Because of fragmentation, an IP datagram can arrive in several pieces, not necessarily in the correct order. The IP entity at the receiving end system must accumulate these fragments until the original datagram is reconstituted. a. Consider that the IP entity creates a buffer for assembling the data field in the original datagram. As assembly proceeds, the buffer will contain blocks of data and "holes" between the data blocks. Describe an algorithm for reassembly based on this concept. b. For the algorithm in part (a), it is necessary to keep track of the holes. Describe a simple mechanism for doing this.