in Computer Networks
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3 votes
3 votes

In the Ethernet, which field is actually added at the physical layer and is not part of the frame.

  1. Preamble
  2. CRC
  3. Address
  4. Location
in Computer Networks
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3 Answers

10 votes
10 votes
Best answer

preamble and SFD use as physical layer header 

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Simple doubt,

Please help me to understand this,

We know Ethernet operates at Data Link Layer, so an Ethernet frame will be formed completely at Data Link Layer itself, then how Physical Layer header is part of Ethernet?

Iam confused here, please correct me if i am wrong.
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Physical layer header is not part of the frame.
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 The layers work in order. Any message received by a host will pass through like this: $PL\rightarrow DLL\rightarrow NL\rightarrow TL\rightarrow AL$

Ethernet frame is not "formed" at DLL, but rather DLL attaches some stuff to the bit-streams arriving through PL and calls that a frame.

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9 votes
9 votes

The first field(Preamble) of 802.3 frame contains 7 bytes of alternating 0s and 1s that alerts the receiving system to the coming frame and enables it to synchronize its input timing. Preamble is added at the physical layer and is not part of the frame.

3 votes
3 votes
Preamble. It only serves as a header at physical layer but not actually a part of frame and is used for synchronization of input.
Answer:

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