Date: Mon, 29 Dec 2008 18:12:29 +0100 From: <ajassal.ext@orange-ftgroup.com> To: <Michael.Tuexen@lurchi.franken.de> Cc: freebsd-net@freebsd.org, khadija.daoud@orange-ftgroup.com Subject: RE: SCTP : problems in sending ASCONF chunks Message-ID: <3418F3471F1CA4409901547349FFAE2E091067E9@ftrdmel2> In-Reply-To: <2C477D99-DB2F-4EDB-950F-23856B58ACAB@lurchi.franken.de> References: <3418F3471F1CA4409901547349FFAE2E0910679F@ftrdmel2> <2C67145C-C26B-4666-B7A5-6EC1C4ABA1E5@lurchi.franken.de> <3418F3471F1CA4409901547349FFAE2E091067B8@ftrdmel2> <2C477D99-DB2F-4EDB-950F-23856B58ACAB@lurchi.franken.de>
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Hello M.Tüxen, I performed a quick test and at the INIT/INIT-ACK exchange, I noticed the following : - In the INIT chunk, the Supported Extensions Parameter field indicates that ASCONF, ASCONF-ACK, FORWARD-TSN, PKTDROP, STREAM_RESET and AUTH are supported - In the INIT-ACK chunk, there is no field indicating that any of the chunks listed above are supported... I didn't think about looking in this before >_< Since there is no indication given to my PC, perhaps my PC assumes that T doesn't support ASCONF, ASCONF-ACK, FORWARD-TSN, PKTDROP, STREAM_RESET and AUTH. Could it be that, because it doesn't see any Supported Extensions Parameter field in the INIT-ACK, my PC doesn't try to send any ASCONF chunk ?? Do we absolutely need to have the ASCONF, ASCONF-ACK and AUTH parameters in the Supported Extensions Parameter, in both the INIT and the INIT-ACK chunks, to have the possibility of sending an ASCONF chunk ? Kind regards Aman Jassal -----Message d'origine----- De : Michael Tüxen [mailto:Michael.Tuexen@lurchi.franken.de] Envoyé : lundi 29 décembre 2008 16:49 À : zze-Abac JASSAL A ext RD-RESA-ISS Cc : freebsd-net@freebsd.org; DAOUD TRIKI Khadija RD-RESA-ISS Objet : Re: SCTP : problems in sending ASCONF chunks Hi Aman, I'm not that familiar with the Linux box configuration. If you look at the INIT/INIT-ACK exchange, does the Linux box support ASCONF and the SCTP-AUTH extension? Both are required... Best regards Michael On Dec 29, 2008, at 2:36 PM, <ajassal.ext@orange-ftgroup.com> <ajassal.ext@orange-ftgroup.com > wrote: > > Hello M.Tüxen, > > No, only the PC is running under FreeBSD 7.0. T is running under Linux > (kernel version is 2.6.21 and the distribution used is Fedora Core 7). > SCTP is running on T thanks to the lksctp implementation, we loaded > the sctp module on it and made the necessary configurations so that it > is loaded at boot time. > > Also, I enable net.sctp.addip_enable=1 on T, just in case, I'm not > exactly sure if it has an effect on my tests. > > Kind regards > > > Aman Jassal > > -----Message d'origine----- > De : Michael Tüxen [mailto:Michael.Tuexen@lurchi.franken.de] > Envoyé : lundi 29 décembre 2008 14:09 > À : zze-Abac JASSAL A ext RD-RESA-ISS > Cc : freebsd-net@freebsd.org; DAOUD TRIKI Khadija RD-RESA-ISS Objet : > Re: SCTP : problems in sending ASCONF chunks > > Hi, > > are both machines (T and you PC) running FreeBSD? > > Best regards > Michael > > On Dec 29, 2008, at 12:33 PM, <ajassal.ext@orange-ftgroup.com> <ajassal.ext@orange-ftgroup.com > > wrote: > >> Hi all, >> >> I have been working with SCTP and more specifically with the mobility >> features of SCTP at my work. Basically, I have been trying to use >> SCTP to perform handover tests between 2 separate Wifi networks. I >> use >> IPv6 >> for all my tests. >> >> I have a local LAN (wired-network), on which I have 3 machines, one >> of them is the machine I use to communicate with for the tests (I'll >> call it T to make things simple), and the other two are used as Wifi >> Access Points (say Wifi1 and Wifi2 respectively). Since I work with >> IPv6, I set up both Access Points to send Router Advertisement >> messages periodically (minimum of 3 seconds, maximum of 4 seconds). >> That way I can have automatic address reconfiguration when I connect >> to either of the access points. >> >> The aim of my tests is to use a PC, connect to Wifi1 (for example), >> launch an SCTP association with T (T sends data to my PC), and then >> perform a handover on Wifi2. I do make address reconfiguration during >> the handover process. The important point is that I work with only >> ONE address on my network interface. Before I start my tests, I set >> the following sysctl parameters : >> >> # sysctl -w net.inet.sctp.mobility_base=1 # sysctl -w >> net.inet.sctp.mobility_fasthandoff=1 >> # sysctl -w net.inet.sctp.debug=0x00f301f0 (that is to dump >> messages in /var/log/messages) >> >> net.inet.sctp.auto_asconf is set to 1 by default. >> >> I use FreeBSD 7.0 on my PC, I don't know if that is extremely useful >> but I'm trying to be thorough. This is the script I use to perform >> handover >> : >> >> ifconfig rum0 inet6 <my old address> delete ifconfig rum0 ssid <the >> target access point> route del -inet6 default <my old gateway> rtsol >> rum0 >> >> If I'm not mistaken, the PC should have sent an ASCONF chunk to >> perform dynamic address reconfiguration. However what I observed is >> that nothing happens. No ASCONF chunks are sent, and therefore, T >> doesn't ever know that it should send data on the PC's newly acquired >> address. >> >> I tried to investigate the problem myself, by adding some debug logs >> in the sctp source code (to see which functions are called during the >> handover process), and it seems as if the kernel doesn't ever add an >> ASCONF chunk to send in its queue... But that's just my understanding >> of the problem... >> >> I looked up in the CVS repository for answers, and to see the various >> changes that were gradually brought on the code. There, I noticed >> that on the revision dating 24th July 2007, changes were made for >> dynamic address reconfiguration : "Change behaviour so that when the >> last address is deleted (auto-asconf on a boudall endpoint) no action >> is taken until an address is added ; at that time an ASCONF >> add+delete is sent (if the asoc is still up)" >> >> In my humble opinion, this is exactly the case that corresponds to my >> handover scenario. But I just haven't been able to successfully >> perform it because I don't seem to send any ASCONF chunk. I'm >> struggling to understand why I do not see any ASCONF chunk sent. >> >> If it can help, I'm also attaching links to the kind of debug logs I >> got when performing a handover test. This is the kind of debug logs >> that I got : >> >> http://www.divshare.com/download/6200509-560 >> >> This is another debug logfile, but with my own debug logs added in >> the sctp source code : >> >> http://www.divshare.com/download/6200504-2e9 >> >> >> Many thanks for your work, and I hope someone will be able to help >> and shed some light on this problem :-) >> >> >> Aman Jassal >> >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to "freebsd-net- >> unsubscribe@freebsd.org" >> > >
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