Networking and Telecommunications

1. Networking and Telecommunications 5. Lan Hardware

2. Cables: TP (STP/UTP) • Shielded and Unshielded • Susceptible to interference (EMI/RFI, crosstalk) • Crosstalk - # of twists per foot • Different Categories • Cat 3 – 10Mbps (3 twists/foot) • Cat 5 – 100Mbps (3-4 twists/inch) • Cat 5e – 1000Mbps • Ease of installation, low cost • Star topology, used within a lan, most popular cable type within lan

4. Coax (Thin / Thick) • Bus topology, backbones primarily today • Original technology • Coax: co-axis (several layers around central axis) • insulation (plenum - teflon, non-plenum - plastic/pvc) • braided shield • foil shield • non conductor (platic/pvc) • center - copper wire

6. Thick Coax (ethernet)

7. Thin Coax (ethernet)

8. Fiber Optics • Expensive, glass or plastic, beam of light • Uses LED or Laser • SingleMode or MultiMode fiber • Newest technology, high bandwidth, expensive • Star or bus topology, backbones (primarily) and within lan (new) • No crosstalk, no emi/rfi, no lightning (excellent outdoors) • Little attenuation • Good security (hard to tap, no external radiation)

9. Non-cable Medium • Wireless lans • Infrared beams or radio waves

10. Connectors • bnc (terminators, barrel, t connectors) • used with thin coax • (British Naval Connectors) • N series • used with thick coax • RJ45 • used with TP network, (RJ-11 voice) • Registered Jack

12. Other Devices • Repeater (attenuation) • Hub - ethernet, star topology, pass packet to all ports • Switch (switching hub) - ethernet, star topology, look at addresson packet and send only to the correct port • Mau - token ring, star topology, pass packet using token passingin a loop (logical ring, physical star)

14. Servers and Clients

15. Clients • Pc • Mac • Unix workstations

17. Servers • Pc, mac, unix-based (Sun, HP, IBM, Linux on a PC), even mainframes/mini-computers • Single server (all tasks) vs. multiple servers (file, print, comm, email, web etc.) • Dedicated vs. non-dedicated • Costs 5-15k (low end), 50-100k (high end) or more

18. Client and Server Hardware • RAM (128 meg min. on clients, 512 meg min on servers) - speed, types of RAM, # slots for expansion, amount of RAM • CPU CHIP- Intel (8086, 286, 386, 486, pentium), motorola (68000 series, power pc chip), others (Sun, HP, etc..), mhz speed • Bus - PCI, ISA, EISA, MCA, Sbus, others - speed and width • Monitor - size, resolution, video adapters - server may be headless - or connect multiple servers to a kvm switch (1 single keyboard, video monitor, mouse) • floppy disk/CDrom/DVD

19. Client and Server (cont.) • Hard drive • Internal or external (most disk space on servers, 40 gig or more) • Size 9, 18, 36, 72, 300, 400 gig drives, more... • Type of connection: IDE, SCSI, SATA, Firewire, USB • Speed of drive: 7200 rpm, 10000 rpm, access time, seek time, etc..

20. Final Client and Server • Keyboard/mouse • NIC - network interface card (very specific for Network Architecture,and hardware on system, and NOS), may be built-in to motherboard • USB / Firewire /SCSI and other ports (for peripherals) • Expansion Slots - for nic and other items (sounds cards, modem cards)

21. Server Hardware (Primarily) • printers (directly on network, or attach to server via serial/parallel cable) • modems - modem pool • UPS • also ups software to shutdown system automatically and gracefully • uninterruptable power supply (surge protection and blackout/brownout protection) • use rs232 cable to talk to software

23. Server Hardware (Primarily) (cont.) • Backups • Offline storage • Why? hard drive crash, erase data files accidentally, security, virus/worms • Tapes, #1 method • keep some offsite • Space and speed • Backup schedules (full and partial backups) • Over network backups or to directly attached devices

24. Tapes: • 8mm 7/14 gig , 4mm (dat) 4/8 gig • DLT (digital linear tape) 35/70 gig • SDLT (Super DLT) - 110/220 gig per tape • Others: QIC 1/4 cartridge, Reel to Reel, and others

25. Other Backup Media? • Floppy disks (in the past) • CDRW, ZIP • Removable hard drives • Local/Remote online backup storage devices • Netapps (network appliance/snapshot feature) • 3rd party Data Backup/Recovery vendors

26. Other Issues • Diskless Booting (diskless workstations) • boot rom chips • Operating system sits on server, apps still run on client • adv. - security, cost, no virus, easy admin. • disadv. - dependent totally on network, slower, more network traffic • Thin Client • applications run on servers • client only does i/o. • Citrix and X-Terminals • Almost like the old days of mainframe/terminals

27. Other Issues (cont.) • Raid (redundant array of inexpensive disks) • different levels (raid 1, 2, 5, …) • hardware vs. software raid • redundancy is key...automatic failover • Disk mirroring. Striping. • Holds Terrabytes of data (1 Terrabye = 1000 gig) • O.S. • multiuser, multitasking • Unix, MacOS, Windows 3.x, Windows 95/98/NT/2000/XP, Dos • NOS • Network Operating System (more info later)

28. Hardware Vendors • 3com • HP • SMC • IBM • Cisco • Bay Networks • Asante • Dell • Sun Microsystems • Linksys • Allied Telesys • Netgear • (Liebert and APC - UPS units) • Many others

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