Hi Jukka, On Tue, Sep 23, 2014 at 05:20:42PM +0300, Jukka Rissanen wrote: > Hi Alex, > > On ti, 2014-09-23 at 11:35 +0200, Alexander Aring wrote: > > Jukka, > > > > I/Simon mainly add you here in cc because this bug what Simon fixed here > > is also inside of bluetooth 6lowpan. > > > > I see now [0]. And it seems to me that this also occurs at bluetooth > > branch. Do you have any questions on how the fix now is? Sorry, but I > > need to clarify that you understood this issue and you/others prepare a > > patch for this. > > I was trying to test this issue and send multicast packets to Bluetooth > 6lowpan until I realized that the interface does not have IFF_MULTICAST > enabled :) So this issue is not valid atm for Bluetooth. > Sorry that confusing me now completely. I don't know how 6LoWPAN Bluetooth works. But sending MULTICAST packets is part of IPv6 so 6LoWPAN need the possibility to send MULTICAST packets at L3. On L2 (that's 802.15.4) we don't support MULTICAST but we sending BROADCAST frames out. So we have a LOGICAL MULTICAST over BROADCAST. I don't know how bluetooth works, if they have some MULTICAST support, we don't have it. Ethernet has MULTICAST support (as L2 example). We already talked about RFC6775 that's mainly an optimzation for neighbor discovery. The ethernet neighbor discovery use's many MULTICAST frames, because ethernet have PHYSICAL MULTICAST support. RFC6775 have different strategy to use LOGICAL MULTICAST which have a PHYSICAL BROADCAST to have less traffic afterwards. That's one of the big benefits to use RFC6775. Sorry, that 6LoWPAN Bluetooth doesn't support MULTICAST sounds for me wrong. I mean the underlaying device supports BROADCAST, but then you have a LOGICAL MULTICAST over a BROADCAST (that's how 802.15.4 deal with that). How can neighbor discovery deal with that? I don't think that the kernel implementation checks on IFF_MULTICAST flag. And now you can't send no MULTICAST 6LoWPAN packets on an IPv6 socket? Don't know but 6LoWPAN is an adaptation layer, it should be support all things what's also supported by IPv6. To the fix: But this issue "could" also occur on non multicast packets, it's better to be sure that the buffer isn't shared when replacing IPv6 with 6LoWPAN header. - 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
