What is physical layer coding violation?

Data link layer translates the physical layers raw bit stream into discrete messages called frames. Now the question is how can a frame be transmitted, so the receiver can recognize the start and end frame?


The techniques we used to find the start and end frame are −

  • Character count
  • Flag byte with byte stuffing
  • Starting and ending flag with bit stuffing
  • Encoding Violation.

Now let us see the Physical layer encoding violation technique.

Physical layer encoding violation

This framing method is used only in those networks in which encoding on the physical medium contain some redundancy.

Some LANs encode each bit of data by using two physical bits that Manchester coding uses.

Here, Bit 1 is encoded into a high-low (10) pair and Bit 0 is encoded into a low-high (01) pair.

The scheme means that every data bit has a transition in the middle, making it easy for the receiver to locate the bit boundaries.

The combinations high-high and low-low are not used for data but are used for delimiting frames in some protocols.

Updated on: 09-Sep-2021

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