[ovs-discuss] ovs-ofctl match NW_DST

[Ben Pfaff]

On Sat, Jan 26, 2013 at 11:19:18PM -0200, Ramon Marques wrote:
> Hello,
> 
> I am trying to use ovs-ofctl to add a flow that matches the nw_dst field.
> I'm running  ovs-ofctl add-flow
> tcp:127.0.0.1:6634nw_dst=10.0.0.2,actions=mod_vlan_vid:1,output:2
> 
> and  I get the following mesasge:
> 
> 2013-01-27T01:09:28Z|00001|ofp_util|INFO|normalization changed ofp_match,
> details:
> 2013-01-27T01:09:28Z|00002|ofp_util|INFO| pre: nw_dst=10.0.0.2
> 2013-01-27T01:09:28Z|00003|ofp_util|INFO|post:
> 
> 
> But the flow is not installed correctly. If I run the ovs-ofctl dump-flows
> the flow table is not matching the nw_dst field.
> 
> 
> Am I  doing something wrong?

This is in the FAQ.

Q: I ran "ovs-ofctl add-flow br0 nw_dst=192.168.0.1,actions=drop"
   but I got a funny message like this:

       ofp_util|INFO|normalization changed ofp_match, details:
       ofp_util|INFO| pre: nw_dst=192.168.0.1
       ofp_util|INFO|post:

   and when I ran "ovs-ofctl dump-flows br0" I saw that my nw_dst
   match had disappeared, so that the flow ends up matching every
   packet.

A: The term "normalization" in the log message means that a flow
   cannot match on an L3 field without saying what L3 protocol is in
   use.  The "ovs-ofctl" command above didn't specify an L3 protocol,
   so the L3 field match was dropped.

   In this case, the L3 protocol could be IP or ARP.  A correct
   command for each possibility is, respectively:

       ovs-ofctl add-flow br0 ip,nw_dst=192.168.0.1,actions=drop

   and 

       ovs-ofctl add-flow br0 arp,nw_dst=192.168.0.1,actions=drop

   Similarly, a flow cannot match on an L4 field without saying what
   L4 protocol is in use.  For example, the flow match "tp_src=1234"
   is, by itself, meaningless and will be ignored.  Instead, to match
   TCP source port 1234, write "tcp,tp_src=1234", or to match UDP
   source port 1234, write "udp,tp_src=1234".