GATE IT 2004 | Question: 22

Question

Which one of the following statements is FALSE?

• A. Packet switching leads to better utilization of bandwidth resources than circuit switching
• B. Packet switching results in less variation in delay than circuit switching
• C. Packet switching requires more per-packet processing than circuit switching
• D. Packet switching can lead to reordering unlike in circuit switching

Comments

https://www.geeksforgeeks.org/gate-gate-it-2004-question-22/

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set2018 The virtual circuit approach in Packet Switching is not used in the Internet.

It is majorly used in X.25 and Asynchronous Transfer mode.

 

So, by default consider the connectionless version of Packet Switching (Datagram approach)

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(2) Packet switching results in less variation in delay than circuit switching. False

Packet switching introduces variable queuing delays, network congestion, and route changes, leading to higher delay variation (jitter) compared to Circuit switching, where a dedicated path ensures consistent delay.

 

Answer 1

Answer is B.

In circuit switching, a fix bandwidth is allocated to each connection, e.g. $64$ $Kb/s$ allocated to each each phone call.

In circuit switching each connection has a dedicated circuit or channel all the way along the path and the circuit is not shared with anyone else.

Thus in circuit switching each call has its own private, guaranteed, isolated data rate from end to end.So we can say that every connection or flow is independent of others.

In the case of packet switching, all flows share the full channel capacity by statistical multiplexing.

So, the bandwidth allocated to each flow depends upon the number of concurrent flows & network traffic.

In packet switching if we know the type of link we are using, the bandwidth allocated, the packet size for any flow then we can calculate the Propagation Delay & Transmission Delays.

But, Queueing Delay is a random variable that depends upon the number of packets arriving at the same time at any switch.

It is the only random variable in our end to end delay expression.All other delays can be calculated precisely if we have enough information about the flows.

So, queueing adds unpredictable & variable delays in the packet switching.

There are delays like propagation delay etc. in circuit switching but they have a very small variance because of independence, privacy & bandwidth guarantees.

Comments

In circuit switching processing is  done at time of connection established but data transfer phase simply data transfer.in packet switching data processed  every router like store data forward data according to routing algorithm. So option C is true.

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What about congestion in circuit switching & packet switching? I think packet switching have more chance of congestion when compared to circuit switching?

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Chetnawadhwa

i think packetization and transmission delay for all intermediate devices..
it stop and forward the packet.

Answer 2

A) in Circuit switching resources (path or in other words Bandwidth)are reserved , it's like suppose you have to reach Z from A and you have many paths and there are many other passengers who also have to reach Z from A. Here in circuit switching you choose some path prior to your journey and then say everyone , hello! you all i'm using this-this path and no one can use the same path , it's mine until i reach Z so in that way even if you don't utilize your path properly , no one can claim to snatch it from you..While in packet switching you're a friendly person , here you say , come on you all brothers we all have to reach Z and we will share paths. our Telephone connection follows circuit switching while Internet follows packet switching.

B)Here he is taking about the delay  between data units. in circuit switching as path is pre determined even before journey so during journey there are no interrupts like it's not an un-planned journey..everything is well planned while Packet switching is an unplanned journey , during the path you have to make many decisions like , now what path we should follow....IP is a connection less protocol so to get some reliability here Routers are Best effort delivery protocols when they receive any packet they store them for temp time and know the best path for them through routing table and them forward them to right interface.So this store and forward is kind of DELAY...which doesn't exist in circuit switching....

C)Here we have to focus carefully , what he is asking ...Circuit switching involve three steps to reach it's destination 1) connection establishment 2) data transfer 3) connection release while packet switching only involve one step 'data transfer' , no connection establishment and release step here  and it's quite common as there is no pre planned path...here he is not asking total time but he is asking per packet processing time , which means during traveling (Data transfer phase) and we know due to store and forward packet switching consume more time than circuit switching..

D) of course when packets are following different-2 paths , who know which packet will reach first ,,,so in that way may we they reach out of order...in circuit switching everything is in order...they only have to worry before journey to plan it , during journey they chill...

so B  is answer in that way...

Comments

Awsome explainations.......

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Nice explanation Brother.

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Thank for such brief explanation

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Nice explanation. This should be the selected Answer !!!!!

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@rohan30

check the times when those two answers were uploaded :)

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this should be selected as best answer :)

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fantastic explanation.

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excellent answer , thanks:)

Answer 3

To answer this question, we'd assume the default technique of Packet Switching, which is Datagram mode.

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Packet switching leads to better utilization of bandwidth resources than circuit switching

Correct, Because in circuit switching, we have a dedicated connection (until it's termination), which will be reserved for the end machines even when they don't transfer data. This wastes bandwidth.

Since Packet Switching is connectionless, bandwidth isn't wasted on dedicated paths.

 

Packet switching results in less variation in delay than circuit switching

Incorrect. In Circuit switching, all the data is sent on the same, dedicated/reserved path. Ideally, all the data takes equal time to reach the destination.

Packet switching may forward packets via different paths (which will have different path lengths) and hence we'd observe a significant variation in delay.

 

Packet switching requires more per-packet processing than circuit switching

Correct. Each packet in packet switching goes through the "store and forward" phase at each switch, which requires higher cost/computation/processing.

 

Packet switching can lead to reordering unlike in circuit switching

Correct. Since each packet may take a different path to reach the destination in Packet switching, the packets taking the shorter paths will reach earlier.

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Option B

Answer 4

B should be the answer

Answer 5

B.

Variation in delay depends on router.

There is no guarantee that if we employ packet switching over circuit switching then we will tend to receive fruitful results over packet transmission and less delay.

It is inherently a false statement

Answer 6

Option A: TRUE
Reason: In packet switching, the bandwidth is shared among multiple users, leading to better utilisation. In circuit switching, the entire bandwidth is reserved for one connection, even if no data is being transmitted.

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Option B: FALSE
Reason: In circuit switching, once a path is established, it remains fixed, and the delay is essentially constant. In packet switching, packets may take different routes to reach the destination. This causes variable delay, as the number of intermediate nodes can change.

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Option C: TRUE
Reason: In packet switching, every packet carries a header containing addressing and control information, which must be processed at each hop to determine the next path. In circuit switching, the path is predetermined during connection setup, so data flows without per-packet headers. Thus, more processing time is required in packet switch.

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Option D: TRUE
Reason: In packet switching, packets may travel through different routes in the network and can arrive out of order at the destination. Reordering may then be required at the receiver’s end.

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✅ Final Answer: Option B is FALSE