Circuit Switching and Packet Switching

Circuit Switching
  • Circuit is established between endpoints before data passes
    • Like a phone call
  • Nobody else can use the circuit when it's idle
    • Inefficient use of resources
  • Connection is always there
    • It's mine. You can't use it.
  • Capacity is guaranteed
    • You'd better use it, you paid for it.
  • POTS (plain old telephone service) and PSTN (public switched telephone network)
  • T1/E1/T3/E3
    • Create a circuit between two sites
  • ISDN
    • Use a phone number to call another ISDN modern
Packet switching
  • Data is grouped into packets
    • Voice, data, video, etc.
    • like a network
  • The media is usually shared
    • Someone else can use it, even when you don't
  • One connection may have more bandwidth allocated than another
    • How much money would you like to spend?
  • SONET, ATM
  • DSL
  • Frame relay
  • MPLS
  • Cable modem
  • Satellite
  • Wireless



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