[ovs-dev] [PATCH] ofp-util: Recognise wildcarded VLAN as NXM only.

[Ben Pfaff]

On Sat, Mar 31, 2012 at 01:30:59AM -0700, Ethan Jackson wrote:
> Is there any reason we can't simply ignore the CFI bit?  Something like the
> following?  I'm having trouble working out exactly how the CFI bit in OpenFlow
> matches interacts with the various versions and the classifier.

OpenFlow 1.0 can accurately encode the following vlan_tci and
vlan_tci_mask combinations:

vlan_tci         vlan_tci_mask   matches a packet that has...
---------------  -------------   --------------------------------------------
0                0               with any 802.1Q header or without one
0                CFI|<any>       no 802.1Q header
CFI|<vid>        CFI|VID         an 802.1Q header with given <vid>
CFI|<pcp>        CFI|PCP         an 802.1Q header with given <pcp>
CFI|<vid>|<pcp>  CFI|VID|PCP     an 802.1Q header with given <vid> and <pcp>
<vid>       [*]  VID             an 802.1Q header with given <vid>
<pcp>       [*]  PCP             an 802.1Q header with given <pcp>
<vid>|<pcp> [*]  VID|PCP         an 802.1Q header with given <vid> and <pcp>

where:
    CFI = 0x1000
    VID = 0x0fff
    PCP = 0xe000
    <any> = an arbitrary 16-bit value
    <vid> = an arbitrary 12-bit value, a subset of bits in the mask 0x0fff
    <pcp> = an arbitrary 3-bit value, a subset of bits in the mask 0xe000
    [*] indicates that the row applies only if the vlan_tci is nonzero.

I think that we should check allow exactly the correct combinations.

Thanks,

Ben.