CS 447 Networks and Data Communication Comparison of Circuit-Switching, Virtual-Circuit and Datagram Data Transmissions Department of Computer Science.

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]


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


File

Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5


Blocked

Dedicated Pipe (path)


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:


Transmission rate is guaranteed (your data will be delivered within certain amount of time).

Highest cost data transmission(= highest quality)


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


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

12

3


Routing


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

123


Routing

Routing


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

1

2

3



Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

1

2

3



Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

1

2

3



Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

12 3


123


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5


32

1

32

1

More packets than S1 can handle could arrive


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5

3


2 13 2 1

Packet Dropped

NACK (Error)

Switches in datagram networksare called “routers”


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:


Transmission rate is NOT guaranteed (“Best-Effort Service).

Lowest cost data transmission (= lowest quality)


Host A

Host X

Host Y

Host B

Switch S1 Switch S2

Switch S3

Switch S4

Switch S5


3

Dropped packet

NACK (Error)

Even a NACK message could be lost


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


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



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:


Transmission rate is guaranteed (your data will be delivered within certain amount of time). Medium cost data transmission (= medium quality)


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


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

CS 447 Networks and Data Communication Comparison of Circuit-Switching, Virtual-Circuit and Datagram Data Transmissions Department of Computer Science.

Documents

CS 447 Networks and Data Communication Comparison of Circuit-Switching, Virtual-Circuit and Datagram Data Transmissions Department of Computer Science.