GATE IT 2004 | Question: 28

Question

In TCP, a unique sequence number is assigned to each

• A. byte
• B. word
• C. segment
• D. message

Comments

TCP provides a reliable, end to end, bi directional byte stream service to the application using it.

In the byte stream it provides every byte a unique sequence number.

The sequence number field in the TCP header indicates the position in the byte stream of the first byte in the TCP data field.

Example: If the sequence number of the first byte in the byte stream is 1000 and this is the first segment, then the sequence number of this segment will be 1000.

If the segment is 500 bytes long then the sequence number of the next segment will be 1500 and so on.

https://tools.ietf.org/html/rfc793#page-15

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In Datalink Layer sequence number is assigned to every frame whereas in TCP sequence number is assigned to every byte in segment.

So option a is correct.

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TCP is a byte-oriented protocol because it treats data as a continuous stream of bytes rather than individual messages.

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References : https://www.cse.iitb.ac.in/~mythili/teaching/cs348m_spring2015/notes/lec09.txt

Sequence number can be per-packet or per-byte. In TCP, sequence number is based in bytes. Sequence number of packet is the number of  the first byte in the packet. Together with length in the TCP header, we know which packet has which bytes.

Answer 1

a) it should be Byte

 https://en.wikipedia.org/wiki/Transmission_Control_Protocol

Comments

why not segment?

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I think message is correct answer because tcp count each bytes but it assign one sequence number to each message. For furst message sequence number selected randomly then i inext sequence number depemds on acknowledgement

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@mayankorigins25  The sequence number is a counter used to keep track of every byte sent outward by a host.

so the option A is correct.

src:https://www.ibm.com/docs/en/zos-basic-skills?topic=layer-transmission-control-protocol-tcp

Answer 2

Sending more than 1 byte at a time called message stream.
TCP is byte stream  in which 1 byte transferred at a time. 
UDP , SCTP are message stream protocol in which set of bytes transferred at once.

refer @Digviajy Pandey answer's

https://gateoverflow.in/8425/gate2015-3_22

Answer 3

In TCP, a unique sequence number is assigned to each

Because TCP is byte stream protocol and it count each and every byte clearly.

Answer 4

Tcp is a byte oriented protocol.

Every byte is numbered from 2^32 options.

Answer 5

Answer is option A ,As in TCP unique seq no assigned to each byte.

Answer 6

TCP is bytes stream protocols.

TCP have 16 bits sequence number i.e 2^32 bytes.