Chapter 15 Network Hardware

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Chapter 15Network Hardware

• Unix System Administration

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If VirtualRatings.Com Had Student Ratings, Youd
Get a 10

• Network technologies topologies
• Ethernet - bus, star
• Token-Ring
• FDDI - ring
• ATM - star
• Networking Devices
• Hubs
• Bridges/switches
• Routers

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Youve Got Some Nice Toplogies

• Ethernet
• Bus technology
• Can be wired in a bus or physical star topology
• The Polite Dinner Party - CSMA/CD
• Carrier sense
• Multiple access
• Collision detection
• Hubs, switches, bridges and routers

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Wirez Wire

• Thicknet
• 10Base5 - 50 ohm RG-11
• Vampire Taps connect drop cable to thicknet
• Max length 117m with 2.5m between devices
• Thinnet
• 10Base2 - 50 ohm RG-58
• BNC T connectors
• Max length 185m

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Twisting The Au Pairs

• Star configs using hubs or switches
• Wires are twisted to compensate for cross-talk -
  Dont use a regular phone cable
• Two pairs (4-wires) are used even though four
  pair cable is usually installed
• RJ-45 connector pins 1,2,3 6 are used
• Cabling is rated in levels
• Level III (3) is for up to 10Mbps
• Level V is for up to 100Mbps

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How About More Fiber In Your Diet?

• Fiber cable is basically a piece of glass covered
  with a reflective cladding
• Fiber devices are always configured in a star
  (point-to-point)
• Fiber is either multi-mode or single-mode
• I wouldnt waste fiber on anything less than
  100Mbps.
• Currently Gigabit Ethernet is only available
  using fiber. SX-short wave, LX-long wave

7
Do It Yourself Laser Eye Surgery

• Fiber-optic safety
• Be Careful not to stick yourself with a broken
  fiber
• Two types of signal source, LED and LASER
• NEVER look into a fiber cable if you dont know
  whats connected to the other end

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Is That a Token In Your Ring, or Are You Just
Happy To See Me?

• Token-Ring use a token passing scheme that
  guarantees each device gets a chance to transmit
  data
• FDDI works similar to token-ring but uses
  fiber-optics in a 100Mbps dual counter-rotating
  ring configuration
• Good at surviving a single ring cut
• Expensive

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ATM, Your PIN Please

• Asynchronous Transfer Mode
• For voice, video and data transmissions
• Uses 53-byte cells instead of packets in a
  switching network similar to a telephone system.
• Never really took off in a LAN environment but is
  very popular in the WAN or backbone
• Feature QoS and RSVP
• Big learning curve over Ethernet technologies

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Hubs and Switches and Routers, Oh My!

• Hubs
• Basically a multi-port repeater
• Ethernet limits repeaters to 4 per segment
• Each hub counts as a single repeater
• Modern hubs usually have a way to connect them
  without incurring a repeater hop
• Hubs being replaced by inexpensive switches
• I wouldnt suggest a hub except in the most
  trivial network setup

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Bridges, Switches. Whats The Difference?

• Bridge connects multiple segments of a network
  together
• Bridges can also connect differing topologies
  (e.g. token-ring Ethernet)
• Switches are fast bridges
• Bridges and switches work at layer 2 of the OSI
  model (data link) which means decisions are based
  on MAC addresses

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Routers Schmouters

• Routers connect networks/IP subnetworks together.
• Routers work at Layer 3 of the OSI model
  (Network)
• Routers are smart and can make decisions based on
  IP (or IPX) addresses and can filter based on
  TCP/UDP port numbers

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Trans-topological Devices

• Layer 3 Switches
• a.k.a. fast routers
• Routes IP/IPX/Appletalk only
• VLANS (port, protocol or network-based)
• Layer 4 Switches/Routers
• Makes decisions based on protocol content, e.g.
  URL

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If You Slept Through Everything Else, Pay
Attention Now
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10- Pure Perfection!..

• When would you pick a switch over a bridge?
• When would you pick fiber over copper?
• When would you want to use ATMs RSVP and QoS?