hi, i am currently working on a project on "design of diffserv testbed in linux". i am using tc utility of iproute2 for it. The qdisc dsmark used for marking the DS codepoint at the first hop router makes number of classes depending on the indices given in the command. But i am not clear how at the first hop router does scheduling takes place. what i mean is if i have two flows, whose packets have been marked by different DSCP, then how to set the order in which they will leave the interface i.e., how to prioritize them . my code at the first hop router is : tc qdisc add dev eth0 handle 1: root dsmark indices 4 tc class change dev eth0 classid 1:1 dsmark mask 0x0 value 0xb8 tc class change dev eth0 classid 1:2 dsmark mask 0x03 value 0x58 tc class change dev eth0 classid 1:3 dsmark mask 0x0 value 0x0 tc filter add dev eth0 parent 1: protocol ip prio 1 u32 match ip dst 144.16.95.66/32 flowid 1:1 tc filter add dev eth0 parent 1: protocol ip prio 1 u32 match ip dst 10.219.80.1/32 flowid 1:2 tc filter add dev eth0 parent 1: protocol ip prio 2 u32 match ip dst 0/0 flowid 1:3 with this code running, i used ethereal to se the DSCP field. My packets were marked properly but i don't how they were scheduled at the interface.What else should i add to this code so that my packets marked with 0xb8 are prioritized compared to other flows or is there some default priority built with respect to DS field? can someone help me out !! Amita Maheshwari