Source, channel and destination

The primary purpose of any network is to provide a method of information communication. From the earliest primitive human beings to the most advanced scientists of today, sharing information with others is the most significant thing in human advancement.

All communication begins with a message, or information, that must be sent from one individual or device to another. The methods used to send, to receive and to interpret messages change over time as technology advances.

All communication methods have three common elements. The first of these elements is the message source, or sender. Message sources are people, or electronic devices, that need to communicate a message to other individuals or devices. The second element of communication is the destination, or receiver, of the message. The destination receives the message and interprets it. A third element, called a channel, provides the pathway over which the message can travel from source to destination.

Communication rules

In any conversation between two people, there are many rules, or protocols, that the two must follow in order for the message to be successfully delivered and understood. Among the protocols for successful human communication are: identification of sender and receiver; agreed-upon medium or channel (face-to-face, telephone, letter, photograph); appropriate communication mode (spoken, written, illustrated, interactive or one-way); common language; grammar and sentence structure; speed and timing of delivery.

Imagine what would happen if no protocols or rules existed to govern how people communicate with each other. Would you be able to understand them? Are you able to read the paragraph that does not follow commonly accepted protocols?

Protocols are specific to the characteristics of the source, channel and destination of the message. The rules used to communicate over one medium, like a telephone call, are not necessarily the same as communication using another medium, such as a letter.

Protocols define the details of how the message is transmitted, and delivered. This includes issues of message format, message size, timing, encapsulation, encoding, standard message pattern.

Many of the concepts and rules that make human communication reliable and understandable also apply to computer communication.

Exercise 1: answer the following questions:

1. How can the primary network purpose be characterized?

2. What are the common elements of any communication method?

3. How can the message delivery and understanding be carried out?

4. How can protocols be determined (what are protocols)?

5. Do the communication rules over different mediums differ from one another?

6. What do protocols define?

Exercise 2: translate the following word combinations:

the primary purpose of any network; to provide a method of information communication; the earliest primitive human beings to the most advanced scientists of today; sharing information with others; human advancement; to begin with a message, or information; to be sent from one individual or device to another; to be changed over time as technology advances; message source or sender; to communicate a message to other individuals or devices; the destination or receiver of the message; an element called a channel; to provide the pathway over which the message can travel from source to destination; to follow some rules in order for the message to be successfully delivered and understood; the protocols for successful human communication; identification of sender and receiver; agreed-upon medium or channel (face-to-face, telephone, letter, photograph); appropriate communication mode (spoken, written, illustrated, interactive or one-way); common language; grammar and sentence structure; speed and timing of delivery; to govern how people communicate with each other; to read the paragraph that does not follow commonly accepted protocols; characteristics of the source, channel and destination of the message; the rules used to communicate over one medium, like a telephone call; communication using another medium, such as a letter; to define the details of how the message is transmitted and delivered; message format, message size, timing, encapsulation, encoding, standard message pattern; to apply to computer communication.

Exercise 3: translate the following statements:

1. Основная задача любой сети заключается в передаче определенной информации. 2. Общение крайне важно для развития любого человеческого существа, начиная от первых человеческих существ до самых продвинутых ученых современности. 3. Любой обмен информацией начинается с сообщения, которое нужно передать от одного человека или устройства к другому. 4. Со временем, в процессе совершенствования технологий, методы отправки, получения и интерпретации сообщений изменяются. 5. Все методы коммуникации имеют три общих элемента: источник сообщения (отправитель); адресат (получатель); канал передачи. 6. В беседе между двумя людьми соблюдается большое количество правил, или протоколов, которым должны следовать оба собеседника для того, чтобы сообщение было успешно доставлено и его содержание было адекватно воспринято и понято. 7. Представьте себе ситуацию отсутствия протоколов общения людей друг с другом. 8. Выбор протоколов зависит от характеристик источника, канала и адресата сообщения. 9. Многие концепции и правила, которые делают человеческое общение более надежным и понятным, применяются и при обмене данными с использованием компьютера.

Exercise 4: make a bilingual translation:

Exercise 5: make a brief summary of the given article.

Exercise 6: work in groups: imagine the situation if the communication protocols would not exist?

Text 7

Message encoding

One of the first steps for sending a message is encoding it. Written words, pictures, and spoken languages each of them uses a unique set of codes, sounds, gestures, and/or symbols to represent the thoughts being shared. Encoding is the process of converting thoughts into language, symbols, or sounds, for their transmission. Decoding reverses this process in order to interpret the thought.

Imagine a person watching a sunset and then calling someone else to talk about how beautiful the sunset is. To communicate the message, the sender must first convert (encode) their thoughts and perceptions about the sunset into words. The words are spoken into the telephone using the sounds and inflections of spoken language that convey the message. On the other end of the telephone line, the person listening to the description, receives and decodes the sounds in order to visualize the image of the sunset described by the sender.

Encoding also occurs in computer communication. Encoding between hosts must be in an appropriate form for the medium. Messages sent across the network are first converted into bits by the sending host. Each bit is encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media over which the bits are transmitted. The destination host receives and decodes the signals in order to interpret the message.

Message formatting

When a message is sent from source to destination, it must use a specific format or structure. Message formats depend on the type of message and the channel that is used to deliver the message.

Letter writing is one of the most common forms of written human communication. For centuries, the agreed format for personal letters has not changed. In many cultures, a personal letter contains the following elements: an identifier of the recipient; salutation or greeting phrases; the message content; a closing phrase; an identifier of the sender.

In addition to the correct format, most personal letters must also be enclosed (encapsulated) in an envelope for delivery. The envelope has the address of the sender and receiver on it, each located at the proper place on the envelope. If the destination address and formatting are not correct, the letter is not delivered.

The process of placing one message format (the letter) inside another message format (the envelope) is called encapsulation. De-encapsulation occurs when the process is reversed by the recipient and the letter is removed from the envelope.

A letter writer uses an accepted format to ensure that the letter is delivered and understood by the recipient. In the same way, a message that is sent over a computer network follows specific format rules for it to be delivered and processed. Just as a letter is encapsulated in an envelope for delivery, so computer messages are encapsulated. Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network. A frame acts like an envelope; it provides the address of the intended destination and the address of the source host.

The frame format and contents are determined by the type of message being sent and the channel over which it is communicated. Messages that are not correctly formatted are not successfully delivered to or processed by the destination host.

Exercise 1: answer the following questions:

1. What is the first step for a message sending?

2. What does the speaker represent by a set of codes, sounds, gestures and symbols?

3. Characterize the encoding process.

4. What is a decoding process?

5. Describe the process of a beautiful sunset explanation for another person who calls you using a telephone.

6. Describe the process of message encoding which is sent across a network?

7. What do message formats depend on?

8. What does a letter consist of?

Exercise 2: translate the following word combinations:

to use a unique set of codes, sounds, gestures, and/or symbols; to represent the thoughts being shared; converting thoughts into language, symbols, or sounds, for their transmission; in order to interpret the thought; a person watching a sunset; to call someone else to talk about how beautiful the sunset is; to communicate a message; to convert (encode) someone’s thoughts and perceptions into words; to use the sounds and inflections of spoken language; to convey the message; to receive and to decode the sounds in order to visualize the image described by the sender; to occur in computer communication; to be in an appropriate form for the medium; to be sent across the network; to be converted into bits by the sending host; to be encoded into a pattern of sounds, light waves, or electrical impulses depending on the network media over which the bits are transmitted; to receive and to decode the signals in order to interpret the message; to be sent from source to destination; to use a specific format or structure; to depend on the type of message and the channel that is used to deliver the message; the most common form of written human communication; to contain an identifier of the recipient; salutation or greeting phrases; the message content; a closing phrase; an identifier of the sender; in addition to the correct format; to be enclosed (encapsulated) in an envelope for delivery; to be located at the proper place on the envelope; the process of placing one message format (the letter) inside another message format (the envelope); to be called encapsulation; to be reversed by the recipient; to use an accepted format to ensure that the letter is delivered and understood by the recipient; to sent over a computer network; to follow specific format rules for it to be delivered and processed; to be encapsulated in a specific format; to be called a frame; to provide the address of the intended destination and the address of the source host; to be determined by the type of message being sent and the channel over which it is communicated.

Exercise 3: translate the following statements:

1. Кодирование является одним из первых этапов отправки сообщения. 2. При передаче мыслей с помощью текста, рисунков или разговорного языка используются уникальные наборы кодов, звуков, жестов и/или символов. 3. Кодирование - это процесс преобразования мыслей в слова, символы или звуки для их последующей передачи. 4. Декодирование представляет собой обратный процесс, то есть расшифровку переданной мысли. 5. Кодирование используется при обмене данными при помощи компьютера. 6. Узел-отправитель преобразует передаваемое по сети сообщение в биты. 7. Каждый бит кодируется набором звуков, световых волн или электрических импульсов, в зависимости от типа сети, хост-адресат принимает и декодирует сигналы и интерпретирует сообщение. 8. При отправке сообщения от источника к адресату необходимо использовать определенный формат или структуру сообщения. 9. Письмо включает в себя следующие элементы: идентификация получателя; форма приветствия; содержание сообщения; заключительная фраза; идентификация отправителя. 10. Для отправки письменного сообщения по почте его нужно не только грамотно составить, но и правильно заполнить конверт, так как если данные окажутся неверными, то письмо не дойдет до адресанта. 11. Процесс размещения сообщения одного формата (письмо) внутри другого (конверт) называется инкапсуляцией. 12. Для доставки и обработки письма в компьютерной сети необходимо придерживаться определенных правил форматирования. 13. Подобно тому, как письмо вкладывается в конверт, компьютерное сообщение также инкапсулируется. 14. Для каждого сообщения используется особый формат, называемый фреймом. 15. В каждом фрейме заложена информация об адресе узла-отправителя и узла-получателя. 16. Формат и содержимое фрейма зависят от типа сообщения и канала его передачи.

Exercise 4: make a bilingual translation:

Exercise 5: summarize the text.