Large Scale Networks-session1 improved by samia snoussi.pdf
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Large Scale Networks – Introduction Instructor: Dr Samia Snoussi Email: [email protected] Relised by: Dr. Sajjad Hussain Chauhdary Recommended Books Policies Quiz Policy The quizzes will be announced and their purpose will be to prepare the...
Large Scale Networks – Introduction Instructor: Dr Samia Snoussi Email: [email protected] Relised by: Dr. Sajjad Hussain Chauhdary Recommended Books Policies Quiz Policy The quizzes will be announced and their purpose will be to prepare the students for the mid or end semester exam. Assignment Students must follow honor code and not cheat by seeking any help. Policy Late assignments will be neither accepted nor graded. Plagiarism Plagiarism in un-ethical & hence university will take strict action against such cases. Large Scale Networks – Introduction Introduction (1/2) A computer network in which the computers connected may be far apart, generally having a coverage are more than 100 km know as Large Scale Networks or Wide Area Networks. Introduction (2/2) A WAN connects more than one LAN and is used for larger geographical areas. “WANs are similar to a banking system, where hundreds of branches in different cities are connected with each other in order to share their official data.” A WAN or Large Scale Networks deployed in a similar fashion to a LAN, just on a larger scale. Typically, TCP/IP (Transmission Control Protocol/Internet Protocol ) is the protocol used for a WAN in combination with devices such as routers, switches, firewalls and modems Introduction (3/3) WAN ( Wide Area Networks ) or Large Area Networks are combination of following components. 1. Hosts 2. Clients 3. Bridges 4. Servers 5. Routers 6. Links of various media 7. Applications 8. Protocols 9. Hardware, software and more.. Brief History of WAN ( Wide Area Networks) 1940 - George Stibitz invented teletype (an electromechanical typewriter that can be used to send and receive typed messages) 1964 – IBM implement the SABRE (A reservation system and online transaction processing is born. Using telephone lines, SABRE links 2,000 terminals in 65 cities to a pair of IBM 7090 computers and is able to deliver data on any flight in less than three seconds) 1980s – ARPANET: The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control (Access to the ARPANET is expanded in 1981. In 1982, the internet protocol suite (TCP/IP) is introduced as the standard networking protocol on the ARPANET) 2000s – ADSL (In the UK, on March 31st 2000, Telewest launches home ADSL – asymmetric digital subscriber line. Goldsmith Road in Gillingham, Kent, is the first street to receive the technology) Brief History of WAN ( Wide Area Networks) 2011 (Fiber-optic broadband and new DOCSIS standards make broadband speeds easily reach 100Mbps. This in turn means end users need better routers to match the broadband speed.) 2014 (The new Wi-Fi standard 802.11ac launches, offering faster speed (over 2Gbps) compared to 450Mbps of the previous 802.11n standard. Along with this comes better signal coverage. 802.11ac was ratified in 2014.) Today and tomorrow, world of connectivity Standards of WAN or Larger Scale Networks 1. ATM (Asynchronous Transfer Mode) 2. Dial-up Internet 3. DSL 4. ISDN 5. SONET 6. SD-WAN 7. Cellular Technologies and more ATM (Asynchronous Transfer Mode) Asynchronous transfer mode (ATM) is a switching technique used by telecommunication networks that uses asynchronous time-division multiplexing to encode data into small, fixed-sized cells. This is different from Ethernet or internet, which use variable packet sizes for data or frames. Time-division multiplexing ATM Types ( As per bit rate) ATM services generally have four different bit rate choices: Available Bit Rate (ABR): Provides a guaranteed minimum capacity but data can be bursted to higher capacities when network traffic is minimal. Constant Bit Rate (CBR): Specifies a fixed bit rate so that data is sent in a steady stream. This is analogous to a leased line. Unspecified Bit Rate (UBR): Doesn’t guarantee any throughput level and is used for applications such as file transfers that can tolerate delays. Variable Bit Rate (VBR): Provides a specified throughput, but data is not sent evenly. This makes it a popular choice for voice and videoconferencing. ATM Network Architecture Development of ATM 1. ATM designers faced a difficult challenge because the three intended uses (voice, video, and data) have different sets of requirements. 2. For example, both voice and video require low delay and low jitter (i.e. low variance in delay) that make it possible to deliver audio and video smoothly with gaps or delays in the output. 3. Video requires a substantially higher data rate than audio. 4. Most data networks introduce jitter as they handle packets. Development of ATM To allow packet switches to operate at high speeds and to achieve low delay, low jitter, and echo cancellation, ATM technology divides all data into small, fixed-size packets called cells. Each ATM cell contains exactly 53 octets. 5 octets for header 48 octets for data ATM Cell Structure Bits: 0 7 Flow Control VPI (First 4 bits) VPI: Virtual Path Identifier VPI (Last 4 bits) VCI (First 4 bits) VCI: Virtual VCI (Middle 8 bits) Channel Identifier VCI (Last 4 bits) Payload type PRIO Cyclic Redundancy Check 48 Data Octets start here Format of the ATM Cell Header HEC (Header Error Control), is for the protection of the header 3 bits PT (Payload Type) define the type of information transported into the cell, including the management and control of the network. Advantages ATM supports fixed-length cells 53 bytes in length and virtual data circuits between 45 megabits per second (Mbps) and 622 Mbps Asynchronous transmission has a low system overhead, is straightforward to implement, and does not require synchronous clocks. Asynchronous transmission has no limitations on the frequency or timing of data packet transfer, therefore it can begin delivering data at any moment Disadvantages ATM has not been widely accepted. Although some phone companies still use it in their backbone networks. The expense, complexity and lack of interoperability with other technologies have prevented ATM from becoming more prevalent. Dial-up Internet A form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialling a telephone number on a conventional telephone line. The user's computer or router uses an attached modem to encode and decode information into and from audio frequency signals, respectively. Dial up Internet Architecture List of dial-up speeds Baud: the number of bits per second that the user can push through the transmission system Disadvantages of Dial-up Internet The key disadvantage of dial-up Internet access is that it is slow. As of the date of publication, the fastest dial-up modems available have a maximum speed of 53 kilobits per second - - this equates to 0.053 megabits per second. Actually, it attempts 56 Kbits per second. Furthermore, when you're using dial-up service, your landline is tied you DSL ( Digital Subscriber Line ) A digital subscriber line (DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line service for connectivity to the Internet, which is often called DSL broadband (transmission of wide bandwidth data over a high-speed internet connection). DSL ( Digital Subscriber Line ) Network Architecture Integrated Services Digital Network Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network (a singular line ). It is also defined as circuit-switched telephone network system ISDN services Digitized voice services (caller ID, messaging, persistent calls, redirected calls, multicast calls, waiting calls, in-call functions) Multimedia quality exchange Enhanced digital services – to improve computer interconnection Entertainment services - TV, VOD (video on demand) Integrated Services Digital Network Architecture Bit Rates for Different Applications in ISDN Advantages of DSL DSL transmits data far faster than an ISDN line can. That's because ISDN is a dial-up service that goes through a singular line. DSL connections never need to dial. DSL operates over the same phone lines as dial-up but uses higher frequencies to provide much faster speeds. While dial-up is limited to 56 kbps (0.056 Mbps), even the slowest DSL connections provide 3-5 Mbps—around 100 times faster. SONET or SDH (Synchronous optical networking) Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). SONET is the standard used in the United States and SDH is the standard used outside the United States. SONET Network Architecture DS-n: Digital Signal, OC : Optical Carrier refers to a range of digital signals that can be transmitted over fiber optic lines. Advantages of SONET and SDH Today's carrier backbone networks are supported by synchronous optical network (SONET) and synchronous digital hierarchy (SDH) transmission technologies. SONET/SDH specification outlines the frame format, multiplexing method, and synchronization method between the equipment, as well as the specifying optical interface (a physical connection that transfers audio digital signals by light). Advantages of SONET and SDH SONET/SDH will continue to play a key role in the next generation of networks for many carriers. In the core network, the carriers offer services such as telephone, dedicated leased lines, and Internet protocol (IP) data, which are continuously transmitted. The individual data is not transmitted on separate lines; instead it is multiplexed into higher speeds and transmitted on SONET/SDH networks at up to 10 gigabits per second (Gbps). SD-WAN ( Software Define-WAN) The software-defined wide area network (SD-WAN) is a specific application of software-defined networking (SDN) technology applied to WAN connections, which are used to connect enterprise networks – including branch offices and data centers – over large geographic distances. SD-WAN ( Software Define-WAN) Architecture *Multiprotocol Label Switching (MPLS)) is a technique for speeding up network connections SD-WAN ( Software Define-WAN SD-WAN routers can combine the bandwidth of multiple WAN connections. Organizations using SD-WANs can easily add or remove WAN connections as needed. Internet links are generally much less expensive than carrier-grade MPLS connections, which are typically encumbered by long provisioning times and expensive contracts. An SD-WAN can improve network security by encrypting WAN traffic as it moves from one location to another, and by segmenting the network so that if a breach occurs, the damage is minimized. MPLS networks typically offer highly reliable packet delivery. Internet uplinks, on the other hand, often fail. Multiprotocol Label Switching, or MPLS, is a networking technology that routes traffic using the shortest path based on “labels,” rather than network addresses, to handle forwarding over private wide area networks LSR: Label-Switching Router Cellular Networks Cellular Networks Cellular Networks
