Networking and Telecommunications

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Networking and Telecommunications

• 5. Lan Hardware

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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

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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

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Thick Coax (ethernet)
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Thin Coax (ethernet)
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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)

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Non-cable Medium

• Wireless lans
• Infrared beams or radio waves

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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

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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)

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• Servers and Clients

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Clients

• Pc
• Mac
• Unix workstations

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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

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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

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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..

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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)

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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

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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

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• 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

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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

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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

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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)

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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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