>I don't know anything about the driver, but I know a few things about 
>Ethernet and multicast.
>
>The proper way to address a multicast packet on Ethernet, is to map the 
>last 23 bits of the multicast IP address to the last 23 bits of a 48 bit 
>Ethernet multicast address range 01:00:5e:00:00:00 to 01:00:5e:7f:ff:ff.
>This applies to both IPv4 and IPv6.  (Note that there is no 1-1 mapping 
>from IP address to MAC address.)

	yup, I know.

>However, since many switches get problems when interfaces on more than 
>one port listen to the same MAC address, multicast is often sent using 
>the Ethernet broadcast address instead.  Quick and dirty.  
>
>If your router maps the addresses the proper way and the driver depends 
>on the qiuck and dirty way (as the oposite may have a bad effect on 
>switches), then you will get these kinds of problems.  Try to figure 
>out which ethernet address the multicast packets are sent to, and see if 
>this could be the problem.

	The packet is IPv6 multicast packet.  It was sent from "sender" node
	that shares the same ethernet link as the "receiver".
	No router is involved.  It was also verified that the packet is
	actually on the wire, by the third-party node ("watcher").

	==+=======+===============+==
	  |	  |hme0		  |
	sender	receiver	watcher

	it was also verified that hme0 joins ethernet multicast address
	33:33:0:0:0:1, so if hme driver is working right, the packet would
	be received by hme driver and sent to the upper layer.  This is not
	happening and I wonder if hme driver supports multicast at all, or
	hme driver has some issue with programming multicast filter.

itojun


(NOTE: this was not the one on the bug report, I made the similar packet
dump for this email)

21:47:31.690173 8:0:5a:38:6f:86 33:33:0:0:0:1 86dd 70: fe80::a00:5aff:fe38:6f86 > ff02::1: icmp6: echo request
0x0000   6000 0000 0010 3a40 fe80 0000 0000 0000        `.....:@........
0x0010   0a00 5aff fe38 6f86 ff02 0000 0000 0000        ..Z..8o.........
0x0020   0000 0000 0000 0001 8000 5bf8 1ab0 0038        ..........[....8
0x0030   63d0 4839 8287 0a00                            c.H9....