On Thu, Jul 24, 2014 at 06:46:10PM +0200, Alexander Aring wrote: > > > > > >When using the fragmentation mechanism described in > > >Section 5.3 of [RFC4944], any header that cannot fit within the first > > >fragment MUST NOT be compressed. > > > > > > > > >Any header == sum of headers. > > Maybe they mean to cover further application headers that can be compressed. > > Look at the draft GHC spec for instance. > > But we don't support these right now and on the receiving side it should > be okay to check if a fragmented 6LoWPAN header is compressed or not. > It's simple to check on IPHC or IPv6 dispatch value after fragmentation. > > > > > > >>are more than the MTU of the device sending the packet, for us 127 MTU of > > >>the 802.15.4 device. ie the sum of all the MAC headers/6 LoWPAN headers > > >>and the compressed IPv6 header > 127. > > >Okay, I agree. That makes more sense, but when could happen this? > > Not sure, what about ipv6 options?? again maybe they are future proofing > > for future compression algorithms like GHC. > > I think they mean all header MAC + 6LoWPAN and NHC (next header > compression). The only one NHC which we support is UDP at the moment. >
I have a possible reason because this. Normally if we get FRAG1 we can run decompression of HEADER on the fly after receiving FRAG1, but this assumes we need to know that the whole compressed header is in FRAG1. Now the RFC6282 says that, otherwise it's not compressed, which is great. If this would be compressed we can't decompress the IPHC on the fly after receiving FRAG1. At the moment we don't do that because it was simpler to implement it not on the fly, but in the future we should decompress the header after receiving FRAG1. I already thought about that. - Alex ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Linux-zigbee-devel mailing list Linux-zigbee-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-zigbee-devel
