[ovs-discuss] Discrepancy between ofproto/trace output and dpctl dump-flows output

Ben Pfaff blp at ovn.org
Wed Mar 14 23:49:26 UTC 2018


I finally fixed this upstream in Git, and the fix will be in the next
releases on the 2.8 and 2.9 branches.

On Thu, Dec 07, 2017 at 06:06:22AM +0000, Amar Padmanabhan wrote:
> Yup thanks we are unblocked!
> - Amar
> 
> On 12/6/17, 12:36 PM, "Ben Pfaff" <blp at ovn.org> wrote:
> 
>     OK.
>     
>     In the meantime, you can add "eth()" to the flows you're tracing to get
>     the expected results.
>     
>     On Wed, Dec 06, 2017 at 07:02:42PM +0000, Amar Padmanabhan wrote:
>     > Thanks Ben for taking a look,
>     > Regards,
>     > - Amar
>     > 
>     > On 12/6/17, 10:17 AM, "Ben Pfaff" <blp at ovn.org> wrote:
>     > 
>     >     On Wed, Dec 06, 2017 at 05:58:41AM +0000, Amar Padmanabhan wrote:
>     >     > We are debugging a setup and are seeing something that we are finding it hard to explain.
>     >     > 
>     >     > 1 - Here is the ovs-dpctl dump-flows output.
>     >     > recirc_id(0),in_port(3),eth_type(0x0800),ipv4(dst=192.168.128.0/255.255.255.0,frag=no), packets:550, bytes:53900, used:0.364s, actions:userspace(pid=3276048382,slow_path(controller))
>     >     
>     >     OK, the above datapath flow just says that packets in this flow have to
>     >     be handled in the userspace slow path because 
>     >     
>     >     > 2 - We are now trying to trace this flow and are not seeing the output to controller flow getting hit in the trace.
>     >     > sudo ovs-appctl ofproto/trace "in_port(3),eth_type(0x0800),ipv4(dst=192.168.128.0/255.255.255.0,frag=no)"
>     >     > Flow: packet_type=(1,0x800),in_port=32770,nw_src=0.0.0.0,nw_dst=192.168.128.0,nw_proto=0,nw_tos=0,nw_ecn=0,nw_ttl=0
>     >     > bridge("gtp_br0")
>     >     > -----------------
>     >     > 0. priority 0 resubmit(,1)
>     >     > 1. in_port=32770, priority 10 set_field:0->metadata resubmit(,2)
>     >     > 2. priority 0 resubmit(,3)
>     >     > 3. No match. drop Final flow: unchanged Megaflow: recirc_id=0,packet_type=(1,0x800),in_port=32770,nw_frag=no Datapath actions: drop ---> Why isn’t the output to controller flow getting hit?
>     >     > 
>     >     > 
>     >     > 3 - We are also seeing the flow counts go up for the output to controller flow per the ofctl dump-flows output (pasting relevant flows)
>     >     > 
>     >     > NXST_FLOW reply (xid=0x4): cookie=0x0, duration=1482.245s, table=0, n_packets=1408, n_bytes=148464, idle_age=1, priority=0 actions=resubmit(,1)
>     >     > cookie=0x0, duration=1482.244s, table=1, n_packets=1283, n_bytes=123662, idle_age=1, priority=10,in_port=32770 actions=set_field:0->metadata,resubmit(,2)
>     >     > cookie=0x0, duration=1482.244s, table=2, n_packets=1247, n_bytes=122150, idle_age=1, priority=0 actions=resubmit(,3)
>     >     > cookie=0x0, duration=1482.245s, table=3, n_packets=1245, n_bytes=122010, idle_age=1, priority=0,ip,metadata=0,nw_dst=192.168.128.0/24 actions=CONTROLLER:65535 ---> Notice that this is getting hit as well
>     >     
>     >     OK, I spent a few minutes to mock up your environment (thanks for all
>     >     the details!) and experiment.  It looks like the problem is actually a
>     >     mismatch between the formatting and parsing code for datapath flows.  If
>     >     I run:
>     >     
>     >         ovs-appctl ofproto/trace "in_port(3),eth(),eth_type(0x0800),ipv4(dst=192.168.128.0/255.255.255.0,frag=no)"
>     >     
>     >     that is, add "eth()" to the datapath flow, then I get the expected
>     >     results:
>     >     
>     >         $ ovs-appctl ofproto/trace "in_port(1),eth(),eth_type(0x0800),ipv4(dst=192.168.128.0/255.255.255.0,frag=no)"
>     >         Flow: ip,in_port=32770,vlan_tci=0x0000,dl_src=00:00:00:00:00:00,dl_dst=00:00:00:00:00:00,nw_src=0.0.0.0,nw_dst=192.168.128.0,nw_proto=0,nw_tos=0,nw_ecn=0,nw_ttl=0
>     >     
>     >         bridge("br0")
>     >         -------------
>     >          0. priority 0
>     >             resubmit(,1)
>     >          1. in_port=32770, priority 10
>     >             load:0->OXM_OF_METADATA[]
>     >             resubmit(,2)
>     >          2. priority 0
>     >             resubmit(,3)
>     >          3. ip,metadata=0,nw_dst=192.168.128.0/24, priority 0
>     >             CONTROLLER:65535
>     >     
>     >         Final flow: unchanged
>     >         Megaflow: recirc_id=0,eth,ip,in_port=32770,nw_dst=192.168.128.0/24,nw_frag=no
>     >         Datapath actions: drop
>     >         This flow is handled by the userspace slow path because it:
>     >                 - Sends "packet-in" messages to the OpenFlow controller.
>     >     
>     >     Clearly that's a bug.  I'll see what I can do about it.
>     >     
>     >     > Also, Whoever improved the output of ofproto/trace thanks a ton!
>     >     
>     >     That was me :-)  You're welcome.
>     >     
>     > 
>     
> 


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