This happens because the TOS and DSCP are the same field. TOS is the first implementation of QoS on the IP header, DSCP is it's evolution and uses the same field on the IP header, you can use only one of the two at the same time.<div>
<br></div><div>Best Regards, <br><br><div class="gmail_quote">On Wed, May 7, 2008 at 8:59 AM, Vikas <<a href="mailto:topgun9@gmail.com">topgun9@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Concise summary: When I set the TOS to Minimize-Delay the DSCP field<br>
in the packet changes from "Expedited Forwarding" to "Unknown"<br>
<br>
Here are the details:<br>
<br>
Scenario 1: IpTables is not used to set the TOS<br>
<br>
This is what the packet looks like using wireshark:<br>
Internet Protocol, Src: 59.93.192.xx (59.93.192.xx), Dst:<br>
64.62.134.yyy (64.62.134.yyy)<br>
Version: 4<br>
Header length: 20 bytes<br>
Differentiated Services Field: 0xb8 (DSCP 0x2e: Expedited<br>
Forwarding; ECN: 0x00)<br>
1011 10.. = Differentiated Services Codepoint: Expedited<br>
Forwarding (0x2e)<br>
.... ..0. = ECN-Capable Transport (ECT): 0<br>
.... ...0 = ECN-CE: 0<br>
<br>
<br>
Scenario 2: IpTables is used to set the TOS<br>
<br>
Output of $/etc/rc.d/init.d/iptables status<br>
Table: mangle<br>
Chain PREROUTING (policy ACCEPT)<br>
num target prot opt source destination<br>
<br>
Chain INPUT (policy ACCEPT)<br>
num target prot opt source destination<br>
<br>
Chain FORWARD (policy ACCEPT)<br>
num target prot opt source destination<br>
1 TOS udp -- <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> udp<br>
dpts:5060:5069 TOS set 0x10<br>
2 TOS tcp -- <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> tcp<br>
dpts:5060:5069 TOS set 0x10<br>
3 TOS udp -- <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> <a href="http://0.0.0.0/0" target="_blank">0.0.0.0/0</a> udp<br>
dpts:10000:20000 TOS set 0x10<br>
<br>
This is what the packet looks like using wireshark:<br>
Internet Protocol, Src: 59.93.192.xx (59.93.192.xx), Dst:<br>
64.62.134.xxx (64.62.134.xxx)<br>
Version: 4<br>
Header length: 20 bytes<br>
Differentiated Services Field: 0xb0 (DSCP 0x2c: Unknown DSCP; ECN: 0x00)<br>
1011 00.. = Differentiated Services Codepoint: Unknown (0x2c)<br>
.... ..0. = ECN-Capable Transport (ECT): 0<br>
.... ...0 = ECN-CE: 0<br>
<br>
<br>
I have no idea what am I doing wrong.<br>
<br>
Here is some reference reading I did:<br>
<a href="http://www.tucny.com/dscp&tos" target="_blank">http://www.tucny.com/dscp&tos</a><br>
<br>
Any pointers in the right direction will be very much appreciated.<br>
<br>
Thanks for your time,<br>
<br>
Sysadmin<br>
<a href="http://www.debtconsolidationcare.com" target="_blank">http://www.debtconsolidationcare.com</a><br>
Internets First get out of debt community<br>
<br>
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