[ovs-dev] proposed flow key compatibility rules

[Jesse Gross]

On Tue, Nov 8, 2011 at 5:03 PM, Ben Pfaff <blp at nicira.com> wrote:
> Jesse and I spent some time pondering this face-to-face, so there's a
> bunch of discussion that hasn't shown up on the mailing list.
>
> My understanding of what we concluded is:
>
>        - We will add a new "encap" flow key attribute that contains
>          nested attributes.  An "encap" is used whenever layering is
>          duplicated or jumps down (e.g. when a L2, L3, or L4 header
>          is followed by an L2 header).
>
>        - The "set" action is explicitly defined to act on the
>          outermost instance of a header.
>
>        - We will abandon the pretense that "push" and "pop" can be
>          generic and introduce explicit "push_vlan" and "pop_vlan"
>          actions.

I agree that this is what we concluded.  I had one additional thought
though: In general, this format is now ordering independent but the
encap attribute is linked to the encapsulating tag but is separate.  I
think this is not actually ambiguous because there can only be one
level of encapsulation at a given nesting level and it is always
essentially at the end.  It's a little strange though.

A couple of unimportant notes:
 * Some of the flow lines are really long.
 * The vlan example uses 0x800 instead of 0x0800 like in other places.
 * I would explicitly specify that duplicate tags are not allowed and
that ordering is not significant.