The Indian E-commerce system has always seen a broad array of operational issues starting from logistics to payment. While the first one has been taken care of (thanks to Amazon’s one day delivery and similar practices!) . Over the years the payment system has always created a severe migraine for CEO and CFOs, we try to understand the factors leading to such issues in an info graphic.
An idea can change your life. It can also change a nation.
Aam Admi party began with an idea – to make India corruption free. Arvind Kejriwalbecame the entrepreneur who has built an enterprise around that idea.
The enterprise that came up was for the people, by the people and of the people.
But how have corporates reacted to this new enterprise? Do they find a place for themselves in this new enterprise or are they fighting for their own space? Didn’t we hear somebody saying that AAP has borrowed every bit of its manifesto from the Communist Manifesto written in 1848 for the working class in Germany?
Aam Aaadmi Party was the product of a frustrated, struggling young nation that has been cheated in ways unimaginable since independence. It’s a product that puts people in charge and not babus. The nation wanted a clean government and clean governance.
In the days of Anna Hazare, emotions coupled with strong determination were the all-essential fuel to fire up the Jan-Lok pal bill. Though the movement faced a clear decline from the government after endless protests and fasts, it however led to a clear thinking:
“If you’re going to set things right, you have to get your hands dirty”
Whoever had said the above statement, clearly knew the road ahead, and decided to work on it. Something similar happened, Arvind kejriwal and Anna Hazare were (stillare) two distinctive individuals with strong morals; however their ideologies are diametrically opposite! In this chase of doing substantial, measurable work in bringing about change, Anna fizzled out quite early. Arvind Kejriwal strayed away from the common ideology and developed a concrete method to work against the system: to contest against the government.
Promise of AAP (image: AAP site)
An impossible task of cleaning–up a Nation? Yes you have read it right, a NATION.
A quick search on the internet gives us a brief insight into what’s fuelling the ideology of AAP. One may find swaraj and anti-corruption as the key drivers to the AAP’s foundation, but it’s the generic start-up style attitude towards their functioning that has managed to attract attention of India Inc. Corporate India views AAP as one of the hottest start-ups in recent times and the figures speak for themselves: with a vote share of more than 50%, its way ahead of comparable state-wide electoral party debuts; like the Telegu Desam Party in Andhra in 1983 (46%), Asom Gana Parishad in Assam in 1985 (35%), and Bahujan Samaj Party in UP in 1989 (10%).
Political debut vote-share in comparable State elections.
In the earlier days before the formation/inception of Aam Aadmi Party, what seemed to be an endless stock of mockery among other political parties and media debates; soon and surely turned out to be something they didn’t expect. AAP came to power and Arvind had taken the centre stage of a revolution in the history of Indian politics. Yes this was the time when the babus were forced to get up from their comfort zones and make a run for their money.
“It has really sent a message of hope across the country that it is possible to contest and win elections without money and muscle power. That people with ideas and ideals can contest elections and win.” –Meera Sanyal, chairperson of RBS India.
“Arvind Kejriwal and AAP have walked the talk on clean politics and tasted success as a result. AAP’s amazing debut says it all – people want corruption free politics based th on transparency n responsibility”– Kiran Mazumdar Shaw, chairman and MD, Biocon.
Just like any start-up, you don’t make it to fame or earn revenues from the first month, AAP faced something quite similar. But as with any entrepreneur who has raised their first round of external funding, living up to expectations requires a transition of mind set, skills and rhetoric. Arvind Kejriwal made it nearly impossible to ignore his bandwagon when he was swore-in as the CM of Delhi last month.
The party pitches with a fresh context.
In a country with a rising population of more than 1.2 billion, it never is, was or will be easy to define the limitations of every problem unless we work together with the government. The controversies that AAP faces are nothing to be surprised about, it takes time to work our way through. As of now AAP is only the moderator to keep a check in corruption, not an entire force to curb it once and for all. The magic wand is not with AAP but with us. A clean conscience and a strong will power are the only effective tools we have to clean this nation and with all that instrumental support AAP has garnered over time from not just the corporate biggies and previous politicians, it’s the sheer unpredictability of a start-up that worries investors…
Investors like you and me.
Jai Hind!
Alarm clock: time-savers, punctuality instructors or simply little mean machines who don’t let you sleep that extra five minutes, (oh darn!). They come in different shapes, sizes and noise-makers : the buzzers/ beepers/ annoying traditional ringers or radio.
now for a minute leave them aside; next time, let your intelligence answer that alarm clock!
Say again??
yup,
You heard me right. An alarm clock that throws in random math, physics, science problems as the alarm goes-off!!
“Geeky clock”
You can trust an engineer to invent such a thing as a Geeky Alarm.
Imagine this scene. You have finally decided to call it a day after working on a project late into the night. You have set your alarm clock for 6.00 am, reminding yourself that you also need physical exercises, not just the exercises at the end of the chapter for your survival. You are dreaming the sweetest dreams at the bewitching hour when you are rudely awakened by a noise.
Habituated to the snooze button, you frantically look for it,only to see an exercise (!) flashing on your alarm clock
“How many sleep modes are there in MSP430?”
Concerned more about your own sleep mode, you hurriedly answer the question. Assuming you answered it right, you will be asked yet another question from the quiz bank of the alarm, such as
“What is the limit of sin(x) / x as x tends to 0?” or “What is the meaning of life?”
The hope is that you are now wide awake.
Mission accomplished.
Geeks rule! 😉
“bazinga!”
//enter: your code here// (the Nuts and bits!)
Geeky Alarm
>> It is a micro controller based clock which calculates time and comes with an alarm facility in which snooze button is replaced by answering a question through matrix keypad interface..
>> it is different in the sense it actually questions the tech freaks to wake them up in the morning.. The snooze button is replaced by a medium to difficult question relating to science or mathematics and the intended person needs to answer it to turn the alarm off.. until it is done the result is achieved i. e. intended person is wide awake!
A couple of days back I was brainstorming about topics to write about, then I realized that Rockstar Games Inc. had just released their newest installment of the Grand Theft Auto series: GTA5. Having been a big fan of the series in my childhood, I decided to try writing something about them, connecting it to entrepreneurship.
Hope you like it
I’ve had profane memories of shooting at cops and civilians, smashing anything and everything on my way, driving insanely out of control, running over people, causing untold mayhem, and even expanding the thug life vocabulary all thanks to the Grand Theft Auto Series.
Grand Theft Auto by Rockstar Games is one of the most critically acclaimed game series ever created. It has a cult following all over the world, with people waiting in lines for hours/days together, chipping in possibly every dime out of their savings to get their hands on their newly released titles – GTA V: case in point.
There are many factors which have contributed to their success. Here a few lessons that add an extraordinary appeal to Entrepreneurs.
Show your Passion, Originality is the way!
Rockstar Games intentionally avoided developing in the first person shooter (FPS) genre. They said, “It’s in our DNA to AVOID doing what other companies are doing. You have to have originality in your games; you gotta have some kind of interesting message. You could say that the goal of Rockstar is to have the players really feel what we’re trying to do.”
They didn’t rely on testimonials in business textbooks to do what they did. They succeeded precisely because they didn’t concentrate on profit.
Their philosophy was “If we make the sort of games we want to play, then we believe people are going to buy them.”
No detail is too small
The total cost in developing GTA V was close to $250 million to get it up and running. About 3 million copies Of GTA V were pre-ordered at $60 a pop. It makes even more sense when you consider the fact that Grand Theft Auto IV sold $500 million worth of units during its first week. You do the math. The combined Length of GTA Talk Radio Stations Is Over 9 Hours.
Create a bigger target customer base
Rockstar Games (DMA Design as it was known then) realized that almost all games were targeted at kids and geeks. They decided to develop something for the masses that people could relate to.
They saw a huge untapped market where usually only kids were into gaming. Their aim was to generate interest in gaming for people from all walks of life.
So what if you’re 32 go grab a controller and get glued.
Stand out of the crowd!
Rockstar Games thought out a brilliant scheme to market their creation. They hired a controversial PR Guru, Max Clifford to deliberately give them a negative review citing the game to be ‘ too violent and not suitable for kids’.
This brought out two results:
Now let’s see how GTA as a game prepares you for a life as an Entrepreneur:
“Give a Man a mask and he will show you his true self”
Playing GTA lets you unleash your wild side and gives you an insight into what you would do if there were no consequences. To be a successful entrepreneur you have to unleash the beast inside you and do what your heart tells you to.
It teaches you that when it comes to the real world everyone starts out with a clean slate. It does not matter where you come from, it matters how much effort you are willing to put in.
Every action has its own consequences. Beat up people ,the cops will come after you. You dont pay up what you owe in time, the underworld mafia will put a bounty on your head. Similarly for entrepreneurs if you try to make a quick buck illegally, cops and lawyers will come knocking at your door. Don’t pay employees’ salaries, they will abandon ship.
Consider this scenario: Your character has been given the task of making a guy ‘sleep with the fishes’ but you do not have your weapon of choice with you. All you have with you is a Swiss army knife or even worse a pair of brass knuckles? So what do you do? Wait till you make enough money to buy a .44 Magnum (Do I feel lucky? Well, do ya, punk?) or do the deed immediately with the resources at hand, even though things might get messy.
An entrepreneur has to make optimum use of all the resources available to him. He does not need to have the best and most expensive resources to get a job done. Also the most precious resource that an Entrepreneur cannot afford to waste or misuse is: time.
‘Carl CJ Johnson’, the protagonist in GTA San Andreas, and also the ones from other games in the series are misfits in society. The society at large does not accept them, and they have to prove to their peers.
In a similar vein, Entrepreneurs too are misfits in society. Certain people do look down upon entrepreneurs and even advice to ‘get a real job’. Every entrepreneur’s mission is to break and rise above such stereotypes and prove himself/herself.
Cheers!
This post originally appeared on the rodinhoods
Entrepreneur: en·tre·pre·neur /ˌäntrəprəˈno͝or/
(Noun) A person who organizes and operates a business or businesses, taking on financial risk to do so. A promoter in the entertainment industry.
Synonyms
contractor – undertaker – businessman – impresario
In a world filled with rat-races and restless challenges, Success is a word that belongs to those who wear an attitude to work against the crowd. Chaos and mayhem, Entrepreneurs are built on this very foundation. Often facing challenges and situations just like others, they choose to either work around them or through them.
The definition of success is something that one places usually as an after thought.
Regardless of the definition of success, there are, oddly enough, a great number of common characteristics that are shared by successful business people. One can place a check beside each characteristic that they feel that they possess. This way, one can see how they stack up. Even if you don’t have all of these characteristics, don’t fret. Most can be learned with practice and by developing a winning attitude, especially if you set goals and apply yourself, through strategic planning, to reach those goals in incremental and measurable stages.
Watch this as we try to understand what it really takes to be an Entrepreneur.
DISCLAIMER: I do not own any rights on this video, this video is shot with the speakers from the GROW Conference (www.growconf.com). This video is part of an ongoing series where entrepreneurs were asked about their greatest fears, failures, and the lessons learned.
Mother nature has blessed us with abundance, enough to sustain our requirements for quite some time. The power-hungry Homo-sapien diggs in to the deepest end he possibly can to reap Mother Nature’s gifts. The want is and has always been endless. In today’s fast rapidly increasing crude oil prices, the day isn’t too far when we run out underneath.
Its not just alternatives but a change in perspective what we really need.
Enter WIRELESS POWER
Not just an alternative but a 100% environmentally-friendly measure that can potentially change the way we use energy.
Based on the concept of simple Induction charging we introduce you to the world of WIRELESS POWER TRANSMISSION.
In the modern day to day scenario we deal head on with real time Automotive short falls like engine emissions, carbon footprints, mileage and of course an alternative to make gas obsolete!
We start with the basics.
The method is focused on removing all the requirement of running and routing any wires for signal and power for applique lamp via tail gate.
Wireless battery charging for electric and hybrid vehicles
The small batteries of electric vehicles can be re-charged in portions by magnetic
induction. Wherever an electric vehicle stops, it is re-charged. In company parking lots, in parking garages, public service stations, park & ride facilities, and even at traffic lights: The vehicle stops above an induction plate that is embedded in the road surface or a charging mat installed on the road surface.
The applications of wireless power is innumerable. This is just the beginning of how innovative and creative tech’s gonna your lifestyle.
Its time for fossil fuel to stay fossil!
We present you an opportunity to collaborate on such innovations at the incubator room. Watch out more Incubies are coming soon 🙂
When you’re ready to quit, you are closer than you think – Bob Parsons (Founder Of Go Daddy)
Most people might say that the best days of automotive designing were in the 60’s and early 70’s, I beg to differ; this is one of those café racers in our time that tells a different story. Meet Tushar jaitely, he’s one of those hustlepreneurs who visualizes designs not meant for the average joe! His design mantra is heavily influenced in the fact of keeping things minimal, simple built, to the point, subtle yet explosive- a true eye popper in the crowd! 
Tushar Jaitly with Chail
An individual’s need to be different or unique has opened up a whole new market that breaks away from mass production and forays into personalized products that are entirely representational of the individual’s sensibilities. In today’s day and age, any item that one aspires can be tweaked and modified or even be created from scratch in order to accommodate one’s personal tastes. Keeping this trend in mind, multiple youngsters who are starting out in the industry are turning towards providing bespoke items, for instance, bike enthusiasts & designers-Tushar jaitly, Bobee Singh and Akash Das are seen creating bikes that are highly customized and unique.
Based in Delhi, he hails from a humble middle class family that follows strict army level discipline and code of conduct, after all his family works like a mini-FOB quite literally, comprising of army men from various cadre. A true inspiration always shapes with a child’s heart. Since his younger days, Tushar has had this zeal to learn more about cars and bikes.
Following this passion, Tushar moved to Italy to master this art of Bike Designing. Working under the sharp lens of the faculty who have had handled world class brands like BMW and PINIFARNIA, his prime achievement during his graduation was the thesis he did under the watchful eyes of Mr. Anders Warming, Design Director at BMW. 
Nadia
The first time he set his hands on an automotive was when he rode with his granddad on a vintage HM ambassador. Overtaking trucks and automotive’s , he developed a strong passion of leaving behind something that only auto-connoisseurs’ and enthusiasts could applaud, apart from the endless and restless fans who’d do anything to get their hands on them beauties- Nadia and Chail. Seven months ago he built his first darling, Nadia.
Primarily inspired from the intriguing, hand-crafted rigid tail Harley Davidson 883 Iron, this bobber speaks in terms of the rich history in the past and the pro-activeness of the present. From then on a fire started that only grew in more and more. Incepted in September 2013, TJ-Moto’s pet project, ‘Nadia’, was the first bike to be customized by Tushar. This was a customization of Harley Davidson 883 Iron. The Bike acclaimed high anticipation for its aesthetic appeal and ground breaking design. In early 2014, TJ-Moto had come up with their latest project; a cafe racer named ‘Chail’. This bike derives its name after a hill station in Himachal Pradesh. Chail has received a great amount of attention from various bike enthusiasts and reputed bike events.
TJ-Moto is equipped with variety of ideas and designs for bikes and intends to design a wide range of Cruisers and Café Racers including Harley Davidson, Royal Enfield and Bullet. The Brand is armed to turn any wheel into a sweet ride. By this summer, TJ-Moto plans for a full fledged expansion through a wide range of merchandise in form of apparel and accessories.
CHAPTER 1
INTRODUCTION
The fundamental purpose of a communication system is to exchange information between two or more devices. Such system can be optimized for voice, data, or both. In its simplest form, a communication system can be established between two nodes (or stations ) that are directly connected by some form of point-to-point transmission medium. A station may be a PC, telephone, fax machine, mainframe, or any other communicating device. This may, however, be impractical, if there are many geographically dispersed nodes or the communication requires dynamic connection between different nodes at various times. An alternative method to a point-to-point connection is establishing a communication Callee . In a communication Callee, each communicating device (or station) is connected to a Callee node. The interconnected nodes are capable of transferring data between stations. Depending on the architecture and techniques used to transfer data, two basic categories of communication Callees are broadcast Callees and switched Callees .
1.1 Need for SWITCHING systems
In the early days when there were many devices, it was necessary to develop a suitable mechanism for communication between any two devices. One alternative was to establish point-to-point communication between each pair of devices using mesh topology. However, mesh topology is impractical for large number of devices, because the number of links increases exponentially (n(n-1)/2, where n is the number of devices) with the number of devices. A better alternative is to use switching techniques leading to switched communication Callee.
In the switched Callee methodology, the Callee consists of a set of interconnected nodes, among which information is transmitted from source to destination via different routes, which is controlled by the switching mechanism. The end devices that wish to communicate with each other are called stations. The switching devices are called nodes. Some nodes connect to other nodes and some are to connected to some stations. Key features of a switched communication Callee are given below:
Their purpose is to provide a switching facility that will move data from node to node until they reach the destination.
The switching performed by different nodes can be categorized into the following three types:
1.2 Circuit switching
A circuit-switched Callee is a Callee in which there exists a dedicated connection. A dedicated connection is a circuit or channel set up between two nodes so that they can communicate. After a call is established between two nodes, the connection may be used only by these two nodes. When the call is ended by one of the nodes, the connection is canceled.
There are two basic types of circuit-switched Callees: analog and digital. Analog was designed for voice transmission. For many years, the PSTN was only analog, but today, circuit-based Callees such as the PSTN have transitioned from analog to digital. To support an analog voice transmission signal over a digital Callee, the analog transmission signal must be encoded or converted into a digital format before it enters the telephony WAN. On the receiving end of the connection, the digital signal must be decoded or converted back into an analog signal format.
A circuit-switched communication system involves three phases: circuit establishment (setting up dedicated links between the source and destination); data transfer (transmitting the data between the source and destination); and circuit disconnect (removing the dedicated links). In circuit switching the connection path is established before data transmission begins. Therefore, the channel capacity must be reserved between the source and destination throughout the Callee and each node must have available internal switching capacity to handle the requested connection. Clearly, the switching nodes must have the intelligence to make proper allocations and to establish a route through the Callee.
The most common example of a circuit-switched Callee can be found in public telephone Callee (PSTN) supporting services such as POTS (plain old telephone systems) and long-distance calls. Other examples of circuit switched services are integrated services digital Callee (ISDN), and switched 56, 64, and 384 (Kbps) services. The majority of wireless application protocols (WAP)– enabled phones also operate on top of circuit-switched Callees. Furthermore, many public Callees dedicated to data transport also use circuit-switching techniques; an example of a Callee in Europe is circuit-switched public data Callee (CSPDN), which transports data on circuit-switched Callees using the X.21 protocol. Circuit switching also has wide applications in optical Callees including wavelength division multiplexed (WDM) systems and WDM SONET Callees.
Example : PSTN
1.2.1 Public Switched Telephone Callees (PSTN)
Public switched telephone Callee (PSTN) is an example of circuit-switched Callee. It’s also known as Plain Old Telephone Service (POTS). The switching centres used for the switching are organised in different levels, namely: Regional offices (class 1), Section offices (class 2), primary offices (class 3), Toll offices (class 4) and finally End offices.(class 5). Level 1 is at the highest level and Level 5 is the lowest level. Subscribers or the customers are directly connected to these end offices. And each office is connected directly to a number of offices at a level below and mostly a single office at higher level.
Subscriber Telephones are connected, through Local Loops to end offices (or central offices). A small town may have only one end office, but large cities have several end offices. Many end offices are connected to one Toll office, which are connected to primary offices. Several primary offices are connected to a section office, which normally serves more than one state. All regional offices are connected using mesh topology. Accessing the switching station at the end offices is accomplished through dialling. In the past, telephone featured rotary or pulse dialling, in which digital signals were sent to the end office for each dialled digit. This type of dialling was prone to errors due to inconsistency in humans during dialling. Presently, dialling is accomplished by Touch-Tone technique. In this method the user sends a small burst of frequency called dual tone, because it is a combination of two frequencies. This combination of frequencies sent depends on the row and column of the pressed pad.
Fig.1.1: Basic organization of a Public Switched Telephone Callee (PSTN)
The connections are multiplexed when have to send to a switching office, which is one level up. For example, Different connections will be multiplexed when they are to be forwarded from an end-office to Toll office.
Fig. 1.2: Typical medium distance telephone circuit
CHAPTER 2
Need for a faster data switching Callee
Over the past decade data communications has been revolutionized by a radically new technology called packet switching. In 1968 virtually all interactive data communication Callees were circuit switched, the same as the telephone Callee. Circuit switching Callees pre-allocate transmission bandwidth for an entire call or session. However, since interactive data traffic occurs In short bursts 90 percent or more of this bandwidth Is wasted. Thus, as digital electronics became inexpensive enough, it became dramatically more cost-effective to completely redesign communications Callees, introducing the concept of packet switching where the transmission bandwidth is dynamically allocated, permitting many users to share the same transmission line previously required for one user. Packet switching has been so successful, not only in improving the economics of data communications but in enhancing reliability and functional flexibility as well, that in 1978 virtually all new data Callees being built throughout the world are based on packet switching.
There have always been two fundamental and competing approaches to communications: pre-allocation and dynamic-allocation of transmission bandwidth. The telephone, telex, and TWX Callees are circuit-switched systems, where a fixed bandwidth is pre-allocated for the duration of a call. Most radio usage also involves pre-allocation of the spectrum, either permanently or for single call. On the other hand, message, telegraph, and mail systems have historically operated by dynamically allocating bandwidths or space after a message is received, one link at a time, never attempting to schedule bandwidth over the whole source-to-destination path. Before the advent of computers, dynamic-allocation systems were necessarily limited to nonreal time communications, since many manual sorting and routing decisions were required along the path of each message. However, the rapid advances in computer technology over the last two decades have not only removed this limitation but have even made feasible dynamic- allocation communications systems that are superior to pre-allocation systems in connect time, reliability, economy and flexibility. This new communications technology, called “packet switching,” divides the input flow of information into small segments, or packets, of data which move through the Callee in a manner similar to the handling of mail but at immensely higher speeds. Although the first packet-switching Callee was developed and tested less than ten years ago, packet systems already offer substantial economic and performance advantages over conventional systems. This has resulted in rapid worldwide acceptance of packet switching for low-speed interactive data communications Callees, both public and private.
2.1 Milestones in the evolution of packet switching
In 1960’s Telephone Callee was the dominant communication Callee. It used Circuit Switching because voice must be transmitted at a constant rate. In 1967 ARPANET was started by the government research agency ARPA. This was the first packet-switched Callee. By 1972, ARPANET was up to a whopping 15 nodes. During this time, various other packet-switched Callees were introduced. Also during this time Ethernet was introduced as a technology that worked well for small distances. In 1974 the notion of a Callee of Callees” was introduced and people started talking about minimalism, best effort service, stateless routers, and decentralized control. During the 1980’s ATM (a circuit-switching technology) became huge because of its speed and almost won out against the ARPANET. However, the ARPANET prevailed
and became what we now call the Internet. A lot of the work on ARPANET was done via Computer Science departments, and other Callees like CSnet, that connected only CS departments.In 1989 the Web was introduced. In 1995 the US government transferred control of the Internet backbone to private carriers {all those ISPs and NBPs. More recently delay-sensitive applications (interactive-audio) have encouraged re-
searchers to start thinking about how to make packet-switching more like circuit-switching.
Today we have about 100 million machines on the Internet.
2.2 Packet switching
Packet switching is a digital Calleeing communications method that groups all transmitted data – regardless of content, type, or structure – into suitably-sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams (sequences of packets) over a shared Callee. When traversing Callee adapters, switches, routers and other Callee nodes, packets are buffered and queued, resulting in variable delay and throughput depending on the traffic load in the Callee.
Packet switching contrasts with another principal Calleeing paradigm, circuit switching, a method which sets up a limited number of dedicated connections of constant bit rate and constant delay between nodes for exclusive use during the communication session. In case of traffic fees, for example in cellular communication, circuit switching is characterized by a fee per time unit of connection time, even when no data is transferred, while packet switching is characterized by a fee per unit of information. Two major packet switching modes exist; connectionless packet switching, also known as datagram switching, and connection-oriented packet switching, also known as virtual circuit switching. In the first case each packet includes complete addressing or routing information. The packets are routed individually, sometimes resulting in different paths and out-of-order delivery. In the second case a connection is defined and preallocated in each involved node before any packet is transferred. The packets include a connection identifier rather than address information, and are delivered in order.
Packet mode communication may be utilized with or without intermediate forwarding nodes (packet switches). In all packet mode communication, Callee resources are managed bystatistical multiplexing or dynamic bandwidth allocation in which a communication channel is effectively divided into an arbitrary number of logical variable-bit-rate channels or data streams. Each logical stream consists of a sequence of packets, which normally are forwarded by the multiplexers and intermediate Callee nodes asynchronously using first-in, first-outbuffering. Alternatively, the packets may be forwarded according to some scheduling discipline for fair queuing or for differentiated or guaranteed quality of service, such as pipeline forwarding or time-driven priority (TDP). Any buffering introduces varying latency and throughput in transmission. In case of a shared physical medium, the packets may be delivered according to some packet-mode multiple access scheme.
2.3 Comparison between packet circuit switching
Two basic approaches are common to Packet Switching:
2.3.1 Virtual Circuit Packet Switching Callees
An initial setup phase is used to set up a route between the intermediate nodes for all the packets passed during the session between the two end nodes. In each intermediate node, an entry is registered in a table to indicate the route for the connection that has been set up. Thus, packets passed through this route can have short headers, containing only a virtual circuit identifier (VCI) and not their destination. Each intermediate node passes the packets according to the information that was stored in it in the setup phase. In this way, packets arrive at the destination in the correct sequence and it is guaranteed that essentially there will not be errors. This approach is slower than Circuit Switching, since different virtual circuits may complete over the same resources and an initial setup phase is needed to initiate the circuit. As in Circuit Switching, if an intermediate node fails, all virtual circuits that pass through it are lost.The most common forms of Virtual Circuit Callees are X.25 and Frame Relay, which are commonly used for public data Callees (PDN).
2.3.2 Datagram Packet Switching Callees
This approach uses a different, more dynamic scheme to determine the route through the Callee links. Each packet is treated as an independent entity and its header contains full information about the destination of the packet. The intermediate nodes examine the header of the packet and decide to which node the packet has to be sent, so that it will reach its destination.
In the decision two factors are taken into account:
since packets can reach the destination in alternate routes.
Thus, in this method, the packets don’t follow a pre-established route, and the intermediate nodes (the routers) don’t have pre-defined knowledge of the routes that the packets should be passed through. Packets can follow different routes to the destination, and delivery is not guaranteed (although packets usually do follow the same route, and are reliably sent). Due to the nature of this method, the packets can reach the destination in a different order than they were sent, thus they must be sorted at the destination to form the original message. This approach is time consuming, since every router has to decide where to send each packet. Packet switching is similar to message switching using short messages. Any message exceeding a Callee-defined maximum length is broken up into shorter units, known as packets, for transmission; the packets, each with an associated header are then transmitted individually through the Callee. The fundamental difference in packet communication is that the data is formed into packets with a pre-defined header format (i.e. PCI), and well-known “idle” patterns which are used to occupy the link when there is no data to be communicated.
Packet Callee equipment discards the “idle” patterns between packets and processes the entire packet as one piece of data. The equipment examines the packet header information (PCI) and then either removes the header (in an end system) or forwards the packet to another system. If the out-going link is not available, then the packet is placed in a queue until the link becomes free. A packet Callee is formed by links which connect packet Callee equipment.
Fig. 2.1: Packet switching Callee
There are two important benefits from packet switching.
of each packet. The implication is that packets belonging to other messages may be sent between the packets of the message being sent from A to D. This provides a much fairer sharing of the resources of each of the links.
CHAPTER 3
Message switching
In telecommunications, message switching was the precursor of packet switching, where messages were routed in their entirety, one hop at a time. It was first introduced by Leonard Kleinrock in 1961. Message switching systems are nowadays mostly implemented over packet-switched or circuit-switched data Callees. each message is treated as a separate entity. Each message contains addressing information, and at each switch this information is read and the transfer path to the next switch is decided. Depending on Callee conditions, a conversation of several messages may not be transferred over the same path. Each message is stored (usually on hard drive due to RAM limitations) before being transmitted to the next switch. Because of this it is also known as a ‘store-and-forward’ Callee. Email is a common application for Message Switching. A delay in delivering email is allowed unlike real time data transfer between two computers. Message-switched data Callees are hop-by-hop systems that support two distinct characteristics: store-andforward and message delivery.
In a message-switched Callee, there is no direct connection between the source and destination nodes. In such Callees, the intermediary nodes (switches) have the responsibility of conveying the received message from one node to another in the Callee. Therefore, each intermediary node within the Callee must store all messages before retransmitting them one at a time as proper resources become available. This characteristic is often referred to as store-and-forward In message switching systems (also called store-and-forward systems), the responsibility of the message delivery is on the next hop, as the message travels through the path In message switching systems (also called store-and-forward systems), the responsibility of the message delivery is on the next hop, as the message travels through the path.toward its destination. Hence, to ensure proper delivery, each intermediate switch may maintain a copy of the message until its delivery to the next hop is guaranteed. In case of message broadcasting, multiple copies may be stored for each individual destination node. The store-and-forward property of message-switched Callees is different from queuing , in which messages are simply stored until their preceding messages are processed. With store-and-forward capability, a message will only be delivered if the next hop and the link connecting to it are both available. Otherwise, the message is stored indefinitely. For example, consider a mail server that is disconnected from the Callee and cannot receive the messages directed to it. In this case, the intermediary server must store all messages until the mail server is connected and receives the e-mails. The store-and-forward technology is also different from admission control techniques implemented in packet-switched or circuit switched Callees. Using admission control, the data transmission can temporarily be delayed to avoid over provisioning the resources. Hence, a message-switched Callee can also implement an admission control mechanism to reduce Callee’s peak load. The message delivery in message-switched Callees includes wrapping the entire information in a single message and transferring it from the source to the destination node. The message size has no upper bound; although some messages can be as small as a simple database query, others can be very large. For example, messages obtained from a meteorological database center can contain several million bytes of binary data. Practical limitations in storage devices and switches, however, can enforce limits on message length. Each message must be delivered with a header. The header often contains the message routing information, including the source and destination, priority level, expiration time. It is worth mentioning that while a message is being stored at the source or any other intermediary node in the Callee, it can be bundled or aggregated with other messages going to the next node. This is known as message interleaving . One important advantage of message interleaving is that it can reduce the amount of overhead generated in the Callee, resulting in higher link utilization.
Fig.3.1: A message-switched Callee
Fig.3.2: A message-switched Callee
CHAPTER 4
Graphical analysis in computer usage in the past decade
Fig.4.1: graph of the internet users
4.1 Analysis of the exponential growth of the mobile users
Fig.4.2: Growth of mobile users
Analysis:
From the above two graphs we can see there has been an exponential growth in computer and mobile cell phone users. As the communication between computer Callee and mobile Callee was booming up, there was a need for Callee integration between both the Callees, also as the next generation Callees were coming up rapidly message switching was the next revolutionary change: SIP was born.
4.2 Comparing SIP with H.323
CHAPTER 5
An Overview of SIP
Introduction
The growing thirst among communications providers, their partners and subscribers for a new generation of IP-based services is now being quenched by SIP – the Session Initiation Protocol. An idea born in a computer science laboratory less than a decade ago, SIP is the first protocol to enable multi user sessions regardless of media content and is now specification of the Internet Engineering Task Force (IETF). SIP application examples include audio, video conferencing, instant messaging, file transfer or other real-time data communication sessions.
SIP is designed to provide signaling and session management for voice and multimedia connections over packet-based Callees. It is a peer-to-peer protocol with intelligent endpoints and distributed call control, such as H.323. Gateways that use SIP do not depend on a call agent, although the protocol does define several functional entities that help SIP endpoints locate each other and establish a session.
SIP is built on a client-server model, using requests and responses that are similar to Internet applications. It uses the same address format as e-mail, with a unique user identifier (such as telephone number) and a domain identifier. A typical SIP address looks like one of the following:
sip:1112223344@nmims.com.
This allows Domain Name System (DNS) to be used to locate users, and it also allows SIP to integrate easily with e-mail. SIP uses Multipurpose Internet Mail Extension (MIME) to describe the contents of its messages.
5.1 SIP Architecture
SIP’s basic architecture is client / server in nature. The main entities in SIP are the User Agent, the SIP Proxy Server, the SIP Redirect Server and the Registrar. The User Agents, or SIP endpoints, function as clients (UAC’s) when initiating requests and as servers (UAS’s) when responding to requests. User Agents communicate with other User Agents directly or via an intermediate server. The User Agent also stores and manages call states. SIP intermediate servers have the capability to behave as proxy or redirect servers. SIP Proxy Servers forward requests from the User Agent to the next SIP server, User Agent within the Callee and also retain information for billing/accounting purposes. SIP Redirect Servers respond to client requests and inform them of the requested server’s address. Numerous hops can take place until reaching the final destination. SIP’s tremendous flexibility allows the servers to contact external location servers in order to determine user or routing policies and therefore, does not bind the user into only one scheme to locate users. In addition, in order to maintain scalability, the SIP servers can either maintain state information or forward requests in a stateless fashion.
Fig.5.1: session initiation
The third entity comprising SIP is the SIP Registrar. The User Agent sends a registration message to the SIP Registrar and the Registrar stores the registration information in a location service via a non-SIP protocol. Once the information is stored, the Registrar sends the appropriate response back to the user agent.
Fig.5.2: Session registration
CHAPTER 6
SIP Entities
6.1 SIP Entities
SIP endpoints are called user agents (UA) and can be various devices, including IP phones, cell phones, PDAs, Cisco routers, or computers running a SIP-based application. UAs can act as either clients or servers. The user agent client (UAC) is the device that is initiating a call, and the user agent server (UAS) is the device that is receiving the call. The SIP protocol defines several other functional components. These functional entities can be implemented as separate devices, or the same device can perform multiple functions.
Some of the devices that can have a UA function in a SIP Callee are: workstations, IP-phones, telephony gateways call agents, automated answering services. SIP User Agent APIs provide interface to services from SIP protocol stack. 3rd party developers can write their own SIP based applications by using SIP UA.
All these functions work together to accomplish the goal of establishing and managing a session between two UAs. SIP servers can also interact with other application servers to provide services, such as authentication or billing. We can configure Cisco routers as SIP gateways. As such, they can act as a SIP UAC or UAS, they can register E.164 numbers with a SIP registrar, and they can act as SIP registrar and redirect servers. In addition, they can set up SIP trunks to another SIP gateway or to Call Manager. A Cisco SIP gateway that is using Survivable Remote Site Telephony (SRST) can provide registration and redirection services to SIP phones when Call Manager and proxy servers are unavailable. SRST is not on by default; we must configure it. Both SIP and SCCP phones can fail over to a router that is running SIP SRST. Cisco CME and SRST also support B2BUA functionality beginning in Cisco IOS 12.(4)T. SIP SRST.
6.2 SIP Messages
SIP is a text-based protocol with syntax similar to that of HTTP. There are two different types of SIP messages:
6.2.1 Message Requests:
| Request name | Description | Defined in |
| INVITE | Initiates a call, i.e indicates that a client is being invited to participate in a call session. | RFC 3261. |
| ACK | Confirms that the client has received a final response for INVITE. | RFC 3261. |
| BYE | Terminates a call. | RFC 3261. |
| CANCEL | Cancels any pending request. | RFC 3261. |
| OPTIONS | Queries the capabilities of servers. | RFC 3261. |
| REGISTER | Registers the address with a SIP server. | RFC 3261. |
| NOTIFY | Notify the subscriber of a new event. | RFC 3261. |
| INFO | Sends mid-session information that does not modify the session state | RFC 3261. |
Table. 6.1: SIP request messages
6.2.2 Message Responses
Response messages contain numeric response codes. The SIP response code set is partly based on HTTP response codes. There are two types of responses and six classes:
CLASSES:
1xx = provisional, searching, ringing, queuing etc.
2xx = success.
3xx = redirection, forwarding.
4xx = request failure (client mistakes).
5xx = server failures.
6xx = global failure (busy, refusal, not available anywhere).
Table. 6.1: SIP response messages
6.2.3 MESSAGE PARTS:
SIP messages are composed of the following three parts:
START LINE: Every SIP message begins with a Start Line. The Start Line conveys the message type (method type in requests, and response code in responses) and the protocol version. The Start Line may be either a Request-line (requests) or a Status-line (responses).
HEADERS: SIP header fields are used to convey message attributes and to modify message meaning. They are similar in syntax and semantics to HTTP header fields and thus take the format:
<name>:<value>
BODY: A message Body is used to describe the session to be initiated for example, in a multimedia session this may include audio and video codec types, sampling rates etc. Message bodies can appear both in request and in response messages.
Possible body types include:
SDP: Session Description Protocol (SDP).
MIME: Multipurpose Internet Mail Extensions (MIME).
CHAPTER 7
SIP CALL FLOWS
7.1 SIP call flows
Session Initiation
The following samples show the message exchange between two User Agents for the purpose of setting up a voice call. SIP user xyz@mpstme.com invites SIP user abc@nmims.com . Xyz sends an INVITE request containing an SDP body. Abc replies with a 200 OK response also containing an SDP body.
Fig. 7.1: Typical message flow in a SIP voice call
SESSION TERMINATION
The session termination call flow proceeds as follows:
7.2 Types of call flow:
7.2.1 Call Flow between Two SIP Gateways
Cisco routers, including CME routers, can act as SIP gateways for calls that originate from non-SIP phones. The gateways function as SIP UAs and set up a SIP session between them for each call. Fig. 3 shows two routers handling analog phones, using SIP between them. In this example, SIP GW-A originates the calls and acts as a UAC, and SIP GW-B acts as a UAS. The signaling from the PBX to the gateway is just normal analog call signaling. Only the two gateways exchange SIP messages.
Fig. 7.2 : Call flow between two SIP gateways.
The first phone initiates the call, the call flow proceeds as follows:
7.2.2 Call Flow Using a Proxy Server
SIP UAs register with a proxy server or a registrar. Proxy servers then act as an intermediary for SIP calls. Cisco routers that are acting as SIP gateways can use the services of a SIP proxy server, either contacting the server or receiving requests from it. They can additionally register E.164 numbers with a proxy server or a registrar. Proxy servers can either leave the signaling path when the call is connected or can enable “Record-route” to stay in the signaling path. If Record-route is disabled, the proxy server does not know of any changes to the call or when the call is disconnected. Fig. 4 shows call flow when Record-route is disabled. In Fig. 4 a SIP endpoint places a call using a proxy server. The figure shows several types of endpoints:
In Fig.7.2, one of these endpoints places a call to an analog phone behind SIP gateway GW-B. The call flow proceeds as follows:
Fig. 7.3: SIP call flow with proxy server
7.2.3 Call Flow Using Multiple Servers
SIP UAs and SIP proxy servers can contact a redirect server to determine where to send an INVITE. They typically do this when the called number is outside the local domain. The redirect server returns the most detailed information it has either endpoint location(s) or the location of the next-hop server. Then it relies on the proxy server or UAC to route its INVITE appropriately.
Fig. 6 shows the call flow in a more complex Callee with registrar, redirect, and proxy servers. (Recall that these are functional units and can all reside in the same device.) The figure shows the messages that are necessary to route the initial INVITE method to the UAS. After GW-B, the UAS, receives the INVITE, call flow is similar as the above types.
Fig. 7.4: SIP call flow with multiple servers.
In Fig. 7.4 one of the SIP endpoints in Callee A calls an analog phone behind gateway GW-B in Callee B. The following steps take place:
Following these steps, GW-B sets up the call with the PBX. It sends responses to Proxy-B, which forwards them through Proxy-A to the calling endpoint. If Record-route is enabled, all further signaling goes through the proxies. If not, call signaling proceeds as shown in Fig. 5.
7.3 Establishing A SIP Session within the Same Domain
A SIP session between two users who subscribe to the same ISP and uses same domain . Suppose user A relies on a SIP phone. User B has a PC running a soft client that can support voice and video. Upon powering up, both users register their availability and their IP addresses with the SIP Proxy Server in the ISP’s Callee. User A, who is initiating this call, tells the SIP Proxy Server he/she wants to contact User B. The SIP Proxy Server then asks for and receives User B’s IP address from the SIP Registrar Server. The SIP Proxy Server relays User A’s invitation to communicate with User B, including — using SDP – the medium or media User A wants to use. User B informs the SIP Proxy Server that User A’s invitation is acceptable and that he/she is ready to receive the message. The SIP Proxy Server communicates this to User A, establishing the SIP session. The users then create a point-to-point RTP connection enabling them to interact.
7.3.1 SIP to SIP using ZOIPER:
Fig 7.5: ZOIPER
To create a new SIP account in Zoiper
Fig 7.6: configuration window
Configure the terminal in both host and client .
Tracing Call Using WIRESHARK
DESCRIPTION
Wireshark is a GUI network protocol analyzer. It lets you interactively browse packet data from a live network or from a previously saved capture file. Wireshark‘s native capture file format is libpcap format, which is also the format used by tcpdump and various other tools.
Wireshark can read / import the following file formats:
There is no need to tell Wireshark what type of file you are reading; it will determine the file type by itself. Wireshark is also capable of reading any of these file formats if they are compressed using gzip. Wireshark recognizes this directly from the file; the ‘.gz’ extension is not required for this purpose.
Like other protocol analyzers, Wireshark‘s main window shows 3 views of a packet. It shows a summary line, briefly describing what the packet is. A packet details display is shown, allowing you to drill down to exact protocol or field that you interested in. Finally, a hex dump shows you exactly what the packet looks like when it goes over the wire. In addition, Wireshark has some features that make it unique. It can assemble all the packets in a TCP conversation and show you the ASCII (or EBCDIC, or hex) data in that conversation. Display filters in Wireshark are very powerful; more fields are filterable in Wireshark than in other protocol analyzers, and the syntax you can use to create your filters is richer. As Wireshark progresses, expect more and more protocol fields to be allowed in display filters. Packet capturing is performed with the pcap library. The capture filter syntax follows the rules of the pcap library. This syntax is different from the display filter syntax. Compressed file support uses (and therefore requires) the zlib library. If the zlib library is not present, Wireshark will compile, but will be unable to read compressed files. The pathname of a capture file to be read can be specified with the -r option or can be specified as a command-line argument.
Fig 7.7:Wireshark Window.
Fig.7.8 : Packet trace between two SIP clients
Fig.7.9: Call flow between two SIP clients
7.4 Establishing A SIP Session in Dissimilar Domains
The difference between this scenario and the first is that when User A invites User B — who is now using a multimedia handset — for a SIP session the SIP Proxy Server in Domain A recognizes that User B is outside its domain. The SIP Proxy Server then queries the SIP Redirect Server — which can reside in either or both Domain A or B — for User B’s IP address. The SIP Redirect Server feeds User B’s contact information back to the SIP Proxy Server, which forwards the SIP session invitation to the SIP Proxy Server in Domain B. The Domain B SIP Proxy Server delivers User A’s invitation to User B, who forwards his/her acceptance along the same path the invitation travelled.
Fig.7.10: Basic Call Flow between SIP & PSTN
Fig.7.11 : Packet trace between SIP & PSTN
Fig.7.12: Call flow between SIP & PSTN
CHAPTER 8
Server Applications
Asterisk
Asterisk supports SIP as one protocol to connect with, and out of the other protocols mentioned in this article both IAX and SCCP are also supported. Asterisk uses a concept of channels, where different terminals can connect with different VoIP protocols or traditional telephony interfaces, but administering the different channels is – as far as possible – independent of the channel type used. Therefore Asterisk is not really a great way to learn about SIP, even though it supports SIP well, since its inner architecture does not reflect the philosophy of SIP.
Due to the architecture of Asterisk it is also straightforward to use it in a configuration where all RTP traffic too is routed through the server, contrary to how SIP is intended to be used. This is one way of overcoming firewall and NAT problems but Asterisk is also sometimes used as an intermediary between two otherwise incompatible SIP terminals. It
can serve as a media gateway translating from one codec to another, or simply help in connecting two devices using incompatible SIP dialects. Asterisk can also easily be used as a media gateway, connecting a SIP client to a phone on the traditional telephone Callee. This is in fact a very valuable and often used function of Asterisk. In this way Asterisk can also be used in tandem with OpenSER (see below), letting OpenSER be the SIP Proxy and Asterisk function as a media gateway or also an application server (such as voice mail).
Asterisk is usually available in most Linux distributions today. A custom Linux distribution called AsteriskNow has also been produced by the Asterisk project. If one wants to build a dedicated Asterisk server it is probably the easiest way to go. Asterisk from version 1.4. comes with a comparably easy graphical interface, putting Asterisk competing with the plethora of commercial IP-PBX offerings available.
CHAPTER 9
Modeling in SIP
9.1 Sip Modeling using Rational Rhapsody Modeler:
Rational Rhapsody is the visual prograCallerng environment (VPE) of choice for real-time, embedded software developers. Rational Rhapsody goes beyond defining requirements and designing a solution. It implements your solution from design diagrams, automatically generating ANSI-compliant code that is optimized for the most widely used real-time, embedded target environments. Rational Rhapsody is the industry leading Model-Driven Development environment based on UML 2.0 and SysML for systems, software, and test, and has the unique ability to extend its modeling environment to allow both functional and object oriented design methodologies in one environment. Rational Rhapsody generates full production C++, C, Java, or Ada code for a variety of target platforms based on UML 2.0 behavioral and structural diagrams as well as providing reverse engineering of code for reuse of your intellectual property within a Model-Driven environment. Rational Rhapsody Modeler Edition helps users develop easy to understand systems and software designs, including structure and intended behavior of a system. It helps users increase productivity and shorten design cycles.
9.2 Using Rational Rhapsody Modeler Edition
Rational Rhapsody Modeler is a visual design tool for developing object-oriented embedded software and performing structural and systems modeling. It enables you to perform the following tasks:
CHAPTER 10
CREATING USE CASE DIAGRAM
Use Case Diagrams (UCDs) model relationships between one or more users (actors) and a system or class (classifier). They enable you to specify requirements for system behavior.
To create the Use Case Diagram (UCD):
Fig.10.1: Creating a new User Case Diagram
10.1 Drawing the Functional Overview UCD
The following are the system requirements, including the actors, the major function points of the system, and the relationships between them, for this procedure:
– Caller – The one who initiates a call.
– Callee – The one who receives a call request from caller.
– Call to be established between two subscriber via SIP Server.
– The SIP Server receives incoming and outgoing call requests and tracks users in Registrar.
– The Caller and Callee places and receives calls.
– The SIP Server checks the authentication in Registrar and establishes path for communication if authenticated.
10.1.1 Drawing a Boundary Box and Actors
The boundary box defines the system under design from the external actors. Use cases are inside the boundary box and actors are outside the boundary box. In this procedure, you draw a boundary box and actors, as shown in the following illustration.
To draw a boundary box and actors:
(Note: Do not include spaces in the names of the actors. Use an underscore instead.)
10.1.2 Drawing the Use Cases
A Use Case represents a particular function of the system. In this procedure, we draw the following use cases, as shown in the following illustration:
Fig.10.2: drawing the use cases
To draw the use cases:
10.1.3 Entering a Use Case Description
In this procedure, we enter a description for each use case. To enter a use case description:
Fig10.3: entering a use case description
10.1.4 Associating Actors with Use Cases
The Caller actor places a calls request to SIP Server. SIP Server checks for authentication of both Caller and Callee.
To draw association lines:
Fig.10.4: Associationg actors with use cases
10.1.5 Drawing Generalizations
A Generalization is a relationship between a general element and a more specific element. The more specific element inherits the properties of the general element and is substitutable for the general element. A generalization lets us derive one use case from another. In this procedure, we draw generalizations indicating that SIP Server use case is derived from the Registrar use case and the Registrar use case, as shown in the following illustration.
To draw a generalization:
Fig.10.5: Drawing the generalizations
10.1.6 Adding Remarks to Model Elements and Diagrams
We can add remarks to specify additional information about a model element or diagram. In this procedure, we add a comment to the Functional Overview UCD, as shown in the following illustration.
To add a remark:
SIP application examples include audio, video conferencing, instant messaging.”
10.2 Creating the SIP Overview UCD
The SIP Overview UCD breaks down the SIP use case and identifies the different types of service that can be placed as use cases. In this exercise, we develop the SIP Overview UCD, as shown in the following illustration
To create the Registrar Overview UCD:
Fig.10.6: creating an user case description
10.2.1 Entering a Use Case Description
In this procedure, we enter a description for each use case. To enter a use case description:
Fig.10.7 entering the user case description
Click the Description tab and type the following text: “A SIP Server is an entity that acts as both a Server and a Client for the purpose of making requests on behalf of other client.
It also play a role of routing which means it ensure that a request is sent to another entity.SIP Server are also useful for enforcing policy. ”
10.2.2 Drawing Generalizations
In this procedure, we draw generalizations to show that the SIP Serer and the Redirect Server use cases derive from the Registrar, as shown in the following illustration.
To draw a generalization:
10.2.3 Adding Requirement Elements
Adding Requirement Elements to the Model We can represent requirements in the browser window and diagrams as requirement elements. Requirement elements are textual annotations that describe the intent of the element.
In this procedure, we add the handset model requirements to the RequirementsPkg package in the Browser Window, as shown in the following illustration.
To add requirements elements:
Fig.10.8: adding the requirement elements
Click the Description tab and type the following text: “The Caller and Callee shall register themself in Registrar before a place call sequence begins..”
Click OK to apply the changes and to close the Features dialog box.
10.2.4 Adding Requirement Elements to a Diagram
In this procedure, we add requirement elements to the Registrar Overview UCD to show the requirements trace to the use cases.
To add the requirement elements to the Registrar Overview UCD:
Setting the Display Option to Show the Requirement the Element Name
In this procedure, we set the display option to show the requirement the names of the elements, as shown in the following illustration.
To set the display option to show the requirement element name:
Fig:10.9: adding the requirement cases
10.2.5 Drawing Dependencies
A dependency is a direct relationship in which the function of an element requires the presence of and may change another element. We can show the relationship between requirements, and between requirements and model elements using dependencies. In this procedure, we can draw dependencies between the requirement elements and the use cases, as shown in the following illustration…
To draw dependencies:
Fig.10.10: adding the requirement dependencies
10.2.6 Defining the Stereotype of a Dependency
We can specify the ways in which requirements relate to other requirements and model elements using stereotypes. A stereotype is a modeling element that extends the semantics of the UML metamodel by typing UML entities. Modeler includes predefined stereotypes and we can define ourr own stereotypes. Stereotypes are enclosed in guillemets on diagrams, for example, «derive». In this procedure, we set the following types of dependency stereotypes, as shown in the following illustration:
Fig: 10.11: defining the stereotype
To define the stereotype of a dependency:
Fig: 10.12: defining the stereotype of a dependency
Fig.10.13: final model
10.3 Summary of the model
In this module, we created UCDs that show the functions and requirements of the wireless telephone and placing a call. We became familiar with the parts of a UCD and created the following:
SIP Pros & Cons
Pros:
Cons:
Conclusion:
This paper introduces SIP clients & servers, User agents, Proxy server, Redirect servers & Registrars. Message Request & Responses. Different call flow & call scenario are also discussed.
SIP is promising because it is a simple, open protocol that can be deployed in carrier and enterprise networks and because it enables new multimedia applications in voice, data, and video. For service providers, H.323 is a legacy technology that will eventually give way to SIP because of the inherent simplicity of SIP and potential for new media-blending services (Internet telephony). However, in the enterprise market, H.323 has gained significant support because of its manageability, reliability, and interoperability with the PSTN and will continue to do so for some time. Most serious implementers of SIP are considering a SIP-to-H.323 inter-working function / gateway as an essential element of any network.
There is a general consensus among standards organizations, companies, and technology experts that standardized procedures need to be specified to allow seamless inter-working between the two protocols. Bodies such as TIPHON (ETSI), IMTC, and IETF are working to address this topic.
References:
The Incubatoroom 