Field Name

Size (bytes)

Description

Next Header

1

Next Header: Contains the protocol number of the next header after the Fragment header. Used to link headers together as described above.

Reserved

1

Reserved: Not used; set to zeroes.

Fragment Offset

13/8 (13 bits)

Fragment Offset: Specifies the offset, or position, in the overall message where the data in this fragment goes. It is specified in units of 8 bytes (64 bits) and used in a manner very similar to the field of the same name in the IPv4 header.

Res

1/4 (2 bits)

Reserved: Not used; set to zeroes.

M Flag

1/8 (1 bit)

More Fragments Flag: Same as the flag of the same name in the IPv4 header—when set to 0, indicates the last fragment in a message; when set to 1, indicates that more fragments are yet to come in the fragmented message.

Identification

4

Identification: Same as the field of the same name in the IPv4 header, but expanded to 32 bits. It contains a specific value that is common to each of the fragments belonging to a particular message, to ensure that pieces from different fragmented messages are not mixed together.