On Thu, Sep 18, 2014 at 08:53:48PM +0200, Alexander Aring wrote: > On Thu, Sep 18, 2014 at 07:30:34PM +0100, Martin Townsend wrote: > ... > > >and I hope we clarified now that promiscuous mode with NODE/WPAN type > > >doesn't make any sense than increasing cpu load. You don't get more > > >frames into userspace. > > We are implementing 802.15.4 on powerline. If we had say a peer to peer > > network involving 4 different PANs and because we aren't restricted by > > distance as much as wireless we could potentially put one of the Coordinator > > nodes into promiscuous mode and then capture traffic from all 4 PAN's > > whereas if we are filtering we only see the traffic for the PAN(s) we are > > involved in. Wouldn't this be more frames that just the filter? > > > > I can't follow, with monitor interface you will get any frame from pans, > also all frame types like ACK's etc... you can also send some frames > (okay the 802.15.4 standard doesn't say that) but at86rf231 seems to > allow this. > > I need to show you moooore implementation details, then you know what a > WPAN/NODE type does on receiving and MONITOR will do on receiving. > > WPAN/NODE/COORD -> have hardwware filtering, addresses, FCS etc.. > > MONITOR -> Doesn't filter anything, okay it filters when a SFD was > receivied but nothing more. > > Now LINUX the "mac802154" does also do filtering stuff, but only on > WPAN/NODE/COORD because these are to interact practical in a network, > not just sniffing. > > On WPAN/NODE/COORD we have filter in mac802154, see [0]. This shows > frame parsing of data frames. You can more look into this how this works. > Now if you have address filter on PHY you will decreasing the load of > mac802154, because most of these frames are already filtered by the phy. > > NOW if you set promiscuous mode on WPAN/NODE you increasing workload but > the most frames will dropped at [0]. You don't get more frames into the > interface (userspace). You only increasing the workload of the cpu. > > > On Monitor interface the PHY doesn't filter anything and the filtering > of [0] is disabled. It's directly send it to the interface so you can > see all frames, also frames which doesn't belong to you. > What a monitor interface does on receiving is [1]. Don't check anything > directly send it to the MONITOR interface. That's why I said "the > monitor interface is a big userspace playground - no filtering on PHY > and kernel is involved". > Is there maybe some practical use for being in promiscuous mode and operate as coordinator/node? Is that what you want? Because at the moment you need to ifconfig down/ip set link dev foo0 down on all non monitor interfaces and up then a monitor interfaces to get all unfiltered frames. After that you can do wireshark -i monitor0 or something else... to debug network traffic. I see no sense to run promiscuous mode while coordinator/node. I think more to handle this correctly would make the stack much complicated. - Alex -- To unsubscribe from this list: send the line "unsubscribe linux-wpan" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
