The DS codepoint (DSCP) defines in the packet header the action that any Diffserv-aware system should take on a marked packet. The diffserv architecture defines a set of DS codepoints for the IPQoS-enabled system and diffserv router to use. The Diffserv architecture also defines a set of actions that are called forwarding behaviors, which correspond to the DSCPs. The IPQoS-enabled system marks the precedence bits of the DS field in the packet header with the DSCP. When a router receives a packet with a DSCP value, the router applies the forwarding behavior that is associated with that DSCP. The packet is then released onto the network.
The dlcosmk marker does not use the DSCP. Rather, dlcosmk marks Ethernet frame headers with a CoS value. If you plan to configure IPQoS on a network that uses VLAN devices, refer to Marker Module.