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.T=FCxen, 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 =20 -----Message d'origine----- De : Michael T=FCxen [mailto:Michael.Tuexen@lurchi.franken.de]=20 Envoy=E9 : lundi 29 d=E9cembre 2008 16:49 =C0 : 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.T=FCxen, > > 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=20 > 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=3D1 on T, just in case, I'm not=20 > exactly sure if it has an effect on my tests. > > Kind regards > > > Aman Jassal > > -----Message d'origine----- > De : Michael T=FCxen [mailto:Michael.Tuexen@lurchi.franken.de] > Envoy=E9 : lundi 29 d=E9cembre 2008 14:09 > =C0 : zze-Abac JASSAL A ext RD-RESA-ISS > Cc : freebsd-net@freebsd.org; DAOUD TRIKI Khadija RD-RESA-ISS Objet :=20 > 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=20 > > 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=20 >> SCTP to perform handover tests between 2 separate Wifi networks. I=20 >> use >> IPv6 >> for all my tests. >> >> I have a local LAN (wired-network), on which I have 3 machines, one=20 >> of them is the machine I use to communicate with for the tests (I'll=20 >> call it T to make things simple), and the other two are used as Wifi=20 >> Access Points (say Wifi1 and Wifi2 respectively). Since I work with=20 >> IPv6, I set up both Access Points to send Router Advertisement=20 >> messages periodically (minimum of 3 seconds, maximum of 4 seconds).=20 >> That way I can have automatic address reconfiguration when I connect=20 >> to either of the access points. >> >> The aim of my tests is to use a PC, connect to Wifi1 (for example),=20 >> launch an SCTP association with T (T sends data to my PC), and then=20 >> perform a handover on Wifi2. I do make address reconfiguration during = >> the handover process. The important point is that I work with only=20 >> ONE address on my network interface. Before I start my tests, I set=20 >> the following sysctl parameters : >> >> # sysctl -w net.inet.sctp.mobility_base=3D1 # sysctl -w >> net.inet.sctp.mobility_fasthandoff=3D1 >> # sysctl -w net.inet.sctp.debug=3D0x00f301f0 (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=20 >> but I'm trying to be thorough. This is the script I use to perform=20 >> handover >> : >> >> ifconfig rum0 inet6 <my old address> delete ifconfig rum0 ssid <the=20 >> target access point> route del -inet6 default <my old gateway> rtsol=20 >> rum0 >> >> If I'm not mistaken, the PC should have sent an ASCONF chunk to=20 >> perform dynamic address reconfiguration. However what I observed is=20 >> that nothing happens. No ASCONF chunks are sent, and therefore, T=20 >> 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=20 >> 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=20 >> 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=20 >> that on the revision dating 24th July 2007, changes were made for=20 >> dynamic address reconfiguration : "Change behaviour so that when the=20 >> last address is deleted (auto-asconf on a boudall endpoint) no action = >> is taken until an address is added ; at that time an ASCONF=20 >> 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=20 >> perform it because I don't seem to send any ASCONF chunk. I'm=20 >> 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=20 >> got when performing a handover test. This is the kind of debug logs=20 >> that I got : >> >> http://www.divshare.com/download/6200509-560 >> >> This is another debug logfile, but with my own debug logs added in=20 >> 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=20 >> 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-=20 >> unsubscribe@freebsd.org" >> > >
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