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[topgun9 at gmail.com]

Concise summary: When I set the TOS to Minimize-Delay the DSCP field
in the packet changes from "Expedited Forwarding" to "Unknown"

Here are the details:

Scenario 1: IpTables is not used to set the TOS

This is what the packet looks like using wireshark:
Internet Protocol, Src: 59.93.192.xx (59.93.192.xx), Dst:
64.62.134.yyy (64.62.134.yyy)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0xb8 (DSCP 0x2e: Expedited
Forwarding; ECN: 0x00)
1011 10.. = Differentiated Services Codepoint: Expedited
Forwarding (0x2e)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Scenario 2: IpTables is used to set the TOS

Output of $/etc/rc.d/init.d/iptables status
Table: mangle
Chain PREROUTING (policy ACCEPT)
num target prot opt source destination

Chain INPUT (policy ACCEPT)
num target prot opt source destination

Chain FORWARD (policy ACCEPT)
num target prot opt source destination
1 TOS udp -- 0.0.0.0/0 0.0.0.0/0 udp
dpts:5060:5069 TOS set 0x10
2 TOS tcp -- 0.0.0.0/0 0.0.0.0/0 tcp
dpts:5060:5069 TOS set 0x10
3 TOS udp -- 0.0.0.0/0 0.0.0.0/0 udp
dpts:10000:20000 TOS set 0x10

This is what the packet looks like using wireshark:
Internet Protocol, Src: 59.93.192.xx (59.93.192.xx), Dst:
64.62.134.xxx (64.62.134.xxx)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0xb0 (DSCP 0x2c: Unknown DSCP; ECN: 0x00)
1011 00.. = Differentiated Services Codepoint: Unknown (0x2c)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0


I have no idea what am I doing wrong.

Here is some reference reading I did:
http://www.tucny.com/dscp&tos

Any pointers in the right direction will be very much appreciated.

Thanks for your time,

Sysadmin
http://www.debtconsolidationcare.com
Internets First get out of debt community

[glwgoes at gmail.com]

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.
Best Regards,

On Wed, May 7, 2008 at 8:59 AM, Vikas <topgun9 at gmail.com> wrote: