GSM AND CCNA

MID TRAINING REPORT

ON

GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS

DEPARTMENT OF

ELECTRONICS & COMMUNUCATION ENGINEERING

SUBMITTED BY

ARVIND GOSWAMI

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Rayat-Bahra Institute of Engineering & Nano Technology Hoshiarpur2011-12

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Acknowledgment

I have taken efforts in this project. However, it would not have been possible without the kind support and help of many individuals and organizations. I would like to extend my sincere thanks to all of them.

I am highly indebted to Mr. Sandeep Rana for their guidance and constant supervision as well as for providing necessary information regarding the project & also for their support in completing the project.

I would like to express my gratitude towards my parents & member of RELIANCE COMMUNICATIONS for their kind co-operation and encouragement which help me in completion of this project.

I would like to express my special gratitude and thanks to industry persons for giving me such attention and time.

My thanks and appreciations also go to my colleague in developing the project and people who have willingly helped me out with their abilities

I also extend thanks to all other faculty members of Rayat Bahra Institute of Engineering And Nanotechnology, Hoshiarpur for their support and guidance.

Arvind Goswami

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Contents

GLOBAL SYSTEM FOR MOBILE COMMUNICATION

Introduction to GSM. GSM Carrier Frequency. Network Structure. SIM (Subscriber Identity Module). Phone Locking. Mobile Station. BTS (Base Transceiver Station). BSC (Base Station Controller). MSC (Mobile Service Switching Centre). HLR VLR Advantages & Disadvantages of GSM.

INTRODUCTION TO CCNA

Network Layers. Network Devices. IP Addresses. Subnetting And Submask. IP Routing. Ethernet Cabling.

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Introduction

Reliance Group, an offshoot of the Group founded by Shri Dhirubhai H Ambani (1932-2002), ranks among India’s top three private sector business houses in terms of net worth. The group has business interests that range from telecommunications (Reliance Communications Limited) to financial services (Reliance Capital Ltd) and the generation and distribution of power (Reliance Infrastructure Limited).

Reliance Group’s flagship company, Reliance Communications, is India's largest private sector information and communications company, with over 100 million subscribers. It has established a pan-India, high-capacity, integrated (wireless and wireline), convergent (voice, data and video) digital network, to offer services spanning the entire infocomm value chain.

The late Dhirubhai Ambani dreamt of a digital India — an India where the common man would have access to affordable means of information and communication. Dhirubhai, who single-handedly built India’s largest private sector company virtually from scratch, had stated as early as 1999: “Make the tools of information and communication available to people at an affordable cost. They will overcome the handicaps of illiteracy and lack of mobility.”

It was with this belief in mind that Reliance Communications (formerly Reliance Infocomm) started laying 60,000 route kilometres of a pan-India fibre optic backbone. This backbone was commissioned on 28 December 2002, the auspicious occasion of Dhirubhai’s 70th birthday, though sadly after his unexpected demise on 6 July 2002.Reliance Communications has a reliable, high-capacity, integrated (both wireless and wireline) and convergent (voice, data and video) digital network. It is capable of delivering a range of services spanning the entire infocomm (information and communication) value chain, including infrastructure and services — for enterprises as well as individuals, applications, and consulting.

Today, Reliance Communications is revolutionising the way India communicates and networks, truly bringing about a new way of life.

Other major group companies — Reliance Capital and Reliance Infrastructure — are widely acknowledged as the market leaders in their respective areas of operation.

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GSM INTRODUCTION

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (or "2G") digital cellular networks. Developed as a replacement for first generation analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS. Packet data transmission speeds were later increased via EDGE. The GSM standard is succeeded by the third generation (or "3G") UMTS standard developed by the 3GPP. GSM networks will evolve further as they begin to incorporate fourth generation (or "4G") LTE Advanced standards. "GSM" is a trademark owned by the GSM Association.

Technical details

Fig: GSM cell site antennas

GSM is a cellular network, which means that mobile phones connect to it by searching for cells in the immediate vicinity. There are five different cell sizes in a GSM network—macro, micro, pico, femto and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level; they are typically used in urban areas. Picocells are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors. Femtocells are cells designed for use in residential or small business environments and connect to the service provider’s network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.

Cell horizontal radius varies depending on antenna height, antenna gain and propagation conditions from a couple of hundred metres to several tens of kilometres. The longest distance the GSM specification supports in practical use is 35 kilometres (22 mi). There are also several implementations of the concept of an extended cell, where the cell radius could be double or even more, depending on the antenna system, the type of terrain and the timing advance.

Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station, or an indoor repeater with distributed indoor antennas fed through power splitters, to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors; for example, in shopping centers or airports. However, this is

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not a prerequisite, since indoor coverage is also provided by in-building penetration of the radio signals from any nearby cell.

The modulation used in GSM is Gaussian minimum-shift keying (GMSK), a kind of continuous-phase frequency shift keying. In GMSK, the signal to be modulated onto the carrier is first smoothened with a Gaussian low-pass filter prior to being fed to a frequency modulator, which greatly reduces the interference to neighboring channels (adjacent-channel interference).

GSM carrier frequencies

GSM networks operate in a number of different carrier frequency ranges (separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the 850 MHz and 1900 MHz bands were used instead (for example in Canada and the United States). In rare cases the 400 and 450 MHz frequency bands are assigned in some countries because they were previously used for first-generation systems.

Most 3G networks in Europe operate in the 2100 MHz frequency band.

Regardless of the frequency selected by an operator, it is divided into timeslots for individual phones to use. This allows eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615 ms.

The transmission power in the handset is limited to a maximum of 2 watts in GSM850/900 and 1 watt in GSM1800/1900.

Voice codecs

GSM has used a variety of voice codecs to squeeze 3.1 kHz audio into between 5.6 and 13 kbit/s. Originally, two codecs, named after the types of data channel they were allocated, were used, called Half Rate (5.6 kbit/s) and Full Rate (13 kbit/s). These used a system based upon linear predictive coding (LPC). In addition to being efficient with bitrates, these codecs also made it easier to identify more important parts of the audio, allowing the air interface layer to prioritize and better protect these parts of the signal.

GSM was further enhanced in 1997 with the Enhanced Full Rate (EFR) codec, a 12.2 kbit/s codec that uses a full rate channel. Finally, with the development of UMTS, EFR was refactored into a variable-rate codec called AMR-Narrowband, which is high quality and robust against interference when used on full rate channels, and less robust but still relatively high quality when used in good radio conditions on half-rate channels.

Network structure

Fig: The structure of a GSM network.

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The network is structured into a number of discrete sections:

The Base Station Subsystem (the base stations and their controllers). The Network and Switching Subsystem (the part of the network most similar to a fixed network). This is

sometimes also just called the core network. The GPRS Core Network (the optional part which allows packet based Internet connections). The Operations support system (OSS) for maintenance of the network.

Subscriber Identity Module (SIM)

One of the key features of GSM is the Subscriber Identity Module, commonly known as a SIM card. The SIM is a detachable smart card containing the user's subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this practice is known as SIM locking.

Phone locking

Sometimes mobile network operators restrict handsets that they sell for use with their own network. This is called locking and is implemented by a software feature of the phone. Because the purchase price of the mobile phone to the consumer may be subsidized with revenue from subscriptions, operators must recoup this investment before a subscriber terminates service. A subscriber may usually contact the provider to remove the lock for a fee, utilize private services to remove the lock, or make use of free or fee-based software and websites to unlock the handset themselves.

In some countries (e.g., Lebanon, Bangladesh, Hong Kong, India, Malaysia, Pakistan, Singapore) all phones are sold unlocked. In others (e.g., Finland, Singapore) it is unlawful for operators to offer any form of subsidy on a phone's price.

GSM service security

GSM was designed with a moderate level of service security. The system was designed to authenticate the subscriber using a pre-shared key and challenge-response. Communications between the subscriber and the base station can be encrypted. The development of UMTS introduces an optional Universal Subscriber Identity Module (USIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user – whereas GSM only authenticates the user to the network (and not vice versa). The security model therefore offers confidentiality and authentication, but limited authorization capabilities, and no non-repudiation.

GSM uses several cryptographic algorithms for security. The A5/1 and A5/2 stream ciphers are used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. Serious weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time with a ciphertext-only attack, and in February 2008, Pico Computing, Inc revealed its ability and plans to commercialize FPGAs that allow A5/1 to be broken with a rainbow table attack. The system supports multiple algorithms so operators may replace that cipher with a stronger one.

On 28 December 2009 German computer engineer Karsten Nohl announced that he had cracked the A5/1 cipher. According to Nohl, he developed a number of rainbow tables (static values which reduce the time needed to carry out an attack) and have found new sources for known plaintext attacks. He also said that it is possible to build "a full GSM interceptor ... from open source components" but that they had not done so because of legal concerns.

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New attacks have been observed that take advantage of poor security implementations, architecture and development for smart phone applications. Some wiretapping and eavesdropping techniques hijack the audio input and output providing an opportunity for a 3rd party to listen in to the conversation. At present such attacks often come in the form of a Trojan, malware or a virus and might be detected by security software.

GSM uses General Packet Radio Service (GPRS) for data transmissions like browsing the web. The most commonly deployed GPRS and EDGE ciphers were publicly broken in 2011, and the evidence indicates that they were once again intentionally left weak by the mobile industry designers.

The researchers revealed flaws in the commonly used GEA/1 and GEA/2 ciphers and published the open source "gprsdecode" software for sniffing GPRS/EDGE networks. They also noted that some carriers don't encrypt the data at all (i.e. using GEA/0) in order to detect the use of traffic or protocols they don't like, e.g. Skype, leaving their customers unprotected. GEA/3 seems to remain relatively hard to break and is said to be in use on some more modern networks. If used with USIM to prevent connections to fake base stations and downgrade attacks, users will be protected in the medium term, though migration to 128-bit GEA/4 is still recommended.

But since GEA/0, GEA/1 and GEA/2 are widely deployed, applications should use SSL/TLS for sensitive data, as they would on wi-fi networks.

Standards information

The GSM systems and services are described in a set of standards governed by ETSI, where a full list is maintained.

GSM open-source software

Several open-source software projects exist that provide certain GSM features:

GSMD daemon by Openmoko. Open BTS develops a Base transceiver station. The GSM Software Project aims to build a GSM analyzer for less than $1000. OsmocomBB developers intend to replace the proprietary baseband GSM stack with a free software

implementation.

Issues with patents and open source

Patents remain a problem for any open-source GSM implementation, because it is not possible for GNU or any other free software distributor to guarantee immunity from all lawsuits by the patent holders against the users. Furthermore new features are being added to the standard all the time which means they have patent protection for a number of years.

The original GSM implementations from 1991 are now entirely free of patent encumbrances and it is expected that Open BTS will be able to implement features of that initial specification without limit and that as patents subsequently expire, those features can be added into the open source version. As of 2011, there have been no law suits against users of OpenBTS over GSM use.

Mobile station

The mobile station (comprises all user equipment and software needed for communication with a mobile network.

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The mobile station refers to global system connected to the mobile network, i.e. mobile phone or mobile computer connected using a mobile broadband adapter. This is the terminology of 2G systems like GSM. In the 3G systems, mobile station (MS) is now referred as user equipment (UE).

In GSM, the Mobile Station consists of four main components:

Mobile Termination (MT) - offers common functions of a such as: radio Transmission and handover, speech encoding and decoding, Error detection and correction, signalling and access to the SIM. The IMEI code is attached to the MT. It is equivalent to the network termination of an ISDN access.

Terminal Equipment (TE) - is any device connected to the MS offering services to the user. It does not contain any functions specific to GSM.

Terminal adapter (TA) - Provides access to the MT as if it was an ISDN network termination with extended capabilities. Communication between the TE and MT over the TA takes place using AT commands.

Subscriber Identity Module (SIM) - is a removable subscriber identification token storing the IMSI a unique key shared with the mobile network operator and other data.

In a mobile phone, the MT, TA and TE are enclosed in the same case. However, the MT and TE functions are often performed by distinct processors. The application processor serves as a TE, while the baseband processor serves as a MT, communication between both takes place over a bus using AT commands, which serves as a TA.

Base Transceiver Station

The base transceiver station, or BTS, contains the equipment for transmitting and receiving radio signals (transceivers), antennas, and equipment for encrypting and decrypting communications with the base station controller (BSC). Typically a BTS for anything other than a picocell will have several transceivers (TRXs) which allow it to serve several different frequencies and different sectors of the cell (in the case of sectorised base stations).

A BTS is controlled by a parent BSC via the "base station control function" (BCF). The BCF is implemented as a discrete unit or even incorporated in a TRX in compact base stations. The BCF provides an operations and maintenance (O&M) connection to the network management system (NMS), and manages operational states of each TRX, as well as software handling and alarm collection.

The functions of a BTS vary depending on the cellular technology used and the cellular telephone provider. There are vendors in which the BTS is a plain transceiver which receives information from the MS (mobile station) through the Um (air interface) and then converts it to a TDM (PCM) based interface, the Abis interface, and sends it towards the BSC. There are vendors which build their BTSs so the information is preprocessed, target cell lists are generated and even intracell handover (HO) can be fully handled. The advantage in this case is less load on the expensive Abis interface.

The BTSs are equipped with radios that are able to modulate layer 1 of interface Um; for GSM 2G+ the modulation type is GMSK, while for EDGE-enabled networks it is GMSK and 8-PSK.

Antenna combiners are implemented to use the same antenna for several TRXs (carriers), the more TRXs are combined the greater the combiner loss will be. Up to 8:1 combiners are found in micro and pico cells only.

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Base Station Controller

The base station controller (BSC) provides, classically, the intelligence behind the BTSs. Typically a BSC has tens or even hundreds of BTSs under its control. The BSC handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers from BTS to BTS (except in the case of an inter-BSC handover in which case control is in part the responsibility of the anchor MSC). A key function of the BSC is to act as a concentrator where many different low capacity connections to BTSs (with relatively low utilisation) become reduced to a smaller number of connections towards the mobile switching center (MSC) (with a high level of utilisation). Overall, this means that networks are often structured to have many BSCs distributed into regions near their BTSs which are then connected to large centralised MSC sites.

The BSC is undoubtedly the most robust element in the BSS as it is not only a BTS controller but, for some vendors, a full switching center, as well as an SS7 node with connections to the MSC and serving GPRS support node (SGSN) (when using GPRS). It also provides all the required data to the operation support subsystem (OSS) as well as to the performance measuring centers.

A BSC is often based on a distributed computing architecture, with redundancy applied to critical functional units to ensure availability in the event of fault conditions. Redundancy often extends beyond the BSC equipment itself and is commonly used in the power supplies and in the transmission equipment providing the A-ter interface to PCU.

The databases for all the sites, including information such as carrier frequencies, frequency hopping lists, power reduction levels, receiving levels for cell border calculation, are stored in the BSC. This data is obtained directly from radio planning engineering which involves modelling of the signal propagation as well as traffic projections.

Mobile Switching Centre

The mobile switching center (MSC) is the primary service delivery node for GSM/CDMA, responsible for routing voice calls and SMS as well as other services (such as conference calls, FAX and circuit switched data).

The MSC sets up and releases the end-to-end connection, handles mobility and hand-over requirements during the call and takes care of charging and real time pre-paid account monitoring.

In the GSM mobile phone system, in contrast with earlier analogue services, fax and data information is sent directly digitally encoded to the MSC. Only at the MSC is this re-coded into an "analogue" signal (although actually this will almost certainly mean sound encoded digitally as PCM signal in a 64-kbit/s timeslot, known as a DS0 in America).

There are various different names for MSCs in different contexts which reflects their complex role in the network, all of these terms though could refer to the same MSC, but doing different things at different times.

The Gateway MSC (G-MSC) is the MSC that determines which visited MSC the subscriber who is being called is currently located at. It also interfaces with the PSTN. All mobile to mobile calls and PSTN to mobile calls are routed through a G-MSC. The term is only valid in the context of one call since any MSC may provide both the gateway function and the Visited MSC function, however, some manufacturers design dedicated high capacity MSCs which do not have any BSSs connected to them. These MSCs will then be the Gateway MSC for many of the calls they handle.

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The visited MSC (V-MSC) is the MSC where a customer is currently located. The VLR associated with this MSC will have the subscriber's data in it.

The anchor MSC is the MSC from which a handover has been initiated. The target MSC is the MSC toward which a Handover should take place. A mobile switching centre server is a part of the redesigned MSC concept starting from 3GPP Release 4.

Home Locator Register

The home location register (HLR) is a central database that contains details of each mobile phone subscriber that is authorized to use the GSM core network. There can be several logical, and physical, HLRs per public land mobile network (PLMN), though one international mobile subscriber identity (IMSI)/MSISDN pair can be associated with only one logical HLR (which can span several physical nodes) at a time.

The HLRs store details of every SIM card issued by the mobile phone operator. Each SIM has a unique identifier called an IMSI which is the primary key to each HLR record.

The next important items of data associated with the SIM are the MSISDNs, which are the telephone numbers used by mobile phones to make and receive calls. The primary MSISDN is the number used for making and receiving voice calls and SMS, but it is possible for a SIM to have other secondary MSISDNs associated with it for fax and data calls. Each MSISDN is also a primary key to the HLR record. The HLR data is stored for as long as a subscriber remains with the mobile phone operator.

Examples of other data stored in the HLR against an IMSI record are:

GSM services that the subscriber has requested or been given.

GPRS settings to allow the subscriber to access packet services.

Current location of subscriber (VLR and serving GPRS support node/SGSN).

Calls divert settings applicable for each associated MSISDN.

The HLR is a system which directly receives and processes MAP transactions and messages from elements in the GSM network, for example, the location update messages received as mobile phones roam around.

Other GSM core network elements connected to the HLR

The HLR connects to the following elements:

The G-MSC for handling incoming calls The VLR for handling requests from mobile phones to attach to the network The SMSC for handling incoming SMSs The voice mail system for delivering notifications to the mobile phone that a message is waiting The AuC for authentication and ciphering and exchange of data (triplets)

Procedures implemented

The main function of the HLR is to manage the fact that SIMs and phones move around a lot. The following procedures are implemented to deal with this:

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Manage the mobility of subscribers by means of updating their position in administrative areas called 'location areas', which are identified with a LAC. The action of a user of moving from one LA to another is followed by the HLR with a Location area update procedure.

Send the subscriber data to a VLR or SGSN when a subscriber first roams there.

Broker between the G-MSC or SMSC and the subscriber's current VLR in order to allow incoming calls or text messages to be delivered.

Remove subscriber data from the previous VLR when a subscriber has roamed away from it.

Visitor Locator Register

The visitor location register is a database of the subscribers who have roamed into the jurisdiction of the MSC (Mobile Switching Center) which it serves. Each base station in the network is served by exactly one VLR, hence a subscriber cannot be present in more than one VLR at a time.

The data stored in the VLR has either been received from the HLR, or collected from the MS (Mobile station). In practice, for performance reasons, most vendors integrate the VLR directly to the V-MSC and, where this is not done, the VLR is very tightly linked with the MSC via a proprietary interface. Whenever an MSC detects a new MS in its network, in addition to creating a new record in the VLR, it also updates the HLR of the mobile subscriber, apprising it of the new location of that MS. If VLR data is corrupted it can lead to serious issues with text messaging and call services.

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Introduction to CCNA

Definition :-

A network is a system that transmits any combination of voice, video and/or data between users. A network can be defined by its geographical dimensions and by which the user’s PC access it.

A network consists of a: The network operating system (Windows NT/2000TM/Xp) on the user’s PC (client) and server. The cables connecting all network devices (user’s PC, server, peripherals, etc.). All supporting network components (hubs, routers and switches, etc.).Computer Network means an interconnected collection of autonomous computers.

Requirement of Networking

Resource sharing- To make all programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource and the user.

High reliability- As all files could be replicated on two or three machines, so if one of them is unavailable (due to hardware failure), the other copies could be used.

Scalability- It is the ability to increase system performance gradually as the workload grows just by adding more processors.A computer network can provide a powerful communication medium along widely separated employees.

The use of networks to enhance human-to-human communication will probably prove more important than technical goals such as improved reliability.

These are the requirement with respect to companies but computer networking is required even in the normal day to day life as we have to access the internet to get information about what all new happening in the world, to have communication with people staying far away using the e mail service.

These are the reasons that forced the inventerors to invent the networking devices, models and protocols etc.

And the birth of Networking took place in 1844 when for the first time Samuel Morse send the first telegraph message.

Network Layers

Functions of Network Layers in Brief:

APPLICATION LAYER

Used for applications specifically written to run over the network Allows access to network services that support applications; Directly represents the services that directly support user applications Handles network access, flow control and error recovery Example apps are file transfer, e-mail, Net BIOS-based applications

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PRESENTATION LAYER

Translates from application to network format and vice-versa All different formats from all sources are made into a common uniform format that the rest of the OSI

model can understand Responsible for protocol conversion, character conversion, data encryption / decryption, expanding

graphics commands, data compression Sets standards for different systems to provide seamless communication from multiple protocol stacks Not always implemented in a network protocol

SESSION LAYER

Establishes, maintains and ends sessions across the network Responsible for name recognition (identification) so only the designated parties can participate in the

session Provides synchronization services by planning check points in the data stream => if session fails, only

data after the most recent checkpoint need be transmitted Manages who can transmit data at a certain time and for how long Examples are interactive login and file transfer connections, the session would connect and re-connect if

there was an interruption; recognize names in sessions and register names in history

TRANSPORT LAYER

Additional connection below the session layer Manages the flow control of data between parties across the network Divides streams of data into chunks or packets; the transport layer of the receiving computer reassembles

the message from packets "Train" is a good analogy => the data is divided into identical units

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Provides error-checking to guarantee error-free data delivery, with on losses or duplications Provides acknowledgment of successful transmissions; requests retransmission if some packets don’t

arrive error-free Provides flow control and error-handling TCP, ARP, RARP;

NETWORK LAYER

Translates logical network address and names to their physical address (e.g. computer name ==> MAC address)

Responsible for addressing and determining routes for sending Managing network problems such as packet switching, data congestion and routing If router can’t send data frame as large as the source computer sends, the network layer compensates by

breaking the data into smaller units. At the receiving end, the network layer reassembles the data Think of this layer stamping the addresses on each train car IP; ARP; RARP, ICMP; RIP; OSFP;

DATA LINK LAYER

Turns packets into raw bits 100101 and at the receiving end turns bits into packets. Handles data frames between the Network and Physical layers The receiving end packages raw data from the Physical layer into data frames for delivery to the Network

layer Responsible for error-free transfer of frames to other computer via the Physical Layer This layer defines the methods used to transmit and receive data on the network. It consists of the wiring,

the devices use to connect the NIC to the wiring, the signaling involved to transmit / receive data and the ability to detect signaling errors on the network media

Logical Link Control

Error correction and flow control Manages link control and defines SAPs

PHYSICAL LAYER

Transmits raw bit stream over physical cable Defines cables, cards, and physical aspects Defines NIC attachments to hardware, how cable is attached to NIC Defines techniques to transfer bit stream to cable

IP ADDRESSING

Every machine on the internet has a unique identifying number, called an IP Address. A typical; IP address looks like this:216.27.61.45

IP ADDRESS is a 32-bit number, usually written in dotted decimal form, that uniquely identifies an interface of some computer. This 32-bit number is divided into 4 octets each separated by a decimal. Out so many values certain values are restricted for use as typical IP address. For example, the IP address 0.0.0.0 is reserved for the default network and the address 255.255.255.255is used for broadcast.

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Each IP address is split into 2 sections:

1) Network address

2) Host address

Individual IP address in same network all have a different value in the host part of address, but they have identical value in network part, just as in town there are different street address but same ZIP code.

There are five IP classes:

Class A – This class is for very large networks, such as a major international company. IP addresses with a first octet from 1 to 126 are part of this class. The other three octets are each used to identify each host.

Net Host or Node

54. 24.54.43

Loopback- The IP address 127.0.0.1 is used as the loopback address. This means that it is used by the host computer to send a message back to itself. It is commonly used for troubleshooting and network testing.

Class B- Class B is used for medium-sized networks. A good example is a large college campus. IP addresses with a first octet from 128 to191 are part of this class. Class B addresses also include the second octet as part of the Net identifier. The other two octets are used to identify each host.

Net Host or Node

145.24 53.198

Class C- Class C addresses are commonly used for small to mid-size business. IP addresses with a first octet from192 to 223 are part of this class. Class C addresses also include the second and third octets as part of Net identifier. The last octet is used to identify each host.

Net Host or Node

196.54.34 86

Class D- It is used for multicast. It has first bit value of 1, second bit value of 1, third bit value of 1 and fourth bit value of 0. The other 28 bits are used to identify the group of computers the multicast messages is intended for.

Net Host or Node

224 24.54.145

Class E- It is used for experimental purpose only.

Net Host or Node

240. 23.45.105

Private IP

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It is not necessary that every time we make a network we are connected to some ISP (Internet Service Provider). So in that case we require some private IP also which can be used in indigenous networks .In each class a range of IP addresses have been defined for this purpose

CLASS A 10.0.0.1 to 10.255.255.244

CLASS B 172.16.0.1 to 172.34.255.254

CLASS C 192.168.0.0/16

MASKING

Computers use a mask to define size of network and host part of an address. Mask is a 32-bit number written in dotted decimal form. It provides us the network address when we perform a Boolean AND of mask with the IP address. It also define number of host bits in an address.

Class of address

Size of network Part of address, in bits

Size of Host Part of address, in bits

Default Mask for Each Class of Network

A8 24 255.0.0.0

B16 16 255.255.0.0

C 24 8 255.255.255.0

SUBNETTINGBasically it is a process of subdividing networks into smaller subnets. In case we have 2-3 small networks but we cant buy IP address for each and every network. So here we use the basic concept of SUBNETTING i.e using one public IP address we will give them IP address and make them independent networks. For this we take some bits of host address and use them for network address so we have different independent networks

Address Format when Subnetting Is Used (class A,B,C resp.):

8 24-x x

Network Subnet Host

16 16-x x

Network Subnet Host

24 8-x x

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Network Subnet Host

And due to this mask changes to subnet mask and now the network address also includes subnet address.

Example

If subnet mask is 255.255.240.0

And an IP address for a computer is given as 142.16.52.4

142.16.0.0 is network address

0.0.48.0 is the subnet address

0.0.4.4 is the host address of the computer

10001110.00010000.00110100.00000100 is ANDed with

11111111.11111111.11110000.00000000

and output is 10001110.00010000.00110000.00000000

here first two octets represents Network address and third octet represents subnet address.

It can be compared with a postal address as there is only one ZIP code (Network address), different streets (Subnet address), and different house number (Host address).

Some terminologies those are used with Networking models:

Collision Domain- It is the group of PC’s in which collision will occur when two PC will transmit data simultaneously.

Broadcast Domain- It is the group of PC’s those will receive same broadcast message.

CSMA/CD (Carrier Sense Multiple Access/ Collision Detection)- In this protocol when a PC wants to transmit any packet it sense the carrier i.e the path ,if no other PC is using the carrier then only it sends. If two PCs starts sending data simultaneously collision will occur. Both PCs will wait for some random time and then initiate the same process.

MAC (Media Access Control) . The IEEE 802.3 (Ethernet) and 802.5

(Token Ring) are the MAC sub layers of these two LAN data-link protocols.

Burned-in address: The 6-byte address assigned by the vendor making

the card. It is usually burned in to a ROM or EEPROM on the LAN card and begins with a 3-byte organizationally unique identifier (OUI) assigned by

the IEEE.

Locally administered address: Through configuration, an address that is used instead of the burned-in address.

Unicast address: Fancy term for a MAC that represents a single LAN

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interface.

PASSIVE COMPONENTS

Passive components are those devices which are used to provide connectivity between different networking devices.It includes Cables Patch Panel Patch Cord I/O box Racks RJ-45 Connectors

CABLES

There are different Cabling options depending on the access method :

Twisted pair

The wires are twisted around each other to

minimize interference from other twisted pairs in the cable.

Twisted pair cables are available unshielded (UTP)

or shielded (STP). UTP is the most common type

and uses a RJ-45 Connector.

Typical lengths are up to 100m.

Twisted pair network uses a star topology.

Coaxial

Coaxial cable uses BNC connectors.

The maximum cable lengths are around 500m.

Coaxial networks use a single bus topology

Fiber Optic

UTP and Co-axial cables are not capable for driving the data signals for long distance i.e. UTP is capable of transmitting up to a distance 100 meters only By using the Fiber cables it is possible to send the data about 10 kilometers. Fiber optic cable uses SC, ST, LC connectors (most common in use is SC connector)

In fiber cables the data is converted to light signals and the signal is made to propagate through the fiber cable. There are two types of Fibre optic cable available.

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1. Single mode: In this mode typical length is up to 12km and data rate is 1000Mbps. The core diameter is about 9.25 nm cable is known as 1000 base LX cable.

2. Multi mode: This mode is further categorised in two:

1) SX: Typical length is up to 500m and data rate is 1000Mbps.

2) FX: Typical length is up to 220m and data rate is 100Mbps.

PATCH PANEL

A patch panel provides a convenient place to terminate (connect) all of the cable coming from different locations into the wiring closet. We connect the cables coming from various locations willing to connect to switch through the patch panel.

NEED OF PATCH PANEL

We can label the patch panel so we know that which wire belongs to which location. Without a patch panel, it is chaotic. If we want to disconnect a station from the switch, it's a lot easier if there's a label.

Most cabling is wired "straight-through" from end to end. But sometimes we need to cross-wire some of the pairs between switch and station, like with a cable modem, or cross-wire to connect two switches. With a patch panel, all of this cross-wiring is done in the patch cable. If you have to make any changes, like moving a station or switch, you just move the patch cable with it, instead of having to reterminate the cable run.

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PATCH CORD

RACK

We have to mount the patch panel somehow. The best way is to buy a rack. Basically, a rack is a pair of vertical rails with holes drilled in them so that we can mount patch panels, hubs, and other network equipment. This made it easy to access the back of the patch panel and other networking components.

Cabling Guidelines

The RJ-45 ports on the switch support automatic MDI/MDI-X operation, so wecan use standard straight-through twisted-pair cables to connect to any other network device (PCs, servers, switches, routers, or hubs). We use only twisted-pair cables with RJ-45 connectors that conform to FCC standards.

Connecting to PCs, Servers, Hubs and Switches

1. Attach one end of a twisted-pair cable segment to the device’s RJ-45 connector. Making Twisted-Pair Connections

2. The port where we are connecting the RJ-45 is a network card, attach the other end of the cable segment to a modular wall outlet that is connected to the wiring closet . Otherwise, attach the other end to an available port on the switch.

Make sure each twisted pair cable does not exceed 100 meters (328 ft) in length.

Wiring Closet Connections

Today, the punch-down block is an integral part of many of the newer equipment racks. It is actually part of the patch panel. Instructions for making connections in the wiring closet with this type of equipment follow.

1. Attach one end of a patch cable to an available port on the switch, and the other end to the patch panel. 2. If not already in place, attach one end of a cable segment to the back of the patch panel where the

punch-down block is located, and the other end to a modular wall outlet. 3. Label the cables to simplify future troubleshooting.

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NETWORKING DEVICES

Networking devices do various kind of jobs like transferring the data to signals, providing connectivity to different network devices, transferring the data in form of packets or frames form one device to other. These are the central connections for all the network equipments and handles a data type known as frame or packet. Actually frames/ packet contain data and the destination address of where it is going. When a frame is received, it is amplified and then transmitted on to port of destination PC. But different networking components do this job in diff form at diff layers.

NETWORK INTERFACE CARD

A Network Interface Card (NIC) is a circuit board that plugs into both clients and servers and controls the exchange of data between them (A specific software “driver” must be installed depending on the make of the NIC. A physical transmission medium, such as twisted pair or coaxial cable interconnects all network interface cards to network hubs or switches. Ethernet and Token Ring are common network interface cards. Today’s cards supports 10baseT and 100baseT with automatic recognition.

HUB

When the need for interconnecting more then 2 devices together then a device known as hub comes to picture. Basically hub is a layer one device. i.e. it operates on the physical layer of the OSI model. It is designed to do broadcasting i.e when it gets any frame it broadcasts it to every port irrespective that whether it is destined for that port or not. Hub has no way of distinguishing which port a frame should be sent. Broadcasting results in lot of traffic on the network which lead to poor network response. If two PC simultaneously transmit there

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data packets and both are connected to a HUB, then collision will occur, so we can say, it creates a single collision domain. On the other hand all PCs connected to a hub will get a same message so a single broadcast domain will be created.

A 100/1000 Mbps hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the max available bandwidth. If, however, multiple PC’s are broadcasting, then that bandwidth will need to be divided between all of these systems, which will degrade the performance. They are usually Half-Duplex in nature.

SWITCHHubs are capable of joining more than two PC but having some demerits like if two PC would want to communicate at a time then there would be a collision and the both PC would have to send the data once again. This shortcoming of Hub is overcame by Switches. Switches are intelligent devices which work on the Layer2 of the OSI model. Basically a switch keeps a record of MAC addresses of all the devices connected to it. Using this information, it builds a MAC address table. So when a frame is received, it knows exactly which port to send it to, which increases the network response time.

Basic Working Principle of Switch.

1. At the time of initializing the switch the MAC address table is yet to be built up. When a frame is send by some of the PC, it recognises the source MAC address and update the MAC address table.

2. If the destination is available in the MAC table then forward to the corresponding PC.

3. If the destination MAC address is not present in the table then forwards in all the port available expect the incoming one. The designated PC will respond for the data and it will send the acknowledge for the data received. This acknowledged data will be examined by the switch and the MAC address table would be up dated accordingly.

If two PC simultaneously transmit there data packets and both are connected to a SWITCH, then collision will not occur, so we can say, it creates a multiple collision domain.

The switch supports broadcast. Hence we can call switches create single broadcast domain and multiple collision domains.

A 100/1000Mbps switch will allocate a full 100/1000 Mbps to each of its ports. So regardless of the no of PC’s transmitting user will always have access to max amt of bandwidth. They are usually Full-Duplex in nature.

Bridge

Bridge is another device like switch which also operates basing on the MAC address. But the Basic difference between the bridge and the switch is that bridge works on software bases, but the switch works on hardware basic. The Switch works on ASICs ( Application Specific Integrated Circuits)

ROUTER

Switch and the Hub can only interconnect devices in a single LAN. For interconnecting two LAN or two or more different networks anther device known as router is used. Its main job is to route ( sends ) packets to

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other networks and to do the routing ( establishing paths between networks ) it uses the IP address. A router is typically connected to at least two networks, commonly two LAN’s or WAN’s or a LAN and its ISP’s network. Routers are located at gateways, the places where two or more networks connect. Routers to determine the best path for forwarding the packet are using forwarding tables.

It is a layer 3 device i.e it operates at network layer of OSI model. The working principle of the router is totally different from a switch. Router makes a table known as routing table, which contains all the IP address in the network, the information for IP address router obtains directly ( all configured IP address on it ) or indirectly ( from neighbour routers ). When a packet is received it compares the destination IP address of the packet with the available IP addresses in its Routing table. If the IP address is not available in the routing table then it simply discard the packet instead of flooding in all the ports like a switch.(Detailed Information about router in chap )

Comparison between Hub, Bridge, Switch & RouterFeature Hub Bridge Switch Router

Number of broadcast domains Segment 1 1 1 per router interface

Number of collision domains 1

1 per bridge port

1 per switch port 1 per router interface

Forwards LAN broadcasts? 1 Yes Yes No

Forwards LAN multicasts N/A Yes

Yes; can be optimized for less forwarding No

OSI layer used when making forwarding decision N/A Layer 2 Layer 2 Layer 3

Internal processing variants N/A

Store-and- forward

Store-and-forward, cut-through, FragmentFree Store-and- forward

Frame/packet fragmentation allowed? N/A No No Yes

Multiple concurrent equal-cost paths to same destination allowed? N/A No No Yes

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