TCP/IP Illustrated

Chapter 10. IP Fragmentation and Reassembly

10.1. Introduction

In this chapter we describe the IP fragmentation and reassembly processing that we postponed in Chapter 8.

IP has an important capability of being able to fragment a packet when it is too large to be transmitted by the selected hardware interface. The oversized packet is split into two or more IP fragments, each of which is small enough to be transmitted on the selected network. Fragments may be further split by routers farther along the path to the final destination. Thus, at the destination host, an IP datagram can be contained in a single IP packet or, if it was fragmented in transit, it can arrive in multiple IP packets. Because individual fragments may ...