Vikas
2008-May-07 11:59 UTC
[asterisk-users] Setting the TOS using IPtables screws up the DSCP field
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
Guilherme Loch Waltrick Góes
2008-May-07 12:18 UTC
[asterisk-users] Setting the TOS using IPtables screws up the DSCP field
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:> 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 > > _______________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >-- Guilherme Loch G?es Visite nossa loja virtual: http://www.shopvoip.com.br Not?cias e F?rum sobre VoIP com software livre: http://www.asteriskexperts.com.br -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20080507/72d91b25/attachment.htm
Matt Watson
2008-May-07 12:28 UTC
[asterisk-users] Setting the TOS using IPtables screws up the DSCP field
Why are you trying to change the ToS from 46 (0x2e) Expedited for the RTP/RTCP packets to 16 (0x10)? I mean... these values really only need to be meaningful to yourself, your switches, your routers etc.... however ToS 46 (0x2e) is the "standard" value for RTP / RTCP as it is basically the highest priority value you can assign to something... ToS 46 is basically suppose to indicate that it trumps all other traffic and should be send before anything else (Which is a good thing for the RTP traffic) The SIP Signalling traffic is a little less important and its standard ToS value is 26 (0x1a). You also don;t need to use IPTables to set these values... Asterisk will do it for you as long as you have installed libcaps (I believe its required for it). And I don;t know what phones you are using... but your phones are probably also setting these values for you.... I know the Aastra phones have QoS/ToS settings under Options -> Network -> Type of Service -- Matt ________________________________________ From: asterisk-users-bounces at lists.digium.com [asterisk-users-bounces at lists.digium.com] On Behalf Of Vikas [topgun9 at gmail.com] Sent: Wednesday, May 07, 2008 7:59 AM To: Asterisk Users Mailing List - Non-Commercial Discussion Subject: [asterisk-users] Setting the TOS using IPtables screws up the DSCP field 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 _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users