[ovs-discuss] Problem in using packet values against register values in ovs-flow

[Ben Pfaff]

On Wed, Jul 08, 2015 at 09:38:06AM +0530, Pritam Kharat wrote:
> 1) In a ovs flow how do I load a nw_src with mask value  from a packet to
> register say reg0 ? Doc says we can load only integer or hex value to a
> register ? Is there any way to do it ?
> 
> e.g
> *table=0,<flow-match>,actions=load:(nw_src/mask)->NXM_NX_REG0[],load:(nw_dst/mask)->NXM_NX_REG1[],resubmit(,1)*

I guess you want the "move" action.

> 2) Can we create ovs flow which compares values in two registers. ?
>  e.g * match -> table=1,reg0==reg1*
> *       actions -> drop*
> 
> What I am trying to do is, see if packet is destined to vm of same subnet.
> If yes then drop the packet.This I want to do using registers so that way I
> will have only one flow ?

OVS doesn't have a general-purpose comparison operator or an easy way to
construct one.

> 3) Can I compare value from packet with value in register ?
> 
> e.g *table=1,nw_src=reg0,actions=drop*

Same as #2.