Hi, On Wed, Jun 8, 2022 at 9:47 AM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote: > > Hi Alex, > > > > 3. coordinator (any $TYPE specific) userspace software > > > > > > May the main argument. Some coordinator specific user space daemon > > > does specific type handling (e.g. hostapd) maybe because some library > > > is required. It is a pain to deal with changing roles during the > > > lifetime of an interface and synchronize user space software with it. > > > We should keep in mind that some of those handlings will maybe be > > > moved to user space instead of doing it in the kernel. I am fine with > > > the solution now, but keep in mind to offer such a possibility. > > > > > > I think the above arguments are probably the same why wireless is > > > doing something similar and I would avoid running into issues or it's > > > really difficult to handle because you need to solve other Linux net > > > architecture handling at first. > > > > Yep. > > The spec makes a difference between "coordinator" and "PAN > coordinator", which one is the "coordinator" interface type supposed to > picture? I believe we are talking about being a "PAN coordinator", but > I want to be sure that we are aligned on the terms. > I think it depends what exactly the difference is. So far I see for address filtering it should be the same. Maybe this is an interface option then? > > > > > You are mixing things here with "role in the network" and what > > > > > the transceiver capability (RFD, FFD) is, which are two > > > > > different things. > > > > > > > > I don't think I am, however maybe our vision differ on what an > > > > interface should be. > > > > > > > > > You should use those defines and the user needs to create a new > > > > > interface type and probably have a different extended address > > > > > to act as a coordinator. > > > > > > > > Can't we just simply switch from coordinator to !coordinator > > > > (that's what I currently implemented)? Why would we need the user > > > > to create a new interface type *and* to provide a new address? > > > > > > > > Note that these are real questions that I am asking myself. I'm > > > > fine adapting my implementation, as long as I get the main idea. > > > > > > > > > > See above. > > > > That's okay for me. I will adapt my implementation to use the > > interface thing. In the mean time additional details about what a > > coordinator interface should do differently (above question) is > > welcome because this is not something I am really comfortable with. > > I've updated the implementation to use the IFACE_COORD interface and it > works fine, besides one question below. > > Also, I read the spec once again (soon I'll sleep with it) and > actually what I extracted is that: > > * A FFD, when turned on, will perform a scan, then associate to any PAN > it found (algorithm is beyond the spec) or otherwise create a PAN ID > and start its own PAN. In both cases, it finishes its setup by > starting to send beacons. > What does it mean "algorithm is beyond the spec" - build your own? > * A RFD will behave more or less the same, without the PAN creation > possibility of course. RFD-RX and RFD-TX are not required to support > any of that, I'll assume none of the scanning features is suitable > for them. > > I have a couple of questions however: > > - Creating an interface (let's call it wpancoord) out of wpan0 means > that two interfaces can be used in different ways and one can use > wpan0 as a node while using wpancoord as a PAN coordinator. Is that > really allowed? How should we prevent this from happening? > When the hardware does not support it, it should be forbidden. As most transceivers have only one address filter it should be forbidden then... but there exists a way to indeed have such a setup (which you probably don't need to think about). It's better to forbid something now, with the possibility later allowing it. So it should not break any existing behaviour. > - Should the device always wait for the user(space) to provide the PAN > to associate to after the scan procedure right after the > add_interface()? (like an information that must be provided prior to > set the interface up?) > > - How does an orphan FFD should pick the PAN ID for a PAN creation? > Should we use a random number? Start from 0 upwards? Start from > 0xfffd downwards? Should the user always provide it? > I think this can be done all with some "fallback strategies" (build your own) if it's not given as a parameter. > - Should an FFD be able to create its own PAN on demand? Shall we > allow to do that at the creation of the new interface? > I thought the spec said "or otherwise"? That means if nothing can be found, create one? - Alex
