Hi,everybody I met a problem when i configured diffserv edge router using tc.I want to use "dsmark" qdisc to remark the DS field of the packets going through the router and also use some other qdisc (such as pfifo,red) to implement the EF and AF PHB. My script is listed below: #################################################### #!/bin/bash tc qdisc add dev eth1 handle 1:0 root dsmark indices 64 tc class change dev eth1 classid 1:1 dsmark mask 0x3 value 0xb8 tc class change dev eth1 classid 1:2 dsmark mask 0x3 value 0x68 tc class change dev eth1 classid 1:3 dsmark mask 0x3 value 0x48 tc filter add dev eth1 parent 1:0 protocol ip prio 4 handle 1: u32 divisor 1 tc filter add dev eth1 parent 1:0 protocol ip prio 5 handle 2: u32 divisor 1 tc filter add dev eth1 parent 1:0 prio 4 u32 match ip dst 10.15.35.167/32 match ip dport 0x15 0xffff police rate 1Mbit burst 2K continue flowid 1:1 tc filter add dev eth1 parent 1:0 prio 5 u32 match ip dst 10.15.35.167/32 match ip dport 0x15 0xffff flowid 1:2 tc filter add dev eth1 parent 1:0 prio 4 u32 match ip dst 10.15.35.167/32 match ip dport 0x17 0xffff flowid 1:3 echo EF data ... tc qdisc add dev eth1 parent 1:1 pfifo limit 5 echo AF1 data ... tc qdisc add dev eth1 parent 1:2 red limit 60KB min 15KB max 45KB burst 20 avpkt 1000 bandwidth 10Mbit probability 0.4 echo AF2 data ... tc qdisc add dev eth1 parent 1:3 red limit 60KB min 5KB max 30KB burst 20 avpkt 1000 bandwidth 10Mbit probability 0.4 #################################################### When I ran the script,I got such messge: "EF data ... AF1 data ... RTNETLINK answers: File exists AF2 data ... RTNETLINK answers: File exists " And when I typed the command "tc qdisc ls dev eth1" to see the qdisc information,only the "dsmark" qdisc and "pfifo" qdisc are configured,missing the "red" qdisc: "qdisc pfifo 800b: limit 5p qdisc dsmark 1: indices 0x0040 " What's wrong with my script and how can I correct my script to meet my ends. Waiting for your reply...Thank you.