6' Network Architecture

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6. Network Architecture
Network and Telecommunications
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Past

• Arcnet - token passing along a bus, later also a
  star - 1977, 2.5 mbps, old technology based on
  coax
• ATT Starlan - 1/10 mbps, star topology, similar
  ethernet
• Macs using Localtalk - described later.

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Present

• Ethernet - IEEE 802.3
• speed- 10 mbps, hubs, switches (new)
• Channel access method - csma/cd
• 10base5 (thick coax, bus), 10base2 (thin coax,
  bus)
• 10baseT (UTP, star), 10baseF (fiber, star).
• 1 Predominant network architecture in lans today
• Baseband

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Present - Ethernet

• Topology- physical bus (bi-directional) or star
• packets passed to all stations (except for
  switch).
• Star topology - can connect hubs/switches to each
  other either via a bus backbone, or cascading.
• Mature standard, many vendors, interoperability,
  inexpensive.
• Developed 1980 -Intel, Dec, Xerox
• Non-Deterministic. Good with low/medium level of
  traffic (bad at high levels of traffic).
• Works with many protocols (tcp/ip, appletalk,
  ipx/spx)
• Useful in backbones and within a lan and over a
  wan.

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Rules
IEEE 802.3
10 base 2
10 base 5
- 4 repeaters max
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Star Ethernet (ieee 802.3 10 base T)

• 100 meters from hub or switch using UTP (2 km
  with fiber)
• 1024 nodes max. 4 hubs max cascaded
• (10baseF/100baseF) Fiber over 2km

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Ethernet Address

• 48bit (6 bytes)
• unique in world, burnt into NIC
• IEEE central administered
• ex 01FFA1BD5A3C (12 hex digits)

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Ethernet Packet
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Note

• Different Network Architectures (like Ethernet,
  Token Ring, ATM, FDDI, and others)
• All use different packets (different size,
  fields, info)
• All use different addressing schemes

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Token Ring

• IEEE 802.5
• speed - 4/16 mbps
• channel access method-token passing
• uni-directional
• topology- logical ring/physical star (could
  possibly be a physical ring or bus)
• mau (multistation access unit)
• developed by IBM 1985
• Deterministic (predictable). No collisions.
  

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More Token Ring

• Primarily shielded TP cables.
• token (3 byte special packet).
• Token Ring NIC.
• "IBM SHOPS".
• Good Perf. at High Traffic levels.
• disadv - more expensive, overhead of token, less
  vendor support

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Token Ring Mau
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Macs!

• Appleshare NOS
• Appletalk - protocol
• Localtalk - original mac cabling scheme

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Macs! Part 2.

• Appletalk over Localtalk (old days)
• simple network, share files, printers...
• peer to peer primarily, can be client/server
• slow, 230 k (slowwwwwww)
• built in NOS, built in network connector
• (localtalk port - uses t.p. cable)
• csma/ca, bus topology

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Macs! Part 3

• localtalk - appletalk over localtalk cable (230k)
  (more in past)
• ethertalk - appletalk over ethernet (10 mbps)
  (today!)
• tokentalk - appletalk over token ring (4/16 mbps)
  (today!)

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Today

• Networks need greater bandwidth than 10
  Mbps..this leads to 100 Mbps and greater Network
  Architectures. Why?
• more users on lan
• more bandwidth intensive applications (web
  browsers, video, multi-media, audio, peer to
  peer apps, etc..)
• faster servers/clients

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Fast Network Architetures (Today and Future)

• FDDI - Fiber Distributed Data Interface
• - 100 Mbps, token passing on a fiber
  ring (dual ring)
• - good backbones, but expensive, not very
  popular
• - high bandwidth
• CDDI - Copper DDI
• SDDI - Shielded DDI

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The Last Information Pertaining to Today.

• Fast Ethernet - 100 mbps. UTP wire (category 5
  normally). Like ethernet, special nic's and
  switches are needed. Compatible with ethernet.
  100BaseT. csma/cd, star topology. Very Popular
  Today. Also 100baseF (fiber). Used within lans
  and backbones.
• Full Duplex Fast Ethernet- 200mpbs...no
  collisions, switch based
• (vs. Half-Duplex)

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Something Different! Even Higher Speeds

• ATM - Asynchronous Transfer Mode
• - 155 mbps - up to 600 mbps
• - mostly used within WANS...backbones. (not
  within lans)
• Gigabit Ethernet - 1 gig per second. 1000BaseT
• Super Fast. New standard. Backbones.
• Maybe used with servers within lan
• Backward compatible, primarily fiber (copper
  short runs)
• HSTR - High Speed Token Ring - 100 mbps (too
  little too late?)
• Fibre Channel - 100 mbps speeds.

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Annual Cow Day Races!

• In todays race is
• Ethernet
• Localtalk
• Fast Ethernet
• ATM
• Gigabit Ethernet
• Place your bets!!

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GO!
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Other Lan Devices

• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets
• repeater - simply regenerate and pass all packets

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Other Lan Devices

• nic - 10 meg ethernet nics. 10/100 ethernet
  nics. 10/100/1000 ethernet nics. token ring
  nics, etc.. (nics dependent on network arch.)
• hub - star configuration. Take a packets and
  pass to
• all connecting ports simultaneously.
  (like a repeater). SHARED. Ethernet. 10 Mbps
  port hubs, 100 Mbps port hubs.
• mau - token ring. Star configuration. Pass a
  packet in
• a logical ring.

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Some More Lan Devices

• switches (switching hubs) - like a hub, used in
  ethernet,
• but instead of passing a packet to all ports,
  it reads
• the destination address and passes the packet
  to only the
• port in question. Lessens traffic everyone
  sees and lessens
• collisions. Can open up multiple connections
  (switches)
• simultaneously. DEDICATED PIPE.
• Switches come with 10 mbps ports, or a combo of
  10/100 mbps ports, or all 100 mbps ports. Gig
  switches are now available as well (10/100/1000
  ports).
• New technology, more expensive, but better
  (faster, less traffic, less collisions, more
  secure ) than hubs.

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Some More Lan Devices

• routers, bridges, gateways - part of WAN.

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Other Terms That Were Not Mentioned Earlier

• runts - small junk packets, less then 60 bytes in
  ethernet caused by collisions or bad hardware.
• jabber - excessive electrical noise on cable,
  caused by bad hardware or cable problem
• MAC address - Media Access Control Address - when
  talking ethernet, the MAC address Ethernet
  Address. Low level address.

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Other Terms That Were Not Mentioned Earlier

• Traffic Levels - rules of thumb. If traffic over
  50 on ethernet, needs watching. Under 50 is
  fine. Over 80-90 may collapse network
• Collision Level - rule of thumb. If collisions
  less then 5 of traffic, on ethernet, then all is
  fine. 5-10 needs watching. Over 10 can be a
  problem.

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Last Terms

• unicast-server sends packet to just one client
• broadcast - server sends packets to all clients
  (special broadcast address), they all must listen
• multicast-server sends packet to a group of
  clients, client decides whether to listen

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The Last Thing

• Ether-n.
• 1. A. A colorless volatile organic liquid used
  as an anesthetic or solvent. Also, called
  diethyl ether, ethoxyethane. Chem. Formula
  C2H5OC2H5.
• B. Any of a class of organic compoundswith
  similarstructure to this, having an oxygen joined
  to two alkyl etc. groups.
• A clear sky the upper regions of air beyond the
  clouds.
• A. A medium formerly assumed to permeate space
  and fill the interstices between particles of
  matter
• B. A medium through which electromagnetic waves
  were formerly thought to be transmitted

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Dr. Metcalfs Ethernet Design
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?

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THE END