Hi Tengfei, I am interested like Christian to see the poll mechanism into this draft. I don't think it is right to refer to RFC7554 (problem statement) which is an informational RFC, while this draft is a proposed standard, I think it is better to state the mechanism into the use case of minimum scheduling. Furthermore, the RFC7554 does not mention once Keep-Alive message, but mentions signalling messages, which may confuse users.
Best regards AB On Fri, Oct 11, 2019 at 3:41 PM Tengfei Chang <tengfei.ch...@gmail.com> wrote: > Hi Christian, > > Thanks for pointing this issue out! > The neighbor polling section is removed at 03 version. Can't remember why > we removed it. > > I re-edited this sections to fit the current content of MSF draft. I paste > it below. It will the be last step of boot behavior after it starts sending > EB and DIO. > > The node SHOULD send some form of keep-alive messages to all its > neighbors it has negotiated cell with. The Keep-Alive (KA) > mechanism is detailed in [RFC7554 <https://tools.ietf.org/html/rfc7554>]. > It uses the keep-alive messages > to its preferred parent to stay synchronized. It MAY use the keep- > alive messages to other neighbors to have statistics on link quality. > It MAY use the keep-alive messages to its children to ensure the > child is still reachable. The RECOMMENDED period for sending keep- > alive messages is KA_PERIOD. > > > If the keep-alive message to a child fails at the link layer (i.e. > the maximum number of link-layer retries is reached), the node SHOULD > declare the child as unreachable. This can happen for example when > the child node is switched off. > > When a neighbor is declared unreachable, the node MUST remove all > negotiated cells with that neighbor from its own schedule. In > addition, it MAY issue a 6P CLEAR to that neighbor (which can fail at > the link-layer). The node MAY be removed from the neighbor table. > > > If this is good for you, I will update the MSF to 07 with this change and > propose WGLC right after. > Thanks! > > Tengfei > > On Fri, Oct 11, 2019 at 1:09 PM Christian Hopfner < > christian.hopf...@endress.com> wrote: > >> Hi authors, >> >> I may raise a clarification question before issuing WGLC for this draft. >> >> In the past there was a section in the draft dealing with neighbor >> polling which seems to me beeing an important topic in terms of schedule >> consistency. >> >> In the latest version I don't see a mechanism which explains how a parent >> keeps its schedule clean after some children silently disappeared (e.g.. >> batteries are gone). As per my understanding in such a case the negotiated >> RX cell towards the child remains in the schedule forever right? >> >> Previously this was handled by neighbor polling. Which required the >> parent to send KA packets in a periodic manner to its childset. (This could >> be identified by evaluation of the neighbor set where a negotiated RX cell >> was scheduled to) >> >> What is the idea now how to deal with that issue? >> >> >> Mit freundlichen Grüßen I Best regards >> >> Christian Hopfner >> ------------------------------ >> Developer | TPI F&E Plattform Informatik >> Endress+Hauser SE+Co. KG | Hauptstrasse 1 | 79689 Maulburg | Germany >> Phone: +49 7622 28 1883 >> christian.hopf...@endress.com | www.pcm.endress.com >> >> ------------------------------ >> >> Endress+Hauser SE+Co. KG >> Registergericht: Amtsgericht Freiburg i.Br. HRA 670225 >> Sitz der Gesellschaft: Maulburg >> Persönlich haftender Gesellschafter: Endress+Hauser Administration SE >> Sitz des persönlich haftenden Gesellschafters: Maulburg >> Registergericht: Amtsgericht Freiburg i.Br. 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