On Friday 24 October 2008, Javier Cardona wrote: > Andrey, > > On Thu, Oct 23, 2008 at 2:49 PM, Andrey Yurovsky <andrey@xxxxxxxxxxx> wrote: > > I've come across a problem with the RX filter setting while testing mesh point > > operation in the rt2x00 driver (my hardware is rt73usb). We transmit and > > receive mesh beacons but mesh peer link action frames are dropped. A patch > > for enabling mesh point mode is included here, this works except that: > > > > The RX filter, as set by mac80211 in mesh mode is 0x02, that is FIF_ALLMULTI is > > set. This is sufficient for other drivers but not for rt2x00. I noticed that > > running tcpdump on the MP interface sets the filter to 0x43, this adds > > FIF_OTHER_BSS and FIF_PROMISC_IN_BSS, and rt2x00 is then able to make peer > > links and mesh point mode works correctly. > > > > Actually for rt2x00, setting either FIF_OTHER_BSS or FIF_PROMISC_IN_BSS is the > > key here because they are both treated as FIF_PROMISC_IN_BSS, which causes the > > driver to enable TXRX_CSR0_DROP_TO_DS. > > Mesh frames have 4 addresses and no BSSID, so BSSID filtering should > be disabled (i.e. FIF_OTHER_BSS should be set). > The ALL_MULTI flag is also needed for mesh mode because an > intermediate node has to forward multicast traffic for addresses that > it may not be listening to. > > But promiscuous mode is not necessary: mesh points don't need to > receive unicast frames not addressed¹ to them. Furthermore, enabling > promiscuous mode normally disables acknowledgments, which are needed > for proper mesh operation. > > So my recommendation would be to configure the RX filter in mesh mode > to be ( FIF_ALLMULTI | FIF_OTHER_BSS ) For rt2x00 this would turn into: FIF_ALLMULTI | FIF_OTHER_BSS | FIF_PROMISC_IN_BSS because it cannot filter on other BSS, but this conversion is within rt2x00 based on capabilities by the driver. So as long as mac80211 provides the flags it wants (FIF_ALLMULTI | FIF_OTHER_BSS), rt2x00 will convert it to the flags that make sure those frames will at least get through (FIF_ALLMULTI | FIF_OTHER_BSS | FIF_PROMISC_IN_BSS), including some additional noise from frames mac80211 didn't request specifically, but those can be filtered out in mac80211. Ivo -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
