Circuit Switching and Packet Switching

Question 1

Circuit switching

Answer 1

• 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.

Question 2

Circuit switching examples

Answer 2

• 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 modem

Question 3

Packet switching

Answer 3

• 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?

Question 4

Packet switching examples

Answer 4

• SONET, ATM
• DSL
• Frame relay
• MPLS
• Cable modem
• Satellite
• Wireless