Hi Pascal, Thanks for having put this together. I have read the draft v01 since long time, and only now finally able to provide you some feedback.
The draft explains well how the 6TiSCH architecture works, when a centralized approach is used, and what is needed from DetNet to build schedules in a centralized fashion, for setting up tracks, tagging packets, etc. There is only one concept that IMHO is not that clear, and it creates a bit of confusion. You use Track for explaining two different concepts (based on my understanding). At the beginning (pag. 5) you describe a track as: << is a complex form of a uni-directional Circuit ([I-D.ietf-6tisch-terminology]). As opposed to a simple circuit that is a sequence of nodes and links, a Track is shaped as a directed acyclic graph towards a destination to support multi-path forwarding and route around failures. A Track may also branch off and rejoin, for the purpose of the so-called Packet Replication and Elimination (PRE), over non congruent branches. >> and still according to this, at pag. 9 you refer to a track as a possible <<6TiSCH topology>>. This in IMHO in conflict with the definition of track to which we are (or at least I am) used, according to [I-D.ietf-6tisch-terminology]), and which you also use inside this draft: << A Track is a unidirectional path between a source and a destination. In a Track cell, the normal operation of IEEE802.15.4 Automatic Repeat-reQuest (ARQ) usually happens, though the acknowledgment may be omitted in some cases, for instance if there is no scheduled cell for a retry..... A Track is thus formed end-to-end as a succession of paired bundles, a receive bundle from the previous hop and a transmit bundle to the next hop along the Track, and a cell in such a bundle belongs to at most one Track.>> Is there maybe the need to differentiate the two concepts with two different terms, or is it me missing something? Another thing, that I would like to discuss is about chunk. At pag. 8, you write: << The appropriation of a chunk can be requested explicitly by the PCE to any node. After a successful appropriation, the PCE owns the cells in that chunk, and may use them as hard cells to set up Tracks. >> In my understanding, it should be other nodes to request the appropriation of a chunk to the PCE. The PCE should own all of them, being the one building the CDU, and the chunks. Then different (parent) nodes in the network may ask for chunks, and they will assign the cells within the chunk to their children. Is it correct? Finally, something that 6TiSCH may need from DetNet is also the management/coordination of several PCEs. It is luckily that we will have more than one PCE, and we will need some mechanisms to coordinate the inter-controllers synchronization, especially if a track is crossing several domains, under the control of different PCEs. Of course we first need to solve the simplest scenario, with one PCE, but we should take into account also this. Thank you, Maria Rita -----Original Message----- From: detnet [mailto:[email protected]] On Behalf Of Pascal Thubert (pthubert) Sent: Thursday, June 4, 2015 6:02 PM To: [email protected] Cc: [email protected] Subject: [Detnet] FW: New Version Notification for draft-thubert-6tisch-4detnet-00.txt Dear all: I prepared this based on Archie-1 to support 6TiSCH needs at DetNet. It is only a 00 and I'll enrich it soon. Still I thought relevant to share the early work. What do you all think? Pascal -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: jeudi 4 juin 2015 17:58 To: Pascal Thubert (pthubert); Pascal Thubert (pthubert) Subject: New Version Notification for draft-thubert-6tisch-4detnet-00.txt A new version of I-D, draft-thubert-6tisch-4detnet-00.txt has been successfully submitted by Pascal Thubert and posted to the IETF repository. Name: draft-thubert-6tisch-4detnet Revision: 00 Title: 6TiSCH requirements for DetNet Document date: 2015-06-04 Group: Individual Submission Pages: 19 URL: https://www.ietf.org/internet-drafts/draft-thubert-6tisch-4detnet-00.txt Status: https://datatracker.ietf.org/doc/draft-thubert-6tisch-4detnet/ Htmlized: https://tools.ietf.org/html/draft-thubert-6tisch-4detnet-00 Abstract: This document builds on the 6TiSCH architecture that defines, among others, mechanisms to establish and maintain deterministic routing and scheduling in a centralized fashion. The document details dependencies on DetNet and PCE controller to express topologies and capabilities, as well as abstract state that the controller must be able to program into the network devices to enable deterministic forwarding operations. Please note that it may take a couple of minutes from the time of submission until the htmlized version and diff are available at tools.ietf.org. The IETF Secretariat _______________________________________________ detnet mailing list [email protected] https://www.ietf.org/mailman/listinfo/detnet _______________________________________________ 6tisch mailing list [email protected] https://www.ietf.org/mailman/listinfo/6tisch
