[ovs-dev] [PATCH 2/6] vxlan: Group Policy extension

[Thomas Graf]

On 01/12/15 at 06:28pm, Tom Herbert wrote:
> On Mon, Jan 12, 2015 at 5:03 PM, Thomas Graf <tgraf at suug.ch> wrote:
> >>
> >> Creating a level of indirection for extensions seems overly
> >> complicated to me. Why not just define IFLA_VXLAN_GBP as just another
> >> enum above?
> >
> > I think it's cleaner to group them in a nested attribute.
> > It clearly separates the optional extensions from the base
> > attributes. RCO, GPE, GBP can all live in there.
> 
> This is inconsistent with similar things in GRE and GUE. For instance,
> GRE keyid is set as its own attribute. It just seems like this adding
> more code to the driver than is necessary for the functionality
> needed.

The major difference here is that we have to consider backwards
compatibility specifically for VXLAN. Your initial feedback on GPE
actually led me to how I implemented GBP.

I think the axioms we want to establish are as follows:
 1. Extensions need to be explicitly enabled by the user. A previously
    dropped frame should only be processed if the user explitly asks
    for it.
 2. As a consequence: only share a VLXAN UDP port if the enabled
    extensions match (vxlan_sock_add), e.g. user A might want RCO
    but user B might be unaware. They cannot share the same UDP port.

The 2nd lead me to introduce the 'exts' member to vxlan_sock so we can
compare it in vxlan_find_sock() and only share a UDP port if the
enabled extensions match.

Your patch currently implements (1) but not (2).