[ovs-discuss] Drop action behaviour

[Ben Pfaff]

On Wed, Oct 09, 2013 at 03:54:36PM +0000, Kavanagh, Mark B wrote:
> I have a question regarding the behaviour of the drop action.

There is no drop action.

> The FAQ states:
> 
>         "An empty set of actions causes a packet to be dropped.  You can
>         specify an empty set of actions with "actions=" on the ovs-ofctl command line".
> 
> So, for example if I add a flow using ofctl, specifying the action as
> 'drop', I assume that a flow table entry, consisting of the flow key
> and an empty actions field is added to the vswitchd's flow table.

Yes.

> In terms of how the drop action actually works, is there an explicit
> DROP action that is executed for flows that match this flow entry
> (similar to the PUSH_VLAN, OUTPUT, SET, etc. actions), and if not,
> what is the mechanism by which packets are dropped?

No.  There is no drop action.  When a switch "drops" a packet, that just
means that it doesn't forward it anywhere.  By specifying no actions,
the packet is not forwarded anywhere and, thus, it is dropped.