The Truth About Journalism Media Essay

The Truth About Journalism Media Essay Journalism, a profession of unveiling truth, bringing facts in front of people has been under discussion for quite a while. The main reason why media and journalism has attracted so many spotlights in recent years is the freedom of speech and independence of media from any governmental influence. It was a profession of honor, now has become a taboo in some of the societies. Should journalism be verdicts or just another literature in a hurry? Journalism has been a respectful profession not just a game of mud splashing and money making in no time, it was a source of information for the people belonging to that nation. It should be so today as well as tomorrow. What is journalism in real? Is it just the challenge of satisfying the space or it is a discipline of assembling, authenticating, covering and analyzing information drawn together regarding current events, including development, problems and people? Journalism informs society about itself and makes public that which would otherwise be private (Tony Harcup, 2004). Those who practice journalism are known as journalists. Journalism plays a vital role in society. Different journalists have different viewpoints, some say that it is important to go in depth of the issue and trace back its history, while others say that it is not important to know the history of power and authority however only to put the fact as it is in real is foremost important (Tony Harcup, 2004). Supportive arguments with documented evidence Journalists who think that it is vital to find out about the history of politics and power related to any issue in a certain place hold this perception because of many reasons. Firstly knowing the societies through their own perceptions is very necessary. Until a person understands the historical context of that area or society, it will be very difficult to judge their behavior and give a verdict about what is being done wrong here. Learn from the article Different societies have different norms and values. They think differently and act differently, for them there might be something wrong which is right in our society. So to decide whether this should make the newspaper as someones gossip, it is necessary to find out about the right and wrong from the eye of the commoner (Bird, E. 1990). Supportive arguments with documented evidence If journalists are to live up to the principles of their occupation, they need to glance further than the expected confines of politics and journalism as they now survive-limits which, in large gauge, they themselves have set since they take pleasure in a relatively elevated extent of autonomy in democratic societies. Too often, the master narratives are about disagreement, and winners and losers, which in turn produce the shallow story that not passes to effect necessary social change and development (Ron Smith, 2008). Learn from the article News, issues facts and information about a society does not hang outside in just some ethereal way that journalists pass it on. News is not a commodity to be sold or that can be apportioned for readers and viewers. This is the point where a journalist comes in and extracts the important matter and makes it into news. For that understanding the cultural, historical context of the society is most important. There are journalists who do not think that it is important to understand the context and background of the news before making it public. They believe that truth and honest facts should reach the nation as they are in real. No manipulation should be done to the facts to show the concerned people in a positive spotlight. Facts should be made public no matter how gross they might be. Supportive arguments with documented evidence These types of journalists think that in journalism, assertions should be reported as if they were true, whether or not they have been stranded in a thorough process of confirmation. In fact, the assumption is such a fundamental constituent of all journalism that it extends to both so-called excellence and tabloid reporting. Learn from the article A tabloid story is accurate if it realistically reports what was said or printed by sources. By this standard much of what is written in tabloids can be claimed to be extremely accurate including, one might add, the declaration of experts on alien abductions (Bird, 1990: 378). Wilkinss argument, then, is a call for a much more sophisticated understanding of what comprises truth and fact than journalists are typically armed with. I as a person interested in journalism would rather prefer the truth based journalism. No doubt that the historical contexts are very important but now the political conditions all around the world has worsened so much that giving the right facts and timely information to the public is more important. Learn from the article Honesty is integral part of journalism which is for what the public and nation keep their eyes in search for. Whether the news is related to local and common people or any breaking news about the well known figures of the state, the news should be authenticated and should be without any manipulation. Learn from the article Recently in Jamaica there was uproar about the government that it sold the Sandals Whitehouse hotel to Gordon Butch Stewart. One week after this announcement that Cabinet has approved the proposed sale of the five-star Sandals Whitehouse hotel to Gordon Butch Stewarts company, Gorstew Limited, the office of Contractor General has asked to halt the sale. It must be made unmistakably obvious here, that the contractor general is entirely correct when he says his office, the Office of the Contractor General, is an autonomous anti-corruption commission of Parliament which is authorized by law to perform enquiry into the award of government awards and to make sure that everything is above board (John Maxwell, 2010). Learn from the article He is right again when he says that it is against the law for a contractor general in the effect of his authority, to be subject to the dictates, direction or control of any person or authority. He must be totally satisfied that the Gorstew deal is in the best interest of the country and complies with all the necessary protocols and rules. Supportive arguments with documented evidence The transaction of the embattled Whitehouse hotel in Westmoreland to Gorstew has obtained many remarks with some quarters laboring under the misinterpretation that it is a sweetheart deal that is injurious to taxpayers. Learn from the article The news channels and news papers are making this issue their front page headlines, no matter that the government is involved in the deal of this sale of the hotel, the facts and figures related to this matter has been made public with entire openness, may be with not so much honesty, only to get the high rating on news channels and papers, yet these facts reach the public knowledge. Learn from the article Journalism is a tool to effect the needed change in society.   But unluckily, with the course of time, its real meaning has gone astray. Today, for the so-called journalists, robust salaries and of course, quick promotions alone, matter. And the insincerity is that while publishing any news what concerns them most is that they should beat their counterpart. The purpose should be to take on the troubling rudiments and explain to people who bank on the media to keep themselves knowledgeable and updated. Its not at all a felony to provide amusement but if it starts corrupting the roots/base obviously it will raise many eyebrows.    Journalism is sometimes said as the mirror of any society, but this was the ideology long time back, now it has changed. According to Thomas Jefferson I do not take a single newspaper, nor read one a month, and I feel myself infinitely the happier for it  People think that newspapers and media has gained too much freedom that it has forgotten the ethical values. Supportive arguments with documented evidence Journalism in the 20th century was explicitly an instrument of state control; this gave way to its becoming comparatively independent however it still remained liable to manipulation by those in power. This means that the conventional role of the journalist may actually become evanescent within a decade (E Quinn 1980) If the role of the journalism is to help us make decisions in national affairs, then we could ask for fewer retrospective stories and more challenging questions about governmental activities plans for the future and instead of only raising our eyebrows to communicate our anguish, we should get up against it so the line of work regains its lost grandeur. Though it sounds studious, I dont see any other solution. If we have an unflinching desire, I think we can do it (DB Bobrow 1973) Conclusion Journalism is a revolutionary aspect where individuals can decide to spread the truth, or make their own. Governments dont need liberated press, but liberated journalism needs egalitarianism or democracy. Free journalism is simply unattainable without one. A democratic system would be unachievable without trying to incorporate the community into governmental dealings. A French novelist once said, Free press can, of course, be good or bad, but, most certainly without freedom, the press will never be anything but bad. Journalism, for healthier or for poorer, is the best paradigm of the freedom of individuals and the significance of free deliberation in a dictatorship. If we can come to a conclusion why society needs to be well educated about the issues, matters and troubles going on in the world, then we can ask what kind of journalism they need and how they should use the existing media. It is our by and large conclusion that raising questions would be the superlative way to encourage debate among journalists and political theorists.

Reflective Account Essay

Introduction This assignment will show a detailed account based on an experience in my second year community placement. The framework I shall be using to reflect is Gibbs’ (1988) model of reflection. Within this model are six phases incorporated into a cycle. Each phase will allow me to think systematically about the experience and identify areas where improvement is needed. This reflective account will incorporate the Scottish Patient Safety Programme (SPSP) aim to ‘Prevent Pressure Ulcers’ (SPSP, n.d.a). Pressure ulcers are defined as â€Å"an area of damage to the skin and underlying tissue that is caused by unrelieved pressure, friction and/or sheer forces† (Posnett and Franks, 2008). The SPSP is co-ordinated by Healthcare Improvement Scotland (HIS) and aims to improve patient safety and reduce adverse events. (SPSP. n.d.b). This aim is relevant to the patient involved in this experience as they are a high risk of developing a pressure ulcer therefore preventative measures need to be addressed. To ensure privacy and confidentiality in accordance with the Nursing and Midwifery Council (NMC, 2012a), I have renamed this patient Mathew for the purpose of this assignment. Description Mathew is an 82 year old man who recently suffered a fall within his home and was admitted to hospital with a fractured hip and subsequently had to have a total hip replacement. Mathew was discharged from hospital back to his home with the care of District Nurses visiting him on a daily basis to administer his Clexane injection. Due to Mathew’s injury his mobility has been compromised and has subsequently become incontinent. During our first visit with Mathew my mentor asked me to carry out a ‘Waterlow’ assessment with him. This tool is a scoring system which identifies if a patient is at risk of developing a pressure ulcer (HIS, 2009). As the score was above 10 Mathew was deemed ‘at risk’. Both my Mentor and I discussed with Mathew regarding his risk level, we suggested a pressure†¦ In this assignment, I need to reflect on the situation that taken place during my clinical placement to develop and utilize my interpersonal skills in order to maint ain the therapeutic relationships with my patient. In this reflection,  I am going to use Gibbs (1988) Reflective Cycle. This model is a recognized framework for my reflection. Gibbs (1988) consists of six stages to complete one cycle which is able to improve my nursing practice continuously and learning from the experience for better practice in the future. The cycle starts with a description of the situation, next is to analysis of the feelings, third is an evaluation of the experience, fourth stage is an analysis to make sense of the experience, fifth stage is a conclusion of what else could I have done and final stage is an action plan to prepare if the situation arose again (NHS, 2006). Bairdand Winter (2005, p.156) give some reasons why reflection is require in the reflective practice. They state that a reflect is to generate the practice knowledge, assist an ability to adapt new situations, develop self-esteem and satisfaction as well as to value, develop and professionalizing practice. However, Siviter (2004,p.165) explain that reflection is about gaining self-confidence, identify when to improve, learning from own mistakes and behavior, looking at other people perspectives, being self-aware and improving the future by learning the past. In my context with the patient, it is important for me to improve the therapeutic relationship which is the nurse-patient relationship. In the therapeutic relationship, there is the therapeutic rapport establish from a sense of trust and a mutual understanding exists between a nurse and a patient that build in a special link of the relationship (Harkreader and Hogan, 2004, p.243). (Peplau 1952, citedin Harkreader and Hogan 2004, p.245) note that a good contact in a therapeutic relationship builds trust as well as would raise the patient’s self-esteem which could lead to new personal growth for the patient. Besides, (Ruesch 1961, cited in Arnold and Boggs 2007, p.200) mention the purpose of the therapeutic communication is to improve the patient’s ability to function. So in order to establish a therapeutic nurse-patient interaction, a nurse must show up caring, sincerity, empathy and trustworthiness (Kathol, 2003, p.33). Those attitudes could be expressed by promoting the effective communication and relationships by the implementation of interpersonal skills. Johnson (2008) define the interpersonal skills is the total ability to communicate effectively with other people. Chitty and Black (2007, p.218) mention that communication is the exchange of information, thought and ideas via verbal and non-verbal which both present simultaneously. They explain  that verbal communication is consists of all speech whereas non-verbal communication consists of gestures, postures, facial expressions, tone and level of volume. Thus, in my reflection in this assignment would be discussed on my development of therapeutic relationship in the circumstance of the nurse-patient relationship using the interpersonal skills. My reflection is about one patient whom I code her as Mrs. A, not a real name(Appendix I) to protect the confidentiality of patient’s information (NMC, 2004).In this paragraph I would describe on the event takes place and describe that event during my clinical placement. I was on the female psychiatric ward having a 2 weeks clinical placement for mental health care in semester 3.Generally, there were two separated psychiatric wards which were male psychiatric ward and female psychiatric ward but both wards were sharing the small cafeteria in the area of psychiatric ward. The psychiatric wards were locked up from one main entrance. In the ward, the female psychiatric patients were encouraged to walk out from the female ward and combine with the male psychiatric patients at the small cafet eria during their meal time. During lunch, I noticed one lady was still sitting on her bed. She was Mrs. A, 76 years old been diagnosed a schizophrenia. She was unable to control the muscle also called tremor due to lack of the chemical as she was having a side effect of antipsychotic medication which was a Parkinsonism (Sahelian, 2005). She could not walk herself and need to be assisted if she wanted to stand or walk. So I took the Mrs. A’s lunch meal and fed on the bed. This old lady was unable to feed on her own. So I checked her diet and served her meal. I fed her meal until finished. In this paragraph, I would discuss on my feelings or thinking that took place in the event happened. Before I started to feed her, I introduced myself and approached Mrs. A. So I tried to build a good rapport with her as I do not want her to feel strange as I was not her family members or her relatives. My first approached was to her was to ask whether she wanted or refused to take her lunch. She was on soft diet as she was having a difficulty in swallowing or dysphasia. Then I asked her permission to feed her. She looked at me and looked like blur. In this situation, I showed up my emphatic listening as I put myself in her shoes and assuming I was having a hearing problem. According to Wold (2004, p73) the emphatic listening is about the willingness to understand the other person not just judging the person’s  fact. Then, I touched her shoulder, kept saying, and raise my tone a bit because I was afraid if she had a hearing trouble. At the same time, I did somebody gesturers which could be interpreted an action of eating. I paused, repeated my actions but this time I was using some simple words in the patient dialect. Then she looked at me again and nodded her head. Fortunately the body gesturers also helped me in the conversation with her. In the meantime, I was thinking whether the first language was not her mother tongue but I kept myself communicate verbally with her including using my body gesturers and facial expression. Body gesturers and facial expressions are referred as a non-verbal communication (Funnellet al , 2005, p.443). In my thinking, I needed to speak louder and know more words in her language so that she could understand and interpret of my actions towards her. I thought of the language barrier that breaks our verbal communication. Castledine (2002, p.923) mention that the language barrier arises when there are individuals comes from a different social background use their own slang or phrases in the conversations. Luckily, those particular body gesturers could make her understand that I was going to feed her lunch. During the feeding I maintained the eye contact as I do not want her to feel shy. This is because; my eye contact could show up my interest to help her in feeding. This is supported by Caris-Verhallenet al (1999) which mentioned that the direct of eye contact could express a sense of interesting the person to the other person involves in that communication. In the meantime I communicated with my best with her do that she felt comfortable. As a result, she gave a good cooperation and e njoyed the meal until finished. In my evaluating, I feel I make the right decision to accompany and assist Mrs. A in feeding. Furthermore, I could develop my nurse-patient relationship. Although McCabe (2004, p.44) would describe it as a task-centered communication as one of the element caused the lack communication among nurses, but I think my nurse-patient relationship communication both involved a good patient-centered communication and task-centered communication. In my personal opinion, I attended to Mrs. A as a patient to show my empathy because she was unable to feed herself. It was also as my duty to feed her so that I could make sure the patient get the best care in the ward. So my involvement in this nurse-patient relationship does not only restrict to the task-centered communication because (Burnard 1990, and Stein-Parbury 1993,  cited in McCabe 2002, p.44) define attending as a patient-centered process as wells as to fulfill the basic conditions as a nurse to provide the genuineness, warmth and empath y towards the patient. I was able to improve my non-verbal communication skills in my conversation with her during the feeding. As she was having a hearing problem and could not communicate in the first language properly, so the non-verbal communication plays a role. Caris-Verhallen et al (1999, p.809) state that the non-verbal communication becomes important when communicating with the elderly people who develop a hearing problem. Hollman et al (2005, p31) suggests some effective ways to maximize the communication with hearing impairment people such as always gains the person’s attention before speaking, visible yourself to prevent them feel frighten and try to use some sensitive touch. I feel this is a good experience to me because I learn to develop my non-verbal communication. I used most of the body gesturers because of the language barrier was being a gap in my conversation with Mrs. A. She could speak very limited in the first language so I tried to speak in her dialect. Furthermore, Wold (20 04, p.76) mention that gesturers are one specific type of non-verbal communication intended to express ideas and are useful for people who cannot use much words. However I also used my facial expressions to advise her to finish the meal. It might be not so delicious because she withdraws the meal after few scopes but I smiled and assured Mrs. A that it was good for her health to finish her meal. In addition, the facial expressions are most expressive which are not limited to certain cultural and age barriers (Wold, 2004,p.76). Therefore my facial expression worked out to encourage her to finish the meal. Although I could not explain detail to her about the important nutrition diet that she should take, but I could advocate her to finish the meal served because the meal was prepared according to her condition. In order to analysis of the event, I could evaluate that, my communication skills are very important to provide the best nursing care to Mrs. A. My communication with Mrs. A was the interpersonal communication. This is because the interpersonal communication is a communication which involved of two persons (Funnell et al 2005, p.438). I realized that my nonverbal communication did help me a lot in my duty to provide the nursing care to Mrs. A. Even though she could understand few simple words when I was asking her but I noticed that one of the  problems occurs within the communication was the language barrier. As the patient was not using the official language and the second language, I tried to speak in her language. I still could manage the communication in our conversation. However, it was quite difficult to promote the effective verbal communication with the patient. Besides, White (2005, p.112) recommend that a nurse should learn a few words or phrases in the predominant second language to put a patient at ease for better understanding. Although it was quite difficult but using the nonverbal simultaneously with the verbal communication did encou rage her to speak on her best to make me understand her words. In the event showed that, there was a response from Mrs. A. when I was asking her questions. Funnel et al (2005, p.438) point out that a communication would occur when a person responds to a message received and assigns meaning to it. She nodded her head to assign that she agreed with me. Delaune and Ladner (2002, p.191) explain that the channel is one of the component of the communication process which act as a medium during the message is sent out. In addition, Mrs. A also gave me a feedback that she understood my message by transmitting the message via her body gesturers and eye behavior. Thus I could consider that the communication channels used in my conversation were visual and auditory. Delaune and Ladner (2002, p.191) state a feedback is that the sender receives the information after the receiver react to the message. However, Chitty and Black (2007, p.218) define feedback is a response to a message. In my situation, I was a sender who conveyed the message receiving the information from Mrs. A, the receiver who agreed to take lunch and allow me to feed. Consequently, I could analyze that my communication with Mrs. A involved of five component of communication process which are sender, message, channel, receiver and feedback (Delaune and Ladner, 2002, p.191).In a nutshell, for my reflection of this event explores about on how the communication skills play a role on the nurse-patient relationship in order to deliver the nursing care towards the patient especially the adult. She needed quite some time to adapt the ability changes in her daily activities living where I was trying to help her in feeding. I was concerning my feeling and thoughts during the feeding so that I could improve more skills in my communication. I successfully communicated with her effectively as she enjoyed finishing the meal. So it  is vital to build rapport with her to encourage her ability to speak up ver bally and non-verbal. Moreover, this ability could help her to communicate effectively with other staff nurses. Later, she would not be neglected because of her age or her disability to understand the information given about her treatment.(Hyland and Donaldson 1989, cited in Harrison and Hart 2006 p.22) mention that communication express what the patients think and feel. In order to communicate with adult, it is important to assess her common communication language and her ability to interact in the other languages. As I used some words in her dialect, I essentially encouraged the patient to speak out verbally and communicate non-verbal so that the message could be understood and do not break the nurse-patient communication. In my opinion, I evaluated that it does not a matter whether it was a patient-centered communication or task-centered communication because both communication mentioned by McCabe (2004) actually does involves communication to the patients. So it was not a problem to argue which type of communication involves in my conversation with my patient. After I analyzed the situation, I could conclude that I was be able to know the skills for effective communication with the patient such as approach the patient, asking questions, be an active listening, show my empathy and support the patient emotions (Walsh, 2005, p.34). Actually helping the adult was a good practice in delivering the nursing care among adults. My action plan for the clinical practice in the future, if there were patients that I need to help in feeding or other nursing procedure, I would prepare myself better to handle with the patients who would have some difficulty in communication. This is because, as one of the health care worker, I want the best care for my patients. So in related to deliver the best care to my patients, I need to understand them very well. I have to communicate effectively as this is important to know what they need most during warded under my supervision as a nurse. According to my experience, I knew that communication was the fundamental part to develop a good relationship. Wood (2006, p.13) express that a communication is the key foundation of relationship. Therefore a good communication is essential to get know the patient’s individual health status (Walsh, 2005, p.30). Active listening could distinguish the existence of barrier communication when interactions with the patients. This is because, active listening means listening without  making judgment to listen the patients ’opinions or complaints which give me chances to be in the patients’ perspective(Arnold, 2007, p.201). On the other hand, it also crucial to avoid the barriers occurs in the communication with the patients. I could detect the language barriers by interviewing the patients about their health or asking them if they needed a ny help in their daily activities living. However, I would remind myself for not interfere my communication with barriers such as using the open-ended questions, not attending to non-verbal cues, being criticizing and judging, and interrupting (Funnell et al, 2005, p.453). Walsh (2005, p.31) too summary that making stereotyping and making assumptions about patients, perceptions and first impression of patients, lack awareness of communication skills are the main barriers to communications. I must not judge the patients by making my first impression and assumption about the patients but I have to make patients fee devalued as an individual. I should be capable to respect their fundamental values, beliefs, culture, and individual means of communication (Heath, 2000,p.27). I would be able to know on how to build rapport with the patients. There are eleven ways suggest by Crellin (1998, p.49) which are becomes visible, anticipate needs, be reliable, listening, stay in control, self-disclosure, care for each patient as an individual, use humour when appropriate, educate the patient, give the patient some control, and use gestures to show some supports. This ways could help and give me some guidelines to improve my communication skills with the patients. Another important thing to add on my action plan list is to know which the disabilities of the patients have such as hearing disability, visual impairment and mental disability. Once I could know the disability that a patient has, I could well-prepared my method of communication effectively as Heath(2000, p28) mention that communicating with people who was having some hearing impairment, sight impairment and mental health needs required the particular skills and considerations. Nazarko (2004, p.9) suggest that do not repeat if the person could not understand but try to rephrase and speak a little more slowly when communicating with the hearing difficulties people. Hearing problem commonly occurs among adults because of ageing process (Schofield,2002, p.21). To summarize for my action plan, I would start a communication with a good rapport to know what affects the patients’ ability to communicate well and  to avoid barriers in effective communication in future. In conclusion of my reflective assignment, I mention the model that I chose, Gibbs (1988) Reflective Cycle as my framework of my reflective. I state the reasons why I am choosing the model as well as some discussion on the important of doing reflection in nursing practice. I am able to discuss every stage in the Gibbs (1988) Reflective Cycle about my ability to develop my therapeutic relationship by using my interpersonal skills with one patient for this reflection. Reflection on a Clinical Skill The purpose of this assignment is to reflect upon a clinical skill that I undertook whilst on my second year community placement. I have chosen to use Gibbs (1988) model of reflection. In accordance with the Nursing and Midwifery Council (NMC), The Code of Professional Conduct (2008), confidentiality shall be maintained and all names changed to protect identity. The clinical skill I have chosen to reflect upon during this assignment is the monitoring of capillary blood glucose (CBG). I have chosen this skill as during my previous acute placements as a student I was not permitted to undertake them, and whilst in the community the Primary Care Trust (PCT) allows it. Having yet to develop this skill I thought that by reflecting on carrying it out would help me to gain the knowledge and confidence needed to perform it in the future. According to Siviter (2004) reflection is about gaining confidence, identifying when you could have improved, learning from your mistakes and about your beha viour, viewing yourself as others do, self awareness and changing the future by learning from the past. Description During a routine daily visit with my mentor Jane, a District Nurse, to Nisha, an elderly Asian lady who was Diabetic, Jane asked me whether I would like to take Nishas CBG. As I had only started doing CBGs during this placement I thought it would be a good learning opportunity so I agreed to do it. Jane asked Nisha whether she minded me doing her CBG and although she did not speak very much English she understood and consented for me to do it. I went into the kitchen and washed my hands. I returned to the living room where  Nisha was and asked her whether her hands were clean, to which she answered yes. I then assessed that Nisha was sat down on a low sofa, and thought it best to kneel down and lay my equipment out on the coffee table so that they were all to hand. Once checking that the blood glucose monitor had been calibrated and that the test strips were in date I opened a test strip and placed it into the monitor. I then put on gloves and asked Nisha whether she was comfortable and ready and which finger she wanted me to use, she said yes and held up her right third finger so I got the single use lancet and pricked the side of Nishas finger, disposing of the lancet into the sharps box. The blood came immediately and I applied it to the test strip and waited for the result, in the meantime I held a clean cotton wool ball to Nishas finger to stop the bleeding. I discarded the test strip and my gloves and recorded the CBG.I then washed my hands again. Once we had left Nishas property my mentor commented that I had done very well, but should have asked Nisha to wash her hands before commencing the CBG test. Feelings When Jane, my mentor, first asked me if I wanted to do Nishas CBG I felt slightly nervous as I had only done a few previously and was aware that she would be observing me through the procedure which also gave me reassurance that if I were to do anything wrong she would be there to highlight it. Once Nisha had consented to me doing the CBG I felt pleased that she trusted me to carry out the process, which allayed my nerves. During the procedure I was aware that my mentor was watching me, which once again made me anxious, but she was encouraging me the whole time and totally supportive. When I instantly got blood once pricking Nishas finger I felt a sense of relief that I had done it correctly. Once the whole process was over Nisha held my hand and smiled and in broken English said â€Å"thank you, thank you†, I was humbled by her response as I felt I was just doing my job. Overall I was satisfied with my performance and felt positive that I wouldn’t be so nervous next ti me round. Evaluation On the whole performing this clinical skill went really well, and having not had much practice at doing this particular skill I was glad to have had the  opportunity to do it whilst under direct supervision from my mentor. I think that my communication with Nisha, even though she spoke little English was very good and that I had formed a strong therapeutic relationship with her. I feel that on reflection I should of asked Nisha to wash her hands before the procedure, and that my mentor should have ensured this, to guarantee that the reading was not contaminated. Analysis I will start by looking at the skill and the evidence supporting it. CBG monitoring is part of many diabetics daily routine. If a patient’s CBG goes up (hyperglycaemia) or down (hypoglycaemia) it can cause the patient to become unwell (Baillie, 2009). Dougherty & Lister (2008) state that in the short term CBG monitoring can prevent hypoglycaemia and ketoacidosis and in the long term can considerably lower complications arising that could affect the patient both vascularly and neurally. Patients can control their condition through diet, oral hypoglycaemic agents, insulin therapy or a combination of the above, (Higgins, 2008). By asking Nisha whether she minded me performing the CBG my mentor had gained informed consent in accordance with the NMC (2008), who say that consent must be gained before any treatment is commenced. I washed my hands following the Ayliffe (1978) technique in order to prevent the spread of infection, Pratt et al (2007) state that hands must be decontamina ted between each and every episode of patient care. I asked Nisha whether her hands were clean, as one of the main causes of inaccuracy of CBG readings are fingers that are contaminated with foodstuffs (Alexander et al, 2000). I assessed that Nisha was sat comfortably on a low sofa, Jamieson et al (2007) says to ensure patient comfort and prevent any injury occurring should the patient feel faint during the procedure . I then knelt down and laid my equipment out on the table, as Baillie (2009) suggests that all equipment needed for a procedure should be within easy reach, and avoid any twisting or stooping which could cause me injury, in line with the PCT Moving and Handling Policy and Procedure (2006). I then checked the CBG monitor had been calibrated and that the test strips were in date, to prevent false positive/ negative readings (Hastings, 2009). I then put on my gloves and asked Nisha whether she was ready and which finger she wanted me to use, Jamieson (2007) says  that gloves should be used to prevent the patient and nurse from any potential blood borne infection. The NMC (2008) state that you must allow patients to make decisions about their care, and also that patients should be treated indiv idually and with dignity. Suhonen et al (2007) conclude that individualised patient care leads to positive patient outcomes, such as patient satisfaction, patient autonomy and patients perceptions on health related quality of life. I used both verbal and non-verbal communication, which involved speaking slowly and clearly so that Nisha could understand what I was saying. I also used non-verbal communication through touch, eye contact, facial expressions and body language, (Funnell et al, 2009). I then using a single use lancet, in accordance with PCT (2005) policy on blood glucose monitoring, pricked the side of Nishas right third finger and disposed of the lancet into the sharps box. Baillie (2009) suggests that the third, fourth or fifth finger should be used as the thumb and index finger are important for touch, and to use the side as it is less painful. To prevent injury sharps and unused drugs must be placed in disposal boxes at the point of use, (Dougherty and Lister, 2008). I applied cotton wool to stop any bleeding and then disposed of the test strip and my gloves, washed my hands again using the Ayliffe (1978) technique and recorded my findings. Hastings (2009) recommends applying pressure briefly to the puncture site to prevent painful extravasation of blood into the subcutaneous tissues. The Department of Health (2007) state that to reduce the risk of cross infection any waste must be disposed of appropriately. Flores (2006) maintains that it is important to wash your hands after removing gloves as bacteria can contaminate them through small defects in the gloves or during removal. Records should be completed as soon as possible following an event (NMC, 2008), and as a student all documentation needs to be countersigned (Siviter, 2004). My mentor said that I should have asked Nisha to wash her hands, not if they were clean the rationale being the same as previously stated, (Alexander et al, 2000), and also Cowan (1997) also agreed that patients hands should be washed to ensure a non-contaminated result. Conclusion In conclusion I now appreciate how in depth a â€Å"simple† CBG procedure actually is, when done correctly. I have looked further for evidence stating that patients hands should be washed before the CBG test is performed and realise that I should have asked Nisha to do so as the result could potentially have been wrong. On reflecting on undertaking this skill I have developed my learning of the need to carry out this procedure and the importance of it to a Diabetic. I have also found that following guidelines is vital to accurate results. Action Plan In future when I carry out this procedure I will continue to practice as I have done as long as this is in line with local trust policy and supporting evidence. I will always ensure that the patient washes their hands before commencing the process, as this is what evidence suggests is good practice and also important for an accurate result.

Financial Ratios Analysis Of Pumpkin Patch Limited

Introduction This is the report about financial ratios analysis of Pumpkin Patch Limited(PPL). This children’s clothing retail brand began with one store in 1991, now has about 600 employees across 43 stores in New Zealand and 1000 staff in 117 stores in Australia. However, it tripped into receivership recently. At the same time, Pumpkin Patch managing director Luke Bunt said â€Å"however, despite considerable efforts by the board and its management team, it has become evident that no solution is available to the company, at this time, to address the current over-leveraged and significantly capital constrained position.† (McNicol, 2016) This report will discuss the reasons for PPL’s failure, which is supported by the research mentioned†¦show more content†¦Moreover, comparing zero interest bearing liability in 2014 with 41 million in 2015, the current liability was increased from 30 million to 72 million. It also explained why current ratio was declined from 3.04 in 2014 to 0.88 and 0.73 in 2015 and 2016 separately. The quick ratio is a more rigorous test for the company’s ability to meet its short-term debts than current ratio because inventory was eliminated from current assets. The quick ratio for PPL indicates serious issues as it has decreased from 0.31 in 2012 to 0.07 in 2016. The low quick ratio implies that a considerable portion of the current assets of the company is tied up as part of its inventory (Bragg, 2007), which means that the lower level of quick liquidity ratio indicates a high level of financial risk. The balance sheet for PPL (PPL, 2016) revealed that, particularly in 2016, the inventory accounted for 90% of the current assets. Therefore, the company must improve its working capital to meet its near term current liabilities. The cash conversion cycle is a result of time taken by the company for their collection from receivables (average collection period) and time needed to convert material into goods (day inventory held) after subtracting the time taken to pay its current obligation (day payable outstanding). The average collection period of account receivable and the day inventory held ratio improved in 2016 after rose to the highest days in 2014, whichShow MoreRelatedAnalyses of the 2011 Annual Report of Pumpkin Patch Limited2372 Words   |  10 Pagesshareholders who are thinking to make an investment in Pumpkin Patch Ltd. Pumpkin Patch Ltd. are a child-clothing brand that based in Auckland, New Zealand. It was founded in 1990 by Sally Synnott, who is the current Non-Executive Director. Clothing design, marketing, retail and wholesale are this brand mostly focuses on. There are retail store all around New Zealand, Australia, United Kingdom, Ireland and United States. 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PPL mostly sells clothing for young boys and girls, but also sells accessories like bracelets and beanies etc. They specialise in quality children clothing. Pumpkin Patch is quite a large company around the world, as it generated almost $241m (1) revenue in the year ended July 31st 2014 and is included in the exchangeRead MoreFinancial report analysis Essay1997 Words   |  8 Pagesï » ¿Introduction The following report is an analysis of the consolidated accounts for Hallenstein Glasson Holdings Ltd (HLG) based on the 2013 financial statements and the ratio analysis is based on the group account figures. The terms of this report is to firstly, determine the strengths, weaknesses and prospects of HLG and secondly, to determine if the shares are favourably priced? Business Summary Hallenstein Glasson Holdings Limited is a holding company. 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(c) If you spent all of your income on x, how much x could you buy? 16. (d) If you spent all of your income on y, how much y could you buy? 8. (e) Write a budget equation that gives you this budgetRead More_x000C_Introduction to Statistics and Data Analysis355457 Words   |  1422 Pagesto Statistics and Data Analysis This page intentionally left blank Introduction to Statistics and Data Analysis Third Edition Roxy Peck California Polytechnic State University, San Luis Obispo Chris Olsen George Washington High School, Cedar Rapids, IA Jay Devore California Polytechnic State University, San Luis Obispo Australia †¢ Brazil †¢ Canada †¢ Mexico †¢ Singapore †¢ Spain †¢ United Kingdom †¢ United States Introduction to Statistics and Data Analysis, Third Edition Roxy PeckRead MoreSexually Transmitted Diseases35655 Words   |  143 Pagessignificantly, except under extremely high pressures. These properties make a liquid suitable for applications such as hydraulics. Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in a limited degree of particle mobility. As the temperature increases, the increased vibrations of the molecules cause distances between the molecules to increase. When a liquid reaches its boiling point, the cohesive forces that bind the molecules closely together

English Speech Terrorism Essay example - 506 Words

English Speech: Terrorism Good (morning/afternoon) and welcome to my speech. Today I would like to enlighten you with a subject that I feel strongly about. That subject is terrorism and what it has done to the world. My personal opinion is that terrorism is something that is causing havoc in this place called earth and it should stopped before it gets out of our hands. The word terrorism in the English dictionary means violent action for political purposes. This is the proper definition but my definition differs a little. My definition is a bunch of scumbags trying to kill other people as a hobby. Acts of terrorism has become a major issue in the past year and a half. Who could forget†¦show more content†¦This was a car bomb. Just before midnight on Saturday, Oct. 12, as people from across the globe danced at the Sari, a popular nightclub on the Indonesian resort island of Bali, a car parked outside-and packed with explosives-blew up. The most recent form of terrorism was when 2 terrorists entered a Hindu place of worship and with ease killed 33 innocent victims and injuring many more. This was the most hurtful act of terrorism for me as this Hindu place of worship was where I have prayed before and it was my religious building that got attacked. Fortunately, these 2 terrorists were brought to justice and killed. Due to the acts of terrorism security has been tightened all over the world but yet terrorists find ways of breaking into other countries and causing havoc. Security has been tightened in airports, buildings and even religious places of worship have got to grips with the true meaning of security. Many people i.e. terrorists, think that what they do is for the best and this was what the god Allah has said they have to do. They believe that Americagot what they deserved and there is still more to come. They are trying to make themselves the biggest and baddest people around trying to make everyone respect them. They are trying to build up a reputation and get world publicity but they are going the wrong way about it. TerroristShow MoreRelatedEssay on Human Rights, War and Terrorism1226 Words   |  5 PagesHuman Rights, War and Terrorism After every war come the peace talks; after millions of people had been killed. After the terrorist attacks comes the investigation, reason, or counter-terrorism; after lives had been wasted. There is time for the nations of the world to come together to understand one another in order to avoid war and terrorism and that time is now. War is as old as man. It is a reign of terror when people are always on the run, always hungry, alwaysRead MoreEssay on What Bush Really Means1218 Words   |  5 PagesCenters in New York, President George W. Bush delivered a speech to the nation on September 20, 2001. 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Unfortunately, today we also live in a society in which some of these groups are marginalized and looked down upon by othersRead MoreJorge Lima s Ted Talk Speech1153 Words   |  5 Pagesdied, and now something new must take its place. In this case, that something is the ancient metaphor of the tree, but what is the something new? Manuel Lima believes that he has discovered a new metaphor that is on the horizon. In Lima’s TED Talk speech â€Å"A Visual History of Human Knowledge,† Lima discusses the metaphor of the tree of knowledge and how it connects all things. Lima’s primary concern is that this picture is outdated and offers a new alter native: the network. Lima is correct that

Sports, Basketball, And Football - 975 Words

Sports. Some love them, some hate them, but even those who hate cannot deny their overwhelming popularity. America is home to many sports, basketball, and American football among the most popular. Spectators filling in thousands of seats at open stadiums, and hundreds of thousands more watching at home in front of their television. Both basketball and football have distinct, fundamental differences, however, they do not outweigh the similarities the two sports share. A franchise without their fans is similar to a kingdom without their subjects, and basketball and football share this common thread. Of course, without these adoring fans to watch them, what would they be? Basketball and football are aggressive, energetic sports and with that, aggressive and energetic fans. Fans who will paint their faces, dye their hair and even pay thousands of dollars for ground seats or memorabilia. These fans are very loud as well, as they cheer their teams on with shouts of encouragement or booing the competition. Being a fan of these sports may start as early as childhood, or since birth, and ignite a life-long love for that team or sport. Many children often find playing sports a great outlet or passion, and basketball and football are no exceptions to this. There are youth programs for both sports that a person can enroll their child in. As a child grows older they may be tempted to try out for the middle school teams, and even older the high school varsity or junior varsityShow MoreRelatedSports : Sports Football And Basketball Essay2194 Words   |  9 PagesSports Science 100 G essay – Chosen sports Football/Soccer and Basketball Football/Soccer Football has always been referred to as the beautiful game due to its simplicity and lack of pure physical punishment it is a gentleman’s game per say. 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Notice I said girl, girls can’t play football but they can play basketball. Football is a very rough sport it’s a contact sport meaning you have to make contact with the ball carrier, when playing basketball you don’t have to worryRead MoreThe Similarities and Differences Between Professional Football and Basketball847 Words   |  4 PagesThe Similarities and Differences between Professional Football and Basketball Elbert L. Hereford COM/170 - ELEMENTS OF UNIVERSITY COMPOSITION AND COMMUNICATION I 11/27/2012 Daniel Gleason Thesis There are several similarities and differences between basketball and football as sports. The competitive nature of games calls for the society to express itself in these types of physical activity. Both of these activities require a finish goal where one team loses or wins in return giving theRead More My Favorite Sports Essay example582 Words   |  3 Pagesmovies, music, and sports. 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Data and Computer Communications Free Essays

DATA AND COMPUTER COMMUNICATIONS Eighth Edition William Stallings Upper Saddle River, New Jersey 07458 Library of Congress Cataloging-in-Publication Data on File Vice President and Editorial Director, ECS: Marcia J. Horton Executive Editor: Tracy Dunkelberger Assistant Editor: Carole Snyder Editorial Assistant: Christianna Lee Executive Managing Editor: Vince O’Brien Managing Editor: Camille Trentacoste Production Editor: Rose Kernan Director of Creative Services: Paul Belfanti Creative Director: Juan Lopez Cover Designer: Bruce Kenselaar Managing Editor,AV Management and Production: Patricia Burns  ©2007 Pearson Education, Inc. Pearson Prentice Hall Pearson Education, Inc. We will write a custom essay sample on Data and Computer Communications or any similar topic only for you Order Now Upper Saddle River, NJ 07458 Art Editor: Gregory Dulles Director, Image Resource Center: Melinda Reo Manager, Rights and Permissions: Zina Arabia Manager,Visual Research: Beth Brenzel Manager, Cover Visual Research and Permissions: Karen Sanatar Manufacturing Manager, ESM: Alexis Heydt-Long Manufacturing Buyer: Lisa McDowell Executive Marketing Manager: Robin O’Brien Marketing Assistant: Mack Patterson All rights reserved. No part of this book may be reproduced in any form or by any means, without permission in writing from the publisher. Pearson Prentice Hallâ„ ¢ is a trademark of Pearson Education, Inc. All other tradmarks or product names are the property of their respective owners. The author and publisher of this book have used their best efforts in preparing this book. These efforts include the development, research, and testing of the theories and programs to determine their effectiveness. The author and publisher make no warranty of any kind, expressed or implied, with regard to these programs or the documentation contained in this book. The author and publisher shall not be liable in any event for incidental or consequential amages in connection with, or arising out of, the furnishing, performance, or use of these programs. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 ISBN: 0-13-243310-9 Pearson Education Ltd. , London Pearson Education Australia Pty. Ltd. , Sydney Pearson Education Singapore, Pte. Ltd. Pearson Education North Asia Ltd. , Hong Kong Pearson Education Canada, Inc. , Toronto P earson Educaci n de Mexico, S. A. de C. V. Pearson Education Japan, Tokyo Pearson Education Malaysia, Pte. Ltd. Pearson Education, Inc. , Upper Saddle River, New Jersey For my scintillating wife ATS WEB SITE FOR DATA AND COMPUTER COMMUNICATIONS, EIGHTH EDITION The Web site at WilliamStallings. com/DCC/DCC8e. html provides support for instructors and students using the book. It includes the following elements. Course Support Materials The course support materials include †¢ Copies of figures from the book in PDF format †¢ A detailed set of course notes in PDF format suitable for student handout or for use as viewgraphs †¢ A set of PowerPoint slides for use as lecture aids †¢ Computer Science Student Support Site: contains a number of links and documents that the student may find useful in his/her ongoing computer science education. The site includes a review of basic, relevant mathematics; advice on research, writing, and doing homework problems; links to computer science research resources, such as report repositories and bibliographies; and other useful links. †¢ An errata sheet for the book, updated at most monthly T DCC Courses The DCC8e Web site includes links to Web sites for courses taught using the book. These sites can provide useful ideas about scheduling and topic ordering, as well as a number of useful handouts and other materials. Useful Web Sites The DCC8e Web site includes links to relevant Web sites, organized by chapter. The links cover a broad spectrum of topics and will enable students to explore timely issues in greater depth. iv WEB SITE FOR DATA AND COMPUTER COMMUNICATIONS, EIGHTH EDITION v Supplemental Documents The DCC8e Web site includes a number of documents that expand on the treatment in the book. Topics include standards organizations, Sockets, TCP/IP checksum, ASCII, and the sampling theorem. Internet Mailing List An Internet mailing list is maintained so that instructors using this book can exchange information, suggestions, and questions with each other and the author. Subscription information is provided at the book’s Web site. Simulation and Modeling Tools The Web site includes links to the cnet Web site and the modeling tools Web site. These packages can be used to analyze and experiment with protocol and network design issues. Each site includes downloadable software and background information. The instructor’s manual includes more information on loading and using the software and suggested student projects. This page intentionally left blank CONTENTS Web Site for Data and Computer Communications Preface xv 1 iv Chapter 0 Reader’s and Instructor’s Guide 0. Outline of the Book 2 0. 2 Roadmap 3 0. 3 Internet and Web Resources 5 0. 4 Standards 6 PART ONE OVERVIEW 9 Chapter 1 Data Communications, Data Networking, and the Internet 10 1. 1 Data Communications and Networking for Today’s Enterprise 12 1. 2 A Communications Model 16 1. 3 Data Communications 19 1. 4 Networks 22 1. 5 The Internet 25 1. 6 An Example Confi guration 29 Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications 2. 1 The Need for a Protocol Architecture 33 2. 2 The TCP/IP Protocol Architecture 34 2. 3 The OSI Model 42 2. 4 Standardization within a Protocol Architecture 44 2. Traditional Internet-Based Applications 48 2. 6 Multimedia 48 2. 7 Recommended Reading and Web Sites 53 2. 8 Key Terms, Review Questions, and Problems 54 Appendix 2A The Trivial File Transfer Protocol 57 PART TWO DATA COMMUNICATIONS 62 Chapter 3 Data Transmission 65 3. 1 Concepts and Terminology 67 3. 2 Analog and Digital Data Transmission 78 3. 3 Transmission Impairments 86 3. 4 Channel Capacity 91 3. 5 Recommended Reading and Web Site 96 3. 6 Key Terms, Review Questions, and Problems Appendix 3A Decibels and Signal Strength 99 Chapter 4 Transmission Media 102 4. Guided Transmission Media 104 4. 2 Wireless Transmission 117 4. 3 Wireless Propagation 125 32 96 vii viii CONTENTS 4. 4 4. 5 4. 6 Line-of-Sight Transmission 129 Recommended Re ading and Web Sites 133 Key Terms, Review Questions, and Problems 134 Chapter 5 Signal Encoding Techniques 138 5. 1 Digital Data, Digital Signals 141 5. 2 Digital Data, Analog Signals 151 5. 3 Analog Data, Digital Signals 162 5. 4 Analog Data, Analog Signals 168 5. 5 Recommended Reading 175 5. 6 Key Terms, Review Questions, and Problems 175 Chapter 6 Digital Data Communication Techniques 180 6. Asynchronous and Synchronous Transmission 182 6. 2 Types of Errors 186 6. 3 Error Detection 186 6. 4 Error Correction 196 6. 5 Line Configurations 201 6. 6 Recommended Reading 203 6. 7 Key Terms, Review Questions, and Problems 204 Chapter 7 Data Link Control Protocols 207 7. 1 Flow Control 209 7. 2 Error Control 216 7. 3 High-Level Data Link Control (HDLC) 222 7. 4 Recommended Reading 228 7. 5 Key Terms, Review Questions, and Problems 229 Appendix 7A Performance Issues 232 Chapter 8 Multiplexing 239 8. 1 Frequency-Division Multiplexing 242 8. 2 Synchronous Time-Division Multiplexing 248 8. St atistical Time-Division Multiplexing 258 8. 4 Asymmetric Digital Subscriber Line 265 8. 5 xDSL 268 8. 6 Recommended Reading and Web Sites 269 8. 7 Key Terms, Review Questions, and Problems 270 Chapter 9 Spread Spectrum 274 9. 1 The Concept of Spread Spectrum 276 9. 2 Frequency Hopping Spread Spectrum 277 9. 3 Direct Sequence Spread Spectrum 282 9. 4 Code-Division Multiple Access 287 9. 5 Recommended Reading and Web Site 290 9. 6 Key Terms, Review Questions, and Problems 291 CONTENTS ix PART THREE WIDE AREA NETWORKS 295 Chapter 10 Circuit Switching and Packet Switching 297 10. Switched Communications Networks 299 10. 2 Circuit Switching Networks 301 10. 3 Circuit Switching Concepts 304 10. 4 Softswitch Architecture 307 10. 5 Packet-Switching Principles 309 10. 6 X. 25 317 10. 7 Frame Relay 319 10. 8 Recommended Reading and Web Sites 324 10. 9 Key Terms, Review Questions, and Problems 325 Chapter 11 Asynchronous Transfer Mode 328 11. 1 Protocol Architecture 329 11. 2 ATM Logical Conne ctions 331 11. 3 ATM Cells 335 11. 4 Transmission of ATM Cells 340 11. 5 ATM Service Categories 345 11. 6 Recommended Reading and Web Sites 348 11. Key Terms, Review Questions, and Problems 349 Chapter 12 Routing in Switched Networks 351 12. 1 Routing in Packet-Switching Networks 352 12. 2 Examples: Routing in ARPANET 362 12. 3 Least-Cost Algorithms 367 12. 4 Recommended Reading 372 12. 5 Key Terms, Review Questions, and Problems 373 Chapter 13 Congestion Control in Data Networks 377 13. 1 Effects of Congestion 379 13. 2 Congestion Control 383 13. 3 Traffic Management 386 13. 4 Congestion Control in Packet-Switching Networks 13. 5 Frame Relay Congestion Control 388 13. 6 ATM Traffic Management 394 13. 7 ATM-GFR Traffic Management 406 13. Recommended Reading 409 13. 9 Key Terms, Review Questions, and Problems 410 Chapter 14 Cellular Wireless Networks 413 14. 1 Principles of Cellular Networks 415 14. 2 First Generation Analog 427 14. 3 Second Generation CDMA 429 14. 4 Third Generation Systems 437 14. 5 Recommended Reading and Web Sites 440 14. 6 Key Terms, Review Questions, and Problems 441 387 x CONTENTS PART FOUR LOCAL AREA NETWORKS 444 Chapter 15 Local Area Network Overview 446 15. 1 Background 448 15. 2 Topologies and Transmission Media 451 15. 3 LAN Protocol Architecture 457 15. 4 Bridges 465 15. 5 Layer 2 and Layer 3 Switches 473 15. Recommended Reading and Web Site 478 15. 7 Key Terms, Review Questions, and Problems 479 Chapter 16 High-Speed LANs 482 16. 1 The Emergence of High-Speed LANs 483 16. 2 Ethernet 485 16. 3 Fibre Channel 500 16. 4 Recommended Reading and Web Sites 504 16. 5 Key Terms, Review Questions, and Problems 506 Appendix 16A Digital Signal Encoding for LANs 508 Appendix 16B Performance Issues 514 Appendix 16C Scrambling 518 Chapter 17 Wireless LANs 522 17. 1 Overview 523 17. 2 Wireless LAN Technology 528 17. 3 IEEE 802. 11 Architecture and Services 531 17. 4 IEEE 802. 11 Medium Access Control 535 17. 5 IEEE 802. 1Physical Layer 543 17. 6 IEEE 802. 11 Security Considerations 549 Recommended Reading and Web Sites 550 17. 7 17. 8 Key Terms, Review Questions, and Problems 551 PART FIVE INTERNET AND TRANSPORT PROTOCOLS Chapter 18 Internetwork Protocols 556 18. 1 Basic Protocol Functions 558 18. 2 Principles of Internetworking 566 18. 3 Internet Protocol Operation 569 18. 4 Internet Protocol 576 18. 5 IPv6 586 18. 6 Virtual Private Networks and IP Security 596 18. 7 Recommended Reading and Web Sites 599 18. 8 Key Terms, Review Questions, and Problems 600 Chapter 19 Internetwork Operation 603 19. 1 Multicasting 605 19. Routing Protocols 614 19. 3 Integrated Services Architecture 625 19. 4 Differentiated Services 636 554 CONTENTS xi 19. 5 19. 6 19. 7 19. 8 Service Level Agreements 645 IP Performance Metrics 646 Recommended Reading and Web Sites 649 Key Terms, Review Questions, and Problems 651 657 Chapter 20 Transport Protocols 655 20. 1 Connection-Oriented Transport Protocol Mechanisms 20. 2 TCP 674 20. 3 TCP Congestion Co ntrol 683 20. 4 UDP 693 20. 5 Recommended Reading and Web Sites 695 Key Terms, Review Questions, and Problems 695 20. 6 PART SIX Chapter 21 21. 1 21. 2 21. 3 21. 4 21. 5 21. 6 21. 7 21. 8 21. INTERNET APPLICATIONS 699 Network Security 701 Security Requirements and Attacks 703 Confidentiality with Conventional Encryption 705 Message Authentication and Hash Functions 713 Public-Key Encryption and Digital Signatures 720 Secure Socket Layer and Transport Layer Security 727 IPv4 and IPv6 Security 732 Wi-Fi Protected Access 737 Recommended Reading and Web Sites 739 Key Terms, Review Questions, and Problems 740 Chapter 22 Internet Applications—Electronic Mail and Network Management 22. 1 Electronic Mail: SMTP and MIME 745 22. 2 Network Management: SNMP 760 22. 3 Recommended Reading and Web Sites 770 22. Key Terms, Review Questions, and Problems 771 743 Chapter 23 Internet Applications—Internet Directory Service and World Wide Web 23. 1 Internet Directory Service: DNS 774 23. 2 Web Access: HTTP 784 23. 3 Recommended Reading and Web Sites 795 23. 4 Key Terms, Review Questions, and Problems 796 Chapter 24 Internet Applications—Multimedia 799 24. 1 Audio and Video Compression 800 24. 2 Real-Time Traffic 808 24. 3 Voice Over IP and Multimedia Support—SIP 811 24. 4 Real-Time Transport Protocol (RTP) 820 24. 5 Recommended Reading and Web Sites 831 24. 6 Key Terms, Review Questions, and Problems 832 773 ii CONTENTS APPENDICES 835 Appendix A Fourier Analysis 835 A. 1 Fourier Series Representation of Periodic Signals 836 A. 2 Fourier Transform Representation of Aperiodic Signals 837 A. 3 Recommended Reading 840 Appendix B Projects for Teaching Data and Computer Communications B. 1 Practical Exercises 842 B. 2 Sockets Projects 843 B. 3 Ethereal Projects 843 B. 4 Simulation and Modeling Projects 844 B. 5 Performance Modeling 844 B. 6 Research Projects 845 B. 7 Reading/Report Assignments 845 B. 8 Writing Assignments 845 B. 9 Discussion Topics 846 Refer ences Index 858 ONLINE APPENDICES WilliamStallings. om/DCC Appendix C Sockets: A Programmer’s Introduction C. 1 Versions of Sockets C. 2 Sockets, Socket Descriptors, Ports, and Connections The Client/Server Model of Communication C. 3 C. 4 Sockets Elements C. 5 Stream and Datagram Sockets C. 6 Run-Time Program Control C. 7 Remote Execution of a Windows Console Application Appendix D Standards Organizations D. 1 The Importance of Standards D. 2 Standards and Regulation D. 3 Standards-Setting Organizations Appendix E Appendix F The International Reference Alphabet Proof of the Sampling Theorem 847 841 Appendix G Physical-Layer Interfacing G. 1 V. 24/EIA-232-F G. ISDN Physical Interface Appendix H The OSI Model H. 1 The Model H. 2 The OSI Layers CONTENTS xiii Appendix I Queuing Effects I. 1 Queuing Models I. 2 Queuing Results Appendix J Orthogonality, Correlation, and Autocorrelation J. 1 Correlation and Autocorrelation J. 2 Orthogonal Codes Appendix K The TCP/IP Checksum K. 1 O nes-Complement Addition K. 2 Use in TCP and IP Appendix L TCP/IP Example Appendix M Uniform Resource Locators (URLs) and Uniform Resource Identifiers (URIs) M. 1 Uniform Resource Locator M. 2 Uniform Resource Identifier M. 3 To Learn More Appendix N Glossary Augmented Backus-Naur Form This page intentionally left blank PREFACE Begin at the beginning and go on till you come to the end; then stop. —Alice in Wonderland, Lewis Carroll OBJECTIVES This book attempts to provide a unified overview of the broad field of data and computer communications. The organization of the book reflects an attempt to break this massive subject into comprehensible parts and to build, piece by piece, a survey of the state of the art. The book emphasizes basic principles and topics of fundamental importance concerning the technology and architecture of this field and provides a detailed discussion of leading-edge topics. The following basic themes serve to unify the discussion: †¢ Principles: Although the scope of this book is broad, there are a number of basic principles that appear repeatedly as themes and that unify this field. Examples are multiplexing, flow control, and error control. The book highlights these principles and contrasts their application in specific areas of technology. †¢ Design approaches: The book examines alternative approaches to meeting specific communication requirements. †¢ Standards: Standards have come to assume an increasingly important, indeed dominant, role in this field. An understanding of the current status and future direction of technology requires a comprehensive discussion of the related standards. INTENDED AUDIENCE The book is intended for both an academic and a professional audience. For the professional interested in this field, the book serves as a basic reference volume and is suitable for self-study. As a textbook, it can be used for a one-semester or two-semester course. It covers the material in Networking (NET), a core area in the Information Technology body of knowledge, which is part of the Draft ACM/IEEE/AIS Computing Curricula 2005. The book also covers the material in Computer Networks (CE-NWK), a core area in Computer Engineering 2004 Curriculum Guidelines from the ACM/IEEE Joint Task Force on Computing Curricula. PLAN OF THE TEXT The book is divided into six parts (see Chapter 0): †¢ Overview †¢ Data Communications †¢ Wide Area Networks xv xvi PREFACE †¢ Local Area Networks †¢ Internet and Transport Protocols †¢ Internet Applications In addition, the book includes an extensive glossary, a list of frequently used acronyms, and a bibliography. Each chapter includes problems and suggestions for further reading. The chapters and parts of the book are sufficiently modular to provide a great deal of flexibility in the design of courses. See Chapter 0 for a number of detailed suggestions for both top-down and bottom-up course strategies. INSTRUCTIONAL SUPPORT MATERIALS To support instructors, the following materials are provided: †¢ Solutions Manual: Solutions to all end-of-chapter Review Questions and Problems. †¢ PowerPoint Slides: A set of slides covering all chapters, suitable for use in lecturing. †¢ PDF files: Reproductions of all figures and tables from the book. Projects Manual: Suggested project assignments for all of the project categories listed below. Instructors may contact their Pearson Education or Prentice Hall representative for access to these materials. In addition, the book’s Web site supports instructors with: †¢ Links to Webs sites for other courses being taught using this book †¢ Sign up information for an Internet mailing list for instruct ors INTERNET SERVICES FOR INSTRUCTORS AND STUDENTS There is a Web site for this book that provides support for students and instructors. The site includes links to other relevant sites, transparency masters of figures in the book, and sign-up information for the book’s Internet mailing list. The Web page is at WilliamStallings. com/DCC/DCC8e. html; see the section, Web Site for Data and Computer Communications, preceding the Table of Contents, for more information. An Internet mailing list has been set up so that instructors using this book can exchange information, suggestions, and questions with each other and with the author. As soon as typos or other errors are discovered, an errata list for this book will be available at WilliamStallings. om. PROJECTS AND OTHER STUDENT EXERCISES For many instructors, an important component of a data communications or networking course is a project or set of projects by which the student gets hands-on experience to reinforce concepts from the text. This book provides an unparalleled degree of support for including a projects component in the course. The instructor’s supplement not only includes guidance on how to assign and structure the projects but also includes a set of User’s PREFACE xvii Manuals for various project types plus specific assignments, all written especially for this book. Instructors can assign work in the following areas: †¢ Practical exercises: Using network commands, the student gains experience in network connectivity. †¢ Sockets programming projects: The book is supported by a detailed description of Sockets available at the book’s Web site. The Instructors supplement includes a set of programming projects. Sockets programming is an â€Å"easy† topic and one that can result in very satisfying hands-on projects for students. †¢ Ethereal projects: Ethereal is a protocol analyzer that enables students to study the behavior of protocols. Simulation projects: The student can use the simulation package cnet to analyze network behavior. †¢ Performance modeling projects: Two performance modeling techniques are provided a tools package and OPNET. †¢ Research projects: The instructor’s supplement includes a list of suggested research projects that would involve Web and literature searches. †¢ Reading/repor t assignments: The instructor’s supplement includes a list of papers that can be assigned for reading and writing a report, plus suggested assignment wording. Writing assignments: The instructor’s supplement includes a list of writing assignments to facilitate learning the material. †¢ Discussion topics: These topics can be used in a classroom, chat room, or message board environment to explore certain areas in greater depth and to foster student collaboration. This diverse set of projects and other student exercises enables the instructor to use the book as one component in a rich and varied learning experience and to tailor a course plan to meet the specific needs of the instructor and students. See Appendix B for details. WHAT’S NEW IN THE EIGHTH EDITION This eighth edition is seeing the light of day less than four years after the publication of the seventh edition. During that time, the pace of change in this field continues unabated. In this new edition, I try to capture these changes while maintaining a broad and comprehensive coverage of the entire field. To begin the process of revision, the seventh edition of this book was extensively reviewed by a number of professors who teach the subject. The result is that, in many places, the narrative has been clarified and tightened, and illustrations have been improved. Also, a number of new â€Å"field-tested† problems have been added. Beyond these refinements to improve pedagogy and user friendliness, there have been major substantive changes throughout the book. Every chapter has been revised, new chapters have been added, and the overall organization of the book has changed. Highlights include: †¢ Updated coverage of Gigabit Ethernet and 10-Gbps Ethernet: New details of these standards are provided. †¢ Updated coverage of WiFi/IEEE 802. 11 wireless LANs: IEEE 802. 11 and the related WiFi specifications have continued to evolve. viii PREFACE †¢ New coverage of IP performance metrics and service level agreements (SLAs): These aspects of Quality of Service (QoS) and performance monitoring are increasingly important. †¢ Address Resolution Protocol (ARP): This important protocol is now covered. †¢ New coverage of TCP Tahoe, Reno, and NewReno: These congestion control algorithms are now common in most commercial impleme ntations. †¢ Expanded coverage of security: Chapter 21 is more detailed; other chapters provide overview of security for the relevant topic. Among the new topics are Wi-Fi Protected Access (WPA) and the secure hash algorithm SHA-512. †¢ Domain Name System (DNS): This important scheme is now covered. †¢ New coverage of multimedia: Introductory section in Chapter 2; detailed coverage in Chapter 24. Topics covered include video compression, SIP, and RTP. †¢ Online appendices: Fourteen online appendices provide additional detail on important topics in the text, including Sockets programming, queuing models, the Internet checksum, a detailed example of TCP/IP operation, and the BNF grammar. In addition, throughout the book, virtually every topic has been updated to reflect the developments in standards and technology that have occurred since the publication of the seventh edition. ACKNOWLEDGMENTS This new edition has benefited from review by a number of people, who gave generously of their time and expertise. The following people reviewed all or a large part of the manuscript: Xin Liu- (UC, Davis), Jorge Cobb, Andras Farago, Dr. Prasant Mohapatra (UC Davis), Dr. Jingxian Wu (Sonoma State University), G. R. Dattareya (UT Dallas), Guanling Chen (Umass, Lowell), Bob Roohaprvar (Cal State East Bay), Ahmed Banafa (Cal State East Bay), Ching-Chen Lee (CSU Hayward), and Daji Qaio (Iowa State). Thanks also to the many people who provided detailed technical reviews of a single chapter: Dave Tweed, Bruce Lane, Denis McMahon, Charles Freund, Paul Hoadley, Stephen Ma, Sandeep Subramaniam, Dragan Cvetkovic, Fernando Gont, Neil Giles, Rajesh Thundil, and Rick Jones. In addition, Larry Owens of California State University and Katia Obraczka of the University of Southern California provided some homework problems. Thanks also to the following contributors. Zornitza Prodanoff of the University of North Florida prepared the appendix on Sockets programming. Michael Harris of the University of South Florida is responsible for the Ethereal exercises and user’s guide. Lawrie Brown of the Australian Defence Force Academy of the University of New South Wales produced the PPT lecture slides. Finally, I would like to thank the many people responsible for the publication of the book, all of whom did their usual excellent job. This includes the staff at Prentice Hall, particularly my editor Tracy Dunkelberger, her assistants Christianna Lee and Carole Snyder, and production manager Rose Kernan. Also, Patricia M. Daly did the copy editing. CHAPTER READER’S AND INSTRUCTOR’S GUIDE 0. 1 0. 2 0. 3 0. 4 Outline of the Book Roadmap Internet and Web Resources Standards 0 1 2 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE â€Å"In the meanwhile, then,† demanded Li-loe, â€Å"relate to me the story to which reference has been made, thereby proving the truth of your assertion, and at the same time affording n entertainment of a somewhat exceptional kind. † â€Å"The shadows lengthen,† replied Kai Lung, â€Å"but as the narrative in question is of an inconspicuous span I will raise no barrier against your flattering request, especially as it indicates an awakening taste hitherto unexpected. † —Kai Lung’s Golden Hours, Earnest Bramah This book, with its accompanying Web site, covers a lot of material. Here we give the reader some basic background information. 0. 1 OUTLINE OF THE BOOK The book is organized into five parts: Part One. Overview: Provides an introduction to the range of topics covered in the book. This part includes a general overview of data communications and networking and a discussion of protocols, OSI, and the TCP/IP protocol suite. Part Two. Data Communications: Concerned primarily with the exchange of data between two directly connected devices. Within this restricted scope, the key aspects of transmission, interfacing, link control, and multiplexing are examined. Part Three. Wide Area Networks: Examines the internal mechanisms and user-network interfaces that have been developed to support voice, data, and multimedia communications over long-distance networks. The traditional technologies of packet switching and circuit switching are examined, as well as the more recent ATM and wireless WANs. Separate chapters are devoted to routing and congestion control issues that are relevant both to switched data networks and to the Internet. Part Four. Local Area Networks: Explores the technologies and architectures that have been developed for networking over shorter distances. The transmission media, topologies, and medium access control protocols that are the key ingredients of a LAN design are explored and specific standardized LAN systems examined. Part Five. Networking Protocols: Explores both the architectural principles and the mechanisms required for the exchange of data among computers, workstations, servers, and other data processing devices. Much of the material in this part relates to the TCP/IP protocol suite. Part Six. Internet Applications: Looks at a range of applications that operate over the Internet. A more detailed, chapter-by-chapter summary of each part appears at the beginning of that part. 0. 2 / ROADMAP 3 0. 2 ROADMAP Course Emphasis The material in this book is organized into four broad categories: data transmission and communication; communications networks; network protocols; and applications and security. The chapters and parts of the book are sufficiently modular to provide a great deal of flexibility in the design of courses. The following are suggestions for three different course designs: †¢ Fundamentals of Data Communications: Parts One (overview) and Two (data communications) and Chapters 10 and 11 (circuit switching, packet switching, and ATM). Communications Networks: If the student has a basic background in data communications, then this course could cover Parts One (overview), Three (WAN), and Four (LAN). †¢ Computer Networks: If the student has a basic background in data communications, then this course could cover Part One (overview), Chapters 6 and 7 (data communication techniques and data link control), Part Five (protocols), and part or all of Part Six (applications). In addition, a m ore streamlined course that covers the entire book is possible by eliminating certain chapters that are not essential on a first reading. Chapters that could be optional are Chapters 3 (data transmission) and 4 (transmission media), if the student has a basic understanding of these topics; Chapter 8 (multiplexing); Chapter 9 (spread spectrum); Chapters 12 through 14 (routing, congestion control, cellular networks); Chapter 18 (internetworking); and Chapter 21 (network security). Bottom-Up versus Top-Down The book is organized in a modular fashion. After reading Part One, the other parts can be read in a number of possible sequences. Figure 0. 1a shows the bottom-up approach provided by reading the book from front to back. With this approach, each part builds on the material in the previous part, so that it is always clear how a given layer of functionality is supported from below. There is more material than can be comfortably covered in a single semester, but the book’s organization makes it easy to eliminate some chapters and maintain the bottom-up sequence. Figure 0. 1b suggests one approach to a survey course. Some readers, and some instructors, are more comfortable with a top-down approach. After the background material (Part One), the reader continues at the application level and works down through the protocol layers. This has the advantage of immediately focusing on the most visible part of the material, the applications, and then seeing, progressively, how each layer is supported by the next layer down. Figure 0. 1c is an example of a comprehensive treatment and Figure 0. 1d is an example of a survey treatment. 4 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE Part One Overview Part Two Data Communications Part Three Wide Area Networks Part Four Local Area Networks Part Five Internet and Transport Protocols Part Six Internet Applications (a) A bottom-up approach Part One Overview Chapter 18 The Internet Protocol Part Six Internet Applications Part Five TCP/IP Part Three WANs Part Four LANs Part Two Data Communications (c) A top-down approach (d) Another top-down approach (b) Another bottom-up approach Part One Overview Chapter 18 The Internet Protocol Part Six Internet Applications Part Five TCP/IP Part Three WANs (10, 12) Part Four LANs (15) Part One Overview (1, 2) Part Two Data Communications (3, 6, 7, 8) Part Three WANs (10, 12) Part Four LANs (15) Part Five TCP/IP (18, 20) Figure 0. 1 Suggested Reading Orders Finally, it is possible to select chapters to reflect specific teaching objectives by not sticking to a strict chapter ordering. We give two examples used in courses taught with the seventh edition. One course used the sequence Part One (Overview); Chapter 3 (Data Transmission); Chapter 6 (Digital Data Communications Techniques); Chapter 7 (Data Link Control); Chapter 15 (LAN Overview); Chapter 16 (High-Speed LANs); Chapter 10 (Circuit and Packet Switching); Chapter 12 (Routing); Chapter 18 (Internet Protocols); and Chapter 19 (Internet Operation). The other course used the sequence Part One (Overview); Chapter 3 (Data Transmission); Chapter 4 (Guided and Wireless Transmission); Chapter 5 (Signal Encoding Techniques); Chapter 8 (Multiplexing); Chapter 15 (LAN 0. 3 / INTERNET AND WEB RESOURCES 5 Overview); Chapter 16 (High-Speed LANs); Chapter 10 (Circuit and Packet Switching); Chapter 20 (Transport Protocols); Chapter 18 (Internet Protocols); and Chapter 19 (Internet Operation). 0. 3 INTERNET AND WEB RESOURCES There are a number of resources available on the Internet and the Web to support this book and to help one keep up with developments in this field. Web Sites for This Book A special Web page has been set up for this book at WilliamStallings. com/DCC/ DCC8e. html. See the two-page layout at the beginning of this book for a detailed description of that site. As soon as any typos or other errors are discovered, an errata list for this book will be available at the Web site. Please report any errors that you spot. Errata sheets for my other books are at WilliamStallings. com. I also maintain the Computer Science Student Resource Site, at WilliamStallings. com/StudentSupport. html. The purpose of this site is to provide documents, information, and links for computer science students and professionals. Links and documents are organized into four categories: †¢ Math: Includes a basic math refresher, a queuing analysis primer, a number system primer, and links to numerous math sites †¢ How-to: Advice and guidance for solving homework problems, writing technical reports, and preparing technical presentations †¢ Research resources: Links to important collections of papers, technical reports, and bibliographies †¢ Miscellaneous: A variety of useful documents and links Other Web Sites There are numerous Web sites that provide information related to the topics of this book. In subsequent chapters, pointers to specific Web sites can be found in the Recommended Reading and Web Sites section. Because the addresses for Web sites tend to change frequently, I have not included URLs in the book. For all of the Web sites listed in the book, the appropriate link can be found at this book’s Web site. Other links not mentioned in this book will be added to the Web site ove r time. The following are Web sites of general interest related to data and computer communications: †¢ Network World: Information and links to resources about data communications and networking. †¢ IETF: Maintains archives that relate to the Internet and IETF activities. Includes keyword-indexed library of RFCs and draft documents as well as many other documents related to the Internet and related protocols. 6 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE †¢ Vendors: Links to thousands of hardware and software vendors who currently have Web sites, as well as a list of thousands of computer and networking companies in a phone directory. †¢ IEEE Communications Society: Good way to keep up on conferences, publications, and so on. ACM Special Interest Group on Communications (SIGCOMM): Good way to keep up on conferences, publications, and so on. †¢ International Telecommunications Union: Contains a listing of ITU-T recommendations, plus information on obtain ing ITU-T documents in hard copy or on DVD. †¢ International Organization for Standardization: Contains a listing of ISO standards, plus information on obtaining ISO documents in hard copy or on CD-ROM. †¢ CommWeb: Links to vendors, tutorials, and other useful information. †¢ CommsDesign: Lot of useful articles, tutorials, and product information. A bit hard to navigate, but worthwhile. USENET Newsgroups A number of USENET newsgroups are devoted to some aspect of data communications, networks, and protocols. As with virtually all USENET groups, there is a high noise-to-signal ratio, but it is worth experimenting to see if any meet your needs. The most relevant are as follows: †¢ comp. dcom. lans, comp. dcom. lans. misc: General discussions of LANs †¢ comp. dcom. lans. ethernet: Covers Ethernet, Ethernet-like systems, and the IEEE 802. 3 CSMA/CD standards †¢ comp. std. wireless: General discussion of wireless networks, including wireless LANs †¢ comp. security. misc: Computer security and encryption †¢ comp. dcom. cell-relay: Covers ATM and ATM LANs †¢ comp. dcom. frame-relay: Covers frame relay networks †¢ comp. dcom. net-management: Discussion of network management applications, protocols, and standards †¢ comp. rotocols. tcp-ip: The TCP/IP protocol suite 0. 4 STANDARDS It has long been accepted in the telecommunications industry that standards are required to govern the physical, electrical, and procedural characteristics of communication equipme nt. In the past, this view has not been embraced by the computer industry. Whereas communication equipment vendors recognize that their 0. 4 / STANDARDS 7 equipment will generally interface to and communicate with other vendors’ equipment, computer vendors have traditionally attempted to monopolize their customers. The proliferation of computers and distributed processing has made that an untenable position. Computers from different vendors must communicate with each other and, with the ongoing evolution of protocol standards, customers will no longer accept special-purpose protocol conversion software development. The result is that standards now permeate all of the areas of technology discussed in this book. There are a number of advantages and disadvantages to the standards-making process. We list here the most striking ones. The principal advantages of standards are as follows: †¢ A standard assures that there will be a large market for a particular piece of equipment or software. This encourages mass production and, in some cases, the use of large-scale-integration (LSI) or very-large-scale-integration (VLSI) techniques, resulting in lower costs. A standard allows products from multiple vendors to communicate, giving the purchaser more flexibility in equipment selection and use. The principal disadvantages are as follows: †¢ A standard tends to freeze the technology. By th e time a standard is developed, subjected to review and compromise, and promulgated, more efficient techniques are possible. †¢ There are multiple standards for the same thing. This is not a disadvantage of standards per se, but of the current way things are done. Fortunately, in recent years the various standards-making organizations have begun to cooperate more closely. Nevertheless, there are still areas where multiple conflicting standards exist. Throughout this book, we describe the most important standards in use or being developed for various aspects of data and computer communications. Various organizations have been involved in the development or promotion of these standards. The following are the most important (in the current context) of these organizations: †¢ Internet Society: The Internet SOCiety (ISOC) is a professional membership society with more than 150 organizational and 6000 individual members in over 100 countries. It provides leadership in addressing issues that confront the future of the Internet and is the organization home for the groups responsible for Internet infrastructure standards, including the Internet Engineering Task Force (IETF) and the Internet Architecture Board (IAB). All of the RFCs and Internet standards are developed through these organizations. †¢ IEEE 802: The IEEE (Institute of Electrical and Electronics Engineers) 802 LAN/MAN Standards Committee develops local area network standards and metropolitan area network standards. The most widely used standards are for the Ethernet family, wireless LAN, bridging, and virtual bridged LANs. An individual working group provides the focus for each area. 8 CHAPTER 0 / READER’S AND INSTRUCTOR’S GUIDE †¢ ITU-T: The International Telecommunication Union (ITU) is an international organization within the United Nations System where governments and the private sector coordinate global telecom networks and services. The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors of the ITU. ITU-T’s mission is the production of standards covering all fields of telecommunications. †¢ ATM Forum: The ATM Forum is an international nonprofit organization formed with the objective of accelerating the use of ATM (asynchronous transfer mode) products and services through a rapid convergence of interoperability specifications. In addition, the Forum promotes industry cooperation and awareness. †¢ ISO: The International Organization for Standardization (ISO)1 is a worldwide federation of national standards bodies from more than 140 countries, one from each country. ISO is a nongovernmental organization that promotes the development of standardization and related activities with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres of intellectual, scientific, technological, and economic activity. ISO’s work results in international agreements that are published as International Standards. A more detailed discussion of these organizations is contained in Appendix D. 1 ISO is not an acronym (in which case it would be IOS), but a word, derived from the Greek, meaning equal. PART ONE Overview The purpose of Part One is to provide a background and context for the remainder of this book. The broad range of topics that are encompassed in the field of data and computer communications is introduced, and the fundamental concepts of protocols and protocol architectures are examined. ROAD MAP FOR PART ONE Chapter 1 Data Communications, Data Networks, and The Internet Chapter 1 provides an overview of Parts Two through Four of the book, giving the â€Å"big picture. † In essence, the book deals with four topics: data communications over a transmission link; wide area networks; local area networks; and protocols and the TCP/IP protocol architecture. Chapter 1 provides a preview of the first three of these topics. Chapter 2 Protocol Architecture, TCP/IP, and Internet-Based Applications Chapter 2 discusses the concept protocol architectures. This chapter can be read immediately following Chapter 1 or deferred until the beginning of Part Three, Four, or Five. After a general introduction, the chapter deals with the two most important protocol architectures: the Open Systems Interconnection (OSI) model and TCP/IP. Although the OSI model is often used as the framework for discourse in this area, it is the TCP/IP protocol suite that is the basis for most commercially available interoperable products and that is the focus of Parts Five and Six of this book. 9 CHAPTER DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 Data Communications and Networking for Today’s Enterprise A Communications Model Data Communications Networks The Internet An Example Configuration 1 10 The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point. The Mathematical Theory of Communication, Claude Shannon KEY POINTS †¢ The scope of this book is broad, covering three general areas: data communications, networking, and protocols; the first two are introduced in this chapter. Data communications deals with the transmission of signals in a reliable and efficient manner. Topics covered include signal transmission, transmission media, signal encoding, interfacing, data link control, and multiplexing. Networking deals with the technology and architecture of the communications networks used to interconnect communicating devices. This field is generally divided into the topics of local area networks (LANs) and wide area networks (WANs). †¢ †¢ The 1970s and 1980s saw a merger of the fields of computer science and data communications that profoundly changed the technology, products, and companies of the now combined computer-communications industry. The computercommunications revolution has produced several remarkable facts: †¢ There is no fundamental difference between data processing (computers) and data communications (transmission and switching equipment). †¢ There are no fundamental differences among data, voice, and video communications. †¢ The distinction among single-processor computer, multiprocessor computer, local network, metropolitan network, and long-haul network has blurred. One effect of these trends has been a growing overlap of the computer and communications industries, from component fabrication to system integration. Another result is the development of integrated systems that transmit and process all types of data and information. Both the technology and the technical standards organizations are driving toward integrated public systems that make virtually all data and information sources around the world easily and uniformly accessible. This book aims to provide a unified view of the broad field of data and computer communications. The organization of the book reflects an attempt to break this massive subject into comprehensible parts and to build, piece by piece, a survey of the state of the art. This introductory chapter begins with a general model of communications. Then a brief discussion introduces each of the Parts Two through Four of this book. Chapter 2 provides an overview to Parts Five and Six 11 12 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET 1. 1 DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE Effective and efficient data communication and networking facilities are vital to any enterprise. In this section, we first look at trends that are increasing the challenge for the business manager in planning and managing such facilities. Then we look specifically at the requirement for ever-greater transmission speeds and network capacity. Trends Three different forces have consistently driven the architecture and evolution of data communications and networking facilities: traffic growth, development of new services, and advances in technology. Communication traffic, both local (within a building or building complex) and long distance, both voice and data, has been growing at a high and steady rate for decades. The increasing emphasis on office automation, remote access, online transactions, and other productivity measures means that this trend is likely to continue. Thus, managers are constantly struggling to maximize capacity and minimize transmission costs. As businesses rely more and more on information technology, the range of services expands. This increases the demand for high-capacity networking and transmission facilities. In turn, the continuing growth in high-speed network offerings with the continuing drop in prices encourages the expansion of services. Thus, growth in services and growth in traffic capacity go hand in hand. Figure 1. 1 gives some examples of information-based services and the data rates needed to support them [ELSA02]. Finally, trends in technology enable the provision of increasing traffic capacity and the support of a wide range of services. Four technology trends are particularly notable: 1. The trend toward faster and cheaper, both in computing and communications, continues. In terms of computing, this means more powerful computers and clusters of computers capable of supporting more demanding applications, such as multimedia applications. In terms of communications, the increasing use of optical fiber has brought transmission prices down and greatly increased capacity. For example, for long-distance telecommunication and data network links, recent offerings of dense wavelength division multiplexing (DWDM) enable capacities of many terabits per second. For local area networks (LANs) many enterprises now have Gigabit Ethernet backbone networks and some are beginning to deploy 10-Gbps Ethernet. 2. Both voice-oriented telecommunications networks, such as the public switched telephone network (PSTN), and data networks, including the Internet, are more â€Å"intelligent† than ever. Two areas of intelligence are noteworthy. First, today’s networks can offer differing levels of quality of service (QoS), which include specifications for maximum delay, minimum throughput, and so on. Second, today’s networks provide a variety of customizable services in the areas of network management and security. 1. 1 / DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE Speed (kbps) Transaction processing Messaging/text apps Voice Location services Still image transfers Internet/VPN access Database access Enhanced Web surfing Low-quality video Hifi audio Large file transfer Moderate video Interactive entertainment High-quality video Performance: Poor Adequate Good 9. 6 14. 4 28 64 144 384 2000 13 VPN: virtual private network Figure 1. 1 Services versus Throughput Rates 3. The Internet, the Web, and associated applications have emerged as dominant features of both the business and personal world, opening up many opportunities and challenges for managers. In addition to exploiting the Internet and the Web to reach customers, suppliers, and partners, enterprises have formed intranets and extranets1 to isolate their proprietary information free from unwanted access. 4. There has been a trend toward ever-increasing mobility for decades, liberating workers from the confines of the physical enterprise. Innovations include voice mail, remote data access, pagers, fax, e-mail, cordless phones, cell phones and cellular networks, and Internet portals. The result is the ability of employees to take their business context with them as they move about. We are now seeing the growth of high-speed wireless access, which further enhances the ability to use enterprise information resources and services anywhere. 1 Briefly, an intranet uses Internet and Web technology in an isolated facility internal to an enterprise; an extranet extends a company’s intranet out onto the Internet to allow selected customers, suppliers, and mobile workers to access the company’s private data and applications. 14 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET Data Transmission and Network Capacity Requirements Momentous changes in the way organizations do business and process information have been driven by changes in networking technology and at the same time have driven those changes. It is hard to separate chicken and egg in this field. Similarly, the use of the Internet by both businesses and individuals reflects this cyclic dependency: the availability of new image-based services on the Internet (i. e. , the Web) has resulted in an increase in the total number of users and the traffic volume generated by each user. This, in turn, has resulted in a need to increase the speed and efficiency of the Internet. On the other hand, it is only such increased speed that makes the use of Web-based applications palatable to the end user. In this section, we survey some of the end-user factors that fit into this equation. We begin with the need for high-speed LANs in the business environment, because this need has appeared first and has forced the pace of networking development. Then we look at business WAN requirements. Finally we offer a few words about the effect of changes in commercial electronics on network requirements. The Emergence of High-Speed LANs Personal computers and microcomputer workstations began to achieve widespread acceptance in business computing in the early 1980s and have now achieved virtually the status of the telephone: an essential tool for office workers. Until relatively recently, office LANs provided basic connectivity services—connecting personal computers and terminals to mainframes and midrange systems that ran corporate applications, and providing workgroup connectivity at the departmental or divisional level. In both cases, traffic patterns were relatively light, with an emphasis on file transfer and electronic mail. The LANs that were available for this type of workload, primarily Ethernet and token ring, are well suited to this environment. In the 1990s, two significant trends altered the role of the personal computer and therefore the requirements on the LAN: 1. The speed and computing power of personal computers continued to enjoy explosive growth. These more powerful platforms support graphics-intensive applications and ever more elaborate graphical user interfaces to the operating system. . MIS (management information systems) organizations have recognized the LAN as a viable and essential computing platform, resul ting in the focus on network computing. This trend began with client/server computing, which has become a dominant architecture in the business environment and the more recent Webfocused intranet trend. Both of these approaches involve the frequent transfer of potentially large volumes of data in a transaction-oriented environment. The effect of these trends has been to increase the volume of data to be handled over LANs and, because applications are more interactive, to reduce the acceptable delay on data transfers. The earlier generation of 10-Mbps Ethernets and 16-Mbps token rings was simply not up to the job of supporting these requirements. The following are examples of requirements that call for higher-speed LANs: †¢ Centralized server farms: In many applications, there is a need for user, or client, systems to be able to draw huge amounts of data from multiple centralized servers, called server farms. An example is a color publishing operation, in 1. 1 / DATA COMMUNICATIONS AND NETWORKING FOR TODAY’S ENTERPRISE 15 which servers typically contain tens of gigabytes of image data that must be downloaded to imaging workstations. As the performance of the servers themselves has increased, the bottleneck has shifted to the network. Power workgroups: These groups typically consist of a small number of cooperating users who need to draw massive data files across the network. Examples are a software development group that runs tests on a new software version, or a computer-aided design (CAD) company that regularly runs simulations of new designs. In such cases, large amounts of data are distributed to several workstations, processed, and updated at very high speed for multiple iterations. †¢ High-speed local backbone: As processing demand grows, LANs proliferate at a site, and high-speed interconnection is necessary. Corporate Wide Area Networking Needs As recently as the early 1990s, there was an emphasis in many organizations on a centralized data processing model. In a typical environment, there might be significant computing facilities at a few regional offices, consisting of mainframes or well-equipped midrange systems. These centralized facilities could handle most corporate applications, including basic finance, accounting, and personnel programs, as well as many of the business-specific applications. Smaller, outlying offices (e. g. , a bank branch) could be equipped with terminals or basic personal computers linked to one of the regional centers in a transaction-oriented environment. This model began to change in the early 1990s, and the change accelerated through the mid-1990s. Many organizations have dispersed their employees into multiple smaller offices. There is a growing use of telecommuting. Most significant, the nature of the application structure has changed. First client/server computing and, more recently, intranet computing have fundamentally restructured the organizational data processing environment. There is now much more reliance on personal computers, workstations, and servers and much less use of centralized mainframe and midrange systems. Furthermore, the virtually universal deployment of graphical user interfaces to the desktop enables the end user to exploit graphic applications, multimedia, and other data-intensive applications. In addition, most organizations require access to the Internet. When a few clicks of the mouse can trigger huge volumes of data, traffic patterns have become more unpredictable while the average load has risen. All of these trends means that more data must be transported off premises and into the wide area. It has long been accepted that in the typical business environment, about 80% of the traffic remains local and about 20% traverses wide area links. But this rule no longer applies to most companies, with a greater percentage of the traffic going into the WAN environment [COHE96]. This traffic flow shift places a greater burden on LAN backbones and, of course, on the WAN facilities used by a corporation. Thus, just as in the local area, changes in corporate data traffic patterns are driving the creation of high-speed WANs. Digital Electronics The rapid conversion of consumer electronics to digital technology is having an impact on both the Internet and corporate intranets. As these new gadgets come into view and proliferate, they dramatically increase the amount of image and video traffic carried by networks. Two noteworthy examples of this trend are digital versatile disks (DVDs) and digital still cameras. With the capacious DVD, the electronics industry has at last 16 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET found an acceptable replacement for the analog VHS videotape. The DVD has replaced the videotape used in videocassette recorders (VCRs) and replaced the CD-ROM in personal computers and servers. The DVD takes video into the digital age. It delivers movies with picture quality that outshines laser disks, and it can be randomly accessed like audio CDs, which DVD machines can also play. Vast volumes of data can be crammed onto the disk, currently seven times as much as a CDROM. With DVD’s huge storage capacity and vivid quality, PC games have become more realistic and educational software incorporates more video. Following in the wake of these developments is a new crest of traffic over the Internet and corporate intranets, as this material is incorporated into Web sites. A related product development is the digital camcorder. This product has made it easier for individuals and companies to make digital video files to be placed on corporate and Internet Web sites, again adding to the traffic burden. 1. 2 A COMMUNICATIONS MODEL This section introduces a simple model of communications, illustrated by the block diagram in Figure 1. 2a. The fundamental purpose of a communications system is the exchange of data between two parties. Figure 1. 2b presents one particular example, which is communication between a workstation and a server over a public telephone network. Another example is the exchange of voice signals between two telephones over the same network. The key elements of the model are as follows: †¢ Source. This device generates the data to be transmitted; examples are telephones and personal computers. Source system Destination system Source Transmitter Transmission System (a) General block diagram Receiver Destination Workstation Modem Public telephone network (b) Example Modem Server Figure 1. 2 Simplified Communications Model 1. 2 / A COMMUNICATIONS MODEL 17 †¢ Transmitter: Usually, the data generated by a source system are not transmitted directly in the form in which they were generated. Rather, a transmitter transforms and encodes the information in such a way as to produce electromagnetic signals that can be transmitted across some sort of transmission system. For example, a modem takes a digital bit stream from an attached device such as a personal computer and transforms that bit stream into an analog signal that can be handled by the telephone network. †¢ Transmission system: This can be a single transmission line or a complex network connecting source and destination. †¢ Receiver: The receiver accepts the signal from the transmission system and converts it into a form that can be handled by the destination device. For example, a modem will accept an analog signal coming from a network or transmission line and convert it into a digital bit stream. †¢ Destination: Takes the incoming data from the receiver. This simple narrative conceals a wealth of technical complexity. To get some idea of the scope of this complexity, Table 1. 1 lists some of the key tasks that must be performed in a data communications system. The list is somewhat arbitrary: Elements could be added; items on the list could be merged; and some items represent several tasks that are performed at different â€Å"levels† of the system. However, the list as it stands is suggestive of the scope of this book. The first item, transmission system utilization, refers to the need to make efficient use of transmission facilities that are typically shared among a number of communicating devices. Various techniques (referred to as multiplexing) are used to allocate the total capacity of a transmission medium among a number of users. Congestion control techniques may be required to assure that the system is not overwhelmed by excessive demand for transmission services. To communicate, a device must interface with the transmission system. All the forms of communication discussed in this book depend on the use of electromagnetic signals propagated over a transmission medium. Thus, once an interface is established, signal generation is required for communication. The properties of the signal, such as form and intensity, must be such that the signal is (1) capable of being propagated through the transmission system, and (2) interpretable as data at the receiver. Not only must the signals be generated to conform to the requirements of the transmission system and receiver, but also there must be some form of synchronization Table 1. 1 Communications Tasks Transmission system utilization Interfacing Signal generation Synchronization Exchange management Error detection and correction Flow control Addressing Routing Recovery Message formatting Security Network management 18 CHAPTER 1 / DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET between transmitter and receiver. The receiver must be able to determine when a signal begins to arrive and when it ends. It must also know the duration of each signal element. Beyond the basic matter of deciding on the nature and timing of signals, there is a variety of requirements for communication between two parties that might be collected under the term exchange management. If data are to be exchanged in both directions over a period of time, the two parties must cooperate. For example, for two parties to engage in a telephone conversation, one party must dial the number of the other, causing signals to be generated that result in the ringing of the called phone. The called party completes a connection by lifting the receiver. For data processing devices, more will be needed than simply establishing a connection; certain conventions must be decided on. These conventions may include whether both devices may transmit simultaneously or must take turns, the amount of data to be sent at one time, the format of the data, and what to do if certain contingencies such as an error arise. The next two items might have been included under exchange managem How to cite Data and Computer Communications, Essay examples