused it”

“The server could not be found. (Account:account name, POPserver:'mail', Error

Number: 0x800ccc0d)”

“Task 'server name - Sending and Receiving' reported error (0x800ccc0f): 'The

connection to the server, was interrupted. If this problem continues, contact the

server administrator or Internet service provider (ISP)”

“Your server has unexpectedly terminated the connection. Possible causes of this include server problems, network problems, or a long period of inactivity.

Account. account name, Server: 'server name', Protocol: POP3, Server

Response: '+OK', Port: 110, Secure(SSL): No, Error Number: 0x800ccc0f”

“Task 'SMTP server name - Sending and Receiving' reported error (0x80042109):

'Outlook is unable to connect to your outgoing (SMTP) e-mail server. If you

continue to receive this message, contact the server administrator or Internet

service provider (ISP).”



You may also receive an error message that includes one or more of the following error codes:

*0x800ccc15

*0x80042108

*0x800ccc0e

*0x8004210b

*0x800ccc0b

*0x800ccc67


CAUSES:

These error messages are frequently caused by one of the

following:

You are not connected to the Internet or a Network

Incorrect account settings

Your user profile in Outlook is damaged

An e-mail item on your POP3 server is damaged

Incorrect configuration of your AV software

Outlook Express has been removed from the computer or the installation is damaged

Incorrect configuration of personal firewall software


Resolution:

The most common causes of these error messages are problems

with Internet connectivity and incorrectly configured account

settings in Outlook or Outlook Express.

Step 1: Verify that you are connected to the Internet.

Step 2: Verify your account settings


Advanced Troubleshooting

Method 1: Start Outlook in safe mode

1.Click Start, and then click Run.

2.In the Open box, type outlook.exe /safe , and then click OK.

Starting Outlook in safe mode starts Outlook without extensions, the

preview pane, or toolbar customizations and could indicate a

damaged profile or conflicting third-party application or add-in.

Method 2: Create a new e-mail profile

We may be able to resolve these problems by creating a new e-

mail profile. For more information about how to create profiles in

Outlook,



Method 3: Delete suspicious messages from your mailbox

If there is a damaged message in your mailbox, we can resolve

this by doing one of the following: Contact your ISP and ask them to delete any suspicious e-

mail. Delete any suspicious e-mail by accessing your mailbox by

using your ISP's Web-based e-mail program.

Method 4: Check your antivirus vendor's Web site for additional

suggestions

If your antivirus solution includes an e-mail scanning feature, you

May have to do additional configuration to use Outlook or Outlook

Express with the antivirus e-mail scanning feature.



Method 5: Remove and then reinstall Outlook Express:

If Outlook Express has been removed from your computer or the

installation of Outlook Express is damaged, Outlook will not

function correctly and may generate one of the error messages

that are mentioned in the "Symptoms" section. To resolve this

problem, reinstall Outlook Express.

Method 6: Verify that all SMTP e-mail addresses in a distribution list

Are Valid:

If one SMTP address in a distribution list is corrupted or incorrectly

formed, error 0x8004210b can occur



Method 5: Remove and then reinstall Outlook Express:

If Outlook Express has been removed from your computer or the

installation of Outlook Express is damaged, Outlook will not

function correctly and may generate one of the error messages

that are mentioned in the "Symptoms" section. To resolve this

problem, reinstall Outlook Express.

Method 6: Verify that all SMTP e-mail addresses in a distribution list

Are Valid:

If one SMTP address in a distribution list is corrupted or incorrectly

formed, error 0x8004210b can occur .

Method 7: Examine the configuration of your firewall software

THANK YOU

3i infotech

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