Hello Michel Seems to me that reducing the datagram tag to one octet or 12 bits is enough. Do you see a need for so many outstanding fragments?
Regards, Pascal Le 8 janv. 2019 à 19:29, Michel Veillette <[email protected]<mailto:[email protected]>> a écrit : Hi Pascal The limit of 2K datagram doesn't hurt us, but can effectively hurt others. I don't things that this draft need to go as far as supporting Jumbogram but should at least support any standard datagrams. Adding a single byte to the RFRAG Dispatch type will help to get rid of these limitations. For example: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 0 1 0 0|X| datagram_tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| sequence| fragment_size | fragment_offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 0 1 0 1 Y| datagram_tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RFRAG Acknowledgment Bitmap (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Regards, Michel From: Pascal Thubert (pthubert) <[email protected]<mailto:[email protected]>> Sent: Tuesday, January 8, 2019 1:01 PM To: Michel Veillette <[email protected]<mailto:[email protected]>>; [email protected]<mailto:[email protected]> Subject: RE: draft-ietf-6lo-fragment-recovery maximum fragment size too small Hello Michel Your proposal is feasible; the datagram space is probably overly large anyway. But it seems to be tailored around your exact problem as opposed to generic. There are alternates like use a different unit, e.g., 4 bytes words as the existing text suggests. Maybe we could make the unit dependent on the MTU, like 1 byte under 128, 2 bytes till 256, and 4 bytes above that? It seems that you are not concerned with the overall IP packet size, which is constrained to 2K by the fragment_offset. Maybe we should also look at that? All the best Pascal From: 6lo <[email protected]<mailto:[email protected]>> On Behalf Of Michel Veillette Sent: mardi 8 janvier 2019 18:38 To: [email protected]<mailto:[email protected]> Subject: [6lo] draft-ietf-6lo-fragment-recovery maximum fragment size too small Hi authors of "draft-ietf-6lo-fragment-recovery" I'm currently working on a fragment forwarding implementation based on "draft-ietf-6lo-fragment-recovery". In some cases, relatively large fragments need to be supported (i.e. minimum MTU transferred using 3 fragments). However, the current format of the RFRAG Dispatch type limits fragment size to only 128 bytes. Is it possible to modify the RFRAG Dispatch type (https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-00#section-5.1<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-6lo-fragment-recovery-00%23section-5.1&data=02%7C01%7C%7C12cb3a341d5e45a5b05308d67593338f%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C0%7C636825672601917911&sdata=CNsPQhDxOFFzB7zOCgfDxZXeZjdoerKCmezSouL0EOE%3D&reserved=0>) and corresponding RFRAG Acknowledgment Dispatch type (https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-00#section-5.2<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-6lo-fragment-recovery-00%23section-5.2&data=02%7C01%7C%7C12cb3a341d5e45a5b05308d67593338f%7C4f6fbd130dfb415085c3d43260c04309%7C0%7C0%7C636825672601917911&sdata=%2FPLtWrX8XdGvLHacKuSRb%2FMfIcxE%2BXV%2BCMFg2CNhTHc%3D&reserved=0>) to allow larger fragments? For example: 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 0 1 0 0| fragment_size |X|E| datagram_tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |sequence | fragment_offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1 1 1 0 1 0 1 Y| R | datagram_tag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RFRAG Acknowledgment Bitmap (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ R = reserved Regards, Michel Veillette
_______________________________________________ 6lo mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lo
