a link connecting the edge nodes of two domains.

an entity which selects packets based on the content of packet headers according to defined rules.

a specific value of the DSCP portion of the DS field. Recommended code points should map to specific standardized PHBs.  Multiple code points may map to the same PHB.   

     a device that performs dropping.

      the process of discarding packets based on specified rules.

    a node which implements IPv4 Precedence as defined in [RFC791,RFC1812] but which is otherwise not DS-compliant.

     The implementation of one or more per-hop behaviors according to a particular algorithm.

 a single instance of an application-to-application flow of packets which is identified by source address, destination address, protocol id, and source port, destination port (where applicable).

a device that performs marking.

the process of setting the DS code point in a packet based on defined rules; pre-marking, re-marking.