[ovs-discuss] Does OpenvSwitch support modify the packet's IP address and then output this packet?

[Shawn Lin]

Hi all,

I am trying to use OpenvSwitch to exchange the source IP address and the
destination IP address of a packet, and then forward this packet out to a
host.

I do this test in *Mininet(2.2.1) *and *OpenvSwitch(2.0.2)*, And below is
the command:

Topology in Mininet is quite simple,
*h1-s1-h2*

I use this command to add the flow.
*mininet> sh ovs-ofctl add-flow s1
dl_type=0x0800,dl_type=0x0800,nw_dst=10.0.0.2,actions=mod_dl_src:00:00:00:00:00:02,mod_dl_dst:00:00:00:00:00:01,mod_nw_src:10.0.0.2,mod_nw_dst=10.0.0.1,output:1
-O OpenFlow13*

And then I could see the result when I show flows in the switch s1,

*mininet>* *sh ovs-ofctl dump-flows s1 -O OpenFlow13*
OFPST_FLOW reply (OF1.3) (xid=0x2):



* cookie=0x0, duration=418.133s, table=0, n_packets=1813, n_bytes=2731190,
ip,nw_dst=10.0.0.2
actions=mod_dl_src:00:00:00:00:00:02,mod_dl_dst:00:00:00:00:00:01,mod_nw_src:10.0.0.2,mod_nw_dst:10.0.0.1,output:1
     *
* In my understanding, this flow would change the packets' src IP, dst IP,
src Mac, dst Mac, and then forward it out port 1 which is s1-eth1.  *

 cookie=0x2b0000000000000f, duration=2982.739s, table=0, n_packets=1,
n_bytes=42, priority=2,in_port=1 actions=output:2,CONTROLLER:65535


 cookie=0x2b0000000000000e, duration=2982.739s, table=0, n_packets=1,
n_bytes=42, priority=2,in_port=2 actions=output:1,CONTROLLER:65535


 cookie=0x2b0000000000000f, duration=2986.774s, table=0, n_packets=0,
n_bytes=0, priority=100,dl_type=0x88cc actions=CONTROLLER:65535


 cookie=0x2b0000000000000f, duration=2986.774s, table=0, n_packets=0,
n_bytes=0, priority=0 actions=drop

And then in terminal, I use tcpdump to catch the packets through s1-eth1,
*tcpdump -i s1-eth1 -w result.pcap*

I scan all packets and find that these packets are all with *src IP
10.0.0.1, and dst IP 10.0.0.2.*
At the same time, the *n_bytes* in flow shows that this flow has been hit.

So Am I doing some wrong configuration? Or which version of OVS support
this feature? Any suggestions or comments are welcomed!

I am looking forward to hearing from you!

Bests,
Shawn Lin
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