crossbow discuss - Aug 2007 - Behavioral difference between VNIC and physical NIC on multicast

Snooping on a VNIC with ipv6 unplumbed , one will not see any ipv6 NS/NA packets
while ipv6 is being plumbed up on another VNIC with the same physical NIC . You
can snoop this traffic after the VNIC has been plumbed up. This  is because ipv6
NS/NA are multicast . Even with ipv6 plumbed up , there are still some traffic
hidden from  snoop , like dhcpv6 solicit message, which are usually sent to
multicast address ff02::1:2 .
   If one is using raw endpoint( datalink layer) on a VNIC , similar problem
will happen. On a physical NIC , all multicast are received . On a VNIC , the
multicast packets are discarded.
   Shouldn''t all multicast packets be delivered to the VNIC while the
VNIC is in promiscous mode , or a raw endpoint has been opened on the VNIC?
 
 
This message posted from opensolaris.org

Samuel,

Good observation. There''s a known bug which prevents all all  
multicast packets to be passed to VNICs in promiscuous mode. This is  
not IPv6 specific BTW. It will be fixed in the crossbow gate as part  
of my MAC layer changes, and David is working on a fix for the Xen  
gate. If you could file a bug to make sure it''s tracked properly that  
would be great.

Thanks,
Nicolas.

On Aug 14, 2007, at 7:56 PM, Ying wrote:
> Snooping on a VNIC with ipv6 unplumbed , one will not see any ipv6  
> NS/NA packets  while ipv6 is being plumbed up on another VNIC with  
> the same physical NIC . You can snoop this traffic after the VNIC  
> has been plumbed up. This  is because ipv6 NS/NA are multicast .  
> Even with ipv6 plumbed up , there are still some traffic hidden  
> from  snoop , like dhcpv6 solicit message, which are usually sent  
> to multicast address ff02::1:2 .
>    If one is using raw endpoint( datalink layer) on a VNIC ,  
> similar problem will happen. On a physical NIC , all multicast are  
> received . On a VNIC , the multicast packets are discarded.
>    Shouldn''t all multicast packets be delivered to the VNIC while
> the VNIC is in promiscous mode , or a raw endpoint has been opened  
> on the VNIC?
>
>
> This message posted from opensolaris.org
> _______________________________________________
> crossbow-discuss mailing list
> crossbow-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/crossbow-discuss
-- 
Nicolas Droux - Solaris Core OS - Sun Microsystems, Inc.
droux at sun.com - http://blogs.sun.com/droux

On Tue, Aug 14, 2007 at 11:55:48PM -0600, Nicolas Droux
wrote:
> Good observation. There''s a known bug which prevents all all  
> multicast packets to be passed to VNICs in promiscuous mode. This is  
> not IPv6 specific BTW. It will be fixed in the crossbow gate as part  
> of my MAC layer changes, and David is working on a fix for the Xen  
> gate. If you could file a bug to make sure it''s tracked properly
that
> would be great.
The fix is back in /ws/matrix-gate, but much of it won''t apply easily
to /ws/crossbow-gate I imagine.

dme.