Seems that large EBs at low rates ended up being a problem in subgig cases after all, Dale.
The discussion at the interim was either to make very large slots => impractical, or preconfigure sometimes, 2 or more consecutive time slots are paired; the second is never scheduled, and is free to accept the remainder of the frame sent in the first… The pairing will be interesting to make work, ince the channel computation is based on ASN so the consecutive time slots to not have the same channel offset…. Cheers Pascal From: 6tisch [mailto:[email protected]] On Behalf Of Thomas Watteyne Sent: vendredi 9 décembre 2016 15:39 To: Dale R. Worley <[email protected]> Cc: Randy Turner <[email protected]>; [email protected] Subject: Re: [6tisch] slot schedluing Dale, +1 on your answer. Thomas On Thu, Dec 8, 2016 at 9:38 PM, Dale R. Worley <[email protected]<mailto:[email protected]>> wrote: Randy Turner <[email protected]<mailto:[email protected]>> writes: > Just re-confirming an assumption -- from a TSCH perspective, slot > scheduling assumes any single transmission "cannot" exceed a slot > boundary -- if transmissions require a certain amount of time, then the > slot width is increased to deal with this ( or possibly increase the > TX bit rate if possible ) > > Is this correct ? As others have noted, extending the slot width can only be done when the network is initialized. In practice, packets that do not fit within a slot time are fragmented. My understanding is that all such packets are IP packets, and are fragmented using using the layer 2 fragmentation defined in RFC 6282 (not the one defined in RFC 4944). Thus, the minimum (layer 3) IPv6 MTU of 1280 bytes is supported. As far as I know, there is no fragmentation mechanism for the EB (extended beacon) layer-2 packets. But that does not seem to be a problem in practice. Dale _______________________________________________ 6tisch mailing list [email protected]<mailto:[email protected]> https://www.ietf.org/mailman/listinfo/6tisch -- _______________________________________ Thomas Watteyne, PhD Research Scientist & Innovator, Inria Sr Networking Design Eng, Linear Tech Founder & co-lead, UC Berkeley OpenWSN Co-chair, IETF 6TiSCH www.thomaswatteyne.com<http://www.thomaswatteyne.com> _______________________________________
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