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  1. 1. Internship report Rutger Rienks (9706291) Internship report from Rutger Rienks (9706291) ‘Decision making and research during the construction of VOIP network components’ January 30th 2002 - April 28th 2002 Surya Infotech Suite 7B, Kirti Towers, Tilak Road, Baroda, India Company supervisor: Mr. Parag Amin Internship supervisor: Mr. Job Zwiers Surya Infotech, Baroda, India
  2. 2. Internship report Rutger Rienks (9706291) Surya Infotech, Baroda, India 2
  3. 3. Internship report Rutger Rienks (9706291) Surya Infotech, Baroda, India 3
  4. 4. Internship report Rutger Rienks (9706291) Summary This report describes the AIESEC Internship from Rutger Rienks at Surya Infotech, an IT company based in Baroda, India. The goal of the Internship was to keep the level of knowledge about the emerging VOIP world on the side of Surya Infotech on such a level, to be able to improve and discuss the work performed and the decisions made by the students participating in ‘Project VOIP’ from Nirma’s Center of excellence based in Ahmedabad, India. After three month the project started implementing and designing an IP Phone and for an IP Gateway all specifications and options were defined. The decision to start developing the gateway was pending on funds. But furthermore all students had achieved great results. The understanding of the technology had grown from nothing to sufficient to start implementing. This was achieved by choosing components which were considered the best amongst all the various components needed. From the internship point of view, expanding knowledge by understanding the various components as well as helping the company in making choices and debating on technical and economical topics regarding their project was an experience hard to forget. The complete project positively contributed to personal development and the acquisition of new skills. The time in India was one of great contrasts. Poverty on the streets and malicious systems everywhere around influenced the way of handling and feelings about things. The absurd richness of a very small minority and the total different culture on the other hand were an absolute eye opener. Good was it to see that lots of good initiatives are taken to heal the illnesses of the country. This all inclusive made it, together with the Indian working environment and the nice people, that it was a time never to be forgotten. Surya Infotech, Baroda, India 4
  5. 5. Internship report Rutger Rienks (9706291) Table of contents Table of contents......................................................................................................................................................................5 1. Introduction..........................................................................................................................................................................8 2. The Internship......................................................................................................................................................................9 Personal expectations...........................................................................................................................................................9 AIESEC..........................................................................................................................................................................10 The country.........................................................................................................................................................................10 India................................................................................................................................................................................10 Baroda............................................................................................................................................................................11 3. The riots..............................................................................................................................................................................12 Background.........................................................................................................................................................................12 What happened in Baroda .................................................................................................................................................14 Corporate Profile ..............................................................................................................................................................15 The working environment...................................................................................................................................................16 Introduction........................................................................................................................................................................18 Nirma Institute....................................................................................................................................................................18 The Nirma centre of excellence.....................................................................................................................................19 The goal of the project........................................................................................................................................................19 The way of working.............................................................................................................................................................19 Involving experts............................................................................................................................................................20 6. An Introduction to VOIP..................................................................................................................................................21 Introduction to IP telephony...............................................................................................................................................21 Why VOIP......................................................................................................................................................................21 The origin.......................................................................................................................................................................22 The (future) applications................................................................................................................................................22 The technology...............................................................................................................................................................23 Example network................................................................................................................................................................23 7. A closer look at the major VOIP network components.................................................................................................25 H.323..................................................................................................................................................................................25 RSVP...................................................................................................................................................................................26 G.168..................................................................................................................................................................................26 G.723.1...............................................................................................................................................................................27 Surya Infotech, Baroda, India 5
  6. 6. Internship report Rutger Rienks (9706291) T.37/T38..............................................................................................................................................................................27 8. The IP Phone reference design.........................................................................................................................................29 The IP Phone hardware architecture reference design......................................................................................................29 The IP Phone software architecture reference design.......................................................................................................30 User interface software..................................................................................................................................................31 Voice processing software.............................................................................................................................................32 Telephony signaling gateway software..........................................................................................................................34 Network management software......................................................................................................................................35 Network interface software............................................................................................................................................36 System services software...............................................................................................................................................36 9. The IP Gateway reference design.....................................................................................................................................38 The IP Gateway hardware reference design......................................................................................................................38 Microprocessor...............................................................................................................................................................38 DSP resources................................................................................................................................................................39 PSTN Interface Modules................................................................................................................................................39 Packet or network Interface Modules............................................................................................................................39 Things not to forget........................................................................................................................................................39 Backplane Interface........................................................................................................................................................39 Alarm Monitor & Control (M&C) Module....................................................................................................................39 Call Processing Modules................................................................................................................................................39 The IP Gateway software reference design........................................................................................................................41 10. The progress: from one phase to another......................................................................................................................43 Phase 1: The initial sessions..............................................................................................................................................43 The work at Nirma.........................................................................................................................................................43 The work from our side..................................................................................................................................................43 Phase 2: Comparison.........................................................................................................................................................44 The work at Nirma.........................................................................................................................................................44 The work at our side.......................................................................................................................................................45 Phase 3: Which products to build?.....................................................................................................................................45 IP Phone, IP Gateway and IPPBX.................................................................................................................................46 The work at Nirma.........................................................................................................................................................46 The work at our side.......................................................................................................................................................46 Phase 4: Which building blocks to use for our products?..................................................................................................47 The work at Nirma.........................................................................................................................................................47 The work at our end.......................................................................................................................................................47 Phase 5: The later decisions and the future.......................................................................................................................49 11. Evaluation ........................................................................................................................................................................50 The company.......................................................................................................................................................................50 The traineeship...................................................................................................................................................................51 Surya Infotech, Baroda, India 6
  7. 7. Internship report Rutger Rienks (9706291) India in general..................................................................................................................................................................53 The time with AIESEC and the trainees.............................................................................................................................53 12. Conclusion........................................................................................................................................................................56 13. Recommendations............................................................................................................................................................57 The project..........................................................................................................................................................................57 The company.......................................................................................................................................................................57 AIESEC...............................................................................................................................................................................58 14. Literature en references*................................................................................................................................................60 APPENDIX A “ A comparison between SIP and H323”............................................................................................63 Introduction........................................................................................................................................................................63 Introduction to H323......................................................................................................................................................63 Introduction to SIP.........................................................................................................................................................63 Background....................................................................................................................................................................63 Reliability.......................................................................................................................................................................63 Extensibility...................................................................................................................................................................64 Scalability.......................................................................................................................................................................64 Capability.......................................................................................................................................................................64 Message definition.........................................................................................................................................................65 Message encoding..........................................................................................................................................................65 Billing.............................................................................................................................................................................65 Call setup........................................................................................................................................................................65 PSTN Integration...........................................................................................................................................................65 Conclusion..........................................................................................................................................................................66 APPENDIX B “A comparison amongst MEGACO gateways”.......................................................................................67 APPENDIX C “A comparison amongst IP Phones”.......................................................................................................70 APPENDIX D “ATMEL and TI IP Phone chipsets compared”.....................................................................................71 APPENDIX E “The Gateway Specifications”...................................................................................................................73 APPENDIX F “The IP Phone Specifications”.................................................................................................................74 Surya Infotech, Baroda, India 7
  8. 8. Internship report Rutger Rienks (9706291) 1. Introduction This report is consists of four major sections, the fist part consisting out of four chapters explains about the background of the internship, the riots during the internship, the company and the internship itself. Chapter two focuses on the expectations of the traineeship, AIESEC as an organization providing the traineeship and it gives background information about India and Baroda, respectively the country and city of where the company is based. During the traineeship there were riots in Baroda that affected the community. Information about the riots and the political background can be found in chapter three. In chapter four the company in general is discussed, it tells about its working conditions and its people. To conclude the first part, chapter five explains the organization of the internship and the targets that had to be met. The second part describes theory about the upcoming VOIP-networks is in general. Chapter six gives an introduction to VOIP. The reasons why VOIP is expected to become a booming business in the coming years as well as the (future) applications are addressed. In chapter seven a closer look at some of the protocols used in a VOIP environment is given. Important issues like H323, RSVP and codec protocols are discussed. In the chapters eight and nine a reference design is given for both software and hardware implementation for the phone and the gateway. The third part which consists of chapter ten describes the development process; it explains about the decisions made and gives an overview of the work done from our side as well as from the side of the institute divided into different phases. It is made clear how we decided on the products that had to be developed, how we were going to develop them and with what building blocks. The fourth and final part evaluates the traineeship in chapter eleven. Conclusions of the project are given in chapter twelve and chapter thirteen concludes the report by giving recommendations to all the organizations involved during the traineeship. Surya Infotech, Baroda, India 8
  9. 9. Internship report Rutger Rienks (9706291) 2. The Internship In this introduction a description is given about the expectations of the internship that existed before any action was taken, how the internship was obtained from AIESEC and how the country as well as the city during the stay in India was like. Personal expectations Since the university curriculum demands from their students that they have to gain some practical experience in the field, everyone has to leave the college campus for three month. In these three months you are to be confronted with a working situation in a real company, this as an addition to the regular, more theoretical, courses. My expectations were a quite unsure. I had always been able to complete my exams, but programming in a serious way on my own, apart from websites, I had actually never done. Nor had I participated in a project being the only one responsible for the deliverables. So therefore I was quite excited. During my first four years at the university I had done a lot of extracurricular activities. Most of them dealt with the European student association AEGEE-Enschede. Here, after being a member of several committees and even joining the board in 1999, it became clear to me that I really liked to be confronted with different people coming from different countries. Their different approach to solving problems and being confronted with another world view really intrigued me during these years. Hence I came up with the plan to apply for the AIESEC exchange program. They offered a unique chance to combine both an internship as well as an international experience. I applied and enrolled. My expectations of working in the company where I would end up, was working hard on an IT project all day, being flexible and show them my best side. Eager to learn something new, gaining experience and fulfill both mine as well as their expectations where the main goals. What I expected regarding the working conditions were, although knowing the destination being India, like normal standards, working 40 hours a week, having a normal table with a decent computer etc. On the salary part I didn’t really mind what the company would pay. The Internship had to be done, not short for money, I didn’t care. It was all about the experience! Surya Infotech, Baroda, India 9
  10. 10. Internship report Rutger Rienks (9706291) AIESEC AIESEC is the world’s largest student association and is spread through 83 countries, covering 800 universities worldwide. [@11] The facilitation of global student exchange through traineeships is one of their key assets, offering both voluntary as well as commercial traineeships; they undoubtedly have a lot to offer. Their mission is to contribute to the development of the countries and their people with an overriding commitment to international understanding and co-operation. AIESEC assures that ‘The experience of a traineeship will undoubtedly affect the trainee forever’ in such a way that the experience where you have gone through is not one easily to be forgotten. ‘The new concepts the trainee acquires combined with the confrontation of mindsets from trainees coming from all over the world will change the way of reasoning and acting underlining the mission.’ All this really suited my ears and off I was. The country The city where the company of my traineeship was based is called Baroda, a ‘normal’ sized Indian city. This paragraph gives a brief overview of the India as well as Baroda. India The civilization of the valley of the river Indus between the Himalayas, Myanmar and Afghanistan is one of the oldest in the world and goes back at least 5,000 years. Aryan tribes from the northwest invaded the land in about 1500 B.C. The Inhabitants from that era created the classical Indian culture. By the 19th century, The British colonized the Indian lands by defeating all the different empires. One of these Empires was the Mughal Empire. One of these Mughal Kings was responsible for India’s main monument to be built: ‘The Taj Mahal’. Mahatma Gandhi and his nonviolent resistance to British colonialism led to independence in 1947. The subcontinent was divided into the state of India, containing most of the Hindus, and into the smaller Muslim state of Pakistan. After a third war between the two countries in 1971 this also resulted in East Pakistan becoming the nation of Bangladesh. Fundamental concerns in India include the ongoing dispute with Pakistan over Kashmir and the massive overpopulation of over one billion people living on 3.3 million square kilometers, especially in the big cities such as Bombay having 18 million inhabitants. Environmental degradation, extensive poverty (A GDP per capita from $2,200 vs. $24.400 in the Netherlands), and ethnic strife are other main concerns. All of this despite impressive gains in economic investment and output. Surya Infotech, Baroda, India 10
  11. 11. Internship report Rutger Rienks (9706291) Baroda Baroda is situated in one of the western states of India, in Gujarat. Baroda has a rich historical background. The historian can trace Baroda’s history over 2000 years back. However, the recent situation actually originated where the Mughal rule over the city came to an end in 1732. This happened when Pilaji brought the Maratha activities in Southern Gujarat to a head and finally captured the city. Except for a short break, Baroda continued to be in the hands of the Gaekwads from 1734 to 1949. The greatest period in the Maratha rule of Baroda started with the accession of Maharaja Sayajirao III in 1875. It was an era of great progress and constructive achievements in all fields. It was the Maharadja who visualized a general scheme of development in all branches of knowledge, with the Maharaja Sayajirao University of Baroda as absolute crown. Modern Baroda owes its beauty, its educational institutions and its masterpieces of architecture, like the arts faculty (having the second biggest dome in India) to the vision of this great ruler. The city has built further on the academic infrastructure established by him. The present educational foundation rests on over 20 public schools and over 100 private schools. The university has around 30.000 students. As you could say, Baroda is synonymous with education. Figure 1: ‘The Baroda arts faculty’ The people of Baroda like to tell visitors that their city is a ‘Sanskari Nagari’, that is, a ‘cultured city’. The city has rich cultural traditions. And today’s Barodians have quite a full and hectic cultural life throughout the year. Nowadays Baroda is having almost 2 million inhabitants. Surya Infotech, Baroda, India 11
  12. 12. Internship report Rutger Rienks (9706291) 3. The riots During the stay in Baroda, all the trainees were confronted with circumstances that they were not used to. Besides from the cultural differences, the situation even became totally unsafe. Riots started from February 28thth onwards in the complete state of Gujarat between Hindu’s and Muslims killing more than 1000 people. All the trainees, including myself, were forced to stay indoors for several days. This chapter gives background information on the origin of the riots and tells how we, as a group of trainees dealt with the situation. Background Ayodhya is the capital of the descendants of Suryavanshi (Sun dynasty) and said to be the birthplace of the Hindu god Rama is a city full of temples that inhabits a majority of Hindu people. Mir Baqi, a Mughal governor, decided to build a mosque in Ayodhya. This happening took place from 1528 until 1529. The reason for this was to praise Babar, the founder of the Mughal Empire. From this moment in time, the land where the mosque was build has turned out to be a bone of contention between Hindus and Muslims. The district Magistrate of Ayodhya declared the mosque a disputed property after a statue of Rama, a Hindu god, miraculously appeared in the mosque on December 22nd 1949 which Hindus called a miracle. Following a petition, the magistrate on January 5th 1950 ordered locking the doors of the mosque and appointed Ayodhya Municipal Corporation as a receiver in the case. It was on February 1st, 1986 the district judge on recommendation by the district collector ordered opening of the locks of the disputed site to the Hindus for prayers. Congress led Rajiv Gandhi government supported this move. The Vishwa Hindu Parishad (VHP), a political party, announced in 1986 about its plan to carry out shilanyas (laying foundation stones for a Hindu temple) at the site. The Government agreed to the shilanyas and the VHP carried out the program on November 11, 1986. The Kalyan Singh government on October 7th 1991 acquired the land in the premises of the site, which Muslims claim to be holy property. The VHP announced its plan to go ahead with temple construction at Ayodhya and announced Kar Sewa (initiating the building process by acquiring volunteers or Kar Sewaks) on December 6, 1992. Kar Sewaks entered the disputed structure and demolished it. The demolition of the disputed structure led to violence in several parts of India and the Government later acquired the land adjoining the site. In 2001, the VHP decided to go ahead with construction of Ram Temple at Ayodhya from March 12th, 2002. VHP announced schedule for Purna Ahuti yagya (another ritual) and Kar Sewaks assembled in Ayodhya on February 2002. Tension gripped the country after the Surya Infotech, Baroda, India 12
  13. 13. Internship report Rutger Rienks (9706291) Sabarmati Express, (a train) carrying Kar Sewaks returning from Ayodhya was burnt in Godhra, Gujarat on February 28th. This incident commenced the series of riots that lasted until the day that I left. Surya Infotech, Baroda, India 13
  14. 14. Internship report Rutger Rienks (9706291) What happened in Baroda From the moment that the actual violence broke out in the state, all the trainees expected that it would pass away quickly and everyone was hopeful that the situation would return normal very soon. After a couple of days however more incidents of violence were reported and people in the city started to burn shops. The spiral went on for a couple of days as over a 100 shops were burnt and 20 people were killed in Baroda. This despite the fact that the police imposed curfew in several area’s in the city. Luckily the majority of the violence took place in the old city and houses and areas from the trainees weren’t directly involved. After two more days the army was send to Ahmedabad and Baroda in order to restore peace. ‘Shoot at sight’ were the instructions for the army man. Everyone had to stay at home for four days on end, dependant on the media and the food in store. After two days of sitting at home and reading books, we decided to go out on the streets to see whether we could buy some food somewhere in the neighborhood. Living on nothing but cookies and some lemonade for two days was long enough. Ellora Park, the neighborhood where I stayed was quite far from the old city, where most of the violence happened. Some of the shops in the streets luckily had their iron roll curtains half open but long queues were standing in front. We managed to buy some food and stuff here though, which made the following days slightly more comfortable. The days at home brought the trainees closer together and even one evening we spend with a small party. The fifth day the tension became less, the curfew was relaxed and we were all able to return to work again. In the days that followed, now and then the curfew was imposed again, depending on the violence of the previous day. The streets in most of the city parts were deserted due to the curfews. The atmosphere remained tense and some of the trainees wanted to return home. With the newspaper as the only resource for information we did not really know what was going on. This made the situation very strange. On one hand everyone was aware that huge clashes were going on outside in the streets, but on the other hand we couldn’t do anything. Seeing the city burning from the rooftop was a terrible sight. My company demanded from their employees to show up for four Sundays on end to compensate for the days lost during the major gulf of violence. And so we did. At this time of writing the violence still is not over and communal clashes are still going on. Now and then curfew is imposed again and in the old city a permanent curfew from 23:00 in the evening is still issued. Rumors are going that the police in Ahmedabad are instructed by the local political parties to misinform the army and prevent them from stopping the riots. Hopefully peace will come back quickly and things can turn back to normal. Surya Infotech, Baroda, India 14
  15. 15. Internship report Rutger Rienks (9706291) 4. The Company In this chapter Surya Infotech, the company where I had my internship, is introduced by looking on some previous and on going projects. Furthermore the working conditions in the company are discussed. Corporate Profile Surya InfoTech Private Limited is an information technology solutions company and a subsidiary of a US based technology and research corporation RADIQAL, LLC“ The company is providing cutting edge technology solutions to large international companies in the areas of satellite communications, gaming and wagering, mobile commerce, ebusiness, Video on Demand (VoD) and financial markets“. [@16] Surya InfoTech is a specialized software and technology solutions provider and has developed applications that are patent protected and copyrighted . Figure 2: ‘The logo of Surya Infotech’ Currently the company is working on a product that provides real time video on demand services to their clients and comprises of industry leading technologies like personal VCR (PVR), record on demand and 20 channel simultaneous video broadcast servers. Applications have been developed for global GSM service providers to enable them in providing services like mobile banking; mobile commerce and SMSC based transaction clearance systems to clear credit and debit card transactions. Surya InfoTech is involved with the regional academic institutes and partner with them in developing leading edge technologies like VoIP Phone, VoIP Enterprise Gateway and VoIP IPPBX. These systems are state of the art telecommunications solutions and are developed by students and faculty of nationally recognized universities along with technical know how and mentoring from companies like them. By helping the state government in drafting the IT policy and procedures the company is actively involved in major industry forums across the state. The company recognizes that innovation cannot stop at the technological level but must extend to all facets of the organization. Surya Infotech, Baroda, India 15
  16. 16. Internship report Rutger Rienks (9706291) To elevate the global thinking within the company, Surya Infotech regularly takes up international interns from associations like AIESEC. These student interns help in understanding the needs and demands of global companies; along with understanding the work ethics and culture of foreign nations and in-turn learn about the company and the Indian culture. This rich interaction sets Surya Infotech apart from their competition. The working environment Surya Infotech is one of the major IT companies in Baroda. The Director, Mr. Parag Amin has spent several years in the US during his studies and therefore the working conditions differ from a general Indian company. The office is located on the seventh floor of the Kirti Towers, a twelve storey high building, with two corporate offices on every floor. The atmosphere inside the company was quite western. Marble floors and walls from glass give the company a nice look. The working hours from 9:00 until 18:00 are quite reasonable. However, working on Saturdays is considered normal and due to the fact that we couldn’t work for four days due to the riots, the company expected us to win the lost days back by working on Sundays, and so we did. During the day there is one break: ‘lunchtime’. All the employees sit on the floor of one of the rooms from the office and all share their lunch prepared by their wife or mother. Since I had no one cooking for me, all the employees were very willing to share their hot, but tasty Indian food. Being amongst them, I used to bring my own bread, jam and honey and let them taste some of the lunches that I was used to. The employees are all nice and talented people. All more or less afraid of the big boss Mr. Parag Amin (always referred to as Sir.) and his ‘independent woman’ office manager. This however brings the employees close to each other and goes along with a lot of hilarious moments. The workspace in the office that I had during the internship was the smallest I ever had in my whole life. Although there was one computer for every employee, there was not more than that. On the other hand the chair was top notch. This also goes for the air-conditioning keeping us far from the 40˚ degrees outside. The figure 2 shows the room where I worked during my internship. Desk one was the place were I used to work and Ekta, my Indian trainee buddy used to work on desk two. Surya Infotech, Baroda, India 16
  17. 17. Internship report Rutger Rienks (9706291) 1 2 3 4 5 6 Figure 3: ‘The working environment’ As far as the hierarchy is concerned all of the projects were led by Parag himself. Some of them had an extra layer of leadership. Looking at our project for example, Deepa (nr 6 on the picture) was the supervisor of Ekta and me. Most of the interaction is going over MSN, which is not favorable, but due to the fact that the space is small and there are many other people in the same room it was the only option. The employees are working without any contract about working conditions and days off. The salary is based on the time the employees are working with the company. Ranging from RS.3000 to RS.10.000 which is comparatively low compared to other IT company’s in India. This all is possible due to the fact that Surya Infotech is a private company without stakeholders. In the next chapter an introduction is given of the project where the traineeship was about and the work that had to be done in and for the company. Surya Infotech, Baroda, India 17
  18. 18. Internship report Rutger Rienks (9706291) 5. The organization of ‘Project VOIP’ This chapter gives the background information of the project of the traineeship in India. First light is shed on the institute which actually initiated the project, thereafter the project goals are defined, and the role from our side is explained as well as the way of working during the project. Introduction The traineeship was involved with a project that again was part of a bigger project from the prestigious Nirma Institute. Nirma’s intention of the project was to let their highly talented students go through a complete product (IP Phone and IP Gateway) development cycle. In order to provide their students with more practical and commercial knowledge they asked Surya Infotech to assist the students and the project. It is clear that this way of working is cheap for the product development and valuable for the students. Mr Parag Amin, the project leader from Surya Infotech who has more than 17 years of experience in the IT world and Dr. Madhu Metha from Anjaleem, responsible for nearly the complete development of the current telephone network in India, were the two industrialists who assisted Nirma Institute in order to give the students this unique chance. Nirma Institute Nirma Institute of Technology (NIT) is a self financed technical institute offering degree level engineering programs and postgraduates in master of computer applications [@10]. It was established in 1995 by the in India philanthropist and industrialist, Shri Karsanbhai K. Patel under the aegis of Nirma Education and Research Foundation (NERF). The institute is recognized by the All India Council for Technical Education (AICTE) and State Government of Gujarat. Located about 15 kilometers from Ahmedabad and accessible from the State capital Gandhinagar. NIT shares a campus of 100 acres with two other premier institutions, Nirma Institute of Management and Nirma Institute of Diploma Studies. Figure 4: ‘The Nirma campus’ Surya Infotech, Baroda, India 18
  19. 19. Internship report Rutger Rienks (9706291) The environment gives full scope for group activities, as also to individual pursuits for development on preferred tracks. Their vision is to set up an institute of international repute. The management believes that to withstand global competition and to fulfill the huge demand of quality professionals, an organization must constantly grow, constantly innovate, build strength, improve efficiency and strive to become more and more self-reliant. The growth of the institute under the dynamic leadership of management has been stupendous. The dedication and commitment with which student, faculty and staff are working for institution building are remarkable. The institute is the most preferred one among the students of Gujarat and they have been securing top ranks in examinations. The Nirma centre of excellence This specific project is carried out by the center of excellence wherein Nirma exposes and trains their students on cutting-edge-technologies which hold the potential to ‘radically alter the future and impact daily life’. The center of excellence consists of 40 students. Since this is the first project for the center, this time the Nirma students were able to join the project just on interest. For the next projects however, the students will be screened on their skills. This all however implies that all the 40 students working on the project belong to the best students in Gujarat. The goal of the project By the institute the Voice Over the Internet Protocol or VOIP has been selected as a first project for the Nirma center for Excellence. The goal of the project was:” to let the students experience how it is to through the development cycle of producing a VOIP Gateway as well as a VOIP Phone.” Together with Ekta Shah I was responsible to keep the knowledge from the company side on at least the same level of the students of Nirma Institute. In this way Surya Infotech was able to help the students and speedup the development and also to make better decisions and choices regarding the development process. The way of working The project was organized mainly by the Nirma Institute. Dr. Madhu Metha (From now on referred to as Madhubhai, how he actually used to be called) and Parag Amin were guiding the students’ trough their way in developing their VOIP product. With weekly sessions at Nirma, the students had to show their progress by means of presentations every Saturday. Unclear points or aspects were debated and deadlines were set for the upcoming week. The complete project was scheduled to last 8 month and the students were expected to work on the project in their free hours and evenings. The budget from the beginning was unclear and Surya Infotech, Baroda, India 19
  20. 20. Internship report Rutger Rienks (9706291) dependant on our demands. But since Nirma is a quite well funded institute there were no major hazards expected. Our side (the team for Surya Infotech) of the project team consisted of Mr. Parag Amin, Deepa, Ekta and Me. During the sessions both Madhubhai and Parag stood in front of the students. Madhubhai’s focus was more on the technical aspect focusing on the progress, the level of understanding of the different concepts, the protocols and the opportunities. Parag on the other side spoke mainly from the business point of view (The product should be cheap, successful, fast to produce, the teams should work efficient etc.). In order to keep up with the students we had to do a lot of research at our end to see that the way the students were going was the right one, that the decisions they made were founded on solid argumentation and that they did not overlook things or made decisions too quickly. In the beginning a lot of reading through all the different aspects of IP telephony had to be done. Thereafter comparative studies amongst protocols, products and applications were made. Our as well as their results were discussed at Nirma and the students used it as guidance to speed up their research and development. All the time our objective was to stay ahead. Ekta and I had to do most of the research. Comparative studies had to be made, concepts had to be cleared and we were expected to tell Deepa how things were supposed to work and what the essential building blocks were to be kept in mind. We discussed the things that arose in meetings with Madhubhai, who visited our office quite regular. During the research a lot of reading had been done. It extended our knowledge substantially. In the meetings with the students we, as Parag’s technical backup, had to explain how techniques were to be applied and what the pro’s and con’s of the various systems or components were. Involving experts Besides our company, Nirma Institute invited experts to meet the students and to discuss the topics they were deciding and working on. The students even had the opportunity to give presentations about their project to India’s richest man and IT guru, Mr. Azim Premji. Although he had just 7 minutes for us and did hardly give us any feedback, it was an amazing experience. The preparation of the presentations and so, however were still useful in way that the students had to reconsider their position and their goal in and of the project. In the next chapter a general introduction to VOIP is given. Surya Infotech, Baroda, India 20
  21. 21. Internship report Rutger Rienks (9706291) 6. An Introduction to VOIP This chapter explains about VOIP and its background. It describes why VOIP is expected to be a huge growth market, what the origin of VOIP is, applications are discussed and an example network is given to provide a basic understanding level for the issues involved in the VOIP world. Introduction to IP telephony An IP Phone is a telephone device able to transport voice over a network using data packets instead of using a circuit switched connection. IP Telephony in that sense refers to the transfer of voice over the Internet Protocol (IP). Other Voice Over Packet (VOP) standards exist for Frame Relay and ATM networks but many people however use the terms Voice over IP (VOIP) or “IP Telephony” for voice over any packet network. Implementation can be seen in various ways e.g. phone to phone, phone to PC or PC to PC. In the future even more than two parties might talk with each other simultaneously. Refer for more information about next generation applications to [MC00]. The number of options is endless as long as there is an IP network somewhere in between the connection lines. A major advantage of VOIP and Internet telephony is that it avoids the tolls charged by ordinary telephone providers, resulting in a likely substantial influence on the telephony market. Before going in any further technical detail it is good to know why the market actually is moving into the direction of VOIP. Why VOIP There are three main reasons according to the Internet Engineering Consortium [@06] for the fact that VOIP is interesting for both the consumer as well as the producer. All are listed below: Cost reduction IP is everywhere. It is on our desktops and it is what the Internet is based on. Many people view the Internet as a "free transport" for data and voice services. With the introduction of Net2Phone and other similar "free" services, many people are making phone calls over the Internet. In addition, businesses and individuals have turned to higher-quality commercial products and services to make voice calls based on IP. The improvement of the IP network, like switches and routers, continues to reduce the cost of providing VOIP. Simplification and consolidation An integrated infrastructure that supports all forms of communication could allow more standardization and could reduce the total equipment. This provides clarity for both Surya Infotech, Baroda, India 21
  22. 22. Internship report Rutger Rienks (9706291) customers as well as for the producers. The differences between the traffic patterns of voice and data offer further opportunities for significant efficiency improvements. Universal use of IP for all applications, voice and data, holds out the promise of both reduced complexity and more flexibility. Advanced applications Even though basic telephony and faxing are the initial applications for VOIP, the longer-term benefits are expected to be derived from multimedia and multiservice applications. For example, Internet commerce solutions can combine World Wide Web access to information with a voice call button that allows immediate access to a call center agent from a PC. In addition, voice is an integral part of conferencing systems that could also include shared screens, white boards, etc. Combining voice and data features into new applications will provide the greatest returns over the longer term. This all will create new possibilities, markets and options for everyone. The origin The origin of IP Phones originally comes from client software running on PCs for low-cost PC-to-PC communications over the Internet. The problems associated with the Internet and the PC resulted in poor voice quality (Low Quality of Service, or QoS) due to long and variable delay and network congestion resulting in lost packets. Nowadays, the QoS provided by the Internet continues to improve as the infrastructure uses faster backbone links and switches resulting in congestion reduction, cut down latency due to faster connections like ADSL, and new protocols like RSVP providing a technique to prioritize amongst packet types. The (future) applications Most of the business focus regarding VOIP is currently concentrating on two applications. The first one is a private business network application. Most businesses with remote branch offices are already connected together via a corporate intranet for data services and can take the huge advantage in cost reducing by adding voice and fax services using VOIP technologies. The second application is VOIP over public networks. ISPs are interested in VOIP as a new way of offering value-added services like voice and fax on a per minute usage basis at rates significantly less than the old voice and fax rates for service through the PSTN. In the long term, as already mentioned, IP networks are more efficient for a wide range of new applications, particularly multimedia applications enabling convergence of voice, video, data, and fax. For example, web-enabled call centers will enhance the ability of companies to deliver new ways of customer service. Surya Infotech, Baroda, India 22
  23. 23. Internship report Rutger Rienks (9706291) The technology From the technology point of view, the development VOIP solutions include the advent of low-cost, low-power and high performance digital signal processors (DSPs) and RISC cores to perform the CPU-intensive function of packetization and mainly (de-)compressing voice and fax data. Another issue is that the arrival of industry standards for voice over packet systems will allow the interoperability of devices from different manufacturers. Recent standards include ITU H.323 (voice) and for T.38 (fax). Example network The next figure shows an example VOIP network. Ordinary analog phones, instead of IP Phones, call each other via an Internet Service Provider (ISP) who transfers the call via the IP network. The gateway from the ISP has to digitize, compress and packetize the call data before transferring it. This is made possible by the network server together with the name server both assuring that the originating ISP gateway is able to connect to the called phone and that the call is to be transferred to the de destination ISP gateway who is able to decode and regenerate the call-data for transferring onto the PSTN again. Now the connection with the called party can be established. Surya Infotech, Baroda, India 23
  24. 24. Internship report Rutger Rienks (9706291) Figure 5: ‘The example VOIP network’ The big profit in these kind of systems is that the customer saves a lot of costs due to the fact that the internet can bridge a huge distance for hardly any costs and on the other side, the customer is still using its ‘legacy’ phone system, which prevents the user from investing in a new telephone. Of course other network topologies exist, this is just meant as an example. In the next chapters the concept of IP Phone and IP Gateway will be examined more closely, but first some major VOIP concepts are explained in more detail. Surya Infotech, Baroda, India 24
  25. 25. Internship report Rutger Rienks (9706291) 7. A closer look at the major VOIP network components This chapter focuses on some of the major components in a VOIP network. It will explain the network components based on the H323 concept. The RSVP protocol for prioritizing voice packets over data packets will be discussed, as well as the G.168 protocol for echo cancellation and the G.723.1 protocol for voice compression. H.323 Since VOIP services need to be able to connect to traditional circuit-switched voice networks. The ITU-T has made this possible by defining H.323, a set of standards for packet-based multimedia networks. The basic elements of the H.323 network are shown in the network diagram below [Bo00] where H.323 terminals such as PC-based phones connect to existing ISDN, PSTN and wireless devices. Figure 6 : ’ Typical H.323 network’ H.323 terminals that are endpoints such as a IP Phone for voice transmission on a LAN, they have at least one CODEC (like G.723.1) to compress the voice. Terminals also need to support signaling functions that are used for call setup, tear down, etc. Gateways are the interface between the LAN and switched circuit network, a gatekeeper on the other hand performs admission control, address translation and routing. The idea behind defining the gatekeeper entity is to allow H.323 designers to separate the raw processing power of the gateway from intelligent network-control functions that can be performed in the gatekeeper The MCU (Multipoint Control Unit) is the last part of the network and enables conferencing between three or more endpoints. Surya Infotech, Baroda, India 25
  26. 26. Internship report Rutger Rienks (9706291) The signaling standard is H.225.0 which is a subset of Q.931 (ISDN) signaling; H.245, used to exchange capabilities such as compression standards between H.323 entities; and RAS (Registration, Admission, Status) that connects a terminal to a gatekeeper. Control messages (Q.931 signaling, H.245 capability exchange and the RAS protocol) are carried over the reliable TCP layer. This ensures that important messages get retransmitted if necessary so they can make it to the other side. Media traffic is transported over the unreliable UDP layer and includes two protocols as defined in IETF RFC 1889 [@15]: RTP (Real-Time Protocol) that carries the actual media and RTCP (Real-Time Control Protocol) that includes periodic status and control messages. Media is carried over UDP because it would not make sense for it to be retransmitted: should a lost sound fragment be retransmitted, it would most probably arrive too late to be of any use in voice reconstruction. RSVP This protocol [@08] is used to assure Quality of Service (QoS) from a network, on behalf of an application data stream. RSVP takes care after the data stream throughout the network, at each node, RSVP attempts to make a resource reservation for the stream. In VOIP networks it is important for the voice data to be delivered as soon as possible. The RSVP protocol comes into picture when there is both ordinary data traffic as well as voice traffic over the same network. In this case it is the task of the protocol to prioritize and schedule voice traffic above the ordinary traffic. To make a resource reservation at a node, the RSVP daemon communicates with two local decision modules: admission control and policy control. Admission control determines whether the node has sufficient available resources to supply the requested QoS and a policy control determines whether the user has administrative permission to make the reservation. If either check fails, the RSVP program returns an error notification to the application process that originated the request. If both checks succeed, the RSVP daemon sets parameters in a packet classifier and packet scheduler to obtain the desired QoS. The packet classifier in each of the network nodes determine the QoS class for each packet and the scheduler orders packet transmission to achieve the promised QoS for each stream. G.168 G.168 is a line echo canceller, which is a voice operated device placed in the 4-wire circuit and is used to reducing the echo by subtracting an estimated echo from the circuit echo. Echo cancellers are able to cancel the delay up to a range of 120-125 ms Surya Infotech, Baroda, India 26
  27. 27. Internship report Rutger Rienks (9706291) G.723.1 G.723.1 is a dual rate speech coder standard from International Telecommunication Union– Telecommunication standardization sector (ITU-T). It is used for compressing quality speech, normally sampled at 8000 samples per second at a rate of 64 Kbps. This codec has two compressing bit rates, 5.3 and 6.3 Kbps. Both bit rates share the same short-term analysis techniques for processing the speech. For long-term analysis of speech, the algorithms used are different. For 5.3 Kbps coder, Algebraic Code Excited Linear Prediction (ACELP) principles are used where as in 6.3 Kbps coder, Multi Pulse-Maximum Likelihood Quantization (MP-MLQ) techniques are used. The coder works on a frame of 240 speech samples (30 ms). Besides, there is a look ahead of 60 samples (7.5 ms). So the total algorithmic delay for the coder is 37.5 ms, other codecs are shown in figure 7 [BO00]. Figure 7 : ’Different kinds of codecs’ T.37/T38 T.38 is the fax transmission protocol selected for H.323. Traditionally there have been two approaches for sending Fax over Packet networks: the real-time method and store and forward method. The primary difference in service between these two approaches is in the delivery and method of receipt confirmation. The ITU and IETF are working together to continue to evolve both the real-time Fax over IP network standard (T.38) as well as the store and forward Fax over IP network standard (T.37). Both T.37 and T.38 were approved by the ITU in June, 1998. Surya Infotech, Baroda, India 27
  28. 28. Internship report Rutger Rienks (9706291) Surya Infotech, Baroda, India 28
  29. 29. Internship report Rutger Rienks (9706291) 8. The IP Phone reference design In this chapter a closer look is taken towards the features of a user terminal, in this case a VOIP Phone. This reference design is made as a reference for the final design as discussed in later chapters. The main difference with a legacy telephone and an IP Phone is that the IP Phone is directly connected to the internet instead of to the PSTN. The IP Phone hardware architecture reference design Thinking about the hardware architecture it is easy to come across the user interface you will need. Other more in depth or underlying components are not so easy to come up with without studying some literature in advance. Figure 8 below shows a block diagram of a complete reference design of a possible IP Phone. This IP Phone consists of the following components: • User Interface • Voice Interface • Network Interface • Processor Core and associated logic. All the major components needed are discussed into more depth below. Surya Infotech, Baroda, India 29
  30. 30. Internship report Rutger Rienks (9706291) Figure 8: ’Architecture of an IP Phone’ The User Interface provides the traditional user interface functions of a telephone. At a minimum, this consists of a keypad for dialing numbers (0-9, *, #) and an audible indicator for announcing incoming calls to the user. On more sophisticated telephone sets, additional keys are provided for features such as mute, redial, hold, transfer, conferencing, etc. A display is also typically provided for displaying user prompts, number dialed, CallerID information for incoming calls, etc. In certain models, the telephone can be equipped with a serial interface to allow communications to a device such as a PDA to allow synchronization of phone information, facilitate automatic dialing, etc. The Voice Interface provides the conversion of analog voice into digital samples. Speech signals from the microphone are sampled at a rate of 8 KHz to create a digitized 64kbps data stream to the processor via a pulse code modulation (PCM) codec. Similarly, the processor passes a 64kbps data stream in the return path to the speaker through the PCM codec to convert digital samples back into speech. The Network Interface allows transmission and reception of voice packets from and to the telephone. For corporate LANs this is most often either 10BaseT or 100BaseT Ethernet running TCP and IP protocols. The IP Phone may offer a second RJ-45 Ethernet connector to allow a PC to plug in and share one connection to the wall jack. The Processor Core performs the voice processing, call processing, protocol processing, and network management software functions of the telephone. As shown in figure 8, this consists of a Digital Signal Processor (DSP) for the voice-related functions and a Micro Controller Unit (MCU) for the remaining functions. The IP Phone software architecture reference design The software architecture of an IP Phone based on the ITU H.323 standard for VOIP is shown in figure 9 [Mo00]. The software consists of the following major subsystems: • User Interface • Voice Processing • Telephony Signaling Gateway • Network Interface Protocols • Network Management Agent • System Services Surya Infotech, Baroda, India 30
  31. 31. Internship report Rutger Rienks (9706291) These subsystems are all described below. The most important software parts are listed. However, as software as well as hardware is subjected to changes. It might happen that some of the protocols listed are outdated. Figure 9: ’ Software overview of an IP Phone’ User interface software The User Interface subsystem provides the software components that handle the interface to the user of the IP Phone and consists of the following software modules: Display Driver Controls the hardware that generates characters to the display. Keypad Driver Performs keypad scanning and detects key presses entered by the user. Surya Infotech, Baroda, India 31
  32. 32. Internship report Rutger Rienks (9706291) Audible Driver Performs control of the hardware that generates the ringing of the telephone. User Procedures Controls the information displayed by the Display Driver and processes user key inputs and converts them into primitives for Call Processing. Voice processing software This software module is used for the processing of the voice coming from the IP network or from the user as well as creating sound over the speakers indicating actions performed by the user. Pulse Code Module Interface Unit Receives PCM samples from the analog interface and forwards then to the appropriate DSP software module for processing. It also forwards processed PCM samples to the analog interface. Tone Generator Generates call progress tones to the user and generates in-band Dual Tone Multi Frequency or DTMF digits to the network based on key presses relayed from the user interface. For certain voice codecs, the compression algorithm does not permit faithful transmission of DTMF tones. For those algorithms, e.g., G.723, the software generates an in-band message to the network that is used by the remote IP Phone (or gateway) to regenerate the DTMF tone. Echo Canceller Unit The Unit Performs ITU G.168 compliant echo cancellation on sampled full-duplex voice port signals. The echo from the telephone network is removed by a digital filter on the transmit path into the packet network. Voice Activity Detector (VAD) Detects voice activity and activates or deactivates the transmission of packets in order to optimize bandwidth. When activity is not detected, the encoder output will not be transported across the network. This software also measures Idle Noise characteristics of the interface and reports this information to the Packet Voice Protocol for periodic forwarding to the remote IP Phone or gateway. Idle noise is reproduced by the remote end when there is no voice activity so that the remote user does think the other party hung up. Voice Codec Unit Surya Infotech, Baroda, India 32
  33. 33. Internship report Rutger Rienks (9706291) Performs packetization of the 64 kbps data stream received from the user. Options are G.711 making just packets without any compression. Another one is G.729 compressing to 6.3 or 5.3 Kbps or G.728 compressing to 16 Kbps. For more details see the previous chapter. Packet Playout Unit Performs compensation for network delay, network jitter and dropped packets. Many proprietary techniques are used to address these problems since there are currently no standards in place for packet playout. Surya Infotech, Baroda, India 33
  34. 34. Internship report Rutger Rienks (9706291) Packet Protocol Encapsulation Unit Performs encapsulation of the packet voice data destined for the network interface. For VOIP this encapsulation goes via the Real-time Transport Protocol (RTP) layer which runs directly on top of UDP. Voice Encryption Provides optional encryption of the voice packet data before transmission over the network to ensure privacy. Control Unit Coordinates the exchange of monitor and control information between the Voice Processing Module and Telephony Signaling and Network Management modules. The information exchanged includes software download, configuration data, signaling information and status reporting. Telephony signaling gateway software The Telephony Signaling Gateway (TSG) subsystem performs the functions for establishing, maintaining and terminating a call. These functions can also be done by an H323 gatekeeper, but in this case they are embedded in the IP Phone itself. The TSG consists of the following software modules: Call Processing Performs the state machine processing for call establishment, call maintenance and call tear down. Address Translation and Parsing Performs digit collection and parsing to determine when a complete number has been dialed and makes this dialed number available for address translation. Network Signaling Performs signaling functions for establishment, maintenance and termination of calls over the IP network. Using : H.323, SIP as well as SGCP/MGCP. H.323 Protocols H.323 is an ITU standard that describes how multimedia communications occur between user terminals, network equipment and assorted services on Local and Wide Area IP networks. The following H.323 standards are used for VOIP in an IP Phone: H.225—Call Signaling Protocols. Performs signaling for establishment and termination of call connections based on Q.931. Surya Infotech, Baroda, India 34
  35. 35. Internship report Rutger Rienks (9706291) • H.245—Control Protocol. Provides capability negotiation between the two end-points such as voice compression algorithm to use, conferencing requests, etc. • RAS—Registration, Admission, and Status (RAS) Protocol. Used to look after the registration, admissions, bandwidth change and status messages between IP Phone devices and servers called Gatekeepers which provide address translation and access control to devices. • RTCP—Real-time Transport Control Protocol (RTCP). Provides statistics information for monitoring the quality of service of the voice call. SGCP/MGCP Protocols Simple Gateway Control Protocol (SGCP) is a standard that describes a master/slave protocol for establishing VOIP calls. The slave side or client resides in the IP Phone and the master could reside in an entity referred to as a Call Agent. SGCP has been adopted by the Cable Modem industry as part of the DOCSIS standard. SGCP is evolving to the Multimedia Gateway Control Protocol (MGCP). SIP The Session Initiation Protocol (SIP), is a signaling protocol for Internet conferencing, telephony, presence, events notification and instant messaging Network management software The Network Management subsystem supports remote administration of the IP Phone by a Network Management System. The Network Management Agent should consists of at least the following software modules: Network Management Agent Performs the network management functions of the IP Phone, including status monitoring and alarm reporting, gathering of statistics in response to SNMP queries, etc. from a network management system. Embedded Web Server The EWS provides administration support via a standard web browser. It presents the user with web pages for configuring the IP Phone and gathering statistics information. Besides that, it may provide Java applets for loading to the user's PC, e.g., for status polling. SNMP Performs the Simple Network Management Protocol (SNMP) functions for processing Management Information Base (MIB) Gets and Sets and generation of Alarm Traps. Surya Infotech, Baroda, India 35
  36. 36. Internship report Rutger Rienks (9706291) TFTP Trivial File Transport Protocol (TFTP) is used to download software updates into Flash memory. Network interface software The Network Interface Protocols support communications over the Local Area Network (LAN) and consists of the following software modules: TCP The Transport Control Protocol (TCP) provides reliable transport of data including retransmission and flow control. It is used for web queries and call signaling functions. UDP The User Datagram Protocol (UDP) provides efficient but unreliable transport of data. It is used for the transport of real-time voice data since retransmission of real-time data would add too much delay to the voice conversation and be unacceptable. UDP is also used for SNMP and TFTP network management traffic. IP The Internet Protocol (IP) provides a standard encapsulation of data for transmission over the network. It contains a source and destination address used for routing. MAC/ARP Performs Media Access Control (MAC) management functions and handles Address Resolution Protocol (ARP) for the device. Ethernet Driver Configures and controls the Ethernet controller hardware, including setting up Direct Memory Access operations. System services software These services are software modules needed in order to make the phone ready for use when switched on and to be able to run the other protocol stacks etc. Startup/Initialization To initialize the phone on startup POST Surya Infotech, Baroda, India 36
  37. 37. Internship report Rutger Rienks (9706291) Power On Self Test RTOS Real time Operating System BSP Board Support package to let the RTOS support the hardware via hardware interface drivers of the BSP Watchdog Timer Driver This Driver controls the WDT in order not to let the phone lock up due to a soft or a hardware failure Flash memory manager This manager is used for reading and writing to the memory DSP interface manager This manager is needed for information exchange between the MCU and DSP Surya Infotech, Baroda, India 37
  38. 38. Internship report Rutger Rienks (9706291) 9. The IP Gateway reference design Since an IP Phone might want to call to a normal legacy phone there is a need for a device able to bridge the gap between two different networks. Such a gap bridging device is called a gateway. In our case the IP Gateway should be able to bridge the gap between the PSTN and the packet network. In this chapter the hardware part as well as the software part of an IP Gateway is examined. The IP Gateway hardware reference design The hardware of the gateway is actually quite simple compared to that of a phone. Figure 10 [in01] shows an abstract implementation of an IP Gateway. All the major system parts of a gateway are shown and are further discussed below. Figure 10: ’ IP Gateway components’ Microprocessor The processor needs to handle signaling, and management and control functions as required by the gateway application. When using H323, the microprocessor is for example required to handle the control portion of H.323. Program and data memory is also required in the system for the microprocessor and the DSP. The choice of microprocessor depends on the processing power required for the application, in addition to scalability requirements and cost. Surya Infotech, Baroda, India 38
  39. 39. Internship report Rutger Rienks (9706291) DSP resources The VOIP Gateway should have more than one DSP, since there are many simultaneous telephone conversations going through the gateway. The DSP performs the actual conversion of the voice streams between the PSTN and packet worlds. It transforms the voice signal form analogue to digital and compresses it by using a codec. The selection of a DSP is based on several criteria. Port density is here quite an important factor. The number of voice and fax channels that can be served by a DSP depends on the available MIPS and the memory to run the algorithms PSTN Interface Modules The PSTN Interface Modules provide the interface to the Public Switched Telephone Network. The connection to the PSTN can be through digital interfaces like T1 or E1. The T1 or E1 interface multiplexes 24 (T1) or 30 (E1) channels of voice, along with signaling, into a single data stream. The connection to PSTN however can also be made through an analog interface if there is a codec able to convert the analog signals into an appropriately coded digital stream Packet or network Interface Modules The Packet Interface Modules provide the interface to the packet switch network. The two most prevalent networks are ATM and IP. 10 or 100Base T Ethernet connection is the standard nowadays. Things not to forget The figure shown on the previous page shows only an abstract gateway. Some other components that should not be forgotten are listed below. Backplane Interface There are many different backplane interfaces that can be used in systems such as these, for communication with other devices for example. Most typical are PCI and cell bus variants like a utopia interface for ATM networks. Alarm Monitor & Control (M&C) Module The Alarm Monitor & Control (M&C) Module should perform the overall network management for the equipment. Call Processing Modules The Call Processing Modules perform call establishment and call tear down for the system and performs bridging functions between the PSTN and packet network. Surya Infotech, Baroda, India 39
  40. 40. Internship report Rutger Rienks (9706291) Aggregation logic In order to concentrate a large number of channels, some aggregation logic is required to route incoming packets from the Backplane or Packet Network Interface to the appropriate DSP Surya Infotech, Baroda, India 40
  41. 41. Internship report Rutger Rienks (9706291) The IP Gateway software reference design There are many features that must be implemented for IP Gateways. The software should be designed to minimize delay & maximize scalability. This all includes: • Efficient and adaptive algorithms • Low-latency implementation • Features to off-load the “host” processor to enhance overall channel density Looking at the figure below it becomes clear that there are three main parts apart from the interfaces. The fax relay should take care of the fax data packetization and relaying. The voice should be (de)compressed, (de)packetized and forwarded and the signaling part should do the translation amongst the signaling used in the PCM and the packet network. Surya Infotech, Baroda, India 41
  42. 42. Internship report Rutger Rienks (9706291) Figure 11: ’ possible gateway software’ The architecture is quite similar to the phone. There are three main parts. The first one is Voice, looking after the echo canceling, conferencing, compressing, VAD, VPU and the packetization. The second one is Fax, which is optional. The third part is the signaling part, looking after the tone detection, caller ID detection and signaling support. The main difference with the software architecture of an IP Phone is the number of channels that have to be considered as well as the signaling which now also have to deal with the analogue phones. Another big issue not to forget is the management to be carried out by the host processor for the various voice lines on the DSP’s. The next chapter will describe the project development phases and the decisions made during the internship. Surya Infotech, Baroda, India 42
  43. 43. Internship report Rutger Rienks (9706291) 10. The progress: from one phase to another This chapter will focus on the processes of the project and the different phase threads of research carried out in the first three months of the project. There are five phases that can be identified in these months of basically research. An attempt has been made to split up the work according to the work done at our end and the work performed by the students at Nirma. Some of the decisions made however were made in the interactive sessions on Saturday’s, others in phone calls or in meetings where Madhubhai visited our company. Phase 1: The initial sessions This part describes the initial stage in the development process. Madhubhai and Parag both started the project on the 30th of January 2002. The work at Nirma In the beginning the situation at Nirma was far from structured. The main issues raised in these days were the things that had to be developed. There was an introduction on why VOIP was chosen as a research environment for the center of excellence. The professor explained was expected from the students taking part in the center of excellence and groups were made in order to perform some first research. The groups formed all had a specific task assigned. The main groups were: • The gateway group • The IP Phone group • The OS group • Protocol study group The work from our side The work in these days mainly consisted out of reading, reading and reading. The VOIP world is not an easy one to understand. It took both Ekta and me around one week before we were able to distinguish amongst the various protocols and solutions available. A lot of the whitepapers Deepa had gathered, before the actual project started, were studied. Hereafter we used around one week reading articles on the web and reading through RFC and ITU standards like MEGACO, H323 and SIP. Besides all this we had to read through the current telephony systems such as the PSTN functionality and SS7 signaling. Deepa initially had identified three steps in the development of the product. Surya Infotech, Baroda, India 43
  44. 44. Internship report Rutger Rienks (9706291) 1) The first product should be an IP Phone that is able to talk to another IP Phone on the same LAN. 2) The second step was to let two legacy phones talk via two gateways and one gateway controller (MGCP) on a same LAN. 3) And the third step would be to let the two legacy phones talk via their own gateway over IP on a different location. The philosophy was based on the idea that by using an IP network a company could cut huge costs by communicating amongst different branch offices over IP. Also, when using a legacy analog phone it should be possible to call to the office, there the IP Gateway should be able to transfer it to IP, connect it to the branch closest to the called party and from there redirect the call over PSTN. However these plans were far future music and abandoned later due to political limitations. A closer look had to be taken at the various components involved in the system. Phase 2: Comparison After a lot of research the first steps were made into the right direction. The various aspects of the system were identified and thoroughly studied. The work at Nirma The students at this point of time made a lot of comparative studies. They put a lot of effort in comparing the different operating systems that could be implemented on the phone as well as the gateway. The cost factor was here of major importance as well as the speed of it. After some research and company responses it was quite clear that as far as the OS was concerned, we had to go with Linux. Other competitors like VxWorks or Nucleus were left far behind regarding costs and real time performance. Other fields of research were about the first specifications for the IP Phone. How should it look and what functionality should it have. The discussions at Nirma were quite good and amusing. The debate on whether to use an LCD was quite nice. A decision was made to have at least support for LCD on the hardware level and if it wasn’t too costly two lines of sixteen characters. Based on Pixels in order to be able to use local languages and with backlight support so that the vendors could use it in the dark. The discussion ended by deciding on a four line display having sixteen to twenty characters. See appendix F for more details. Surya Infotech, Baroda, India 44
  45. 45. Internship report Rutger Rienks (9706291) Many more aspects were debated. One of them was the target market. At this time, according to Madhubhai, the main focus had to be the phone stalls you can find everywhere in India along the roads. Since most of the Indians have only the possibility to make local telephone calls at their home this was the market we had to address. The markets for VOIP are mostly focusing on cutting costs of inter local and international traffic. The work at our side In these days several components were picked out of the network and in depth studies were made of them. Especially the different protocols had to be studied more specific. It was clear that H323 is the standard, but how and why? In this moment in time the opinion at our side was that the MEGACO protocol might be the best to go with since it gained a substantial part of the market that is still expanding. It uses both SIP and H323. One of the documents made at that time is the H323 vs. SIP comparison that can be found in appendix A. The protocol to start with (decided on April 20th) turned out to be H323. This due to the limitations of the law prohibiting us from the MEGACO use and another important aspect was the benefit of error handling of H323 above SIP. Apart from that a database with over 50 different gateways was built. Going through all of them provided more details about the actual components used. In these days it became clear that most of the gateways were using an MIPS [@13] or ARM [@12] microprocessor and a DSP farm from either DSP groups [@14] or Texas Instruments [@05]. Finding these components in the beginning was like looking for coca cola’s receipt. Most of the vendors did not talk about their internals. Luckily some were saying more than others. With this database a comparative study of the gateways supporting MEGACO was made. The results can be found in appendix B. After this, the next goal was to come up with three phones that were the best ones to buy to do some performance testing with them. Three phones were selected. After comparing around 20, the 7 best ones were selected and after being compared more thoroughly. The TNETV1001 from Texas instruments, de Aplio IP Phone from Aplio and the IP Phone from Netergy came out as the best ones to use. Reasons for this were that the phones were not using the appropriate stacks, that they just weren’t providing enough details (E.g. the ‘freeride’ series from e-tel) or the phones were using complete PC’s for implementation (E.g. Nortel’s i2050) . The comparison can be found in appendix C Phase 3: Which products to build? Since the market demands the products now, the plan of buying and playing was dropped and a process was started of building the components from scratch. So the idea of buying an IP Phone was abandoned and the knowledge that was gathered had to be used in a different way. On the other hand, regulations amongst the legalization appeared. From April 1 st 2002 Surya Infotech, Baroda, India 45
  46. 46. Internship report Rutger Rienks (9706291) VOIP was to be legalized in India. One of the conditions was that no PSTN lines were connected to IP and vice versa. This smashed the idea of transferring calls via company branches. New ideas had to be made. Another bad thing was that the implementation had to use either SIP or H323, so the MEGACO efforts also became, apart from the knowledge level, quite useless. IP Phone, IP Gateway and IPPBX In the next meetings with Madhubhai the decision was made to build an IP Phone, an IP Gateway and an IPPBX. The ideas behind this were the ablillity to target on the major market components. A small enterprise gateway having 8 ports targets basically on cyber cafes enabling them to plug in normal phones on their Ethernet to provide telephony service for their customers. The IPPBX should be there as an add-on for the same gateway. The IPPBX was supposed to extend the gateway from a functionality perspective. For more information refer to [SH00]. The IPPBX had to support billing, Interactive Voice Response (IVR), Call lookup and voicemail and is intended for call centers, hotels and hospitals. The demand for the IP Phone is obvious; it should be plugged into the Ethernet and work. The main market would be the phone boot on the Indian streets. The work at Nirma More research was done in the field of DSP’s and microprocessors. After some comparisons at their end only two chipsets remained for the phone. The Texas Instruments C5471 and the Atmel AT75c220, both were having an ARM7 core and a strong DSP. Furthermore there were documents appearing about the requirements for the phone and gateway and things were cleared about compression algorithms and their memory usage. The one page spec sheet for the gateway can be found in appendix E The work at our side In this phase the chipsets most wanted for the implementation were all looked after. On the other side some attention went to some of the VOIP toolkits. One of the things that appeared was that most of the vendors were not providing any specific implementation details. Again looking for coca cola’s receipt? However for the microcontroller there were three different companies we could trace: MIPS, ARM and PowerPC. On the side of the DSP, there were again the Oak DSP and Teak DSP cores from DSP groups and the c54x series from Texas Instruments that appeared as good solutions. Suddenly Ekta and I had to change our field of research again. This time we had to come up with a complete reference implementation of both the IP Phone and the gateway. The results can be found in the chapters 7 and 8. Surya Infotech, Baroda, India 46
  47. 47. Internship report Rutger Rienks (9706291) Phase 4: Which building blocks to use for our products? This phase took over one month. Apart from the riots that kept us indoors for five days, the only decisions taken were those to go for Linux as the OS and, that an IP Phone, an 8 port IP Gateway and an IPPBX would be built. The work at Nirma The students in these days were doing research on the QOS protocols like RSVP and IntServ. They came up with the idea of using a combination of both which provides the best performance. They also were working on 30 pager documents to nail down all the specifications the gateway and the phone should have. The IPPBX also referred to as the PC based Enterprise Gateway (PEG) after a while was shifted to be developed later. This was due to the growing time to market pressure; Madhubhai was receiving two phone calls per day from people asking him whether he had the products ready for production. On the other hand still a lot of research was going on concerning the different protocols. Groups were restructured. Now there were two main groups of students, one for the phone and one for the gateway. Gateway tasks performed by subgroups for example on March 20 th were: • Getting the listing of Open Source of H323 & others and study them • Specifying the PEG software components & PEG board definition • Billing & Call Data Recording module • SIP team • H323 team • Open source DSP software and algorithm gathering The different team findings were all discussed on Saturday meetings and most of them put a lot of effort in it to really understand the more complex codecs and protocols in depth in a way to be able to really do something use full with it on an implementation level afterwards. The work at our end Ekta and I started by comparing complete solutions on chip, or systems on chip for the gateway. Around 10 different options were compared. It was found out that the Monet architecture from Real would be a very nice product to go with. We also came across the TI’s TNETV2020 what appeared to be a complete gateway solution. After various attempts from our side it was not clear whether TI was actually producing the solution as a chip or not. Several emails were written awaiting an answer from their side. Surya Infotech, Baroda, India 47

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