Referring to the process by which a switch or router breaks up or divides a large datagram. If the receiving network cannot accommodate a datagram of a given total length, it must be fragmented.There must be some form of fragmentation control to ensure that the fragments can be re-associated when they exit the network and that the datagram can be reconstituted. In Internet Protocol version 4 (IPv4), for example, fragmentation control requires that each fragment contain a copy of an identification PBX or Router Edge Office Voice or Data Terminals Access Line 2-Wire 2-Wire 4-Wire 4-Wire Switch Tandem Office Switch Edge Office Access Trunk Switch 4-Wire 4-Wire field and certain other fields in the header.The IPv4 header contains a fragment offset field that identifies where a fragment fits in the complete set of fragments that comprise the original datagram. This field is used to sequence the fragments correctly, as they may arrive at the destination device out of sequence. See also datagram, IPv4, IPv6, network, router, and switch.