The DS field defined in [] is frequently used in classification on networks implementing the Differentiated Services architecture ([]).
idiomatic.tc defines the following fields:
ip_dsfield is the same as ip_tos (see section
).
ip_dscp are the upper six bits of ip_dsfield, i.e. the DS field without the ECN bits ([]).
Example:
#include "fields.tc" ... class (<$ef>) if ip_dscp == 0b101110; /* RFC2598 */