January 2008
Intermediate to advanced
624 pages
14h 16m
English
When a source host or a router must transmit an IP datagram on a link and the MTU of the link is less than the IP datagram’s size, the IP datagram must be fragmented. When IP fragmentation occurs, the IP payload is segmented and each segment is sent with its own IP header.
The IP header contains information required to reassemble the original IP payload at the destination host. Because IP is a datagram packet-switching technology and the fragments can arrive in a different order from which they were sent, the fragments must be grouped (using the Identification field), sequenced (using the Fragment Offset field), and delimited (using the More Fragments flag).
Figure 5-6 shows the fragmentation fields in the IP header, ...