Jean Baptiste FAVRE
2009-Feb-23 22:37 UTC
[Xen-users] Xen''s interface in promiscuous mode
Hello all, Playing with Xen on GNU/Debian Lenny, I just discovered that all my virtual network cards are in promiscuous mode by default. Changing that manually does not seems to change anything (that is, everything still works great). Is there any reason to have virtual network cards in promiscuous mode ? And where can I change this default behaviour ? Thanks, JB _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Hello all, > Playing with Xen on GNU/Debian Lenny, I just discovered that all my > virtual network cards are in promiscuous mode by default. > Changing that manually does not seems to change anything (that is, > everything still works great). > > Is there any reason to have virtual network cards in promiscuous mode?> And where can I change this default behaviour ? >The physical network adapters in Dom0 will be in promiscuous mode if they are joined to a bridge. The virtual network adapters in DomU are in promiscuous modem because (as of the version of Xen in Lenny) they don''t support multicast, and so the only way they can receive multicast packets is to be in promiscuous mode. As of 3.3.0 or thereabouts, there is a way for the frontend to tell the backend which multicast packets it is interested in, so the behaviour may be different there. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Ricardo J. Barberis
2009-Feb-25 01:21 UTC
Re: [Xen-users] Xen''s interface in promiscuous mode
El Lunes 23 Febrero 2009, James Harper escribió:> > Hello all, > > Playing with Xen on GNU/Debian Lenny, I just discovered that all my > > virtual network cards are in promiscuous mode by default. > > Changing that manually does not seems to change anything (that is, > > everything still works great). > > > > Is there any reason to have virtual network cards in promiscuous mode > > ? > > > And where can I change this default behaviour ? > > The physical network adapters in Dom0 will be in promiscuous mode if > they are joined to a bridge. > > The virtual network adapters in DomU are in promiscuous modem because > (as of the version of Xen in Lenny) they don''t support multicast, and so > the only way they can receive multicast packets is to be in promiscuous > mode. > > As of 3.3.0 or thereabouts, there is a way for the frontend to tell the > backend which multicast packets it is interested in, so the behaviour > may be different there.Hi James, Can you elaborate on that, or give a link to read more about it? TIA and best regards, -- Ricardo J. Barberis Senior SysAdmin - I+D Dattatec.com :: Soluciones de Web Hosting _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > El Lunes 23 Febrero 2009, James Harper escribió: > > > Hello all, > > > Playing with Xen on GNU/Debian Lenny, I just discovered that all my > > > virtual network cards are in promiscuous mode by default. > > > Changing that manually does not seems to change anything (that is, > > > everything still works great). > > > > > > Is there any reason to have virtual network cards in promiscuous mode > > > > ? > > > > > And where can I change this default behaviour ? > > > > The physical network adapters in Dom0 will be in promiscuous mode if > > they are joined to a bridge. > > > > The virtual network adapters in DomU are in promiscuous modem because > > (as of the version of Xen in Lenny) they don''t support multicast, and so > > the only way they can receive multicast packets is to be in promiscuous > > mode. > > > > As of 3.3.0 or thereabouts, there is a way for the frontend to tell the > > backend which multicast packets it is interested in, so the behaviour > > may be different there. > > Hi James, > > Can you elaborate on that, or give a link to read more about it? >Unless someone has written up some docs, your best bet is to look at the code - specifically the headers in xen/include/public/io James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Ricardo J. Barberis
2009-Feb-26 14:58 UTC
Re: [Xen-users] Xen''s interface in promiscuous mode
El Miércoles 25 Febrero 2009, James Harper escribió:> > El Lunes 23 Febrero 2009, James Harper escribió: > > > The physical network adapters in Dom0 will be in promiscuous mode if > > > they are joined to a bridge. > > > > > > The virtual network adapters in DomU are in promiscuous modem because > > > (as of the version of Xen in Lenny) they don''t support multicast, and > > > so the only way they can receive multicast packets is to be in > > > promiscuous mode. > > > > > > As of 3.3.0 or thereabouts, there is a way for the frontend to tell the > > > backend which multicast packets it is interested in, so the behaviour > > > may be different there. > > > > Hi James, > > > > Can you elaborate on that, or give a link to read more about it? > > Unless someone has written up some docs, your best bet is to look at the > code - specifically the headers in xen/include/public/io > > JamesOK, despite my limited C knowledge I''ll have to digg in :-) Thank you, -- Ricardo J. Barberis Senior SysAdmin - I+D Dattatec.com :: Soluciones de Web Hosting _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users