Retrieving the Differentiated Services Field

The DS field defined in [RFC2474] is frequently used in classification on networks implementing the Differentiated Services architecture ([RFC2475]).

idiomatic.tc defines the following fields:

ip_dsfield is the same as ip_tos (see section 2.13.1).

ip_dscp are the upper six bits of ip_dsfield, i.e. the DS field without the ECN bits ([RFC3168]).

Example:

#include "fields.tc"

...
    class (<$ef>)
        if ip_dscp == 0b101110; /* RFC2598 */