[ovs-dev] ovn ping from VM to external gateway IP failed.

Mickey Spiegel mickeys.dev at gmail.com
Mon Jan 2 20:36:52 UTC 2017


On Mon, Jan 2, 2017 at 3:46 AM, Numan Siddique <nusiddiq at redhat.com> wrote:

>
>
> On Mon, Jan 2, 2017 at 2:07 AM, Mickey Spiegel <mickeys.dev at gmail.com>
> wrote:
>
>>
>> On Sun, Jan 1, 2017 at 10:31 AM, Numan Siddique <nusiddiq at redhat.com>
>> wrote:
>>
>>>
>>>
>>> On Sun, Jan 1, 2017 at 6:39 AM, Mickey Spiegel <mickeys.dev at gmail.com>
>>> wrote:
>>>
>>>>
>>>> On Sat, Dec 31, 2016 at 1:19 AM, Mickey Spiegel <mickeys.dev at gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On Fri, Dec 30, 2016 at 11:37 AM, Mickey Spiegel <
>>>>> mickeys.dev at gmail.com> wrote:
>>>>>
>>>>>>
>>>>>> On Fri, Dec 30, 2016 at 7:46 AM, Numan Siddique <nusiddiq at redhat.com>
>>>>>> wrote:
>>>>>>
>>>>>>> On Fri, Dec 30, 2016 at 5:36 PM, Dong Jun <dongj at dtdream.com> wrote:
>>>>>>>
>>>>>>
>>>>>> <snip>
>>>>>>
>>>>>>
>>>>>>>>>>>>>> Hi Dong Jun, I am also facing the same issue on my setup.
>>>>>>>>>>>>>> These are the findings of my investigation so far
>>>>>>>
>>>>>>> Looks like this issue is seen after the commit
>>>>>>> https://github.com/openvswitch/ovs/commit/f1a8bd06d58f2c5312
>>>>>>> 622fbaeacbc6ce7576e347
>>>>>>>>>>>>>> which removes the usage of patch ports and uses the clone action
>>>>>>> instead.
>>>>>>>>>>>>>>
>>>>>>> I reverted to the commit just before it and SNAT/DNAT is working as
>>>>>>> expected.
>>>>>>>
>>>>>>> In my case, the gateway router is hosted on node 1 and the I am
>>>>>>> trying to
>>>>>>> reach a VM (192.168.0.5) hosted on node 2 using the external ip
>>>>>>> (10.2.7.105) associated ​with it. I could see that the node 1 is
>>>>>>> sending
>>>>>>> the packet to node 2 through the geneve tunnel, but it is dropped by
>>>>>>> node 2
>>>>>>> flows.
>>>>>>>
>>>>>>> Below is the tcpdump of the packet
>>>>>>>
>>>>>>> **************************
>>>>>>> 19:39:44.709907 IP 182.16.0.16.60069 > 182.16.0.15.geneve: Geneve,
>>>>>>> Flags
>>>>>>> [none], vni 0x1: IP nusiddiq.blr.redhat.com > 192.168.0.5: ICMP echo
>>>>>>> request, id 13240, seq 1, length 64
>>>>>>> ***************************
>>>>>>>
>>>>>>> Below is the tcpdump of the packet with the ovn-controller (without
>>>>>>> the
>>>>>>> above commit) in the working case
>>>>>>>
>>>>>>> **************************
>>>>>>> 19:41:56.783570 IP 182.16.0.12.29778 > 182.16.0.15.geneve: Geneve,
>>>>>>> Flags
>>>>>>> [C], vni 0x1, options [8 bytes]: IP nusiddiq.blr.redhat.com >
>>>>>>> 192.168.0.5:
>>>>>>> ICMP echo request, id 13308, seq 1, length 64
>>>>>>> 19:41:56.784270 IP 182.16.0.15.14539 > 182.16.0.12.geneve: Geneve,
>>>>>>> Flags
>>>>>>> [C], vni 0xf, options [8 bytes]: IP 192.168.0.5 >
>>>>>>> nusiddiq.blr.redhat.com:
>>>>>>> ICMP echo reply, id 13308, seq 1, length 64
>>>>>>> **************************
>>>>>>>
>>>>>>> The options data has - 00030005
>>>>>>>
>>>>>>> From the packet, I could see that the packet from node 1 is missing
>>>>>>> the
>>>>>>> geneve option fields which has inport and outport keys.
>>>>>>>
>>>>>>
>>>>>> I am facing the same issue running my distributed NAT patch set.
>>>>>> Between UNSNAT recirc and output to tunnel, a megaflow is installed
>>>>>> that
>>>>>> is missing the geneve option fields.
>>>>>>
>>>>>> I verified that the table=32 openflow rule has the geneve option
>>>>>> fields.
>>>>>> ofproto/trace shows geneve in the "Datapath actions" at the end, so no
>>>>>> problem with whatever ofproto/trace is using.
>>>>>>
>>>>>
>>>>> Throwing some logs in, I see that flow->metadata.present.map is 0
>>>>> rather
>>>>> than 1 coming into tun_metadata_to_geneve_nlattr() in
>>>>> lib/tun-metadata.c,
>>>>> when the problem occurs. That is why the geneve option fields are
>>>>> missing.
>>>>>
>>>>> I have not yet figured out why flow->metadata.present.map is 0. It
>>>>> should
>>>>> be modified when tun_metadata_write() is called due to actions setting
>>>>> tunnel metadata values. I have not checked that yet.
>>>>>
>>>>
>>>> I just posted a fix. I did not try it with the gateway router or with
>>>> OpenStack,
>>>> but with this bug fix all distributed NAT manual test cases are now
>>>> passing.
>>>>
>>>>
>>> ​Thanks for the fix. I just tested it. Its working when I am trying to
>>> reach the ​VM using its floating ip. But not when trying to ping
>>> www.google.com from the VM (SNAT use case)
>>>
>>
>> With distributed NAT, most of my debugging and tests were using SNAT. The
>> bug fix that I posted fixed the problem that was causing ICMP echo replies
>> to be dropped. The openflow path for distributed SNAT is similar to that
>> for SNAT on gateway routers, but there are still some differences, notably
>> one router instead of two routers and no "join" switch. Also I did not try
>> it with DNS.
>>
>> Are you able to debug further, to see whether a missing geneve options
>> field is still the culprit?
>> It is possible that removal of patch ports within br-int uncovered other
>> issues.
>>
>
>
> ​With some testing I could see that in the node where the gateway is
> hosted
>  - The ​reply packet reaches the gateway router pipeline -> to the otls
> switch pipeline (via clone) -> to the router pipeline -> to the peer port
> of the switch.
> ​The packet gets dropped at table 22
>
>  table=22, n_packets=275, n_bytes=26686, priority=65535,ct_state=+inv+trk,metadata=0x1
> actions=drop
>
> Not sure why it is happening. I will try to debug further.
>

I added stateful ACLs, but I am unable to reproduce this. Nothing hits
the invalid ct_state flow, trying switch -> router -> switch, across
localnet at the end, and with various distributed NAT flavors including
DNAT and SNAT. The pings always succeed.

As I suggested on IRC, I think that conntrack state should be cleared
when crossing an OVN patch port. Specifically, in ovn/controller/physical.c,
inside the clone, it should clear ct_state (MFF_CT_STATE, be16),
ct_mark (MFF_CT_MARK, be32), and ct_label (MFF_CT_LABEL, be128).

Mickey


>
> Numan
>
>
>
>> I primarily used ovs-dpctl dump-flows to see installed megaflows, ovs-appctl
>> ofproto/trace (with recirc_id), and ovs-ofctl dump-flows for initial
>> debugging. In particular I could see that the installed megaflows were
>> lacking the geneve options field in the actions.
>>
>> Mickey
>>
>>
>>> Numan
>>>
>>>
>>>> Mickey
>>>>
>>>>
>>>>> Mickey
>>>>>
>>>>>
>>>>>> Mickey
>>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Thanks
>>>>>>> Numan
>>>>>>>
>>>>>>>
>>>>>>> > _______________________________________________
>>>>>>> > dev mailing list
>>>>>>> > dev at openvswitch.org
>>>>>>> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>>>>> >
>>>>>>> _______________________________________________
>>>>>>> dev mailing list
>>>>>>> dev at openvswitch.org
>>>>>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>


More information about the dev mailing list