Hi Carsten, I do understand that IP fragmentation has some serious downsides. Misassociated IP fragments should not be a concern with low data rate use cases though e.g. IoT. But fragment loss is a problem and can result in severely degraded performance especially because of redundant fragment transmissions. I was actually looking for more of a temporary solution to address transmission of payloads in the order of a few kilobytes which would mean 2-4 IP fragments. But it seems like RIOT doesn't support it.
We don't want to use CoAP as we are working with ICN (Information Centric Networking) protocols. And we are working with Attribute-Based Encryption (ABE), a policy based encryption mechanism that may result in significantly increased data after encryption. The increase depends on the complexity of the policy employed. /Adeel -------- Original message -------- From: Carsten Bormann <c...@tzi.org> Date: 8/18/2016 22:54 (GMT+01:00) To: RIOT OS kernel developers <devel@riot-os.org> Cc: Börje Ohlman <borje.ohl...@ericsson.com>, Joakim Borgh <joakim.bo...@ericsson.com>, Adeel Mohammad Malik <adeel.mohammad.ma...@ericsson.com> Subject: Re: [riot-devel] Fragmentation support in IP 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" <t.schm...@haw-hamburg.de> > Date: 8/18/2016 18:11 (GMT+01:00) > To: devel@riot-os.org > 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 > devel@riot-os.org > https://lists.riot-os.org/mailman/listinfo/devel > > _______________________________________________ > devel mailing list > devel@riot-os.org > https://lists.riot-os.org/mailman/listinfo/devel
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