SIP Invite IP fragmentation issue
I am having an *odd* issue, which i am not sure freeswitch is to be blamed for. Sometimes, the SIP invites are bigger than 1500 bytes causing IP fragmentation, but when I look at the TCP dump (on the same machine as freeswitch), I see that only the first packet of the fragment is captured. Is freeswitch trying to do its own IP fragmentation or is it relying on underlying linux (kernel 2.6.18)? I created a small program to send UDP packets of 2000 bytes, and also tried with ping -s 2000, and both were successful, so am leaning towards blaming Freeswitch. Any suggestions? -Saurabh _________________________________________________________________ Stay up to date on your PC, the Web, and your mobile phone with Windows Live http://clk.atdmt.com/MRT/go/119462413/direct/01/
Ok, my bad. Ethereal for some reason was showing only the first fragment (ethereal bug?). But, now it seems I have hit another problem - it seems that the SIP invites (which are fragmented) are being dropped by the firewall in between us and the SIP provider. Is it possible to shrink the size of the SIP invite so that it fits in a single packet? Any optional stuff in the SIP invite that is sent, that can be thrown away? -Saurabh From: saurabh_aggarwal@hotmail.comTo: freeswitch-users@lists.freeswitch.orgDate: Tue, 18 Nov 2008 07:34:11 +0000Subject: [Freeswitch-users] SIP Invite IP fragmentation issue I am having an *odd* issue, which i am not sure freeswitch is to be blamed for. Sometimes, the SIP invites are bigger than 1500 bytes causing IP fragmentation, but when I look at the TCP dump (on the same machine as freeswitch), I see that only the first packet of the fragment is captured. Is freeswitch trying to do its own IP fragmentation or is it relying on underlying linux (kernel 2.6.18)? I created a small program to send UDP packets of 2000 bytes, and also tried with ping -s 2000, and both were successful, so am leaning towards blaming Freeswitch. Any suggestions? -Saurabh Stay up to date on your PC, the Web, and your mobile phone with Windows Live Click here _________________________________________________________________ Stay up to date on your PC, the Web, and your mobile phone with Windows Live http://clk.atdmt.com/MRT/go/119462413/direct/01/
2008/11/18 Saurabh Aggarwal <saurabh_aggarwal@hotmail.com>:
Ok, my bad. Ethereal for some reason was showing only the first fragment (ethereal bug?).
But, now it seems I have hit another problem - it seems that the SIP invites (which are fragmented) are being dropped by the firewall in between us and the SIP provider. Is it possible to shrink the size of the SIP invite so that it fits in a single packet? Any optional stuff in the SIP invite that is sent, that can be thrown away?
Welcome to the reason for which IETF is moving to SIP TCP/SCTP ;) -- Iñaki Baz Castillo <ibc@aliax.net>
Its not really possible other then enabling compact headers or by getting rid of codecs that you don¹t actually want to use... Another thing you could do is get your broken ISP to fix their firewall... It is not correct to just drop fragmented packets just because they are fragmented.. This is something that will happen on a regular basis on the internet as not everything has an MTU of 1500 From: Saurabh Aggarwal <saurabh_aggarwal@hotmail.com> Reply-To: <freeswitch-users@lists.freeswitch.org> Date: Tue, 18 Nov 2008 10:19:55 +0000 To: <freeswitch-users@lists.freeswitch.org> Subject: Re: [Freeswitch-users] SIP Invite IP fragmentation issue Ok, my bad. Ethereal for some reason was showing only the first fragment (ethereal bug?). But, now it seems I have hit another problem - it seems that the SIP invites (which are fragmented) are being dropped by the firewall in between us and the SIP provider. Is it possible to shrink the size of the SIP invite so that it fits in a single packet? Any optional stuff in the SIP invite that is sent, that can be thrown away? -Saurabh From: saurabh_aggarwal@hotmail.com To: freeswitch-users@lists.freeswitch.org Date: Tue, 18 Nov 2008 07:34:11 +0000 Subject: [Freeswitch-users] SIP Invite IP fragmentation issue I am having an *odd* issue, which i am not sure freeswitch is to be blamed for. Sometimes, the SIP invites are bigger than 1500 bytes causing IP fragmentation, but when I look at the TCP dump (on the same machine as freeswitch), I see that only the first packet of the fragment is captured. Is freeswitch trying to do its own IP fragmentation or is it relying on underlying linux (kernel 2.6.18)? I created a small program to send UDP packets of 2000 bytes, and also tried with ping -s 2000, and both were successful, so am leaning towards blaming Freeswitch. Any suggestions? -Saurabh Stay up to date on your PC, the Web, and your mobile phone with Windows Live Click here <http://clk.atdmt.com/MRT/go/119462413/direct/01/> Stay up to date on your PC, the Web, and your mobile phone with Windows Live Click here <http://clk.atdmt.com/MRT/go/119462413/direct/01/> _______________________________________________ Freeswitch-users mailing list Freeswitch-users@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
enabling compact headers - what is that? -Saurabh Date: Tue, 18 Nov 2008 04:29:28 -0600From: krice@suspicious.orgTo: freeswitch-users@lists.freeswitch.orgSubject: Re: [Freeswitch-users] SIP Invite IP fragmentation issueIts not really possible other then enabling compact headers or by getting rid of codecs that you don’t actually want to use... Another thing you could do is get your broken ISP to fix their firewall... It is not correct to just drop fragmented packets just because they are fragmented.. This is something that will happen on a regular basis on the internet as not everything has an MTU of 1500 From: Saurabh Aggarwal <saurabh_aggarwal@hotmail.com>Reply-To: <freeswitch-users@lists.freeswitch.org>Date: Tue, 18 Nov 2008 10:19:55 +0000To: <freeswitch-users@lists.freeswitch.org>Subject: Re: [Freeswitch-users] SIP Invite IP fragmentation issueOk, my bad. Ethereal for some reason was showing only the first fragment (ethereal bug?). But, now it seems I have hit another problem - it seems that the SIP invites (which are fragmented) are being dropped by the firewall in between us and the SIP provider. Is it possible to shrink the size of the SIP invite so that it fits in a single packet? Any optional stuff in the SIP invite that is sent, that can be thrown away? -Saurabh From: saurabh_aggarwal@hotmail.comTo: freeswitch-users@lists.freeswitch.orgDate: Tue, 18 Nov 2008 07:34:11 +0000Subject: [Freeswitch-users] SIP Invite IP fragmentation issueI am having an *odd* issue, which i am not sure freeswitch is to be blamed for. Sometimes, the SIP invites are bigger than 1500 bytes causing IP fragmentation, but when I look at the TCP dump (on the same machine as freeswitch), I see that only the first packet of the fragment is captured. Is freeswitch trying to do its own IP fragmentation or is it relying on underlying linux (kernel 2.6.18)? I created a small program to send UDP packets of 2000 bytes, and also tried with ping -s 2000, and both were successful, so am leaning towards blaming Freeswitch. Any suggestions? -Saurabh Stay up to date on your PC, the Web, and your mobile phone with Windows Live Click here <http://clk.atdmt.com/MRT/go/119462413/direct/01/> Stay up to date on your PC, the Web, and your mobile phone with Windows Live Click here <http://clk.atdmt.com/MRT/go/119462413/direct/01/> _______________________________________________Freeswitch-users mailing listFreeswitch-users@lists.freeswitch.orghttp://lists.freeswitch.org/mailman/listinfo/freeswitch-usersUNSUBSCRIBE:htt... _________________________________________________________________ Get more done, have more fun, and stay more connected with Windows Mobile®. http://clk.atdmt.com/MRT/go/119642556/direct/01/
The rfc also describes why: SIP provides a mechanism to represent common header field names in an abbreviated form. This may be useful when messages would otherwise become too large to be carried on the transport available to it (exceeding the maximum transmission unit (MTU) when using UDP, for example). These compact forms are defined in Section 20. A compact form MAY be substituted for the longer form of a header field name at any time without changing the semantics of the message. A header field name MAY appear in both long and short forms within the same message. Implementations MUST accept both the long and short forms of each header name. On Tue, Nov 18, 2008 at 11:52 AM, Iñaki Baz Castillo <ibc@aliax.net> wrote:
2008/11/18 Saurabh Aggarwal <saurabh_aggarwal@hotmail.com>:
enabling compact headers - what is that?
SIP allows compact headers names for a few heades:
From = f To = t Via = v ...
-- Iñaki Baz Castillo <ibc@aliax.net> _______________________________________________ Freeswitch-users mailing list Freeswitch-users@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
Thanks, how do I "enable" this in freeswitch? Can this be done through the SIP configuration file? -Saurabh Date: Tue, 18 Nov 2008 12:05:18 +0100From: jonas.gauffin@gmail.comTo: freeswitch-users@lists.freeswitch.orgSubject: Re: [Freeswitch-users] SIP Invite IP fragmentation issueThe rfc also describes why:SIP provides a mechanism to represent common header field names in an abbreviated form. This may be useful when messages would otherwise become too large to be carried on the transport available to it (exceeding the maximum transmission unit (MTU) when using UDP, for example). These compact forms are defined in Section 20. A compact form MAY be substituted for the longer form of a header field name at any time without changing the semantics of the message. A header field name MAY appear in both long and short forms within the same message. Implementations MUST accept both the long and short forms of each header name. On Tue, Nov 18, 2008 at 11:52 AM, Iñaki Baz Castillo <ibc@aliax.net> wrote: 2008/11/18 Saurabh Aggarwal <saurabh_aggarwal@hotmail.com>:> enabling compact headers - what is that?SIP allows compact headers names for a few heades: From = f To = t Via = v ...--Iñaki Baz Castillo<ibc@aliax.net>_______________________________________________Freeswitch-users mailing listFreeswitch-users@lists.freeswitch.orghttp://lists.freeswitch.org/mailman/listinfo/freeswitch-usersUNSUBSCRIBE:htt... _________________________________________________________________ Get more done, have more fun, and stay more connected with Windows Mobile®. http://clk.atdmt.com/MRT/go/119642556/direct/01/
the only reliable answer is use TCP. The RFC is daft in this matter. They say when it's bigger than mtu to automatically use TCP instead. And timeout for 10 seconds then fall back to UDP. Its mandatory in SIP to support both TCP and UDP up to 64k per packet. As you can see, since barely anything will do this right, your best bet is to only use TCP when you have this kind of traffic. On Tue, Nov 18, 2008 at 5:52 AM, Saurabh Aggarwal < saurabh_aggarwal@hotmail.com> wrote:
Thanks, how do I "enable" this in freeswitch? Can this be done through the SIP configuration file?
-Saurabh
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Date: Tue, 18 Nov 2008 12:05:18 +0100 From: jonas.gauffin@gmail.com To: freeswitch-users@lists.freeswitch.org Subject: Re: [Freeswitch-users] SIP Invite IP fragmentation issue
The rfc also describes why:
SIP provides a mechanism to represent common header field names in an abbreviated form. This may be useful when messages would otherwise become too large to be carried on the transport available to it (exceeding the maximum transmission unit (MTU) when using UDP, for example). These compact forms are defined in Section 20. A compact form MAY be substituted for the longer form of a header field name at any time without changing the semantics of the message. A header field name MAY appear in both long and short forms within the same message. Implementations MUST accept both the long and short forms of each header name.
On Tue, Nov 18, 2008 at 11:52 AM, Iñaki Baz Castillo <ibc@aliax.net>wrote:
2008/11/18 Saurabh Aggarwal <saurabh_aggarwal@hotmail.com>:
enabling compact headers - what is that?
SIP allows compact headers names for a few heades:
From = f To = t Via = v ...
-- Iñaki Baz Castillo <ibc@aliax.net> _______________________________________________ Freeswitch-users mailing list Freeswitch-users@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
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-- Anthony Minessale II FreeSWITCH http://www.freeswitch.org/ ClueCon http://www.cluecon.com/ AIM: anthm MSN:anthony_minessale@hotmail.com <MSN%3Aanthony_minessale@hotmail.com> GTALK/JABBER/PAYPAL:anthony.minessale@gmail.com<PAYPAL%3Aanthony.minessale@gmail.com> IRC: irc.freenode.net #freeswitch FreeSWITCH Developer Conference sip:888@conference.freeswitch.org <sip%3A888@conference.freeswitch.org> iax:guest@conference.freeswitch.org/888 googletalk:conf+888@conference.freeswitch.org<googletalk%3Aconf%2B888@conference.freeswitch.org> pstn:213-799-1400
participants (5)
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Anthony Minessale
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Iñaki Baz Castillo
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Jonas Gauffin
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Ken Rice
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Saurabh Aggarwal