Why UDP is faster than TCP in Computer Networks - Visual Breakdown

Concept Flow - Why UDP is faster than TCP

Start Sending Data

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UDP: Send Packet Immediately

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No Waiting for Acknowledgment

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No Retransmission or Ordering

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Data Arrives Faster but May Lose Packets

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Start Sending Data

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TCP: Send Packet and Wait for ACK

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If ACK Received, Send Next Packet

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If No ACK, Retransmit Packet

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Ensures Reliable, Ordered Delivery

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Data Arrives Slower but Reliable

UDP sends data without waiting for confirmation, making it faster but less reliable. TCP waits for acknowledgments and retransmits lost data, ensuring reliability but adding delay.

Execution Sample

Computer Networks

UDP:
Send packet -> No wait -> Next packet

TCP:
Send packet -> Wait ACK -> Next packet or Retransmit

Shows how UDP sends packets continuously without waiting, while TCP waits for confirmation before sending more.

Analysis Table

Step	Protocol	Action	Wait for ACK?	Retransmit if Lost?	Result
1	UDP	Send packet 1	No	No	Packet sent immediately
2	UDP	Send packet 2	No	No	Packet sent immediately
3	TCP	Send packet 1	Yes	Yes	Wait for ACK
4	TCP	ACK received for packet 1	N/A	No	Send packet 2
5	TCP	Send packet 2	Yes	Yes	Wait for ACK
6	TCP	ACK lost for packet 2	N/A	Yes	Retransmit packet 2
7	TCP	ACK received for packet 2	N/A	No	Send packet 3
8	UDP	Packets may arrive out of order or lost	N/A	N/A	Faster but less reliable
9	TCP	Packets arrive in order and reliable	N/A	N/A	Slower but reliable

💡 UDP sends continuously without waiting; TCP waits for ACK and retransmits lost packets, causing delay.

State Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	After Step 7	Final
UDP Packet Sent Count	0	1	2	2	2	2	2	2	2
TCP Packet Sent Count	0	0	0	1	1	2	2	3	3
TCP Waiting for ACK	No	No	No	Yes	No	Yes	Yes	No	No
TCP Retransmission Occurred	No	No	No	No	No	Yes	No	No	No

Key Insights - 3 Insights

Why does UDP send packets without waiting for acknowledgment?

UDP is designed to be simple and fast, so it sends packets immediately without waiting, as shown in steps 1 and 2 of the execution_table.

Why does TCP sometimes retransmit packets?

TCP waits for an acknowledgment (ACK) for each packet. If the ACK is lost (step 6), TCP retransmits the packet to ensure reliability.

Why is TCP slower than UDP?

TCP waits for ACKs and retransmits lost packets, adding delay (steps 3-7), while UDP sends continuously without waiting, making it faster but less reliable.

Visual Quiz - 3 Questions

Look at the execution_table at step 3. What is TCP doing?

A Sending packet 2 immediately

B Sending packet 1 and waiting for acknowledgment

C Retransmitting packet 2

D No action

💡 Hint

Refer to the 'Action' and 'Wait for ACK?' columns at step 3 in execution_table.

At which step does TCP retransmit a packet due to lost acknowledgment?

A Step 6

B Step 2

C Step 4

D Step 8

💡 Hint

Look for 'Retransmit packet 2' in the 'Action' column in execution_table.

According to variable_tracker, how many packets has UDP sent after step 2?

A 0

B 1

C 2

D 3

💡 Hint

Check 'UDP Packet Sent Count' after step 2 in variable_tracker.

Concept Snapshot

UDP sends data without waiting for confirmation, making it faster but less reliable.
TCP waits for acknowledgments and retransmits lost packets, ensuring reliability but adding delay.
UDP is good for speed and simplicity.
TCP is good for reliable, ordered delivery.
UDP does not guarantee packet arrival or order.
TCP guarantees delivery and order but is slower.

Full Transcript

This visual execution shows why UDP is faster than TCP. UDP sends packets immediately without waiting for acknowledgments or retransmitting lost packets. This makes UDP fast but less reliable, as packets can be lost or arrive out of order. TCP, on the other hand, sends a packet and waits for an acknowledgment before sending the next one. If the acknowledgment is lost, TCP retransmits the packet to ensure reliable delivery. This waiting and retransmission add delay, making TCP slower but reliable. The execution table traces each step of sending packets for both protocols, showing UDP's continuous sending and TCP's waiting and retransmission. The variable tracker shows how many packets each protocol has sent and TCP's waiting state. Key moments clarify common confusions about waiting for acknowledgments and retransmissions. The quiz questions help reinforce understanding by asking about specific steps and variable values. Overall, UDP is faster because it skips the waiting and retransmission steps that TCP uses to guarantee delivery.