Report

SUMMER TRAINING REPORT ON

“NETWORKING INFRASTRUCTURE

OF ONGC”

SUMMER TRAINING REPORT

ON

“NETWORKING INFRASTRUCTURE

OF ONGC”

Submitted in the partial fulfillment of the requirement for the award of degree

BACHELOR OF TECHNOLOGY

IN

COMPUTER SCIENCE & ENGINIEERING

SUPERVISED BY: SUBMITTED BY:Mr. HARISH KUMAR ADITYA PRATAP SINGHChief Engineer (E & T) 0581152707Corporate Infocom Services ONGC

Bharati Vidyapeeth College of Engineering GGS Indraprastha University, Delhi – 6 (2007-2011)

ACKNOWLEDGEMENT

I take this opportunity to express my profound sense of gratitude and appreciation to all those who helped me throughout the duration of this project.My thanks to the HEAD ONGC Academy, Dehradun for allowing me to undergo 8 weeks training in ONGC Delhi.First and foremost, I would like to express my thanks to Shri Harish Kumar, Chief Engineer (E & T), Corporate Infocom Services, ONGC, DELHI for providing guidance and expert supervision for this project and giving crucial feedback that are critical in the development of the project, without which I would not have been able to complete the project.I would also like to give my special thanks to Mr M. THYAGARAJ, Executive Director - Chief Infocom Officer, ONGC for his encouragement, support and providing necessary facilities.I am truly thankful to the entire networking team of ONGC, New Delhi for their support and timely help in solving problems related to Computer Networks and Data Centre from time to time. I would specially like to thanks Mr.Sajjan Singh of networking team for continuous efforts and guidance in respect of understanding theoretical and practical aspects of computer networking.This report acknowledges to the intense driving and technical competence of the entire individuals that have contributed to it. It would have been almost impossible to make a report without the support of these people. Last but not the least, I would like to thanks my H.O.D Alok Basu for helping me understand the organisational networking needs and encouraging me for undergoing the training.

Aditya Pratap Singh

CERTIFICATE

Certified that this project entitled “NETWORKING INFRASTRUCTURE

OF ONGC” submitted by Mr. Aditya Pratap Singh 05811520707 in the partial

fulfillment of the requirement for the award of Bachelor of Technology

(Computer Science &Engineering) degree of BVCOE, GGSIPU, Delhi is a

record of students own study carried under my supervision & guidance. This

report has not been submitted to any other university or institution for the

award of any degree.

PROJECT LEAD PROJECT GUIDEMr. HARISH KUMAR Mr. SAJJAN SINGHChief Engineer (E & T) Network AdministratorCorporate Infocom Services ONGCONGC

CONTENTS

1. ONGC

1.1 History

1.2 ONGC videsh

1.3 International rankings

1.4 Institutes of ONGC

2. Computer Networking and Reference Models

2.1 Definition

2.2 History of computer netwoks

2.3 OSI and TCP/IP models

3. Local Area Network (LAN)

3.1 Definition

3.2 LAN topologies

3.3 LAN technologies

4. Wide Area Network (WAN)

4.1 Definition

4.2 WAN design options

4.3 WAN connection techniques

5. Virtual LAN (VLAN)

5.1 Definition

5.2 Advantages

6. Routers and Routing

6.1 Definition

6.2 Routers at Layer 3

6.3 Router Hardware

6.4 Startup Procedure of a Router

6.5 Packet Flow in a routed networks

6.6 Routing Protocols

7. LAN Switching

7.1 Definition

7.2 L2 switching

7.3 L3 switching

7.4 L4 switching

7.5 Multilayer Switching

8. Virtual Private Networks (VPN)

8.1 History

8.2 Classification

8.3 Security mechanism

9. ONGC Network Diagrams

9.1 SM data center infocom

9.2 SM data center server connectivity

9.3 SM floor connectivity

9.4 SM WAN links

9.5 WAN links Delhi

10. LOTUS- The mailing system at ONGC

10.1 Definition

10.2 Features

11. Conclusion

OIL AND NATURAL GAS

CORPORATION LIMITED

(ONGC)

Oil and Natural Gas Corporation Limited (ONGC) (incorporated

on 23 June 1993) is a state-owned oil and gas company in India. It is a

Fortune Global 500 company ranked 152nd, and contributes 77% of

India's crude oil production and 81% of India's natural gas production.

It is the highest profit making corporation in India. It was set up as a

commission on 14 August 1956. Indian government holds 74.14%

equity stake in this company.

ONGC is one of Asia's largest and most active companies involved in

exploration and production of oil. It is involved in exploring for and

exploiting hydrocarbons in 26 sedimentary basins of India. It

produces about 30% of India's crude oil requirement. It owns and

operates more than 11,000 kilometres of pipelines in India.

History

Foundation

In August 1960, the Oil and Natural Gas Commission was formed.

Raised from mere Directorate status to Commission, it had enhanced

powers. In 1959, these powers were further enhanced by converting

the commission into a statutory body by an Act of Indian Parliament.

1960-2007

Since its foundation stone was laid, ONGC is transforming India’s

view towards Oil and Natural Gas by emulating the country’s limited

upstream capabilities into a large viable playing field. ONGC, since

1959, has made its presence noted in most parts of India and in

overseas territories. ONGC found new resources in Assam and also

established the new oil province in Cambay basin (Gujarat). In 1970

with the discovery of Bombay High (now known as Mumbai High),

ONGC went offshore. With this discovery and subsequent discovery

of huge oil fields in the Western offshore, a total of 5 billion tonnes of

hydrocarbon present in the country was discovered. The most

important contribution of ONGC, however, is its self-reliance and

development of core competence in exploration and production

activities at a globally competitive level.

Post-1990

Post 1990, the liberalized economic policy was brought into effect,

subsequently partial disinvestments of government equity in Public

Sector Undertakings were sought. As a result, ONGC was re-

organized as a limited company and after conversion of business of

the erstwhile Oil & Natural Gas Commission to that of Oil and

Natural Gas Corporation Ltd in 1993, 2 percent of shares through

competitive bidding were disinvested. Further expansion of equity

was done by 2 percent share offering to ONGC employees. Another

big leap was taken in March 1999, when ONGC, Indian Oil

Corporation (IOC) and Gas Authority of India Ltd.(GAIL) agreed to

have cross holding in each other’s stock. Consequently the

Government sold off 10 per cent of its shareholding in ONGC to IOC

and 2.5 per cent to GAIL. With this, the Government holding in

ONGC came down to 84.11 per cent. In 2002-03 ONGC took over

Mangalore Refinery and Petrochemicals Limited (MRPL) from Birla

Group and announced its entrance into retailing business. ONGC also

went to global fields through its subsidiary, ONGC Videsh Ltd.

(OVL).

In 2009, ONGC discovered a massive oil field, with up to 1 billion

barrel reserves of heavy crude, in the Persian Gulf off the coast of

Iran. Additionally, ONGC also signed a deal with Iran to invest US$3

billion to extract 1.1 billion cubic feet of natural gas from the Farzad

B gas field.

ONGC Videsh

ONGC Videsh is the international arm of ONGC. ONGC has made

major investments in Vietnam, Sakhalin and Sudan and earned its first

hydrocarbon revenue from its investment in Vietnam.

International rankings

ONGC has been ranked at 198 by the Forbes Magazine in their

Forbes Global 2000 list for the year 2007.

ONGC has featured in the 2008 list of Fortune Global 500

companies at position 335, a climb of 34 positions from rank of

369 in 2007.

ONGC is ranked as Asia’s best Oil & Gas company, as per a

recent survey conducted by US-based magazine ‘Global

Finance’

2nd biggest E&P company (and 1st in terms of profits), as per

the Platts Energy Business Technology (EBT) Survey 2004

Ranks 24th among Global Energy Companies by Market

Capitalization in PFC Energy 50 (December 2004).

Economic Times 500, Business Today 500, Business Baron 500

and Business Week recognize ONGC as most valuable Indian

corporate, by Market Capitalization, Net Worth and Net Profits.

Various Institutes Of ONGC

IRS: Institute of Reservoir Studies

The Institute of Reservoir Studies (IRS) was founded in 1978 as a

single-source and multi-service reservoir engineering agency with the

objectives to:

Maximize hydrocarbon recovery at minimum cost

Provide holistic reservoir description through integration of all data

Maximize the value of proven reserves with conventional and

improved recovery techniques

Enhance the skills and knowledge for better reservoir management  

Since its inception, IRS has contributed effectively in the

development of new concepts and innovative techniques besides

adopting state-of-the-art technological advancements as part of its

concern. All investment decisions of ONGC regarding hydrocarbon

exploitation are based on the recommendations given by the IRS.

IRS's resources include 12 modern laboratories with latest equipment

supported by comprehensive engineering services. Over 15 multi-

disciplinary teams, for field development planning and continuous

reservoir management, utilize the latest workstations configured over

an institute wide network. A 400 seat Technical Seminar Hall,

equipped with the latest audio-visual facilities and interpreter desks

provides an ideal setup for technical presentations and conferences.

The IRS library contains a wide range of books ranging from

exploration to revenue management. It also subscribes to various

petroleum industry related journals and magazines. A full set of SPE

papers on microfiche and compact disks are available in the library.

Seamless access to the internet is also available throughout the

Institute through a lease line.

The Institute has been modeled around the concept of 'collaboration

and interaction' to accelerate the process of completing the studies,

improve confidence by using the strengths of latest software and

hardware and increase the accuracy of forecasting. IRS has a

membership and technology transfer agreement with M/s Computer

Modelling Group (CMG) Calgary, Canada. The Institute also has a

technical collaboration for investigation in High-Pressure Air

Injection (HPAI) as Improved Oil Recovery (IOR) process in medium

and light oil reservoirs with the University of Calgary, Canada.

IEOT: Institute of Engineering and Ocean Technology

The Institute of Engineering and Ocean Technology (IEOT) was

founded in 1983 to achieve self-reliance in technology by innovation,

development and acceleration of the future plans of ONGC. The

Institution has developed expertise in the fields of Concept Evaluation

& Risk Analysis, Geo-technical Engineering, Structural Engineering

and Materials& Corrosion Engineering.

The major strength of IEOT lies in its highly qualified, trained and

motivated technical manpower and various advanced laboratories and

the state-of-the-art software for analytical studies.

In search of excellence, IEOT has acquired ISO-9001 Certificate

through implementation of quality assurance system. The Geo-

technical Laboratory and Materials & Corrosion laboratory of IEOT

have both been accredited by National Accreditation Board for

Testing and Calibration Laboratories (NABL) of Department of

Science & Technology, Government of India.

The Institute is abreast with the advanced technologies through in-

house and collaborative R&D efforts and institutional cooperation

programmes with national and international institutes.

IEOT has collaborations with premier research and academic

institutions like Indian Institute of Technology, Mumbai; Bhaba

Atomic Research Centre, Mumbai; Structural Engineering

Research Centre, Chennai; Central Electrochemical Research

Institute, Karaikudi and various other universities for carrying out

studies on different problems related to engineering in oil and gas

industry.

The Institute has also entered into collaboration with Norwegian

Geotechnical Institute (NGI), Norway in the areas like deep-water

soil testing and foundation design. More such collaborations are on

the anvil with Norwegian Institutes in the areas of offshore structural

engineering and Risk & Reliability analysis.

IEOT has already opened its doors to offer specialized services to

outside industry clients and towards that end, it has geared itself to

provide a cutting edge through innovative and radical technologies in

its value added services to the esteemed clients.

IOGPT: Institute of Oil and Gas Production Technology

To meet the technological requirements of oil and gas production, the

Institute of Oil & Gas Production Technology (IOGPT) was

established in 1984 at Panvel about 50 km from Mumbai airport

amidst picturesque surroundings on the Mumbai-Pune Highway. The

objective was to improve the economics of operations and boost

indigenous hydrocarbon production. This is the first institute in the

country to provide integrated R&D support to the entire spectrum of

oil and gas production, beginning with well/field production analysis

to transmission to consumer point. The Institute has the distinction of

providing specialized training including simulator based training to

production engineers.

IOGPT has equipped itself with advanced information technology

tools to keep pace with the ever-changing technology. While

sophisticated computing facilities cater to the computational needs, a

well-designed library with electronic information search facility

through Internet and CD-ROMs and well-stocked books and

international journals on petroleum technology cater to the

information needs. The Institute also has collaboration with many

national/international premier research institutions to share the latest

technological developments in its gamut of operations.

Beyond the quality focus, in pursuit of excellence, IOGPT has also

been awarded the prestigious ISO-9001 Certification.

Over the years, IOGPT has completed about 600 projects related to

various aspects of petroleum technology. Software worth over $0.9

million has also been developed by the Institute.

Some other institutes of ONGC are:

Keshava Deva Malavia Institute of Petroleum Exploration

(KDMIPE), Dehradun.

Institute of Drilling Technology (IDT), Dehradun.

Geo- data Processing and Interpretation Center (GEOPIC),

Dehradun.

ONGC academy, Dehradun.

Institute of Petroleum Safety, Health and Environment

Management, Goa.

Institute of Biotechnology and Geotectonic Studies, Jorhat.

School of Maintenance practices, Vadodara.

Regional Training Institutes, Navi Mumbai, Chennai, Sivasagar

and Vadodara.

COMPUTER NETWORKING AND

REFERENCE MODELS

Computer Networking is the engineering discipline concerned with

the communication between computer systems or devices. A

computer network is any set of computers or devices connected to

each other with the ability to exchange data. Computer networking is

sometimes considered a sub-discipline of telecommunications,

computer science, information technology and/or computer

engineering since it relies heavily upon the theoretical and practical

application of these scientific and engineering disciplines. The three

types of networks are: the Internet, the intranet, and the extranet.

Examples of different network methods are:

Local area network (LAN), which is usually a small network

constrained to a small geographic area. An example of a LAN

would be a computer network within a building.

Metropolitan area network (MAN), which is used for medium

size area. examples for a city or a state.

Wide area network (WAN) that is usually a larger network that

covers a large geographic area.

Wireless LANs and WANs (WLAN & WWAN) are the wireless

equivalent of the LAN and WAN.

All networks are interconnected to allow communication with a

variety of different kinds of media, including twisted-pair copper wire

cable, coaxial cable, optical fiber, power lines and various wireless

technologies. The devices can be separated by a few meters (e.g. via

Bluetooth) or nearly unlimited distances (e.g. via the interconnections

of the Internet). Networking, routers, routing protocols, and

networking over the public Internet have their specifications defined

in documents called RFCs.

Views of networks

Users and network administrators often have different views of their

networks. Often, users who share printers and some servers form a

workgroup, which usually means they are in the same geographic

location and are on the same LAN. A community of interest has less

of a connection of being in a local area, and should be thought of as a

set of arbitrarily located users who share a set of servers, and possibly

also communicate via peer-to-peer technologies.

Network administrators see networks from both physical and logical

perspectives. The physical perspective involves geographic locations,

physical cabling, and the network elements (e.g., routers, bridges and

application layer gateways that interconnect the physical media.

Logical networks, called, in the TCP/IP architecture, subnets, map

onto one or more physical media. For example, a common practice in

a campus of buildings is to make a set of LAN cables in each building

appear to be a common subnet, using virtual LAN (VLAN)

technology.

Both users and administrators will be aware, to varying extents, of the

trust and scope characteristics of a network. Again using TCP/IP

architectural terminology, an intranet is a community of interest under

private administration usually by an enterprise, and is only accessible

by authorized users (e.g. employees). Intranets do not have to be

connected to the Internet, but generally have a limited connection. An

extranet is an extension of an intranet that allows secure

communications to users outside of the intranet (e.g. business

partners, customers).

Informally, the Internet is the set of users, enterprises,and content

providers that are interconnected by Internet Service Providers (ISP).

From an engineering standpoint, the Internet is the set of subnets, and

aggregates of subnets, which share the registered IP address space and

exchange information about the reachability of those IP addresses

using the Border Gateway Protocol. Typically, the human-readable

names of servers are translated to IP addresses, transparently to users,

via the directory function of the Domain Name System (DNS).

Over the Internet, there can be business-to-business (B2B), business-

to-consumer (B2C) and consumer-to-consumer (C2C)

communications. Especially when money or sensitive information is

exchanged, the communications are apt to be secured by some form

of communications security mechanism. Intranets and extranets can

be securely superimposed onto the Internet, without any access by

general Internet users, using secure Virtual Private Network (VPN)

technology.

When used for gaming one computer will have to be the server while

the others play through it.

History of computer networks

Before the advent of computer networks that were based upon some

type of telecommunications system, communication between

calculation machines and early computers was performed by human

users by carrying instructions between them. Many of the social

behaviors seen in today's Internet were demonstrably present in the

nineteenth century and arguably in even earlier networks using visual

signals.

In September 1940 George Stibitz used a teletype machine to send

instructions for a problem set from his Model at Dartmouth College in

New Hampshire to his Complex Number Calculator in New York and

received results back by the same means. Linking output systems like

teletypes to computers was an interest at the Advanced Research

Projects Agency (ARPA) when, in 1962, J.C.R. Licklider was hired

and developed a working group he called the "Intergalactic Network",

a precursor to the ARPANet.

In 1964, researchers at Dartmouth developed the Dartmouth Time

Sharing System for distributed users of large computer systems. The

same year, at MIT, a research group supported by General Electric

and Bell Labs used a computer DEC's to route and manage telephone

connections.

Throughout the 1960s Leonard Kleinrock, Paul Baran and Donald

Davies independently conceptualized and developed network systems

which used datagrams or packets that could be used in a network

between computer systems.

1965 Thomas Merrill and Lawrence G. Roberts created the first wide

area network (WAN).

The first widely used PSTN switch that used true computer control

was the Western Electric introduced in 1965.

In 1969 the University of California at Los Angeles, SRI (in

Stanford), University of California at Santa Barbara, and the

University of Utah were connected as the beginning of the

ARPANET network using 50 kbit/s circuits. Commercial services

using X.25 were deployed in 1972, and later used as an underlying

infrastructure for expanding TCP/IP networks.

Computer networks, and the technologies needed to connect and

communicate through and between them, continue to drive computer

hardware, software, and peripherals industries. This expansion is

mirrored by growth in the numbers and types of users of networks

from the researcher to the home user.

Today, computer networks are the core of modern communication.

All modern aspects of the Public Switched Telephone Network

(PSTN) are computer-controlled, and telephony increasingly runs

over the Internet Protocol, although not necessarily the public

Internet. The scope of communication has increased significantly in

the past decade, and this boom in communications would not have

been possible without the progressively advancing computer network.

OSI AND TCP/IP MODEL:

The Open Systems Interconnection reference model is a layered,

abstract representation created as a guideline for network protocol

design. The OSI model divides the networking process into seven

logical layers, each of which has unique functionality and to which

are assigned specific services and protocols.

In this model, information is passed from one layer to the next,

starting at the Application layer on the transmitting host, and

proceeding down the hierarchy to the Physical layer, then passing

over the communications channel to the destination host, where the

information proceeds back up the hierarchy, ending at the Application

layer.

The Application layer

This is the top layer of both the OSI and TCP/IP models. It is the

layer that provides the interface between the applications we use to

communicate and the underlying network over which our messages

are transmitted. Application layer protocols are used to exchange data

between programs running on the source and destination hosts. There

are many Application layer protocols and new protocols are always

being developed.

Although the TCP/IP protocol suite was developed prior to the

definition of the OSI model, the functionality of the TCP/IP

application layer protocols fit roughly into the framework of the top

three layers of the OSI model: Application, Presentation and Session

layers.

Most TCP/IP application layer protocols were developed before the

emergence of personal computers, graphical user interfaces and

multimedia objects. As a result, these protocols implement very little

of the functionality that is specified in the OSI model Presentation and

Session layers.

The Presentation Layer

The Presentation layer has three primary functions:

Coding and conversion of Application layer data to ensure that data

from the source device can be interpreted by the appropriate

application on the destination device.

Compression of the data in a manner that can be decompressed by the

destination device.

Encryption of the data for transmission and the decryption of data

upon receipt by the destination.

Presentation layer implementations are not typically associated with a

particular protocol stack. The standards for video and graphics are

examples. Some well-known standards for video include QuickTime

and Motion Picture Experts Group (MPEG). QuickTime is an Apple

Computer specification for video and audio, and MPEG is a standard

for video compression and coding.

Among the well-known graphic image formats are Graphics

Interchange Format (GIF), Joint Photographic Experts Group (JPEG),

and Tagged Image File Format (TIFF). GIF and JPEG are

compression and coding standards for graphic images, and TIFF is a

standard coding format for graphic images.

The Session Layer

As the name of the Session layer implies, functions at this layer create

and maintain dialogs between source and destination applications.

The Session layer handles the exchange of information to initiate

dialogs, keep them active, and to restart sessions that are disrupted or

idle for a long period of time.

Most applications, like web browsers or e-mail clients, incorporate

functionality of the OSI layers 5, 6 and 7.

The Transport Layer

The Transport layer provides for the segmentation of data and the

control necessary to reassemble these pieces into the various

communication streams. Its primary responsibilities to accomplish

this are:

Tracking the individual communication between applications on the

source and destination hosts

Segmenting data and managing each piece

Reassembling the segments into streams of application data

Identifying the different applications

The Network Layer

The Network layer, or OSI Layer 3, provides services to exchange the

individual pieces of data over the network between identified end

devices. To accomplish this end-to-end transport, Layer 3 uses four

basic processes:

Addressing

Encapsulation

Routing

Decapsulation

The Data Link Layer

The Data Link layer provides a means for exchanging data over a

common local media.

The Data Link layer performs two basic services:

Allows the upper layers to access the media using techniques such as

framing

Controls how data is placed onto the media and is received from the

media using techniques such as media access control and error

detection

The physical layer

The Physical layer provides the means to transport across the network

media the bits that make up a Data Link layer frame. This layer

accepts a complete frame from the Data Link layer and encodes it as a

series of signals that are transmitted onto the local media. The

encoded bits that comprise a frame are received by either an end

device or an intermediate device.

The delivery of frames across the local media requires the following

Physical layer elements:

The physical media and associated connectors

A representation of bits on the media

Encoding of data and control information

Transmitter and receiver circuitry on the network devices

Local Area Network

(LAN)

A local area network (LAN) is a computer network covering a small

physical area, like a home, office, or small groups of buildings, such

as a school, or an airport. The defining characteristics of LANs, in

contrast to wide area networks (WANs), include their usually higher

data-transfer rates, smaller geographic area, and lack of a need for

leased telecommunication lines.

Network scenario in ONGC

Devices used - Two Cisco 4506 L3 switches with optical

module Fifty 3-COM 4400 series L2 switches

with optical module.

Floor cabling used - Multi –mode Fiber for providing connectivity

floor 5th Floor to 15th Floor core 3 West side

and Core -4 East Copper RJ interconnectivity

of Core 3 west and core 4 East

Servers cabling used- Multi-mode Fiber and copper RJ-45

for single NIC connectivity of each server

from either of L3 switch

Optical module case - Sixteen for housing optical fibers

LAN TOPOLOGIES

There are four common types of LAN topologies

– Bus topology

– Tree topology

– Star topology

– Ring topology

Bus and Tree Topology

Bus and Tree Topology

Star Topology (LAN)

Center: hub, repeater, or concentratorTypically used in both Ethernet and Token Ring5 to 100+ devices

Star Topology

Redundant ring to avoid network failure

Ring Topology

LAN TECHNOLOGIES

There are different types of LAN technologies, the prominent ones are

mentioned below:

Ethernet - Ethernet is a 10Mbps LAN that uses the Carrier Sense

Multiple Access with Collision Detection (CSMA/CD) protocol to

control access network. When an end station (network device)

transmits data, every end station on the LAN receives it. Each end

station checks the data packet to see whether the destination address

matches its own address. If the addresses match, the end station

accepts and processes the packet. If they do not match, it disregards

the packet. If two end stations transmit data simultaneously, a

collision occurs and the result is a composite, garbled message. All

end stations on the network, including the transmitting end stations,

detect the collision and ignore the message. Each end station that

wants to transmit waits a random amount of time and then attempts to

transmit again. This method is usually used for traditional Ethernet

LAN.

Token Ring - This is a 4-Mbps or 16-Mbps token-passing method,

operating in a ring topology. Devices on a Token Ring network get

access to the media through token passing. Token and data pass to

each station on the ring. The devices pass the token around the ring

until one of the computer who wants to transmit data, takes the token

and replaces it with a frame. Each device passes the frame to the next

device, until the frame reaches its destination. As the frame passes to

the intended recipient, the recipient sets certain bits in the frame to

indicate that it received the frame. The original sender of the frame

strips the frame data off the ring and issues a new token.

Fast Ethernet - This is an extension of 10Mbps Ethernet standard

and supports speed up to 100Mbps. The access method used is

CSMA/CD .For physical connections Star wiring topology is used.

Fast Ethernet is becoming very popular as an up gradation from

10Mbps Ethernet LAN to Fast Ethernet LAN is quite easy.

FDDI (Fibre Distributed Data Interface) - FDDI provides data

speed at 100Mbps which is faster than Token Ring and Ethernet

LANs. FDDI comprise two independent, counter-rotating rings: a

primary ring and a secondary ring. Data flows in opposite directions

on the rings. The counter-rotating ring architecture prevents data loss

in the event of a link failure, a node failure, or the failure of both the

primary and secondary links between any two nodes. This technology

is usually implemented for a backbone network

Wide Area Network

(WAN)

A Wide Area Network (WAN) is a computer network that covers a

broad area (i.e., any network whose communications links cross

metropolitan, regional, or national boundaries). This is in contrast

with personal area networks (PANs), local area networks (LANs),

campus area networks (CANs), or metropolitan area networks

(MANs) which are usually limited to a room, building, campus or

specific metropolitan area (e.g., a city) respectively.

WAN design options

WANs are used to connect LANs and other types of networks

together, so that users and computers in one location can

communicate with users and computers in other locations. Many

WANs are built for one particular organization and are private.

Others, built by Internet service providers, provide connections from

an organization's LAN to the Internet. WANs are often built using

leased lines. At each end of the leased line, a router connects to the

LAN on one side and a hub within the WAN on the other. Leased

lines can be very expensive. Instead of using leased lines, WANs can

also be built using less costly circuit switching or packet switching

methods. Network protocols including TCP/IP deliver transport and

addressing functions. Protocols including Packet over SONET/SDH,

MPLS, ATM and Frame relay are often used by service providers to

deliver the links that are used in WANs. X.25 was an important early

WAN protocol, and is often considered to be the "grandfather" of

Frame Relay as many of the underlying protocols and functions of

X.25 are still in use today (with upgrades) by Frame Relay.

Academic research into wide area networks can be broken down into

three areas: Mathematical models, network emulation and network

simulation.

Performance improvements are sometimes delivered via WAFS or

WAN optimization.

WAN connection technology options

There are also several ways to connect Non-stop S-series servers to

WANs, which provides WAN client connectivity to servers that have

Ethernet ports and appropriate communications software. Several

options are available for WAN connectivity:

Option: Description Advantages Disadvantages Bandwidth range

Sample protocols used

Leased line Point-to-Point connection between two computers or Local Area Networks (LANs)

Most secure Expensive PPP, HDLC, SDLC, HNAS

Circuit switching

A dedicated circuit path is created between end points. Best example is dialup connections

Less Expensive Call Setup 28 - 144 kbps PPP, ISDN

Packet switching

Devices transport packets via a shared single point-to-point or point-to-multipoint link across a carrier internetwork. Variable length packets are transmitted over Permanent Virtual Circuits (PVC) or

Shared media across link

X.25 Frame-Relay

Switched Virtual Circuits (SVC)

Cell relay Similar to packet switching, but uses fixed length cells instead of variable length packets. Data is divided into fixed-length cells and then transported across virtual circuits

Best for simultaneous use of voice and data

Overhead can be considerable

ATM

Transmission rates usually range from 1200 bps to 24 Mbps, although

some connections such as ATM and Leased lines can reach speeds

greater than 156 Mbps. Typical communication links used in WANs

are telephone lines, microwave links & satellite channels.

Recently with the proliferation of low cost of Internet connectivity

many companies and organizations have turned to VPN to

interconnect their networks, creating a WAN in that way. Companies

such as Cisco, New Edge Networks and Check Point offer solutions

to create VPN networks.

VIRTUAL LOCAL AREA

NETWORKS (VLAN)

VIRTUAL LAN

Figure 1 - Typical Routed Network

To understand VLANs, it is first necessary to have an understanding

of   LANs. A Local Area Network (LAN) can generally be defined as

a   broadcast domain. Hubs, bridges or switches in the same physical

segment or segments connect all end node devices. End nodes can

communicate with each other without the need for a router.

Communications with devices on other LAN segments requires the

use of a router. Figure 1 illustrates a typical LAN environment

connected by routers.

In Figure 1, each LAN is separated from the other by a router. This

represents the current UCDNet topology. The individual LANs and

broadcast domains are represented by the areas bounded by the dotted

lines and numbered 1 through 5 for future reference. Note that the

router interface for each LAN is included as part of the LAN and

broadcast domain.

As networks expand, more routers are needed to separate users into

broadcast and collision domains and provide connectivity to other

LANs. In Figure 1, LANs 4 and 5 illustrate the use of a router to

separate users in a single building into multiple broadcast domains.

One drawback to this design is that routers add latency, which

essentially delays the transmission of data. This is caused by the

process involved in routing data from one LAN to another. A router

must use more of the data packet to determine destinations and route

the data to the appropriate end node.

Virtual LANs (VLANs) can be viewed as a group of devices on

different physical LAN segments which can communicate with each

other as if they were all on the same physical LAN segment. VLANs

provide a number of benefits over the network described in Figure 1,

which we will discuss in the next section. In order to take advantage

of the benefits of VLANs, a different network topology is needed.

Figure 2 - Typical Switched Network

Using the same end nodes as in Figure 1, the switched network in

Figure 2 provides the same connectivity as Figure 1. Although the

network above has some distinct speed and latency advantages over

the network in Figure 1, it also has some serious drawbacks. The most

notable of these for the purposes of this discussion is that all hosts

(end nodes) are now in the same broadcast domain. This adds a

significant amount of traffic to the network that is seen by all hosts on

the network. As this network grows, the broadcast traffic has the

potential impact of flooding the network and making it essentially

unusable.

Switches using VLANs create the same division of the network into

separate broadcast domains but do not have the latency problems of a

router. Switches are also a more cost-effective solution. Figure 3

shows a switched network topology using VLANs.

Figure 3 - Switched Network with VLANs

ADVANTAGES OF VLANS

As we have seen, there are several benefits to using VLANs. To

summarize, VLAN architecture benefits include:

Increased performance

Improved manageability

Network tuning and simplification of software configurations

Physical topology independence

Increased security options

Increased performance

Switched networks by nature will increase performance over shared

media devices in use today, primarily by reducing the size of collision

domains. Grouping users into logical networks will also increase

performance by limiting broadcast traffic to users performing similar

functions or within individual workgroups. Additionally, less traffic

will need to be routed, and the latency added by routers will be

reduced.

Improved manageability

VLANs provide an easy, flexible, less costly way to modify logical

groups in changing environments. VLANs make large networks more

manageable by allowing centralized configuration of devices located

in physically diverse locations.

Network tuning and simplification of software configurations

VLANs will allow LAN administrators to "fine tune" their networks

by logically grouping users. Software configurations can be made

uniform across machines with the consolidation of a department's

resources into a single subnet. IP addresses, subnet masks, and local

network protocols will be more consistent across the entire VLAN.

Fewer implementations of local server resources such

as BOOTP and DHCP will be needed in this environment. These

services can be more effectively deployed when they can span

buildings within a VLAN.

Physical topology independence

VLANs provide independence from the physical topology of the

network by allowing physically diverse workgroups to be logically

connected within a single broadcast domain. If the physical

infrastructure is already in place, it now becomes a simple matter to

add ports in new locations to existing VLANs if a department expands

or relocates. These assignments can take place in advance of the

move, and it is then a simple matter to move devices with their

existing configurations from one location to another. The old ports

can then be "decommissioned" for future use, or reused by the

department for new users on the VLAN.

Increased security options

VLANs have the ability to provide additional security not available in

a shared media network environment. By nature, a switched network

delivers   frames only to the intended recipients, and broadcast frames

only to other members of the VLAN. This allows the network

administrator to segment users requiring access to sensitive

information into separate VLANs from the rest of the general user

community regardless of physical location. In addition, monitoring of

a port with a traffic analyzer will only view the traffic associated with

that particular port, making discreet monitoring of network traffic

more difficult.

It should be noted that the enhanced security that is mentioned above

is not to be considered an absolute safeguard against security

infringements. What this provides is additional safeguards against

"casual" but unwelcome attempts to view network traffic.

ROUTERS & ROUTING

• Routing is:

– Finding a path between a source and

destination (path determination)

– Moving information across an internetwork

from a source to a destination (switching)

– Very complex in large networks because

of the many potential intermediate nodes

• A router is:

– A network layer device that forwards packets

from one network to another and determines

the optimal path for forwarding network traffic

A router is a more sophisticated device than a hub or a switch. It

determines the appropriate network path to send the packet

along by keeping an up-to-date network topology in memory, its

routing table.

Routers keep track of each other’s routes by alternately

listening, and periodically sending, route information

Bridging is faster than Routing, but unlike Bridging, Routing

provides LAN Segmentation, Broadcast Control, Security and

Scalability.

Routing Table192.168.3.0Frame Relay192.168.1.0Ethernet192.168.2.0FDDI

Network 192.168.2.0FDDI

Remote Location

Network 192.168.1.0Ethernet

Main Site

Routers—Layer 3

ROUTERS AT LAYER 3

System Bus

InterfaceNetwork Controller

Interface:Network Controller

Interface:Network Controller

Flash

NVRAM

ROM

CPU

RAMBus

Interface

ROUTER HARDWARE

ROM MonitorDiagnostic, Console Setup, Memory Sizing

Config Register Check.Loads RxBoot, or stays in ROMMON

RxBootBuilds Basic Data Structures, Interface Setup,

Host Mode Functionality, Startup-config Check.Loads CISCO IOS or Stays in RxBoot

Prompt[router (boot)]

IOSInterface Setup, Router Functionality, Allocate Buffers, Loads

Startup-config.Boot Process Completes. [Router>] Prompts Appears

STARTUP PROCEDURE FOR A ROUTER

X Y

AA

BB

CC

Presentation

Data LinkPhysical

Data LinkPhysical

A B C

Data LinkPhysical

Data LinkNetworkTransportSessionPresentationApplication

PhysicalData LinkNetworkTransportSession

Application

Physical

Network Network Network

PACKET FLOW IN ROUTED NETWORK

• Routers encapsulate and de-encapsulate data packets as they are

transferred from system X to system Y

From the OSI model reference point of view -

• The router de-encapsulates and examines the frame to

determine what type of network layer data is being carried.

The network layer data is sent to the appropriate network

layer process, and the frame itself is discarded.

• The network layer process examines the header to

determine the destination network and then references the

routing table that associates networks to outgoing

interfaces.

• The packet is again encapsulated in the link frame for the

selected interface and sent on.

ROUTING PROTOCOLS

A routing protocol is a protocol that specifies how routers

communicate with each other, disseminating information that enables

them to select routes then any two nodes on a computer network, the

choice of the route being done by routing algorithms. Each router has

a priori knowledge only of networks attached to it directly. A routing

protocol shares this information first among immediate neighbors, and

then throughout the network. This way, routers gain knowledge of the

topology of the network.

The term routing protocol may refer specifically to one operating at

layer three of the OSI model, which similarly disseminates topology

information between routers.

Although there are many types of routing protocols, three major

classes are in widespread use on IP networks:

Interior gateway routing via link-state routing protocols, such as

OSPF and IS-IS

Interior gateway routing via path vector or distance vector

protocols, such as RIP, IGRP and EIGRP

Exterior gateway routing. BGP v4 is the routing protocol used

by the public Internet.

Many routing protocols are defined in documents called RFCs.

The specific characteristics of routing protocols include

the manner in which they either prevent routing loops from

forming or break them up if they do

the manner in which they select preferred routes, using

information about hop costs

the time they take to converge

how well they scale up

many other factors

Routed versus routing protocols

In some cases, routing protocols can themselves run over routed

protocols: for example, BGP runs over TCP which runs over IP; care

is taken in the implementation of such systems not to create a circular

dependency between the routing and routed protocols. That a routing

protocol runs over particular transport mechanism does not mean that

the routing protocol is of layer (N+1) if the transport mechanism is of

layer (N). Routing protocols, according to the OSI Routing

framework, are layer management protocols for the network layer,

regardless of their transport mechanism:

IS-IS runs over the data link layer

OSPF, IGRP, and EIGRP run directly over IP; OSPF and

EIGRP have their own reliable transmission mechanism while

IGRP assumed an unreliable transport

RIP runs over UDP

BGP runs over TCP

Examples

Interior routing protocols

Interior Gateway Protocols (IGPs) exchange routing information

within a single routing domain. A given autonomous system can

contain multiple routing domains, or a set of routing domains can be

coordinated without being an Internet-participating autonomous

system. Common examples include:

IGRP:

Interior Gateway Routing Protocol (IGRP) is a distance vector

interior routing protocol (IGP) invented by Cisco. It is used by routers

to exchange routing data within an autonomous system.

IGRP is a proprietary protocol. IGRP was created in part to overcome

the limitations of RIP (maximum hop count of only 15, and a single

routing metric) when used within large networks. IGRP supports

multiple metrics for each route, including bandwidth, delay, load,

MTU, and reliability; to compare two routes these metrics are

combined together into a single metric, using a formula which can be

adjusted through the use of pre-set constants. The maximum hop

count of IGRP-routed packets is 255 (default 100), and routing

updates are broadcast every 90 seconds (by default).

IGRP is considered a classful routing protocol. Because the protocol

has no field for a subnet mask, the router assumes that all interface

addresses within the same Class A, Class B, or Class C network have

the same subnet mask as the subnet mask configured for the interfaces

in question. This contrasts with classless routing protocols that can

use variable length subnet masks. Classful protocols have become less

popular as they are wasteful of IP address space.

EIGRP

Enhanced Interior Gateway Routing Protocol - (EIGRP) is a

Cisco proprietary routing protocol loosely based on their original

IGRP. EIGRP is an advanced distance-vector routing protocol, with

optimizations to minimize both the routing instability incurred after

topology changes, as well as the use of bandwidth and processing

power in the router. Routers that support EIGRP will automatically

redistribute route information to IGRP neighbors by converting the 32

bit EIGRP metric to the 24 bit IGRP metric. Most of the routing

optimizations are based on the Diffusing Update Algorithm (DUAL)

work from SRI, which guarantees loop-free operation and provides a

mechanism for fast convergence.

OSPF:

OSPF is an interior gateway protocol that routes Internet Protocol (IP)

packets solely within a single routing domain (autonomous system). It

gathers link state information from available routers and constructs a

topology map of the network. The topology determines the routing

table presented to the Internet Layer which makes routing decisions

based solely on the destination IP address found in IP datagrams.

OSPF was designed to support variable-length subnet masking

(VLSM) or Classless Inter-Domain Routing (CIDR) addressing

models.

OSPF detects changes in the topology, such as link failures, very

quickly and converges on a new loop-free routing structure within

seconds. It computes the shortest path tree for each route using a

method based on Dijkstra's algorithm, a shortest path first algorithm.

The link-state information is maintained on each router as a link-

state database (LSDB) which is a tree-image of the entire network

topology. Identical copies of the LSDB are periodically updated

through flooding on all OSPF routers.

The OSPF routing policies to construct a route table are governed by

link cost factors (external metrics) associated with each routing

interface. Cost factors may be the distance of a router (round-trip

time), network throughput of a link, or link availability and reliability,

expressed as simple unit less numbers. This provides a dynamic

process of traffic load balancing between routes of equal cost.

An OSPF network may be structured, or subdivided, into routing

areas to simplify administration and optimize traffic and resource

utilization. Areas are identified by 32-bit numbers, expressed either

simply in decimal, or often in octet-based dot-decimal notation,

familiar from IPv4 address notation.

By convention, area 0 (zero) or 0.0.0.0 represents the core or

backbone region of an OSPF network. The identifications of other

areas may be chosen at will, often, administrators select the IP address

of a main router in an area as the area's identification. Each additional

area must have a direct or virtual connection to the backbone OSPF

area. Such connections are maintained by an interconnecting router,

known as area border router (ABR). An ABR maintains separate link

state databases for each area it serves and maintains summarized

routes for all areas in the network.

OSPF does not use a TCP/IP transport protocol (UDP, TCP), but is

encapsulated directly in IP datagrams with protocol number 89. This

is in contrast to other routing protocols, such as the Routing

Information Protocol (RIP), or the Border Gateway Protocol (BGP).

OSPF handles its own error detection and correction functions.

OSPF uses multicast addressing for route flooding on a broadcast

network link. For non-broadcast networks special provisions for

configuration facilitate neighbor discovery. OSPF multicast IP

packets never traverse IP routers, they never travel more than one

hop. OSPF reserves the multicast addresses 224.0.0.5 for IPv4 or

FF02::5 for IPv6 (all SPF/link state routers, also known as

AllSPFRouters) and 224.0.0.6 for IPv4 or FF02::6 for IPv6

(all Designated Routers, AllDRouters), as specified in RFC 2328

and RFC 5340.

For routing multicast IP traffic, OSPF supports the Multicast Open

Shortest Path First protocol (MOSPF) as defined in RFC 1584.[5]

Neither Cisco nor Juniper Networks include MOSPF in their OSPF

implementations. PIM (Protocol Independent Multicast) in

conjunction with OSPF or other IGPs, (Interior Gateway Protocol), is

widely deployed.

The OSPF protocol, when running on IPv4, can operate securely

between routers, optionally using a variety of authentication methods

to allow only trusted routers to participate in routing. OSPFv3,

running on IPv6, no longer supports protocol-internal authentication.

Instead, it relies on IPv6 protocol security (IPsec).

OSPF version 3 introduces modifications to the IPv4 implementation

of the protocol.[2] Except for virtual links, all neighbor exchanges use

IPv6 link-local addressing exclusively. The IPv6 protocol runs per

link, rather than based on the subnet. All IP prefix information has

been removed from the link-state advertisements and from the Hello

discovery packet making OSPFv3 essentially protocol-independent.

Despite the expanded IP addressing to 128-bits in IPv6, area and

router identifications are still based on 32-bit values.

RIP:

RIP is a distance-vector routing protocol, which employs the hop

count as a routing metric. The hold down time is 180 seconds. RIP

prevents routing loops by implementing a limit on the number of hops

allowed in a path from the source to a destination. The maximum

number of hops allowed for RIP is 15. This hop limit, however, also

limits the size of networks that RIP can support. A hop count of 16 is

considered an infinite distance and used to deprecate inaccessible,

inoperable, or otherwise undesirable routes in the selection process.

RIP implements the split horizon, route poisoning and holddown

mechanisms to prevent incorrect routing information from being

propagated. These are some of the stability features of RIP. It is also

possible to use the so called RIP-MTI (Minimal Topology

Information) algorithm to cope with the count to infinity problem.

With its help, it is possible to detect every possible loop with a very

small computation effort.

Originally each RIP router transmitted full updates every 30 seconds.

In the early deployments, routing tables were small enough that the

traffic was not significant. As networks grew in size, however, it

became evident there could be a massive traffic burst every 30

seconds, even if the routers had been initialized at random times. It

was thought, as a result of random initialization, the routing updates

would spread out in time, but this was not true in practice. Sally Floyd

and Van Jacobson showed in 1994 that, without slight randomization

of the update timer, the timers synchronized over time. In most

current networking environments, RIP is not the preferred choice for

routing as its time to converge and scalability are poor compared to

EIGRP, OSPF, or IS-IS (the latter two being link-state routing

protocols), and (without RIP-MTI) a hop limit severely limits the size

of network it can be used in. However, it is easy to configure, because

RIP does not require any parameters on a router unlike other

protocols.

RIP is implemented on top of the User Datagram Protocol as its

transport protocol. It is assigned the reserved port number 520.

Versions

There are three versions of the Routing Information Protocol: RIPv1,

RIPv2, and RIPng.

RIP version 1

The original specification of RIP, defined in RFC 1058, uses classful

routing. The periodic routing updates do not carry subnet information,

lacking support for variable length subnet masks (VLSM). This

limitation makes it impossible to have different-sized subnets inside

of the same network class. In other words, all subnets in a network

class must have the same size. There is also no support for router

authentication, making RIP vulnerable to various attacks.The RIP

version 1 works when there is only 16 hop counts(0-15).If there are

more than 16 hops between two routers it fails to send data packets to

the destination address.

RIP version 2

Due to the deficiencies of the original RIP specification, RIP version

2 (RIPv2) was developed in 1993 and last standardized in 1998. It

included the ability to carry subnet information, thus supporting

Classless Inter-Domain Routing (CIDR). To maintain backward

compatibility, the hop count limit of 15 remained. RIPv2 has facilities

to fully interoperate with the earlier specification if all Must Be Zero

protocol fields in the RIPv1 messages are properly specified. In

addition, a compatibility switch feature allows fine-grained

interoperability adjustments.

In an effort to avoid unnecessary load on hosts that do not participate

in routing, RIPv2 multicasts the entire routing table to all adjacent

routers at the address 224.0.0.9, as opposed to RIPv1 which uses

broadcast. Unicast addressing is still allowed for special applications.

(MD5) authentication for RIP was introduced in 1997.

RIPv2 is Internet Standard STD-56.

Route tags were also added in RIP version 2. This functionality

allows for routes to be distinguished from internal routes to external

redistributed routes from EGP protocols.

RIPng

RIPng (RIP next generation), defined in RFC 2080, is an extension of

RIPv2 for support of IPv6, the next generation Internet Protocol. The

main differences between RIPv2 and RIPng are:

Support of IPv6 networking.

While RIPv2 supports RIPv1 updates authentication, RIPng

does not. IPv6 routers were, at the time, supposed to use IPsec

for authentication.

RIPv2 allows attaching arbitrary tags to routes, RIPng does not;

RIPv2 encodes the next-hop into each route entries, RIPng

requires specific encoding of the next hop for a set of route

entries.xxx

IS-IS:

IS-IS is an Interior Gateway Protocol (IGP) meaning that it is

intended for use within an administrative domain or network. It is not

intended for routing between Autonomous Systems (RFC 1930), a job

that is the purpose of an Exterior Gateway Protocol, such as Border

Gateway Protocol (BGP).

IS-IS is a link-state routing protocol, meaning that it operates by

reliably flooding Link State information throughout a network of

routers. Each router then independently builds a picture of the

network's topology. Packets or datagrams are forwarded based on the

best topological path through the network to the destination.

IS-IS uses Dijkstra's algorithm for computing the best path through

the network.

LAN

SWITCHING

LAN switching is a form of packet switching used in local area

networks. Switching technologies are crucial to network design, as

they allow traffic to be sent only where it is needed in most cases,

using fast, hardware-based methods.

Layer 2 switching

Layer 2 switching is hardware based, which means it uses the media

access control address (MAC address) from the host's network

interface cards (NICs) to decide where to forward frames. Switches

use application-specific integrated circuits (ASICs) to build and

maintain filter tables (also known as MAC address tables). One way

to think of a layer 2 switch is as a multiport bridge.

Layer 2 switching provides the following

Hardware-based bridging (MAC)

Wire speed

High speed

Low latency

Low cost

Layer 2 switching is highly efficient because there is no modification

to the data packet, only to the frame encapsulation of the packet, and

only when the data packet is passing through dissimilar media (such

as from Ethernet to FDDI). Layer 2 switching is used for workgroup

connectivity and network segmentation (breaking up collision

domains). This allows a flatter network design with more network

segments than traditional 10BaseT shared networks. Layer 2

switching has helped develop new components in the network

infrastructure

Server farms — Servers are no longer distributed to physical

locations because virtual LANs can be created to create

broadcast domains in a switched internetwork. This means that

all servers can be placed in a central location, yet a certain

server can still be part of a workgroup in a remote branch, for

example.

Intranets — Allows organization-wide client/server

communications based on a Web technology.

These new technologies allow more data to flow off from local

subnets and onto a routed network, where a router's performance can

become the bottleneck.

Limitations

Layer 2 switches have the same limitations as bridge networks.

Bridges are good if a network is designed by the 80/20 rule: users

spend 80 percent of their time on their local segment.

Bridged networks break up collision domains, but the network

remains one large broadcast domain. Similarly, layer 2 switches

(bridges) cannot break up broadcast domains, which can cause

performance issues and limits the size of your network. Broadcast and

multicasts, along with the slow convergence of spanning tree, can

cause major problems as the network grows. Because of these

problems, layer 2 switches cannot completely replace routers in the

internetwork.

Layer 3 switching

The only difference between a layer 3 switch and router is the way the

administrator creates the physical implementation. Also, traditional

routers use microprocessors to make forwarding decisions, and the

switch performs only hardware-based packet switching. However,

some traditional routers can have other hardware functions as well in

some of the higher-end models. Layer 3 switches can be placed

anywhere in the network because they handle high-performance LAN

traffic and can cost-effectively replace routers. Layer 3 switching is

all hardware-based packet forwarding, and all packet forwarding is

handled by hardware ASICs. Layer 3 switches really are no different

functionally than a traditional router and perform the same functions,

which are listed here

Determine paths based on logical addressing

Run layer 3 checksums (on header only)

Use Time to Live (TTL)

Process and respond to any option information

Update Simple Network Management Protocol (SNMP)

managers with Management Information Base (MIB)

information

Provide Security

The benefits of layer 3 switching include the following

Hardware-based packet forwarding

High-performance packet switching

High-speed scalability

Low latency

Lower per-port cost

Flow accounting

Security

Quality of service (QoS)

Layer 4 switching

Layer 4 switching is considered a hardware-based layer 3 switching

technology that can also consider the application used (for example,

Telnet or FTP).

Layer 4 switching provides additional routing above layer 3 by using

the port numbers found in the Transport layer header to make routing

decisions.

These port numbers are found in Request for Comments (RFC) 1700

and reference the upper-layer protocol, program, or application.

Layer 4 information has been used to help make routing decisions for

quite a while. For example, extended access lists can filter packets

based on layer 4 port numbers. Another example is accounting

information gathered by NetFlow switching in Cisco's higher-end

routers.

The largest benefit of layer 4 switching is that the network

administrator can configure a layer 4 switch to prioritize data traffic

by application, which means a QoS can be defined for each user.

For example, a number of users can be defined as a Video group and

be assigned more priority, or band-width, based on the need for video

conferencing.

Multi-layer switching (MLS)

Multi-layer switching combines layer 2, 3, and 4 switching

technologies and provides high-speed scalability with low latency. It

accomplishes this high combination of high-speed scalability with

low latency by using huge filter tables based on the criteria designed

by the network administrator.

Multi-layer switching can move traffic at wire speed and also provide

layer 3 routing, which can remove the bottleneck from the network

routers. This technology is based on the idea of "route once, switch

many".

Multi-layer switching can make routing/switching decisions based on

the following

MAC source/destination address in a Data Link frame

IP source/destination address in the Network layer header

Protocol field in the Network layer header

Port source/destination numbers in the Transport layer header

There is no performance difference between a layer 3 and a layer 4

switch because the routing/switching is all hardware based.

VIRTUAL PRIVATE NETWORKS

(VPN)

History

A virtual private network (VPN) links two computers through an

underlying local or wide-area network, while encapsulating the data

and keeping it private. It is analogous to a pipe within a pipe. Even

though the outer pipe contains the inner one, the inner pipe has a wall

that blocks other traffic in the outer pipe. To the rest of the network,

the VPN traffic just looks like another traffic stream.

The term VPN can describe many different network configurations

and protocols. Some of the more common uses of VPNs are described

below, along with the various classification schemes and models

VPN classification

VPN technologies have myriad protocols, terminologies and

marketing influences that define them. For example, VPN

technologies can differ in:

The protocols they use to tunnel the traffic

The tunnel's termination point, i.e., customer edge or network

provider edge

Whether they offer site-to-site or remote access connectivity

The levels of security provided

The OSI layer they present to the connecting network, such as

Layer 2 circuits or Layer 3 network connectivity

Security mechanism

Secure VPNs use cryptographic tunneling protocols to

provide confidentiality by blocking intercepts and packet sniffing,

allow sender authentication to block identity spoofing, and

provide message integrity by preventing message alteration.

Secure VPN protocols include the following:

IPsec (Internet Protocol Security) was originally developed

for IPv6, which requires it. This standards-based security

protocol is also widely used with IPv4. L2TP frequently runs

over IPsec.

Transport Layer Security (SSL/TLS) can tunnel an entire

network's traffic, as it does in the OpenVPN project, or secure

an individual connection. A number of vendors provide remote

access VPN capabilities through SSL. An SSL VPN can connect

from locations where IPsec runs into trouble with Network

Address Translation and firewall rules. However, SSL-based

VPNs use Transmission Control Protocol (TCP) and so may be

vulnerable to denial-of-service attacks because TCP connections

do not authenticate.

Datagram Transport Layer Security (DTLS) is used in Cisco's

next-generation VPN product, Cisco AnyConnect VPN, to solve

the issues SSL/TLS has with tunneling TCP over TCP.

Microsoft's Microsoft Point-to-Point Encryption (MPPE) works

with their PPTP and in several compatible implementations on

other platforms.

Microsoft introduced Secure Socket Tunneling Protocol (SSTP)

in Windows Server 2008 and Windows Vista Service Pack 1.

SSTP tunnels Point-to-Point Protocol (PPP) or L2TP traffic

through anSSL 3.0 channel.

MPVPN (Multi Path Virtual Private Network).

Secure Shell (SSH) VPN -- OpenSSH offers VPN tunneling to

secure remote connections to a network or inter-network links.

This should not be confused with port forwarding. OpenSSH

server provides limited number of concurrent tunnels and the

VPN feature itself does not support personal authentication

ONGC – NETWORK DIAGRAMS

LOTUS - THE MAILING SYSTEM AT

ONGC

Lotus Software (called Lotus Development Corporation before its

acquisition by IBM) is a software company with headquarters in

Westford, Massachusetts.

Lotus is most commonly known for the Lotus 1-2-3 spreadsheet

application, the first feature-heavy, user-friendly, reliable and

WYSIWYG-enabled product to become widely available in

The early days of the IBM PC, when there was no Graphical user

interface. Such a useful tool certainly helped to spread the adoption of

the PC, both for administrative and scientific applications. Much later,

in conjunction with Ray Ozzie's Iris Associates, Lotus also released a

groupware and email system, Lotus Notes. IBM purchased the

company in 1995 for $3.5 billion, primarily to acquire Lotus Notes

and to establish a presence in the increasingly important client–server

computing segment, which was rapidly making host-based products

like IBM's Office Vision obsolete.

Features

Lotus Notes can be used for email, calendaring, PIM, instant

messaging, Web browsing, and a variety of feature-rich custom

applications. It can be used to access both local- and server-based

applications and data. The current version of Lotus Notes is 8.5.

In the early days of the product, the most common applications were

threaded discussions and simple contact management databases.

Today, Notes also provide blogs, wikis, RSS aggregators, CRM and

Help Desk systems, and organizations can build a variety of custom

applications for Notes using Domino Designer.

Lotus Notes can be used as an IMAP and POP e-mail client with non-

Domino mail servers. Recipient addresses can be retrieved from any

LDAP server, including Active Directory. The client also does web

browsing, although it can be configured to launch the default browser

instead.

Features include group calendaring and scheduling, SMTP/MIME-

based e-mail, NNTP-based news support, and automatic HTML

conversion of all documents by the Domino HTTP task.

Notes integration with IBM's Sametime instant messaging allows

users to see other users online and chat with one or more of them at

the same time. Beginning with Release 6.5 this functionality is built

into Notes and presence awareness is available in email and other

Notes applications for users in organizations that use both Notes and

Same time.

Since version 7, Notes has provided a web services interface. Domino

can be a web server for HTML files too; authentication of access to

Domino databases or HTML files uses Domino's own user directory

and external systems such as Microsoft's Active Directory.

A design client is available to allow rapid development of databases

consisting of forms, which allow users to create documents; and

views, which display selected document fields in columns.

In addition to being a groupware system (e-mail, calendaring, shared

documents and discussions), Notes/Domino is also a platform for

developing customized client–server and web applications. Its use of

design constructs and code allows easier construction of "workflow"-

type applications, which typically have complex approval processes

and routing of data.

Since Release 5, Lotus server clustering has been able to provide

geographic redundancy for servers.

Important files of Lotus

NOH.INI

NAMES.NIF

BOOKMARK.NSF

DESKTOP.NDK

ID FILE

ARCHIEVE.NSF

ONGC is using Lotus as their official mailing system

CONCLUSION

Computer Network can be used for numerous services, both for

organization and individuals. For organization, network of personal

computer using shared servers often provide access to corporate

information. Typically they follow the client- server model with

client workstation on employee desktop accessing powerful servers in

the machine room. For individual, network offer access the internet

by calling up an ISP using a modem although increasingly many

people have a fixed connection at home. An up and coming area is

wireless networking with new application such as mobile e-mail and

m- commerce

Roughly speaking, network can be divided up into LANs, MANs,

WANs and internetworks with their own characteristics,

technologies, speed and niches.

Network software consists of protocols, which are rules by which

processes communicate. Protocols are either connectionless or

connection oriented, most network support hierarchies, with each

layer providing service to the layer above it and insulating them from

the details of protocol used in the lower layers.