[Qemu-devel] Re: net packet storms with multiple NICs

[Michael Tokarev]

Andreas Plesner Jacobsen wrote:
> On Fri, Oct 23, 2009 at 08:25:39PM +0400, Michael Tokarev wrote:
> > o why different -net guest -net host pairs are not getting different
> >   vlan= indexes by default, to stop the above-mentioned packet
> >   storms right away?  I think it's a wise default to assign different
> >   pairs to different vlans, by counting -net host and -net guest
> >   sequences.
>
> I think the major issue is that the definition of a "pair" is when the
> vlan-options match. There's no requirement to define the two after each
> other.

I mean something like this (rough approximation:

 int host_vlan_no = 0, guest_vlan_no = 0;

 while(parse_option()) {
    if (option == host-side-net) {
      if (!explicit_vlan) vlan = host_vlan_no;
      ++host_vlan_no;
    }
    if (option == guest-side-net) {
      if (!explicit_vlan) vlan = guest_vlan_no;
      ++guest_vlan_no;
    }
 }

this way, consecutive host-side -net will receive
consecutive vlan=NN, and consecutive guest-side -net
also consecutive vlan=NN numbers.

But having in mind Marc's reply I don't think it's
necessary anymore.

Thanks!

/mjt