Presentation is loading. Please wait.

Presentation is loading. Please wait.

Introduction to Computer Systems Networking Fundamentals Dr. E.C. Kulasekere University of Moratuwa.

Similar presentations


Presentation on theme: "Introduction to Computer Systems Networking Fundamentals Dr. E.C. Kulasekere University of Moratuwa."— Presentation transcript:

1 Introduction to Computer Systems Networking Fundamentals Dr. E.C. Kulasekere University of Moratuwa

2 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems2 Network Technology Connectivity to other computers. Expands the capability of a PC. Satisfies sharing of resources. Expands human communication. Increases security threats. Concurrency effects.

3 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems3 Modem for Home Connectivity Most common mode of HAN connection. Some issues related to modems. Speed: maximum speed 56K Needs dial up for connection. Telephone line usage while on modem. Price is not to high compared to other services. Needs reconnection when the link dies.

4 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems4 Other Methods of Connectivity Cable modem. DSL Wireless Satellite-based services. ISDN Leased Lines All of these are categorized as broadband. Data rates exceeding 128kbps.

5 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems5 Home Connection Infrastructure Modem/NIC/DSL Modem interface. ISP/POTS. Switch/Router. Internet/PSTN Then the sequence is inverted. The links maybe digital or analog.

6 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems6 Cable Modems (Using CATV Services) This is a piggyback on a cable TV service. Faster than ISDN (128 Kbps). Uses a crossover cable with RJ45 connector. The fiber-coax cable configuration (fig) Not found in Sri Lanka.

7 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems7 Digital Subscriber Line (DSL) Uses existing POTS to provide a high speed connection. Low cost alternative to ISDN. The connection sharing is more efficient than cable modems. (fig19.2) Common types ADSL and SDSL. Advantageous and disadvantages of DSL/SDSL Low-pass filters are used to isolate the TP signal from DSL signal...\webDocs\DSL.htm

8 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems8 Wireless Broadband Used for home users that are out of reach from POTS. Should not be confused with wireless internet services provided for PDAs and mobile phones. Uses microwaves (fig 19.3) Uses routers and modems (fig 19.4)

9 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems9 Integrated Services Digital network (ISDN) Uses digital signals on the POTS. Mostly designed for leased lines. Configuration allows for multiple type of terminations (fig 19.7) Uses a terminal adapter (TA) for termination and it is not a modem. Costs more than DSL.

10 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems10 Leased Lines For uses with high bandwidth requirements such as businesses. Leased line is 24 hour permanent connection which can only be changed by the TP company (what about DSL?) T1 line 1.5Mbps, T3 line 45Mbps. The BW is split among users by the ISP. Used for connection that has high utilization.

11 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems11 Sharing Internet Connections One connection may not be enough for small-office and home (SOHO) systems. Windows 98SE, ME, 2K and XP have built in internet connection sharing (ICS) gateway software (fig 19.12) Routers can also be used for internet sharing (fig 19.13/14)

12 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems12 Types of Networks LAN: The smallest office network is referred too as a LAN HAN: LAN in a home environment is called a HAN. Used for internet connection sharing. WAN: LANS at different places can be hooked by a WAN. The Internet: A network of LAN/WAN networks. Intranets: One or more LANs in a SOHO environment is called an intranet. Extranets: Intranets that share a part of the network with customers

13 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems13 Requirements of a Network Physical cable or wireless connection. A common set of communication rules called network protocols. A software to enable transactions called a network operating system. Resources that can be shared. Software that enables computers to access other computers with shared resources: a network client.

14 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems14 Components of a network

15 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems15 Network Components Local area networks contain three basic hardware components Servers (also called hosts or host computers) Clients Circuits Clients and Servers typically work together in client- server networks. Networks without servers are called peer-to-peer networks. Routers are specialized devices responsible for moving information between networks, are also a common network component. Server types: file servers, print servers, Web servers, e-mail and directory servers.

16 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems16 Network Categorization According to Distance A common way of thinking about networks is by the scale of the network. 3 common network types are: Local Area Networks (LANs) which typically occupy a room or building, usually include a group of PCs that share a circuit. Backbone Networks, have a scale of a few hundred meters to a few kilometers. Include a high speed backbone linking the LANs at various locations. Metropolitan Area Networks (MANs) which typically have a scale of a few kilometers to a few tens of kilometers & connects LANs and BNs at different locations, often using leased lines or other commercial services to transmit data. Wide Area Networks (WANs) have a scale of hundreds or thousands of kilometers. Like MANs, leased circuits or other commercially available services are used to transmit data.

17 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems17

18 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems18 LAN Topologies

19 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems19 Bus Topology These are the earliest networks. Single cable (coaxial) is used with terminations at end. If some part of the cable malfunctioned, since the termination is lost the connections are lost. Adding a new computer was troublesome.

20 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems20 Ring Topology This is a bus with the two ends connected. No termination necessary. Examples are fiber distributed data interface (FDDI) used for large high speed networks. Token ring (IBM) is another example. Is SeaMeWe an example? Signals go in a ring and get absorbed at the sender terminal. Malfunction of ring results in failure (solution: Fig 20.11)

21 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems21 Star Topology Most popular type used today. Uses UTP cables to patch panel. Example implementation is a hub. Failure in one link is not catastrophic. For fast Ethernet this is the most commonly used type of configuration. CAT3 (10MB) or CAT5 (100MB) cables are used.

22 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems22

23 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems23 High Speed Networking Switched Ethernet Fast Ethernet 100Base-T Gigabit Ethernet: Used with fiber optic cables. Can use CAT5 cable. Also referred to as 1000Base-T. ATM

24 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems24 Switched Ethernet Switched Ethernet relies on centralized multiport switches to provide a physical link between multiple LAN segments The switch is intelligent and switches between segments with maximum BW allocation. It’s a cost-effective technique for increasing the overall network throughput and reducing congestion on a 10-Mbps network. The infrastructure is the same as usual.

25 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems25 100Base-T 100BASE-T retains the familiar CSMA/CD media access technique used in 10-Mbps Ethernet networks. Hence network management system need not be rewritten. Supports a broad range of cabling options. CAT5 UTP, Type 1 STP or duplex multimode fiber cable. It can easily be integrated into existing 10-Mbps Ethernet LANs, so your previous investment is saved

26 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems26

27 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems27

28 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems28 ATM cell-based fast-packet communication technique that supports data-transfer rates ranging from sub-T1 speeds (less than 1.544 Mbps) up to 10 Gbps An ATM network can be treated as a single network, whether it connects points in a building or across the country The fixed cell length signaling method offers predictable performance. Can be integrated into the existing network.

29 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems29 Gigabit Ethernet The Gigabit Ethernet standard was approved in June 1998, and its speed of 1 Gbps is a tenfold increase over Fast Ethernet. two basic types: shared and switched. Shared Gigabit Ethernet is a higher-speed version of 10/100BASE-T using CSMA/CD Medium Access Control Switched Gigabit Ethernet uses Logical Link Control (LLC) Its primary use is for backbones. The medium is fiber or Category 5e 100-ohm cable.

30 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems30 More on Wireless Networking Advantages Flexibility in installing Flexibility in usage (movement of PCs) Disadvantages Security is not so good. Interference from other devices.

31 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems31 Adhoc Wireless Networks Inexpensive and flexible. Each workstation relates on a peer-to- peer basis with the other PCs. You can add a wireless router to gain access to the internet if required. Only suitable for small networks where security is not an issue.

32 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems32 Adhoc Wireless network

33 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems33 Infrastructure Mode Wireless Network Larger installations in larger buildings. Depends on access points connected together. Each workstation communicates with the access point rather than directly with another workstation. May not offer BW for networks with heavy traffic. Security is still a concern.

34 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems34 Infrastructure mode wireless network

35 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems35 Completely wired network

36 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems36 Integrated Network

37 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems37 Fiber Optic Networks Fiber optic cable is used in applications that require high BW, long distances, and complete immunity to electrical interference. A common application for fiber optic cable is as a network backbone

38 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems38 Fiber Optic Networks (Cont …) Greater BW. Eg. two million telephone conversations have been simultaneously transmitted over a single fiber using Wavelength-Division Multiplexing (WDM). Low attenuation, longer distances: less repeaters are used so cost effective. Security: It’s very easy to monitor taps. If tapped, the cable leaks light, causing the entire system to fail. Immunity to interference.

39 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems39

40 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems40 Cables Most commonly used are the (unshielded twisted pair) UTP cables. The need for better cabling is tied down to the increase in speeds and BW that is required for todays' applications.

41 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems41 CAT5 Cabling Category 5 (CAT5) cabling is good, solid cable for 100-Mbps LANs Category 5 standard has been around since 1991 If you still have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. Also handles 100Mbps fast ethernet as well. If you are hitting the limit at 100Mpbs upgrade to CAT5e.

42 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems42 CAT5e Cabling Enhanced Cat 5, was ratified in 1999. It’s an incremental improvement designed to enable cabling to support full-duplex Fast Ethernet operation and Gigabit Ethernet. CAT5e has stricter specifications for PS- ELFEXT (Power Sum Equal-Level Far- End Crosstalk), NEXT (Near-End Crosstalk), Attenuation, and Return Loss (RL) than those for Category 5 This is also a 100MHz standard.

43 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems43 CAT6 Cabling Features more stringent specifications for crosstalk and system noise. Ratified in 2002. to transmit according to CAT6 specs, jacks, patch cables, patch panels, cross- connects, and cabling must all meet CAT6 standards all CAT6 components must be backward compatible with CAT5e, CAT5, and Category 3. if CAT6 cable is used with CAT5e jacks, the channel will perform at a CAT5e level.

44 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems44 Cable Standards

45 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems45 Cabinets and Racks A cabinet is an enclosure with a door (or doors); a rack is an open frame An enclosed cabinet can be locked with a simple lock and key Fans are installed to cool. Built in power cabling. Cabling infrastructure provided.

46 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems46 Connectors/Data Interfaces..\webDocs\Connector Guide.htm Connectors are important for the cabling infrastructure. If two types of connectors are mixed. The lower speed one will set the limit of operation...\webDocs\Data Interfaces.htm

47 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems47 LAN Hardware In traditional LANs, only one network node transmits data at a time while all other stations listen. This can lead to timing requirements not satisfied for video tx etc. bridges and routers process data packets on an individual basis, switches maintain multiple, simultaneous data conversions among attached LANs Switched circuits are better since they are dedicated connections.

48 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems48

49 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems49 Switch Technologies The switch you have to buy for the LAN depends on the type of switching that have to be carried out...\webDocs\Layer 2, 3, and 4 Switching Overview.htm In depth analysis of such switches will be done next year.

50 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems50 Routers and Bridges Routers and bridges link two or more individual Local Area Networks (LANs) to create an extended-network LAN or Wide Area Network (WAN).

51 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems51 Routers Link networks using different network identities. Transmit only the data needed by the final destination across the LAN. Examine and rebuild packets without passing errors on to the next LAN. Routers are "smarter" than bridges, because they find the best route for all the data sent to them by the previous router or the end station of the LAN.

52 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems52 Bridges Connect two parts of the same LAN network to make it larger. Unlike routers, every bridge builds an internal list of addresses of the attached network devices on both sides of it. If the destination address is on the opposite segment or if the bridge doesn't have the address logged, it forwards the information. Bridges operate on MAC-Layer addresses. They're protocol independent, so they transfer data between workstations without having to understand the protocol.

53 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems53 Media Converters interconnects different cable types— twisted pair, fiber, and Thin or thick coax—within an existing network

54 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems54 Media Converters (Cont …)

55 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems55 Wiring Cable is cable, so buy the cheapest! – Follow this advice to fall in trouble. experts estimate that 70% of network failures are primarily caused by cable-related problems. So what’s a LAN manager to do?

56 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems56 Backbone Wiring Main wiring between closet and floors. Star topology is used for backbone wiring. Starting point for horizonal wiring.

57 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems57 Horizontal Wiring

58 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems58 Horizontal Wiring (Cont…) encompasses all cable from a work-area wallplate or network connection to the telecommunications closet. The outlets, cable, and cross-connects in the closet are all part of the horizontal wiring, which gets its name because the cable typically runs horizontally above ceilings or along the floor...\webDocs\Premise Wiring.htm

59 IESL – Information Technology Part I Dr. E.C. Kulasekere Introduction to Computer Systems59 Other Devices..\webDocs\Routers & Bridges.htm..\webDocs\USB & FireWire.htm..\webDocs\Video Connectors.htm


Download ppt "Introduction to Computer Systems Networking Fundamentals Dr. E.C. Kulasekere University of Moratuwa."

Similar presentations


Ads by Google