Hi Adeel, What do you mean by "lost fragment recovery"? To my knowledge there is no such thing in 6LoWPAN fragmentation.
Regards, Martine Am 19.08.2016 12:59 vorm. schrieb "Adeel Mohammad Malik" < [email protected]>: > Hi again Thomas, > > Do you mean that 6LoWPAN in RIOT does not support lost fragment recovery? > Assuming it does, what I had in mind was that we could segment data in the > application to the IP MTU and leverage the lost fragment recovery feature > in 6LoWPAN to get a decent performance. This way we may not need to > implement lost segment recovery in the application. But if 6LoWPAN in RIOT > does not support recovery of lost fragments we might as well run our > application direclty on link layer (since we dont need IP routing). > > /Adeel > -------- Original message -------- > From: "Thomas C. Schmidt" <[email protected]> > Date: 8/18/2016 23:27 (GMT+01:00) > To: RIOT OS kernel developers <[email protected]> > Cc: Börje Ohlman <[email protected]>, Joakim Borgh < > [email protected]> > Subject: Re: [riot-devel] Fragmentation support in IP > > Hi Adeel, > > adding to this: you should keep in mind that in LowPANs you may easily > trigger multiple layers of fragmentation (loosing one fragment is > loosing all!) ... and that receivers may not be ready to handle UDP > datagrams of 'arbitrary' sizes. > > So if you really want to stay away from upper layer protocols like CoAP, > you should process data segmentation in your application (not sure this > is the best idea, though). > > Cheers, > Thomas > > On 18.08.2016 22:54, Carsten Bormann wrote: > > Hi Adeel, > > > > IP fragmentation is usually a bad idea*), and more so on a constrained > > network. If you need to transfer payloads beyond a kilobyte or so, > > maybe CoAP (RFC 7252) with the block-wise transfer protocol (currently > > being published as RFC-to-be 7959) solves your problem. > > > > Which encryption expands a few bytes of plaintext to kilobytes of > > ciphertext? (You may be thinking about signatures; e.g., hash-based > > signatures can be 3-6 KiB or even more. These might occur in firmware > > updates and are covered quite well by CoAP + block-wise.) > > > > Grüße, Carsten > > > > *) > > https://tools.ietf.org/html/draft-mathis-frag-harmful-00 > > http://www.hpl.hp.com/techreports/Compaq-DEC/WRL-87-3.pdf > > > > Adeel Mohammad Malik wrote: > >> Hi Thomas, > >> > >> I agree that IP fragmentation is not an equivalent for data streaming. > >> However it still facilitates transporting data that exceeds the MTU. The > >> use case we are looking at is encryption of IoT data that may result in > >> a few bytes of plaintext being converted to a few kilobytes of > >> ciphertext. Had IP supported fragmentation in RIOT it would have been > >> possible for us to send such data. > >> > >> /Adeel > >> > >> > >> -------- Original message -------- > >> From: "Thomas C. Schmidt" <[email protected]> > >> Date: 8/18/2016 18:11 (GMT+01:00) > >> To: [email protected] > >> Subject: Re: [riot-devel] Fragmentation support in IP > >> > >> Hi Adeel, > >> > >> GNRC in RIOT supports fragmentation, e.g. in the context of 6LowPAN. > >> > >> However, you seem to be interested in sending UDP datagrams that exceed > >> the MTU payload size. I don't think this is common use ... and I don't > >> think this is clever, either. IP fragmentation is not an equivalent for > >> data streaming. > >> > >> Cheers, > >> Thomas > >> > >> On 18.08.2016 18:04, Adeel Mohammad Malik wrote: > >>> Hi all, > >>> > >>> > >>> > >>> My question is about fragmentation support in IP in RIOT. Does IP in > >>> RIOT support fragmentation? The use case I am after is transferring a > >>> large blob of data (let’s say 5 kilobytes) on the UDP/IP stack in RIOT. > >>> Is that possible? > >>> > >>> > >>> > >>> I know that 6LoWPAN supports fragmentation but that is below the IP > >>> layer. I am interested in fragmentation at the IP layer so that > >>> application running over it in RIOT can send large data. > >>> > >>> > >>> > >>> Regards, > >>> > >>> Adeel > >>> > >> > >> -- > >> > >> Prof. Dr. Thomas C. Schmidt > >> ° Hamburg University of Applied Sciences Berliner Tor > 7 ° > >> ° Dept. Informatik, Internet Technologies Group 20099 Hamburg, > Germany ° > >> ° http://www.haw-hamburg.de/inet Fon: > +49-40-42875-8452 ° > >> ° http://www.informatik.haw-hamburg.de/~schmidt Fax: > +49-40-42875-8409 ° > >> _______________________________________________ > >> devel mailing list > >> [email protected] > >> https://lists.riot-os.org/mailman/listinfo/devel > >> > >> _______________________________________________ > >> devel mailing list > >> [email protected] > >> https://lists.riot-os.org/mailman/listinfo/devel > > _______________________________________________ > > devel mailing list > > [email protected] > > https://lists.riot-os.org/mailman/listinfo/devel > > > > -- > > Prof. Dr. Thomas C. Schmidt > ° Hamburg University of Applied Sciences Berliner Tor 7 ° > ° Dept. Informatik, Internet Technologies Group 20099 Hamburg, Germany ° > ° http://www.haw-hamburg.de/inet Fon: +49-40-42875-8452 > ° > ° http://www.informatik.haw-hamburg.de/~schmidt Fax: +49-40-42875-8409 > ° > _______________________________________________ > devel mailing list > [email protected] > https://lists.riot-os.org/mailman/listinfo/devel > > _______________________________________________ > devel mailing list > [email protected] > https://lists.riot-os.org/mailman/listinfo/devel > >
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