Lecture: Networks and Network Management


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Lecture: Networks and Network Management

  1. 1. MD 240 Telecommunications and the Internet
  2. 2. Overview <ul><li>Background </li></ul><ul><li>Telecommunications Concepts </li></ul><ul><li>Network Technology </li></ul><ul><li>Networked Computing Architectures </li></ul><ul><li>Managing Networks </li></ul>
  3. 3. Background
  4. 4. Background <ul><li>Early Network Technologies </li></ul><ul><ul><li>1791 – French develop “Optical Telegraph Network” … uses cross-arms and pulleys for signals </li></ul></ul><ul><ul><li>1837 – Samuel Morse demonstrates the electric telegraph </li></ul></ul><ul><ul><li>1845 – Morse Magnetic Telegraph Company founded, makes revenue of $413 in October </li></ul></ul><ul><ul><ul><li>U.S. Postmaster General declares that telegraph network will never be profitable </li></ul></ul></ul><ul><ul><li>1873 – Western Union holds assets of $40 Million </li></ul></ul><ul><ul><li>1886 – First telemarketing … Richard Sears sells watches via telegraph </li></ul></ul>(Source: www.silkroad.com/net-history.html)
  5. 5. Background History <ul><li>Early Network Technologies </li></ul><ul><ul><li>1876 – Alexander Graham Bell invents phone </li></ul></ul><ul><ul><li>1879 – Phone service costs businesses $40/month </li></ul></ul><ul><ul><li>1902 – Marconi sends wireless signal across Atlantic </li></ul></ul><ul><ul><li>1930 – Telephone network outgrows telegraph network </li></ul></ul><ul><ul><li>1960s – Packet switching invented … proposed as basis for ARPANET </li></ul></ul><ul><ul><li>1969 – First computer handshake takes place </li></ul></ul><ul><ul><li>1970 – 4 node ARPANET is born </li></ul></ul><ul><ul><li>1972 – First electronic mail message </li></ul></ul>(Source: www.silkroad.com/net-history.html)
  6. 6. Background History <ul><li>Early Network Technologies </li></ul><ul><ul><li>1984 – NSF builds 6 node NSFNET running at 56 kbps </li></ul></ul><ul><ul><li>1988 – U.S. Government mandates the OSI Protocol </li></ul></ul><ul><ul><li>1990 – ARPANET shuts down, having been superceded by NSFNET (300,000 nodes and growing). NSFNET backbone upgraded to 1.5 Mbps </li></ul></ul><ul><ul><li>1990 – Internet services ARCHIE, GOPHER, and WAIS appear </li></ul></ul><ul><ul><li>1992 – Mosaic browser written, leading to development of Netscape Navigator … WWW is born </li></ul></ul><ul><ul><li>2003 – Affordable 802.11g Wi-Fi network devices communicate at 54Mbps </li></ul></ul>(Source: www.silkroad.com/net-history.html, http://www.computerhistory.org/exhibits/internet_history/index.page)
  7. 7. Background History <ul><li>1990 </li></ul><ul><ul><li>Local Area Networks (LAN) come onto the scene </li></ul></ul><ul><ul><ul><li>business case for LANs not obvious, most managers asking “What is a network?” </li></ul></ul></ul><ul><ul><li>Wide Area Networks (WAN) a “strategic technology” … but only affordable for the largest corporations </li></ul></ul><ul><ul><ul><li>Ex: DDB Needham built a new corporate headquarters in Chicago just so that they could have it fully wired and integrated into a new WAN </li></ul></ul></ul>PC #1 80386 PC #2 80386 Artisoft Lantastic LAN Peer-to-Peer Basic File Sharing/Transfer (if you’re lucky) Printer Sharing Laser Printer
  8. 8. Background <ul><li>Today </li></ul><ul><ul><li>LAN - </li></ul></ul><ul><ul><ul><li>Affordable network hardware ($50-$200/device) </li></ul></ul></ul><ul><ul><ul><li>Cable Modem can affordably connect home/office network to Internet and WWW (<$100/month) </li></ul></ul></ul><ul><ul><li>WAN - </li></ul></ul><ul><ul><ul><li>most corporations, big and small, have access to the Internet </li></ul></ul></ul><ul><ul><ul><li>T1 access < $1000/month, Digital Subscriber Line (DSL) even less </li></ul></ul></ul>
  9. 9. Background Small Office LAN TCP/IP Fast Ethernet Router DSL Modem Windows NT Client Windows 2000 Application Server 4-port F.Eth. Hub Linux File Server for Windows Network (Samba program) Windows 95 Client B&W Laser Printer Color Laser Printer 8-Port Fast Ethernet Switch 16-port Eth. Switch To ISP and WWW USB Device
  10. 10. Background Corporate WAN PBX Modem pool router host computer San Francisco Boston
  11. 11. Background Future Networking <ul><li>Internet 2 (www.internet2.org) </li></ul><ul><ul><li>Cooperative effort (in USA only) to develop next generation of the Internet (NGI) </li></ul></ul><ul><ul><ul><li>Government </li></ul></ul></ul><ul><ul><ul><li>Research Universities </li></ul></ul></ul><ul><ul><ul><li>Industry </li></ul></ul></ul><ul><ul><li>Internet 2 website reports on emerging network technologies and networked applications </li></ul></ul><ul><ul><ul><li>BC is now an Internet 2 member org. (as of Dec. 2001) </li></ul></ul></ul><ul><ul><li>Efforts now being made to build a world-wide Internet2 network to allow academics to collaborate </li></ul></ul><ul><ul><ul><li>ABILENE – 10 Gbps network </li></ul></ul></ul>
  12. 12. Telecommunications Concepts
  13. 13. Telecommunication Concepts Definitions <ul><li>Telecommunication </li></ul><ul><ul><li>long-distance communication through the use of common carriers, including telephone, television, and radio. </li></ul></ul><ul><li>Data Communications </li></ul><ul><ul><li>Electronic collection, exchange, and processing of data or information, including text, pictures, voice, and other information that is digitally coded and intelligible to a variety of electronic machines </li></ul></ul>
  14. 14. Telecommunication Concepts Electronic Signals <ul><li>Analog Signals </li></ul><ul><ul><li>continuous waves that “carry” information by altering the characteristics of the waves </li></ul></ul><ul><ul><li>amplitude and frequency </li></ul></ul><ul><li>Digital Signals </li></ul><ul><ul><li>discrete on-off pulses that convey information in terms of 1s and 0s, just like the central processing unit in computers </li></ul></ul>
  15. 15. Telecommunication Concepts Major Task Examples … Modem: copper phone line (analog) into (digital) bits for fiber optic transmission Video/TV: VHS tape (analog) into (digital) MPEG for internet/satellite transmission Digital Information Analog Information Translate analog information into digital information without losing or degrading any information Translate digital information into analog information without losing or degrading any information
  16. 16. Network Technology
  17. 17. Networking Protocols <ul><li>Protocol </li></ul><ul><ul><li>A set of rules and procedures governing transmission across a network </li></ul></ul><ul><ul><ul><li>Some protocols: </li></ul></ul></ul><ul><ul><ul><ul><li>TCP/IP </li></ul></ul></ul></ul><ul><ul><ul><ul><li>FTP </li></ul></ul></ul></ul><ul><ul><ul><ul><li>SMTP </li></ul></ul></ul></ul><ul><ul><ul><ul><li>http:// </li></ul></ul></ul></ul><ul><ul><ul><ul><li>gopher:// </li></ul></ul></ul></ul>
  18. 18. Networking Software Protocols Open Systems Interface (OSI) Reference Model Physical Layer Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer User interface, file transfer, electronic mail programs Data formatting and character code conversion Negotiation and establishment of a connection between two computers (nodes) Provision for end-to-end data delivery User interface, routing of information packets across multiple networks Transfer of units of information, error checking Transmission of raw data over a communications channel 7 6 5 4 3 2 1 Each layer depends on the layer below it. FTP SMTP Telnet TCP UDP IP IEEE 802 X.25
  19. 19. Networking Software Protocols Example: Modem Hardware Front end processor Receiver Telecommunication media (channels) OSI Layer 1 OSI Layer 2 OSI Layer 3 OSI Layer 7 OSI Layer 6 OSI Layer 5 OSI Layer 4 Host Computer PC or Terminal Multiplexor Modem Host Computer PC or Terminal Multiplexor Modem
  20. 20. Networking Transmission Protocols Based Upon the OSI Reference Model <ul><li>NetBEUI </li></ul><ul><ul><li>Microsoft-only networks </li></ul></ul><ul><li>IPX/SPX </li></ul><ul><ul><li>Novell Network, limited support, dying a slow death </li></ul></ul><ul><li>AppleTalk </li></ul><ul><ul><li>Apple-only networks </li></ul></ul><ul><li>TCP/IP </li></ul><ul><ul><li>Microsoft networking, Apple networking, UNIX/Linux networking ... all support it </li></ul></ul><ul><li>PPTP ( Point-to-Point Tunneling Protocol ) </li></ul><ul><ul><li>used for Virtual Private Networks; wraps around NetBEUI </li></ul></ul><ul><li>DHCP ( Dynamic Host Configuration Protocol ) </li></ul><ul><ul><li>dynamically assigns IP addresses to computers on a TCP/IP LAN </li></ul></ul>
  21. 21. Networking Hardware <ul><li>Workstation computers </li></ul><ul><li>Server computers/Mainframe computers </li></ul><ul><li>Network interface cards (NICs) </li></ul><ul><li>Inter-connection hardware </li></ul><ul><li>Cabling </li></ul><ul><ul><li>Unshielded twisted pair (UTP) cable </li></ul></ul><ul><ul><li>Shielded twisted pair (STP) cable </li></ul></ul><ul><ul><li>Coaxial cable </li></ul></ul><ul><ul><li>Fiber-optic cable </li></ul></ul>
  22. 22. Networking Hardware <ul><li>Wide Area Network (WAN) </li></ul><ul><ul><li>A network that spans hundreds of feet to thousands of miles </li></ul></ul><ul><ul><li>Purpose is linking together other networks </li></ul></ul><ul><ul><ul><li>A “network of networks ” </li></ul></ul></ul><ul><li>Local Area Network (LAN) </li></ul><ul><ul><li>A network in which the devices are all fairly close to one another </li></ul></ul><ul><ul><li>The goal is to connect all of the devices </li></ul></ul><ul><ul><ul><li>A “network of devices ” </li></ul></ul></ul>
  23. 23. Networking Hardware <ul><li>Wide Area Network (WAN) Inter-Connection Hardware </li></ul><ul><ul><li>Repeater </li></ul></ul><ul><ul><ul><li>a reamplification device, receives a message and passes it along </li></ul></ul></ul><ul><ul><li>Bridge </li></ul></ul><ul><ul><ul><li>connects two networks together at OSI network layer 2 </li></ul></ul></ul><ul><ul><ul><li>“ dumb” … cannot translate messages from one protocol into another </li></ul></ul></ul><ul><ul><li>Router </li></ul></ul><ul><ul><ul><li>an “intelligent” bridge, works at OSI network layer 3 </li></ul></ul></ul><ul><ul><ul><li>understands network addresses where messages are going, and can route them to the computer </li></ul></ul></ul><ul><ul><li>Gateway </li></ul></ul><ul><ul><ul><li>an “intelligent” router, works at OSI network layers 4-7 </li></ul></ul></ul><ul><ul><ul><li>connects two different types of networks (e.g., AppleTalk and TCP/IP) </li></ul></ul></ul><ul><ul><ul><li>translates data from one protocol into another (e.g., TCP/IP into AppleTalk) </li></ul></ul></ul><ul><ul><ul><li>also provide “bridging” and “network layer routing” services </li></ul></ul></ul>Dumb Intelligent
  24. 24. Networking Hardware <ul><li>Local Area Network (LAN) Inter-Connection Hardware </li></ul><ul><ul><li>Hub </li></ul></ul><ul><ul><ul><li>passes messages between two computers by broadcasting packets to every computer on network </li></ul></ul></ul><ul><ul><ul><li>only one computer can talk at a time … potentially wastes network bandwidth </li></ul></ul></ul><ul><ul><li>Switch </li></ul></ul><ul><ul><ul><li>an “intelligent” hub </li></ul></ul></ul><ul><ul><ul><li>passes messages between two computers by creating a direct connection between the two computers </li></ul></ul></ul><ul><ul><ul><li>multiple computers can talk directly to each other at the same time … makes better use of network bandwidth </li></ul></ul></ul>Dumb Intelligent
  25. 25. Network Topology <ul><li>Topology </li></ul><ul><ul><li>The shape of a network; the network’s layout </li></ul></ul><ul><li>Most Common Network Topologies </li></ul><ul><ul><li>Star Topology </li></ul></ul><ul><ul><li>Ring Topology </li></ul></ul><ul><ul><li>Bus Topology </li></ul></ul><ul><ul><li>Mesh Topology </li></ul></ul><ul><ul><li>Tree (Hybrid) Topology </li></ul></ul>
  26. 26. Network Topologies Star Stations linked to a central node, but each transmission is heard by all users (if host device is a hub) HOST USER USER USER USER
  27. 27. Network Topologies Ring One way transmission, listen and re-transmit, common example is IBM’s Token Ring network HOST USER USER USER
  28. 28. Network Topologies Bus Stations linked to a central cable, easy to add new users USER USER USER USER USER USER terminator terminator
  29. 29. Network Topologies Mesh USER USER USER USER USER USER Devices are connected with many redundant interconnections
  30. 30. Network Topology <ul><li>Which to Choose? </li></ul><ul><ul><li>Depends </li></ul></ul><ul><ul><ul><li>Cost </li></ul></ul></ul><ul><ul><ul><li>Reliability/failsafe requirements </li></ul></ul></ul><ul><ul><li>Organizations mix and match, depending on the type of use </li></ul></ul><ul><ul><ul><li>Ring: connects routers on a network </li></ul></ul></ul><ul><ul><ul><li>Star: connects end users in a local workgroup </li></ul></ul></ul>“ Hybrid” Topology “ Tree” Topology
  31. 31. Network Technology Layout and Implementation Issues <ul><li>Distance (some media are limited) </li></ul><ul><li>Range of services (data, voice, video) </li></ul><ul><li>Security (encryption) </li></ul><ul><li>Multiple access (capacity issues) </li></ul><ul><li>Utilization (light vs. heavy use) </li></ul><ul><li>Cost justifiable (per user) </li></ul><ul><li>Installation (centralized) </li></ul><ul><li>Allow for growth and expansion (people / equipment) </li></ul><ul><li>Facilitate service and maintenance (upgrades) </li></ul>
  32. 32. Networks Make Possible ... Many Architectures
  33. 33. Client/Server Architectures Separating Presentation, Application Logic, and Database revenue = get_data() profit = revenue - cost income.report( profit, revenue) Computer #1 Computer #2 Computer #3 Presentation Layer Application Logic (Business Logic) Layer Database Layer TCP/IP TCP/IP acctid revenue 3443 6789 25 10,000
  34. 34. Client/Server Architectures Distributing Presentation Logic, Application Logic, and Database Mgmt <ul><li>Distributed Presentation </li></ul><ul><ul><li>Client: manages only a portion of presentation processing tasks </li></ul></ul><ul><ul><li>Server: manages presentation, application, database </li></ul></ul><ul><li>Remote Presentation </li></ul><ul><ul><li>Client: presentation logic </li></ul></ul><ul><ul><li>Server: application logic and database management </li></ul></ul><ul><li>Distributed Function </li></ul><ul><ul><li>Client: presentation logic and part of application </li></ul></ul><ul><ul><li>Server: part of application and database management </li></ul></ul><ul><li>Remote Data Management </li></ul><ul><ul><li>Client: presentation logic and application logic </li></ul></ul><ul><ul><li>Server: database management </li></ul></ul><ul><li>Distributed Data Management </li></ul><ul><ul><li>Client: manages presentation, application logic, and portion of database </li></ul></ul><ul><ul><li>Server: manages part of database </li></ul></ul>More and more of presentation, application, and database logic become positioned on client
  35. 35. Internet Technology HTML File-Based Website Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
  36. 36. Internet Technology Website Built from Common Gateway Interface (CGI) Program (2-Tier) Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/ Tier 1 Tier 2
  37. 37. Internet Technology CGI Program Requests Data from Database (3-Tier) Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/ Tier 1 Tier 2 Tier 3
  38. 38. Internet Technology 3-Tier Database-Backed Website Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/ Scripting Languages ASP JSP CFM index.asp
  39. 39. Internet Technology Secure “N-Tier” Website Architecture Source: Philip and Alex’s Guide to Web Publishing, http://www.arsdigita.com/books/panda/
  40. 40. N-Tier Architecture MSNBC.com Web Servers Database Servers
  41. 41. Internet Technology An Enterprise-Wide Network
  42. 42. Managing Enterprise Networks
  43. 43. Management Objectives Open Systems and Enterprise Networking <ul><li>Connectivity </li></ul><ul><ul><li>the ability of the various computer resources to communicate with each other through network devices without human intervention </li></ul></ul><ul><li>Portability </li></ul><ul><ul><li>the ability to move applications, data, and even people form one system to another with minimal adjustments </li></ul></ul><ul><li>Interoperability </li></ul><ul><ul><li>the ability of systems to work together by sharing applications, data, and computer resources. </li></ul></ul><ul><li>Scalability </li></ul><ul><ul><li>the ability to run applications unchanged on any open system where the hardware can range form a laptop PC to a super computer </li></ul></ul>
  44. 44. Managing Enterprise Networks Present Trends <ul><li>Enterprise Application Integration (EAI) </li></ul><ul><ul><li>Organizations have “legacy mainframe applications” </li></ul></ul><ul><ul><ul><li>old systems and applications originating waaay back in time </li></ul></ul></ul><ul><ul><ul><li>organizations have added ERP, CRM, etc., to these </li></ul></ul></ul><ul><ul><li>Organizations already have built “enterprise network” to try to link desktops together </li></ul></ul><ul><ul><ul><li>make the office worker’s desktop resources flexible </li></ul></ul></ul><ul><ul><li>Many other digital devices now used by enterprise </li></ul></ul><ul><ul><ul><li>PDAs, Cash Registers, Laptops, Machines </li></ul></ul></ul><ul><ul><li>Now, integrating them through software that </li></ul></ul><ul><ul><ul><li>“ wraps” around a device and serves as an interface between that device and other “objects” in the enterprise that are allowed to communicate with it </li></ul></ul></ul>
  45. 45. Managing Enterprise Networks Issues of Concern <ul><li>Choose network design satisfactory for user needs </li></ul><ul><li>Procure network components </li></ul><ul><li>Tracking inventory of network hardware </li></ul><ul><li>Network maintenance </li></ul><ul><li>Network failure detection </li></ul><ul><li>Billing customers (internal & external) who use the network resources </li></ul>
  46. 46. Managing Enterprise Networks Tools for Managing Networks <ul><li>Operations Support Systems (OSS) </li></ul><ul><ul><li>Network Planning </li></ul></ul><ul><ul><li>Network Design </li></ul></ul><ul><ul><li>Pre-Implementation Network Analysis </li></ul></ul><ul><ul><ul><li>Visual Layout Tools </li></ul></ul></ul><ul><ul><ul><li>Simulation of System Design </li></ul></ul></ul><ul><ul><li>Network Management </li></ul></ul><ul><ul><ul><li>Inventory of computers, routers, hubs, etc., etc., </li></ul></ul></ul><ul><ul><ul><li>Failure analysis </li></ul></ul></ul><ul><ul><ul><li>OSS Customer Relationship Management </li></ul></ul></ul>
  47. 47. Managing Enterprise Networks Operations Support Systems OSS Pictures
  48. 48. Networking Jobs <ul><li>Network Engineer </li></ul><ul><ul><li>Average starting salary: $62,250-$87,000 </li></ul></ul><ul><ul><li>Skill requirements: </li></ul></ul><ul><ul><ul><li>Microsoft Certified Systems Engineer (MCSE) </li></ul></ul></ul><ul><ul><ul><li>Cisco Certified Internet Expert (CCIE) </li></ul></ul></ul><ul><ul><ul><li>Security related hardware and software experience </li></ul></ul></ul><ul><ul><ul><li>LAN/WAN management and systems administration </li></ul></ul></ul><ul><ul><ul><li>Background in Virtual Private Networks (VPNs), TCP/IP, intrusion detection, firewall implementation </li></ul></ul></ul><ul><ul><li>Who’s hiring: </li></ul></ul><ul><ul><ul><li>Financial services, government </li></ul></ul></ul><ul><li>(Vaas, L., “Networking Skills Still Crucial,” eWeek, Dec. 31, 2001, p. 33) </li></ul>