Question 58 – ISRO-2007

→ Bit stuffing is most easily described as insertion of a 0 bit after a long run of 1 bits.
→ In SDLC the transmitted bit sequence “01111110” containing six adjacent 1 bits is the Flag byte.
→ Bit stuffing ensures that this pattern can never occur in normal data, so it can be used as a marker for the beginning and end of frame without any possibility of being confused with normal data.
→ Bit stuffing is the insertion of non information bits into data. stuffed bits should not be confused with overhead bits. Overhead bits are non-data bits that are necessary for transmission (usually as part of headers, checksums etc).