04 Handout 1 - 04 Data Connections (Midterm).pdf

IT2006 Data Connections A hardware interface is an architecture used to interconnect two (2) devices together. It includes the design of the plug and socket, the type, and the number an...

IT2006 Data Connections A hardware interface is an architecture used to interconnect two (2) devices together. It includes the design of the plug and socket, the type, and the number and purpose of the wires and the electrical signals that are passed across them. Characteristics of Interface Standards De facto standard – it is something that is used so widely that it is considered a standard for a given application although it has no official status. Composition – it is the whole content of an entity of an interface standard. o Electrical component deals with voltages, line capacitance, and other electrical issues. o Mechanical component deals with items such as the connector or plugs description. o Functional component deals with the function of each pin used in an interface. o Procedural component describes how the circuits are used to perform an operation. Examples of Interfaces Universal Serial Bus (USB) - It is a digital interface that uses a standardized connector (plug) for all serial and parallel type devices which provides a digital interface and known for being hot-pluggable. Hot plugging (hot swapping) is the ability to add and remove devices to a computer system while the computer is running and have the operating system automatically recognize the change. Fire Wire – It is a type of interconnection between peripheral devices (such as wireless modems and high-speed digital video cameras) and a microcomputer. This digital interface that is capable of supporting transfer speeds of up to 3.2 Gbps. Thunderbolt – It is currently found on Apple laptops and provides a 10-Gbps connection to peripheral devices. It uses the same connector as the already existing Mini DisplayPort and uses an already existing protocol called PO Express. Lightning - It is an 8-pin connector in which it can be found as the primary connector on the newer versions of Apple's iPhone as well as Apple devices such as the iPad. SCSI - SCSI, which stands for Small Computer System Interface is a technique for interfacing a computer to high-speed devices such as hard disk drives, tape drives, CDs, and DVDs. SCSI was designed to support devices of a more permanent nature such as high-performance workstations and network servers. InfiniBand – This interface is used due to its high-speed connection that is mostly found in networks that require large amounts of peripheral storage. It can carry multiple channels of data at the same time up to 2.5 billion bits (2.5 gigabits) per second (single data rate), 5 gigabits per second (double data rate), and 10 gigabits per second (quad data rate); and it can address (interconnect) thousands of devices using both copper wire and fiber-optic cables. Fibre Channel is like InfiniBand in that it too is a serial, high-speed network that connects a computer to multiple input/output devices. Fibre Channel also supports data transfer rates up to billions of bits per second, but it can support the interconnection of up to 126 devices only. 04 Handout 1 *Property of STI  [email protected] Page 1 of 4  IT2006 Data Link Connections Asynchronous connection - a single character, or byte of data, is the unit of transfer between the sender and receiver. The sender prepares a data character for transmission, transmits that character with irregular timing, and then begins preparing the next data character for transmission. Synchronous connection - the unit of transmission is a sequence of characters. This sequence of characters may be thousands of characters in size with regular timing sent. Isochronous connection - a special kind of data link connection used to support various types of real-time applications such as streaming voice, video, and music. Data Transmission Factors The data transmission capabilities of various media vary differently depending upon the various factors. Bandwidth - refers to the data-carrying capacity of a channel or medium. Higher bandwidth communication channels support higher data rates. Radiation - refers to the leakage of signal from the medium due to undesirable electrical characteristics of the medium. Noise Absorption - refers to the susceptibility of the media to external electrical noise that can cause distortion of the data signal. Attenuation - refers to the loss of energy as signal propagates outwards. The amount of energy lost depends on frequency. Radiations and physical characteristics of media contribute to attenuation. Bandwidth and Throughput Bandwidth is the measurement of the ability of an electronic communications device or system to send and receive information. There are two terms: o Hertz - Bandwidth in hertz is the range of frequencies contained in a composite signal or the range of frequencies a channel can pass. ▪ For example, we can say the bandwidth of a subscriber telephone line is 4 kHz. It refers to the range of frequencies in a composite signal or the range of frequencies that a channel can pass. 𝑩𝑾 = 𝒇𝑯 − 𝒇𝑳 Example: A given signal has frequencies of Wherein: 635 MHz and 7000Mhz. Determine the 𝐵𝑊 – Bandwidth (Hz) bandwidth of the signal. 𝑓𝐻 – Highest Frequency 𝐵𝑊 = 7000 𝑀ℎ𝑧 − 635 𝑀ℎ𝑧 𝑓𝐿 – Lowest Frequency 𝐵𝑊 = 6365 𝑀ℎ𝑧 o Bits per Seconds - The term bandwidth can also refer to the number of bits per second that a channel, a link, or even a network can transmit. ▪ For example, one can say the bandwidth of a Fast Ethernet network (or the links in this network) is a maximum of 100 Mbps. It refers to the speed of bit transmission in a channel or link. Throughput is the amount of data that enters and goes through a system. In layman’s term, it is a measure of how fast we can actually send data through a network. Example: 1. A network with a bandwidth of 10 Mbps can pass 𝑻 = 𝒇𝒓𝒂𝒎𝒆𝒔 × 𝒍𝒐𝒂𝒅 (𝒃𝒊𝒕𝒔) 12000 𝑓𝑟𝑎𝑚𝑒𝑠 × 10000 𝑏𝑖𝑡𝑠 only an average of 12,000 frames per minute with 𝑇= each frame carrying an average of 10,000 bits. What 60 𝑠𝑒𝑐𝑜𝑛𝑑𝑠 𝑇 = 2 𝑀𝑏𝑝𝑠 is the throughput of this network? 2. There is a data that has a file size of 46 𝑀𝑏 with a.) an ethernet overhead of 10 𝑀𝑏. Find the following if 𝐵𝑊 = 46 𝑀𝑏 + 10 𝑀𝑏 there is an amount of data loss of 28 𝑀𝑏𝑝𝑠 due to 𝐵𝑊 = 56 𝑀𝑏 errors and acknowledgments. b.) a.) Total amount of data to be transferred 𝑻 = 𝑩𝑾 − 𝒅𝒂𝒕𝒂 𝒍𝒐𝒔𝒔 b.) Throughput 𝑇 = 56 − 28 𝑇 = 28 𝑀𝑏𝑝𝑠 04 Handout 1 *Property of STI  [email protected] Page 2 of 4  IT2006 Latency It is a measure of delay. It measures the time it takes for data to get to its destination across the network. 𝑳𝒂𝒕𝒆𝒏𝒄𝒚 = 𝒑𝒓𝒐𝒑𝒂𝒈𝒂𝒕𝒊𝒐𝒏 + 𝒕𝒓𝒂𝒏𝒔𝒎𝒊𝒔𝒔𝒊𝒐𝒏 + 𝒒𝒖𝒆𝒖𝒊𝒏𝒈 + 𝒑𝒓𝒐𝒄𝒆𝒔𝒔 𝒅𝒆𝒍𝒂𝒚 o Propagation time measures the time required for a bit to travel from the source to the destination. 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆 (𝒎) 𝑷𝒓𝒐𝒑𝒂𝒈𝒂𝒕𝒊𝒐𝒏 𝒕𝒊𝒎𝒆 (𝒔𝒆𝒄𝒐𝒏𝒅𝒔) = 𝒑𝒓𝒐𝒑𝒂𝒈𝒂𝒕𝒊𝒐𝒏 𝒔𝒑𝒆𝒆𝒅 (𝒎/𝒔) o Transmission time measures the time how long a message will pass in channel corresponding with the bandwidth. 𝒅𝒂𝒕𝒂 𝒑𝒂𝒄𝒌𝒆𝒕 (𝒃𝒊𝒕𝒔) 𝑻𝒓𝒂𝒏𝒔𝒎𝒊𝒔𝒔𝒊𝒐𝒏 𝒕𝒊𝒎𝒆 (𝒔𝒆𝒄𝒐𝒏𝒅𝒔) = 𝒄𝒂𝒑𝒂𝒄𝒊𝒕𝒚 (𝒃𝒊𝒕𝒔 𝒑𝒆𝒓 𝒔𝒆𝒄𝒐𝒏𝒅) o Queuing time measures the time needed for each intermediate or end device to hold the message before it can be processed. o Processing delay measures how data is processed through or from links. Examples: 1. What are the propagation time and the transmission 2. What are the propagation time and the transmission time for a 2.5 𝑘𝑖𝑙𝑜𝑏𝑦𝑡𝑒 message (an email) if the time for a 5𝑀𝐵 message (an image) if the bandwidth of bandwidth of the network is 1 𝐺𝑏𝑝𝑠? Assume that the the network is 1 𝑀𝑏𝑝𝑠? Assume that the distance distance between the sender and the receiver is between the sender and the receiver is 12,000 𝑘𝑚 and 12,000 𝑘𝑚 and that light travels at 2.4 × 108 𝑚/𝑠. that light travels at 2.4 × 108 𝑚/𝑠. 12,000 𝑘𝑚 × 1,000 12,000 𝑘𝑚 × 1,000 𝑃𝑟𝑜𝑝𝑎𝑔𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 = 8 = 50 𝑚𝑠 𝑃𝑟𝑜𝑝𝑎𝑔𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 = = 50 𝑚𝑠 2.4 × 10 𝑚/𝑠 2.4 × 108 𝑚/𝑠 2,500 𝑏𝑦𝑡𝑒𝑠 × 8 𝑏𝑖𝑡𝑠 (5 × 106 𝑏𝑦𝑡𝑒𝑠) × 8 𝑇𝑟𝑎𝑛𝑠𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 = 9 = 20 𝜇𝑠 𝑇𝑟𝑎𝑛𝑠𝑚𝑖𝑠𝑠𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 = = 40 𝑠 1 × 10 𝑏𝑝𝑠 1 × 106 𝑏𝑝𝑠 3. What is the latency of the network in item number 1 when added the queuing time of 0.75 𝑚𝑠 and a processing delay of 2 𝑚𝑠? 𝐿𝑎𝑡𝑒𝑛𝑐𝑦 = 50 𝑚𝑠 + 0.02 𝑚𝑠 + 0.75 𝑚𝑠 + 2𝑚𝑠 = 52.77𝑚𝑠 Bit Rate and Baud Rate Bit Rate is the amount of data (number of bits) that can be transmitted per second. Bit rate is closer to bandwidth, but it is often per host or source to destination devices. Baud Rate refers to the number of signal elements or symbol changes that occur per second. A symbol is one of several voltage, frequency, or phase changes. Wherein: 𝟏 𝑁 – Bit Rate (bits per second) 𝑟 – number of data bits per signal element 𝑺=𝑵× 𝑆 – Baud Rate (signal units per 𝐿 – number of signal elements 𝒓 𝒓 = 𝐥𝐨𝐠 𝟐 𝑳 second) Examples: 1. An analog signal carries 4 bits per signal 2. An analog signal has a bit rate of 8000 𝑏𝑝𝑠 and a baud rate of element. Find the bit rate if 1000 signal 1000 𝑏𝑎𝑢𝑑. How many data elements are carried by each signal elements are sent per second. element? How many signal elements do we need? 1 𝑁 1 𝑆=𝑁× 𝑟= 𝑆=𝑁× 𝑟 𝑆 𝑟 = log 2 𝐿 𝑟 𝑁 = 𝑆 × 𝑟 = 1000 × 4 𝑏𝑖𝑡𝑠 = 4000 𝑏𝑝𝑠 𝑁 8000 𝑏𝑝𝑠 𝑟= = 𝐿 = 2𝑟 = 28 𝑆 1000 𝑏𝑎𝑢𝑑 𝐿 = 256 𝑠𝑖𝑔𝑛𝑎𝑙 𝑒𝑙𝑒𝑚𝑒𝑛𝑡𝑠 𝑟 = 8 𝑏𝑖𝑡𝑠 / 𝑠𝑖𝑔𝑛𝑎𝑙 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 04 Handout 1 *Property of STI  [email protected] Page 3 of 4  IT2006 Data Transfer Technique In a switched network, data is transferred from source to destination through a series of intermediate switching nodes. Data passes through a subset of the network nodes. o Circuit switching involves establishing a path from source to destination before the commencement of communication. The path is dedicated to the source-destination pair for the duration of the communication session. o Packet switching involves organizing data in blocks called packets that are sent in a store-and-forward manner without prior establishment of the communication path. By store-and-forward, we mean that when a node receives a packet, it stores the packet and checks it for errors. In a broadcast network, a transmission from a source is received by all nodes in the network. A broadcast network ensures that all the nodes in the network see the transmitted data. References: Frenzel, L. (April 27, 2012). What’s the Difference Between Bit Rate and Baud Rate? [Web Article]. Retrieved on April 23, 2020 from https://www.electronicdesign.com/technologies/communications/article/21802272/whats-the- difference-between-bit-rate-and-baud-rate Ibe, O. (2018). Fundamentals of Data Communication Networks [1st ed.]. US: Wiley. Kurose, F., et. al. (2017). Computer Networking – A Top-Down Approach [7th ed.]. NY: Pearson. Media Access Methods. (n.d.). In Mysolutionguru.com. [Web Article]. [Web Content]. Retrieved on April 23, 2020 https://www.mysolutionguru.com/ps/media-access-methods/112 Sklar, B. (2017). Digital Communications – Fundamentals and Applications [2nd ed.]. NJ: Prentice Hall. Speidel, J. (2019). Introduction to Digital Communications. Switzerland: Springer Nature. 04 Handout 1 *Property of STI  [email protected] Page 4 of 4