Assume that a SONET receiver resynchronizes its clock whenever a 1 bit appears; otherwise, the receiver samples the signal in the middle of what it believes is the bit’s timeslot.

(a) What relative accuracy of the sender’s and receiver’s clocks is required in order to receive correctly 48 zero-bytes (one ATM AAL5 cell’s worth) in a row?

(b) Consider a forwarding station A on a SONET STS-1 line, receiving frames from the downstream end B and retransmitting them upstream. What relative accuracy of A’s and B’s clocks is required to keep A from accumulating more than one extra frame per minute?