#WIRESHARK IP TOTAL LENGTH WRONG FULL SIZE#

The fragment offset is 13 bits and indicates where a fragment belongs in the original IPv4 datagram. This aids in the reassembly of the fragments of a datagram. The identification is 16 bits and is a value assigned by the sender of an IPv4 datagram.

This image depicts the layout of an IPv4 header. The IPv4 source, destination, identification, total length, and fragment offset fields, along with 'more fragments' (MF) and 'do not fragment' (DF) flags in the IPv4 header, are used for IPv4 fragmentation and reassembly.įor more information about the mechanics of IPv4 fragmentation and reassembly, see RFC 791. IPv4 fragmentation breaks a datagram into pieces that are reassembled later.

#WIRESHARK IP TOTAL LENGTH WRONG FULL SIZE#

The receiving station is responsible for the reassembly of the fragments into the original, full size IPv4 datagram. The design of IPv4 accommodates MTU differences because it allows routers to fragment IPv4 datagrams as necessary. The MTU value depends on the transmission link. IPv4 Fragmentation and ReassemblyĪlthough the maximum length of an IPv4 datagram is 65535, most transmission links enforce a smaller maximum packet length limit, called an MTU. This document describes how IPv4 Fragmentation and Path Maximum Transmission Unit Discovery (PMTUD) work and also discusses scenarios that involve the behavior of PMTUD when combined with different combinations of IPv4 tunnels.

Wireshark ip total length wrong