Networking Fundamentals

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  • 1. Networking Fundamentals Notes: highly technical, constantly changing Goal: give you a sense of the basic choices
  • 2. What is a network?
    • A collection of nodes linked together to allow transmissions between them
    • Basic Parts of a Network Architecture
      • Topology: arrangement of nodes
        • Which node is connected to which node
      • Transmission Media: Mechanism of flow
        • Wire or wireless
      • Network Source
        • Make (build it yourself) or Buy
      • Choices here determine hardware/software
    • Purpose of all networks
      • facilitate communication…
        • internal and external to organization
      • allow sharing of resources
        • hardware, data, applications
  • 3. Network Architecture Components
    • What’s in a node that we link up:
      • Single User Input/Output Devices
          • Dumb terminals, PCs, Thin Clients, Point of Sales, ATMs, etc.
      • Host Systems (multi-user computers, see next slide)
      • Network devices
        • Create net of devices, connect computers to them
    • Transmission media
      • Wires (if wire based)
      • Transceivers (if wireless)
    • Connection hardware
      • M odems, codecs, network interface cards (NIC)
      • Inter-networking: switches, routers, gateways
    • Plus software that runs them, personnel that install maintain hardware + software
  • 4. Host Systems in Networks
    • Multi-user platforms
      • Operating system must
        • Be secure, allocate resources to multiple users
      • May connect I/O devices to them
      • May connect hosts to each other using network
    • Categories
      • Large Scale Processing Power
        • Mainframe or Enterprise Servers
          • 1000s of users, lots of applications
        • Supercomputers
          • Traffic cop on huge networks
      • Mid-Range Processing Power
        • Mid-range servers (minicomputers) - 100s of users
        • PC-based servers - up to 100 users
          • Network server or Specific service
            • Print server, file server, application server
        • Super-mini - traffic cop on large networks
  • 5. I/O Devices on Nets
    • Dumb Terminals
      • Only processing power is ability to ‘talk’ to host
      • Screen + keyboard + comm chip
      • Text interface, control keys, no mouse
    • PC
      • Able to compute + connect
      • Sophisticated graphical user interface
    • Thin Client, Network Machine (other names)
      • Less than PC, more than Dumb Terminal
        • Older technology, no storage only memory, nice screen
      • Designed to display web pgs
    • Computer + Mechanical systems
      • Point of Sales Terminal
        • Automated cash register
      • ATM (automatic teller machines
      • Gas pumps
  • 6. I/O Devices on Nets - Dumb Terminals User Interface of an Application (text based interface) What it looks like if you connect to host using a PC (text based interface inside a window)
  • 7. Networking Architecture Types
    • Centralized ‘legacy’ systems
      • Host does all processing, storage
        • 1st mainframes, later mid-range
      • Users - dumb terminals, then PCs
      • Connecting Devices
        • direct line or dial-up using modem
      • Topology - Star
      • Telecomm Processors
        • multiplexers (Mux’s), front-end processor
  • 8. Networking Architectures
    • Decentralized Architectures
      • Independent machines (no network)
        • PCs = ‘Sneakernet’
      • Peer-to-peer (all machines equal, linked to each other)
        • a bunch of PCs in a LAN
        • or a bunch of minis/mainframes in a WAN
          • topology = mesh
    • Distributed Architectures (Cent + Decent)
      • Network server (manages network)
      • Additional servers (file, apps, print)
        • Topology = star, bus, or ring
  • 9. Topologies - Node layout + (protocol ) Pictures show PC nets (LANs) but can use for internetworking too Star (circuit switch or traffic host) Bus (contention) Tree (a set of bus nets) Ring (packet switch) Peer to Peer (store & forward) A A B B C C D A B C D network ready printer (Switch, router, gateway) or host A B C E D print server net server
  • 10. Networking Choices
    • Step 1: Which Architecture(s)?
      • Decentralize (no net) - Stand-alone machines
      • Centralize - Single Host (s)
        • Which type of I/O device?
      • Decentralized Net - Peer to Peer
        • Who to connect to who?
      • Distributed LAN(s) w/ Network Server(s)
        • Additional servers?
          • Primitive servers: file server, printer server
            • dedicated or not dedicated to the network
          • Advanced servers: web, mail and/or db server(s)
      • Combination of the above
      • Inter networking - connect nets to each other
        • Backbone, hubs, WAN
  • 11. Connection Choices
    • Step 2: Transmission Media Choices
      • Wires
        • metallic (transmit sound)
          • twisted pair - cheap, easy to use, short distance
            • Unshielded (interference prone, slow)
            • Shielded (faster, less interference)
          • coaxial - longer distance, up to 5500 channels
        • fiber-optic (transmit light)
          • Dense (500,000 channels), very fast, secure
      • Wireless
        • Short range options
          • within/between buildings
        • Long range options
          • across town + mobile IS
  • 12. Wireless - Short Range Options
      • Wi-Fi (radio waves) - send sound
        • cheap, slow, interference prone, diffuse
        • distance: 75-800 depending on walls
        • Bluetooth = radio protocol (handhelds)
      • Infrared - send light
        • cheap, faster than radio, distance: 50 ft
        • no interference, stopped by walls
      • Laser - high frequency light
        • very fast, costly, distance:1000 ft
  • 13. Wireless - Long Range Options
    • Microwave - high frequency radio
      • Antenna Based Network
        • line of sight - <= 30 miles apart
        • cellular, pagers, mobile radio
          • honeycomb of antennas
    • Satellites - extends microwave line of sight
      • geosynchronous orbit (22,000 miles)
        • propagation delay
        • global positioning system
      • low-orbit (500 miles)
      • VSAT - very small aperture terminals
        • Must connect to vendor satellites
  • 14. Mobile Options
    • Wireless mouse/keyboard (infrared/radio)
    • Personal Area Network (peer to peer)
      • Bluetooth (radio wave)
        • Link up to 8 devices in 10meter area
      • Wi-Fi in ad-hoc mode (radio)
    • Cellular Radio
      • Honeycomb of antennas (peer to peer stars)
      • Options in Cellular
        • Original Cellular - analog based (800-900 mhz)
        • PCS - digital (1900 mhz)
    • RFID - tag w/ data about item
      • It can transmit via radio over short distance
        • Passive (read only, can chg), Active
  • 15. Other Transmission Concepts
    • Bandwidth - width of highway
      • number of signals can send
        • Send diff signal on diff wire
          • Narrow band - unshielded twisted pair (1 channel)
          • Medium band - multiple shielded (10s of channels)
          • Broadband - large coaxial (100s of channels)
        • Send diff signal on diff frequencies
      • as bandwidth increases
          • speed may increase
          • volume you can send (text vs graphics)
    • Speed
      • Bits per Second (bps), kbs, mbs, gbs
      • Can increase rate thru compression
  • 16. Networking Part II Internetworking Issues Source Issues Telecomm Architectures Telecomm Software
  • 17. Inter-networking
    • Networks that connect networks together
      • Backbone or Campus Network
        • a network that connects…
          • LANs, hosts, enterprise storage, etc.
        • Helper device - concentrator
      • Wide Area Network
        • a long distance network of hubs
        • hub = connects multiple backbones
    • Topology – any of the topologies can be used
      • Internet is peer to peer (mesh)
      • Hub is star (unless has ring,bus inside)
      • FDDI (ring), Ethernet = bus
  • 18. Inter-Networking Devices
    • Switch or Bridge
      • Box with 2 connectors
      • Connects networks of same type
    • Router
      • Box with several connectors
      • Can translate between similar nets
    • Gateway
      • Intelligent device w/ many links
      • Use to connect very different nets
      • Examples:
        • internet gateway for orgs
        • connect US net to European net
  • 19. Step 3: Source of Connection
    • Where do you get your connections?
    • Choices
      • You do it yourself
      • Public Switched Telephone Network
        • Dial-up with phone call + modem
        • Direct connection with ISDN
          • gives you higher bandwidth connection
          • one data channel + one voice channel
            • your home PC will look like a PC on the co network
        • Dedicated line (ex: T1 line w/ 24 channels)
          • High bandwidth, expensive
        • DSL = 1 voice + 2 data channels (2 way)
          • ADSL – Asynchronous (send data channel sm)
  • 20. Sources (cont’d)
      • Other vendors
        • DSL Vendors, Cable co, Satellite Vendor
      • Value Added Network providers
        • PSTN + Satellite
        • VPN - build network off internet or public net
          • Simulates point-to-point (packet in a packet)
            • Public – they dedicate a channel to you
            • Internet – they agree to store and forward for you
      • Industry based networks
        • Swift = banking
      • Build + Buy
        • Lay cable
        • VSAT + Satellite
        • VPN – you work with vendors to create it
        • MAN, National or Regional Networks
  • 21. Traditional Architectures
    • Data Communication architecture
      • online transaction processing
      • bulk data transfer network
    • Voice architecture - PBX
      • phone calls, audioconf, voicemail, etc.
    • Imaging architecture -
      • video, fax, videoconferencing
      • image-based transactions, files, databases
    • Email architecture
      • cluster of email servers (post offices)
  • 22. Newer Architectures
    • Centralized and Distributed Databases
      • Database Servers
      • Storage Area Networks
    • Web-Based Architectures
      • Web Servers (and other devices)
    • Mobile systems
    • Inter-organizational Systems
      • Direct connect/open network, web-based
    • Grid computing
      • Reclaim unused PC resources for all to use
    • Sensor Networks for security
      • Connect cameras, eyes (asset sensors)
  • 23. Client/Server Architecture
    • Client/Server is advanced form of Distributed
      • It is a way of looking at infrastructure
      • “ let the best processor do the job”
        • PCs excel at ...
        • Host systems excel at …
        • So take an activity and let them share it
      • Database Server
        • PC makes query, server retrieves data
      • Mail Server
        • PC creates mail, mail server routs it
      • Web Server
        • Server has web page, PC displays it
  • 24. 2-Tier vs. 3 Tier Architecture
    • Client-Server is 2 tier
      • Applications are split up
        • part of software on client
        • part of software on server
      • Database is on server
      • Problems:
        • when client s/w is updated
        • as volume grows
    • 3 Tier Architecture
      • Separate platforms for three different functions
        • input, process and storage
  • 25. Three-Tier (or n-tier) architecture
    • Front-End (Input - what users see)
      • PCs or Thin Clients w/ GUI
        • Windows or Web-based Interface
        • Give access to middle tier, display what middle tier says
    • Middle Tier (Processing)
      • Application/transaction server(s)
      • Does authentication & processing
    • Back-End (Storage)
      • Database server(s) & SANs
    • Other possible layers
      • Legacy System(s) - old centralized apps
      • Load balancers
  • 26. Telecomm Software
    • Connection Software
      • dialer that talks to modem for dial-up
      • software that controls
        • NIC (wire)
        • Access point (wireless)
    • Network operating systems
      • Host operating system
      • Server vs. Client in a small network
    • Network management software
      • Monitor traffic, security
      • Assists with troubleshooting, planning
  • 27. Typical Tradeoffs
  • 28. Wire Options
    • Twisted Pair
      • 10Base-T = 10Mbs (ethernet)
      • 100Base-T = 100 (fast ethernet)
      • 1000Base-T = 1000 (giga-ether)
      • Token Ring = 4 – 16mbs
      • ISDN (max 1.5m), SDSL (3mps), ADSL (9mps)
    • Coaxial
      • 10Base 2 = 10 mbs (thinwire or thickwire)
      • Broadband - up to giga-bps
        • Frame relay = 56kbs - 45mbs
        • ATM = 1.5m - 9 gbs
      • T1 = 1.5mbs, T3 = 45mps
    • Fiber-Optic
      • 10Base-F (ethernet) = 10mbs
      • 100 Base (fast ether) = 100 mbs
      • FDDI (Fiber Dist Dat Interface) = 100 mbs
      • SONET (synch optical net) = 45m-40gbs
  • 29. Wireless Options
    • Radio = up to 54 mbs
      • Bluetooth radio wave = up to 1 mbs
      • 802.11b = 11/5 mbs, 2.4Ghtz freq (wi-fi)
      • 802.11a = 54/22 mbs, 5Ghtz
        • Less interference (ex: baby monitors)
      • 802.g = /16 to 20mbs, 2.4
        • Can be slower if add 11b devices to it
        • Can get interference from other 2.4 devices
      • 802.11 dualband = a and b or all three
      • 802.11e - future
    • Cellular = .01 mbs to .38 mbs
      • Traditional (analog), PCS (digital)
      • and 3G (faster digital)
    • Microwave = up to 600 mbs
    • Satellite = up to 1 gbs
    • Infrared = 1 mbs to 4 mbs