[ovs-dev] Vlan tag

[nicolas prochazka]

ok so it's not a good news,
it's only about igb or e1000, ixgbe ?

igb dev team  aware about this known issue ?

Can we help ?

Regards,
Nicolas



2011/6/11 Jesse Gross <jesse at nicira.com>

> On Fri, Jun 10, 2011 at 3:31 PM, nicolas prochazka
> <prochazka.nicolas at gmail.com> wrote:
> > I've read some documentation :
> > Support vlan_group workaround implemented in XenServer kernels.
> >
> > Some Linux network drivers support a feature called "VLAN acceleration",
> > associated with a data structure called a "vlan_group".  A vlan_group is,
> > abstractly, a dictionary that maps from a VLAN ID (in the range 0...4095)
> > to a VLAN device, that is, a Linux network device associated with a
> > particular VLAN, e.g. "eth0.9" for VLAN 9 on eth0.
> >
> > Some drivers that support VLAN acceleration have bugs that fall roughly
> > into the following categories:
> >
> >
>     * Some NICs strip VLAN tags on receive if no vlan_group is registered,
> >       so that the tag is completely lost.
> >
> >
>     * Some drivers size their receive buffers based on whether a vlan_group
> >       is enabled, meaning that a maximum size packet with a VLAN tag will
> >       not fit if a vlan_group is not configured.
> >
> >     * On transmit some drivers expect that VLAN acceleration will be used
> >       if it is available (which can only be done if a vlan_group is
> >
>       configured).  In these cases, the driver may fail to parse the packet
> >       and correctly setup checksum offloading and/or TSO.
> >
> >
> The correct long term solution is to fix these driver bugs.  To cope until
> >
> then, we have prepared a patch to the Linux kernel network stack that works
> > around these problems.  This commit adds support for the workaround
> > implemented by that patch.
> >
> >
> >
> > But it seems to be correct since sometime in kernel and igb driver ?
>
> No version of the igb driver works properly with Open vSwitch.  The
> above documentation refers to a workaround patch that can help but it
> only applies to the 2.6.32 kernel.  A proper fix (as would be accepted
> into mainline Linux) requires patching the driver.
>
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