cs 447 networks and data communication comparison of circuit-switching, virtual-circuit and datagram...
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CS 447 Networks and Data Communication
Comparison of Circuit-Switching, Virtual-Circuit andDatagram Data Transmissions
Department of Computer ScienceSouthern Illinois University Edwardsville
Fall, 2015
Dr. Hiroshi FujinokiE-mail: [email protected]
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Circuit Switching Data Transmission
Signaling Message(Path Setup)
Routing
Routing
Routing
Routing
ACK
ACKACK
ACK
CS 447 Networks and Data Communication
File
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Circuit Switching Data Transmission
Blocked
Dedicated Pipe (path)
CS 447 Networks and Data Communication
No resource sharing (a path is dedicated resource for your transmission)
Path set-up delay is always required
Data will be transferred as a continuous stream of bits
All data (all bits) follow exactly the same path (order of bits transmitted by a sender is preserved at a receiver)
Once data transmission starts, no overhead (i.e., node major switching delay) at each switch on a path (since the path is set up).
Path set-up is required before data transmission starts
Major Properties:
Circuit Switching Data Transmission
Transmission rate is guaranteed (your data will be delivered within certain amount of time).
Highest cost data transmission(= highest quality)
CS 447 Networks and Data Communication
File
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
1 2 3
1
2
3
Datagram Data Transmission
Routing
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
12
3
Datagram Data Transmission
Routing
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
123
Datagram Data Transmission
Routing
Routing
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
1
2
3
Datagram Data Transmission
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
1
2
3
Datagram Data Transmission
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
1
2
3
Datagram Data Transmission
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
12 3
Datagram Data Transmission
123
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Datagram Data Transmission
32
1
32
1
More packets than S1 can handle could arrive
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
3
Datagram Data Transmission
2 13 2 1
Packet Dropped
NACK (Error)
Switches in datagram networksare called “routers”
CS 447 Networks and Data Communication
Path set-up is NOT required before data transmission starts
Network resource is shared
Path set-up delay is NOT required
Data will be transferred as a collection of packets
All packets may not follow the same path (order of bits transmitted by a sender is NOT preserved at a receiver)
After data transmission starts, high overhead (i.e., major switching delay) at each switch on a path (error control and flow control are performed for each packet plus “routing” now have to be performed for every packet).
Major Properties:
Datagram Data Transmission
Transmission rate is NOT guaranteed (“Best-Effort Service).
Lowest cost data transmission (= lowest quality)
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Datagram Data Transmission
3
Dropped packet
NACK (Error)
Even a NACK message could be lost
CS 447 Networks and Data Communication
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Signaling Message(Path Setup)
Routing
Routing
Routing
Routing
ACK
ACKACK
ACK
Virtual Circuit Data Transmission
Path set-up is same as Circuit-Switching
CS 447 Networks and Data Communication
File
Host A
Host X
Host Y
Host B
Switch S1 Switch S2
Switch S3
Switch S4
Switch S5
Shared Pipe
(High priority is to host A - but X can send data as best-effort service)
1 2 3
12
3
1
32
12
31231
1
2
2
Virtual Circuit Data Transmission
CS 447 Networks and Data Communication
Path set-up is required before data transmission starts
Network resource can be shared (because data is transferred as packets)
Path set-up delay is required
Data will be transferred as a collection of packets
All data (all packets) follow exactly the same path (order of bits transmitted by a sender is preserved at a receiver)
After data transmission starts, some overhead (i.e., some switching delay) at each switch on a path (error control and flow control are performed for each packet).
Major Properties:
Virtual Circuit Data Transmission
Transmission rate is guaranteed (your data will be delivered within certain amount of time). Medium cost data transmission (= medium quality)
CS 447 Networks and Data Communication
Factors Circuit-Switching Virtual Circuit Datagram
Examples Public Telephone InternetISDN,Frame Relay
ATM,
Resource Sharing NO YES YES
YES NO NODedicated Paths
ContinuousTransmission
Path-setupin advance
YES
YES
NO NO
YES NO
Busy signalif dest. busy YES YES NO
Major delay Path setup delay Path setup delay Packet routing
CS 447 Networks and Data Communication
Factors Circuit-Switching Virtual Circuit Datagram
No overheadafter TX starts?
YES
Routing delay?
NO
No YES
Guaranteed QualityAdvantagesResource sharing
Applications Delay-sensitive Reliable,Delay-sensitive
Service that needsTo be available 24Hrs
(Packet header)YES
(Packet header)
NO (High)(Almost 0)
Guaranteed Quality Resource sharingLow cost
Disadvantages High cost
Blocking service
Non-blocking
Best Effort ServicePoor security
Text-base
Guaranteed TxBandwidth?
YES YES NO
High cost
Blocking service