The following fields are defined for the IP version 4 header, as described in [RFC791]:
The definition of the ip_tos octet2.4revised, and is now called the ``Differentiated Services field''. The corresponding definitions are described in section 2.13.2. Additional convenience fields for the traditional and now deprecated use of ip_tos are described in section 2.13.2.
Note that ip_src and ip_dst are of type ``IPv4 address''.
The following flags are used for handling IP fragments: