Computers, Networks

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Computers, Networks

• Networks

Pierre Vincent
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Summary

• Communication areas
• Physical level
• Data level
• Network - InterNetwork
• General trends

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Communication areas
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Communication areas

• LAN (Local Area Network)
• WAN (Wide Area Network)
• MAN (Metropolitan Area Network)

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Use of networks

• Data exchange
• File sharing
• transaction oriented applications
• messaging

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Elements of a network

• Networks cables connectors equipment
  computers
• Equipment bridges routers computers
• Computers stations servers
• Interconnected networks networks routers
  telecommunication lines

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Communication needs

• Local transfers, internal to the company
• 1980 19200 bits/sec,
• today 10 to 100 megabits (multiplied by 500).
• Remote transfers, external to the enterprise
• 1980 2400 bits /sec,
• today 64 kbits (multiplied by 20)

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Transmission rates

• Low rates
• remote alarm
• remote control
• voice
• fax
• data
• Average rates
• hi-fi sound
• picture phones
• image
• High rates
• video
• tele-diagnostics
• Very high rates
• high quality video
• video distribution
• tele-teaching

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Communications Problems

• Differences between internal and external
  throughput
• With video, the throughput demands become
  enormous
• A generalised network must support different
  levels of communications

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Different layers

• Physical Cable, network
• Data level 2 protocols
• Network core equipement, routers
• Transport, Applications Station - server
• Tools browser, server, etc...

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Physical level
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Network topologies

• Bus
• coaxial cable thin or thick
• all station are on the same cable
• Star requires the connection to a hub
  (concentration point)
• twisted pair
• optical fibre
• wireless
• Ring
• Point to point local links (star configuration)
• switches
• hubs
• Packet switching (FR, X25 ATM)
• Switches

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Wiring features

• Maximum length
• Distance between stations
• Propagation delay
• Dedicated or shared support

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Communication cards

• LAN network
• Ethernet (10 mega-100 mega - Gigabit)
• Token Ring (4mega, 16 mega)
• FDDI (100 mega)
• WAN
• Fax-modem (from 9.6Kbits to 56.8Kbits)
• X25, FR, ATM
• Isdn (2B D)
• Gsm (voice or data channel)

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Ethernet Wiring

• Thin Ethernet (Thin-BNC)
• Thick Ethernet (Thick-AUI)
• Unshielded Twisted Pair (UTP3-4-5 / RJ45)
• Optical fiber

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Equipment for Ethernet networks

• UTP
• Hubs
• trafic concentrator
• Thick
• Repeaters
• Transceivers
• Fanout
• hub for thick ethernet
• allows to share a transceiver connection
• Thin
• BNC connectors

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Ethernet Maximum length without repeater
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Ethernet Wiring

• Minimum frame size
• 10 megas 64 bytes min (Manchester)
• 100 megas 64 bytes min, distances divided by 10
• 4B-5B coding
• 1 Giga 512 bytes min, distances idem 100 mégas
• 8B-10B coding

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Data level
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Local Area Networks LAN

• Filtering bridges
• Switching hubs
• Access methods
• Ethernet CSMA-CD
• Token Ring, FDDI token
• Logical link control protocol
• HDLC like
• Header-data-end of frame (checksum)
• The header involves source and destination
  address
• Ethernet Mac address on 6 bytes

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Wide Area Networks WAN

• Point-to-point
• leased lines (LL)
• Multi - points
• one by time
• telephone network, Isdn circuit switching
• a physical connection is established(potential
  multi-points)
• simultaneous connections
• time multiplexing
• communication by VC (packets or cells)
• X25, Frame Relay, ATM

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Wide Area Networks WAN
New supports

• Satellites VSAT
• TV cable

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Equipment

• Bridge
• Switching hubs
• Remote access servers
• Switches
• Multiplexers

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Bridge (level 2)

• Enables
• the linking of the existing LANs
• load distribution
• Allows an increase in the length of networks
• Physical and logical insulation of the
  subnetworks
• Increases reliability by insulating subnetworks
• Possibilities of access controls

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Bridge (level 2)

• Modification of support
• Coaxial - twisted pair (4 pairs, 2 useful)
• Infra red - optical
• Works at the data link level
• Evolution to the switching-hubs
• Spanning tree
• Different working mode "Store and
  forward","switching on the fly"

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Bridge Filtering algorithm

• Bridge
• learns the position of the different stations
• Reads the source address in the Ethernet frame
  and stores it in an address table
• Other functions
• Modification of the address table entries
• Elimination of the old entries (age)
• Elimination of the loops by the help of the
  spanning tree algorithm

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Network - Internetwork
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X25 , IP, IPX, XNS Protocols
Equipment

• IP or IPX router
• X25 Switch
• Frame relay switch
• ATM switch

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Router

• Routers are used for IP networks
• They are to an IP network what the switches are
  to the phone network
• Connect networks with different IP addresses

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Overview
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Communication equipment

• Internal to the network
• bridges
• routers
• remote access servers
• End equipement
• workstations, personnal computers, network
  computers
• Web server

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System Integrationwith Tcp/Ip and the Web

• The TCP/IP protocol allows the integration of
  different
• communication supports
• communication hardware
• computers
• operating systems
• applications
• Management of interconnection and heterogeneity

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General trends
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Different aspects

• Communication hardware administration
• Network operating system administration
• Operating system administration
• Business administration

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Internet trafic
TransAtlantic

• Increase of Internet trafic on transatlantic
  optical fibers
• 1990 1 of transatlantic trafic
• 1998 50 of transatlantic trafic
• 2002 99 of transatlantic trafic???
• Increase of externel trafic vs internal trafic

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General trends

• UTP5, Ethernet, Switching Ethernet
• Ethernet 10-100-1G
• Generalisation of TCP-IP

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Communication hardware market

• Expanding market,
• bridge, switching hubs
• routers
• Important market in communication equipment or
  boards
• modem
• networks
• micro routers