Network Management OVERVIEW Communication

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Network Management OVERVIEW Communication

  1. 1. Communication & Networking: An Overview Debashis Saha MIS Group, IIM Calcutta E-mail: [email_address]
  2. 2. Organization <ul><li>Communication Systems </li></ul><ul><li>Networking Fundamentals </li></ul><ul><li>The INTERNET </li></ul><ul><li>Network Security </li></ul>
  3. 3. Simple Communication Model Source Destination Transmission media
  4. 4. Example client program server communications channel
  5. 5. Communication System Source Modulator Demodulator Sink Carrier Noise Transmission media
  6. 6. Data Communication Model Modem DCE Modem DCE Computer DTE Computer DTE
  7. 7. Modes of Communication Simplex communications Half-duplex (HDX ) communications Full-duplex (FDX) communications or
  8. 8. Communication Ports 9-pin D-type male connector (COM1:) 9-pin or 25-pin D-type male connector (COM2:)
  9. 9. Transmission Media <ul><li>Wired </li></ul><ul><ul><li>Twisted pair, Coaxial cable, FO </li></ul></ul><ul><li>Wireless </li></ul><ul><ul><li>Short range </li></ul></ul><ul><ul><ul><li>Infrared </li></ul></ul></ul><ul><ul><li>Long Range </li></ul></ul><ul><ul><ul><li>Microwave </li></ul></ul></ul><ul><ul><ul><li>Satellite </li></ul></ul></ul>
  10. 10. Transmission Media Metal sheath Inner conductor Insulating outer conductor Coaxial cable Twisted-pair cable Inner cladding (glass) Inner fibre (glass) Outer cladding (PVC) Fibre optic cable
  11. 11. Telephone Network
  12. 12. Cable TV Network
  13. 13. Multiplexing <ul><li>Time-Division Multiplexing (TDM) </li></ul><ul><li>Frequency-Division Multiplexing (FDM) </li></ul><ul><li>Statistical Time-Division Multiplexing (STDM) </li></ul>L1 L2 L3 R1 R2 R3 Switch 1 Switch 2
  14. 14. Networks
  15. 15. Categories <ul><li>Communication Networks </li></ul><ul><ul><li>PSTN </li></ul></ul><ul><li>Computer Networks </li></ul><ul><ul><li>INTERNET </li></ul></ul><ul><li>Integrated Networks </li></ul><ul><ul><li>Computer & Communication Networks </li></ul></ul>
  16. 16. Building Blocks <ul><li>Nodes: PC, special-purpose hardware… </li></ul><ul><ul><li>hosts </li></ul></ul><ul><ul><li>switches </li></ul></ul><ul><li>Links: coax cable, optical fiber… </li></ul><ul><ul><li>point-to-point </li></ul></ul><ul><ul><li>multiple access </li></ul></ul>…
  17. 17. Switched Networks <ul><ul><li>two or more nodes connected by a link, or </li></ul></ul><ul><ul><li>two or more networks connected by two or more nodes </li></ul></ul><ul><li>A network can be defined recursively as... </li></ul>
  18. 18. Switching Strategies <ul><li>Circuit switching: carry bit streams </li></ul><ul><ul><li>original telephone network </li></ul></ul><ul><li>Packet switching: store-and-forward messages </li></ul><ul><ul><li>Internet </li></ul></ul><ul><ul><ul><li>See the schematic diagram next </li></ul></ul></ul>
  19. 19. Ckt Vs. Pkt Switching Circuit- switching Packet- switching possible routes fixed route PSE
  20. 20. Addressing and Routing <ul><li>Address: byte-string that identifies a node </li></ul><ul><ul><li>usually unique </li></ul></ul><ul><li>Routing: process of forwarding messages to the destination node based on its address </li></ul><ul><li>Types of addresses </li></ul><ul><ul><li>unicast: node-specific </li></ul></ul><ul><ul><li>broadcast: all nodes on the network </li></ul></ul><ul><ul><li>multicast: some subset of nodes on the network </li></ul></ul>
  21. 21. What Goes Wrong in the Network? <ul><li>Bit-level errors (electrical interference) </li></ul><ul><li>Packet-level errors (congestion) </li></ul><ul><li>Link and node failures </li></ul><ul><li>Messages are delayed </li></ul><ul><li>Messages are deliver out-of-order </li></ul><ul><li>Third parties eavesdrop </li></ul>
  22. 22. Layering <ul><li>Use abstractions to hide complexity </li></ul><ul><li>Abstraction naturally lead to layering </li></ul><ul><li>Alternative abstractions at each layer </li></ul>Request/reply channel Message stream channel Application programs Hardware Host-to-host connectivity
  23. 23. Protocols <ul><li>Building blocks of a network architecture </li></ul><ul><li>Each protocol object has two different interfaces </li></ul><ul><ul><li>service interface : operations on this protocol </li></ul></ul><ul><ul><li>peer-to-peer interface : messages exchanged with peer </li></ul></ul><ul><li>Term “protocol” is overloaded </li></ul><ul><ul><li>specification of peer-to-peer interface </li></ul></ul><ul><ul><li>module that implements this interface </li></ul></ul>
  24. 24. Interfaces Host 1 Protocol Host 2 Protocol High-level object High-level object Service interface Peer-to-peer interface
  25. 25. ISO-OSI 7 Layer Ref. Model Application Session Transport Network Data Link Physical Presentation Application Session Transport Network Data Link Physical Presentation DATA DATA DATA DATA DATA DATA A A A A A P P P P S S S T T N DATA A P S T N D D DATA DATA Actual Data Flow Virtual Data Flow
  26. 26. Data Flow in Layered Model DATA DATA Actual Data Flow Virtual Data Flow User application. process and management functions Data interpretation, format and control transformation Administration and control of session between two nodes Network transparent data transfer and transmission control Routing, switching and flow control over a network Maintain and release data: link, error and flow control Electrical and mechanical characteristics Application Session Transport Network Data Link Physical Presentation Application Session Transport Network Data Link Physical Presentation
  27. 27. Logical View of Layers N1 N7 Session Transport Network Physical Data Link N2 N3 N4 N6 N8 N5 NETWORK A NETWORK B
  28. 28. Types of Networks <ul><li>LAN </li></ul><ul><ul><li>Local area </li></ul></ul><ul><li>MAN </li></ul><ul><ul><li>Metropolitan area </li></ul></ul><ul><li>WAN </li></ul><ul><ul><li>Wide area </li></ul></ul>
  29. 29. Ring, Star & Bus LAN Ring network Bus network Star network central server
  30. 30. IEEE LAN Standards Physical MAC LLC Physical MAC LLC LAN Physical Data link Logical link control (LLC) IEEE 802.2 Media access control (MAC) IEEE 802.5 IEEE 802.3 Token ring CSMA/CD OSI model Media access control (MAC)
  31. 31. Campus Wide LAN PRODUCTION_1 PRODUCTION_2 ADMIN_1 ADMIN_2 ELECT_1 INSTR_1 MECH_1 Ethernet backbone ELECT_1 can act as a stand-alone network if required Fan-out box Fan-out box Fan-out box Fan-out box Fan-out box Fan-out box Fan-out box
  32. 32. Internetworking
  33. 33. Definition <ul><li>An internetwork is an inter connected collection of independent network s </li></ul><ul><ul><li>Each independent network is often referred to as an autonomous system (AS) </li></ul></ul><ul><li>Internetwork is the generic name to any kind of network interconnection </li></ul><ul><li>The INTERNET is a special internetwork that uses TCP/IP protocol stack </li></ul>
  34. 34. Difference with network? <ul><li>A network is a collection of interconnected computers </li></ul><ul><li>An internetwork is a collection of inter connected network s (or AS’s) </li></ul>R2 R1 H4 H5 H3 H2 H1 Network 2 (Ethernet) Network 1 (Ethernet) H6 Network 3 (FDDI) Network 4 (point-to-point) H7 R3 H8
  35. 35. Various Internetworking Cases <ul><li>LAN-LAN </li></ul><ul><ul><li>EE LAN to CSE LAN in a campus network </li></ul></ul><ul><li>LAN-WAN </li></ul><ul><ul><li>office LAN to the INTERNET </li></ul></ul><ul><li>WAN-WAN </li></ul><ul><ul><li>ERNET to VSNL-net </li></ul></ul><ul><li>LAN-WAN-LAN </li></ul><ul><ul><li>two offices connected via the INTERNET </li></ul></ul>
  36. 36. Practical Internetworking Scenario <ul><li>LAN for small domains of computers </li></ul><ul><li>LAN-LAN interconnection for a campus </li></ul><ul><li>LAN-WAN interconnection for INTERNET connectivity </li></ul><ul><li>LAN-WAN-LAN interconnection for connectivity between distant computers </li></ul>
  37. 37. A common Example (LAN-LAN, LAN-WAN, LAN-WAN-LAN) LAN A LAN C LAN D Wide area network connection Local network backbone Wide area network Gateway or modem LAN B Bridge
  38. 38. Internetworking Devices <ul><li>Repeater (layer 1) bit-level </li></ul><ul><li>Bridge (layer 2) frame-level </li></ul><ul><li>Router (layer 3) packet-level </li></ul><ul><li>Gateway (layer 4-7) message-level </li></ul><ul><ul><li>Transport layer gateway TPDU-level </li></ul></ul><ul><ul><li>Application layer gateway APDU-level </li></ul></ul>
  39. 39. The INTERNET
  40. 40. Early History <ul><li>1969, Dec – ARPANET went on air:: US DoD </li></ul><ul><li>1974 – TCP/IP discovered :: Cerf & Kahn </li></ul><ul><li>1983, Jan 01 – TCP/IP became the official </li></ul><ul><li>protocol </li></ul><ul><li>MILNET is isolated from ARPANET </li></ul><ul><li>1990 – the Internet takes over, ARPANET dies </li></ul><ul><li>NSFNET is merged with ARPANET </li></ul><ul><li>1992 – the Internet Society was set up </li></ul>
  41. 41. The Internet Structure- Recent Past NSFNET backbone Stanford BARRNET regional Berkeley P ARC NCAR UA UNM Westnet regional UNL KU ISU MidNet regional …
  42. 42. The Internet Structure- Today Backbone service provider Peering point Peering point Large corporation Large corporation Small corporation “ Consumer ” ISP “ Consumer ” ISP “ Consumer ” ISP
  43. 43. Traditional use of the Internet <ul><li>E-mail (SMTP) </li></ul><ul><ul><li>Pine, outlook express, hotmail, yahoo, etc </li></ul></ul><ul><li>News (NNTP) </li></ul><ul><ul><li>Usenet </li></ul></ul><ul><li>Remote login (Telnet) </li></ul><ul><ul><li>Rlogin </li></ul></ul><ul><li>File transfer (FTP) </li></ul><ul><ul><li>CuteFTP, download </li></ul></ul><ul><li>Browsing (HTTP) </li></ul><ul><ul><li>WWW, Explorer, Netscape </li></ul></ul>
  44. 44. How to be on the Internet? <ul><li>A machine is capable to be on the Internet, if it has </li></ul><ul><ul><li>An IP address </li></ul></ul><ul><ul><li>TCP/IP support </li></ul></ul><ul><ul><li>Ability to send IP packets </li></ul></ul><ul><ul><li>Physical connectivity </li></ul></ul><ul><li>Today TCP/IP is built into most OS’s </li></ul>
  45. 45. Connecting from Home <ul><li>Windows/Linux has TCP/IP inbuilt </li></ul><ul><li>Configure TCP/IP for your ISP & modem </li></ul><ul><li>Configure dial-up connection </li></ul><ul><li>Connect modem to your PC (connectivity) </li></ul><ul><li>Dial ISP’s # using PPP </li></ul><ul><li>Login and get temporary IP </li></ul><ul><li>Start browser or e-mail client </li></ul>
  46. 46. Connecting to ISP via Modem Modem Modem Modem stack Modem Modem 33.6 Kbps Modem 56 Kbps Public switched telecommunication network ISP Server INTERNET
  47. 47. TCP/IP Stack <ul><li>Unlike OSI, it is a 5 layer architecture </li></ul><ul><ul><li>Session & presentation layers are merged into application layer </li></ul></ul><ul><li>Lower 2 layers are not specified </li></ul><ul><ul><li>Any LAN can fit into IP </li></ul></ul><ul><ul><li>This is a prime reason for its popularity </li></ul></ul><ul><li>Has its origin in UNIX OS </li></ul>
  48. 48. TCP/IP Architecture Computer on network A Physical medium FTP/TELNET Application TCP IP Application TCP IP Network controller software Network controller software Computer on network B
  49. 49. Internet Routing <ul><li>Overview </li></ul><ul><ul><li>Forwarding vs. routing </li></ul></ul><ul><li>2-level routing </li></ul><ul><ul><li>IGP and EGP </li></ul></ul><ul><li>Distance vector </li></ul><ul><li>Link state </li></ul><ul><li>Route calculation </li></ul><ul><ul><li>Dijkstra’s algorithm </li></ul></ul>
  50. 50. INTERNET PROTOCOL (IP)
  51. 51. Versions <ul><li>Two versions are there: </li></ul><ul><ul><li>Version 4 (IPv4) </li></ul></ul><ul><ul><ul><li>32 bit address </li></ul></ul></ul><ul><ul><li>Version 6 (IPv6) </li></ul></ul><ul><ul><ul><li>128 bit address </li></ul></ul></ul><ul><li>Mobility support </li></ul><ul><ul><li>Mobile IP </li></ul></ul>
  52. 52. Global IP Addresses <ul><li>Properties </li></ul><ul><ul><li>globally unique </li></ul></ul><ul><ul><li>hierarchical: network + host </li></ul></ul><ul><ul><li>32/128 bit </li></ul></ul><ul><li>Dotted Decimal Notation </li></ul><ul><ul><li>10.3.2.4 </li></ul></ul><ul><ul><li>128.96.33.81 </li></ul></ul><ul><ul><li>192.12.69.77 </li></ul></ul>
  53. 53. Subnetting <ul><li>Add another level to address/routing hierarchy: subnet </li></ul><ul><li>Subnet masks define variable partition of host part </li></ul><ul><li>Subnets visible only within site </li></ul>Network number Host number Class B address Subnet mask (255.255.255.0) Subnetted address 111111111111111111111111 00000000 Network number Host ID Subnet ID
  54. 54. How are subnet masks specified? Subnetid Hostid Network ID = 128.138 16 bits 8 bits 8 bits Subnetid (241) Hostid (78) Network ID = 128.138 16 bits 10 bits 6 bits 11111111 11111111 11111111 00000000 255.255.255.0 11111111 11111111 11111111 11 000000 255.255.255.192
  55. 55. IPv6 <ul><li>Though CIDR has given IPv4 some breathing space, its days are numbered. </li></ul><ul><li>In 1990, IETF started work on a new version of IP which will never run out of addresses </li></ul><ul><li>In 19993, it is decided as IPv6 </li></ul><ul><ul><li>Since IPv5 was already in use for an experimental real-time streaming protocol </li></ul></ul>
  56. 56. INTERNET Domain Names edu gov com mil usa uk fr ac ed bath napier man eece cs mmse eece.napier.ac.uk intel sony nec www www.eece.napier.ac.uk
  57. 57. Examples <ul><li>Hosts </li></ul><ul><ul><li>iimcal.ac.in [domain name]  203.197.69.17 [IP address] --> 80:23:A8:33:5B:9F [ethernet MAC address] </li></ul></ul><ul><li>Files </li></ul><ul><ul><li>/usr/llp/tmp/foo (server, fileid) </li></ul></ul><ul><li>Users </li></ul><ul><ul><li>Debashis Saha ds@iimcal.ac.in </li></ul></ul>
  58. 58. Network Security
  59. 59. Common Security Risks
  60. 60. Security Measures <ul><li>Physical Layer: covert channel, </li></ul><ul><li> spread-spectrum </li></ul><ul><li>Data Link Layer: link encryption </li></ul><ul><li>Network Layer: packet-filter </li></ul><ul><li>Application Layer: firewall, </li></ul><ul><li>cryptography </li></ul>
  61. 61. Secret Key System
  62. 62. SSL <ul><li>It is stream- based consisting of three phases </li></ul><ul><li>In initial handshake phase, secure communications are established </li></ul><ul><li>In intermediate data transfer phase, application-to-application dialog (with data encryption) occurs </li></ul><ul><li>In closing handshake phase, connection is terminated </li></ul>
  63. 63. Looking Forward
  64. 64. The Power of “O”
  65. 65. The Power of “M”
  66. 66. F uture = O ptical + M obile <ul><li>Wireless mobile communication has already attracted global attraction </li></ul><ul><li>DWDM optical technology is maturing at a very high speed </li></ul><ul><li>Future global trends show- </li></ul><ul><li>Wide-spread adoption of wireless mobile </li></ul><ul><li>access to optical backbones </li></ul>

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