It's because DSCP is not just an extention of the TOS with a one to one mapping. In other words, 0x08 (DSCP) is not 0x08 (TOS). Take a look at the bitsdefinition of both.
Ramin On Mon, Apr 15, 2002 at 04:05:34PM -0700, Alex wrote: > Hi gurus > > I recently tried to mangle the DSCP value for all traffic coming into eth1 > to > MAX THROUGHPUT like so > > $ipt -t mangle -A PREROUTING -i eth1 -j DSCP --set-dscp 0x08 > > when I run the firewall script it doesn't complain and > /etc/rc.d/init.d/iptables status > gives me this : > > Chain PREROUTING (policy ACCEPT) > target prot opt source destination > MARK tcp -- anywhere anywhere tcp dpt:http > MARK set 0x1 > DSCP all -- anywhere anywhere DSCP set 0x08 > > so I assume the syntax and all is correct. Yet, if I capture packets on eth1 > they all still have the default TOS value of 0x00. > > where am I wrong ? > > thx Alex >
