> On Nov 30, 2016, at 8:50 PM, Ben Pfaff <b...@ovn.org> wrote:
> 
> On Wed, Nov 30, 2016 at 06:58:57PM -0800, Jarno Rajahalme wrote:
>> 
>>> On Nov 30, 2016, at 8:41 AM, Ben Pfaff <b...@ovn.org> wrote:
>>> 
>>> On Wed, Nov 30, 2016 at 12:05:46PM +0100, Thomas Morin wrote:
>>>> Hi Ben,
>>>> 
>>>> 2016-11-30, Ben Pfaff:
>>>>> Do you have any idea what in your OpenFlow pipeline might do that,
>>>>> i.e. is there anything especially tricky in the OpenFlow flows?
>>>>> 
>>>>> Are you willing to show us your OpenFlow flow table?
>>>> 
>>>> The setup involves three OVS bridges connected with patch-ports: br-int --
>>>> br-tun -- br-mpls, with the traffic that triggers the assert being 
>>>> processed
>>>> by br-int with a NORMAL action (ie. MAC learning).
>>>> 
>>>> The flows in this setup aren't particularly tricky, I think, although I'm
>>>> not sure what qualifies as tricky or non-tricky :)
>>>> 
>>>> Anyway, since yesterday I managed to identify the event that trigger the
>>>> assert, by adding more logging before the assert and displaying the actions
>>>> taken:
>>>> 
>>>> 2016-11-29T14:44:40.126Z|00001|odp_util(revalidator45)|WARN|commit_set_ipv4_action
>>>> assert would fail....
>>>> 2016-11-29T14:44:40.126Z|00002|odp_util(revalidator45)|WARN|  base_flow: 
>>>> ip,in_port=5,dl_vlan=3,dl_vlan_pcp=0,dl_src=fa:16:3e:33:f7:fe,dl_dst=00:00:5e:00:43:64,nw_src=0.0.0.0,nw_dst=0.0.0.0,nw_proto=0,nw_tos=0,nw_ecn=0,nw_ttl=0
>>>> 2016-11-29T14:44:40.126Z|00003|odp_util(revalidator45)|WARN|  flow: 
>>>> tcp,in_port=5,dl_vlan=3,dl_vlan_pcp=0,dl_src=fa:16:3e:33:f7:fe,dl_dst=00:00:5e:00:43:64,nw_src=10.0.1.22,nw_dst=10.0.0.3,nw_tos=0,nw_ecn=0,nw_ttl=64,tp_src=53295,tp_dst=8080,tcp_flags=psh|ack
>>>> 2016-11-29T14:44:40.126Z|00004|odp_util(revalidator45)|WARN|  masks: 
>>>> recirc_id=0xffffffff,reg0=0xffffffff,in_port=4294967295,dl_vlan=4095,dl_vlan_pcp=7,dl_src=ff:ff:ff:ff:ff:ff,dl_dst=ff:ff:ff:ff:ff:ff,dl_type=0xffff
>>>> 2016-11-29T14:44:40.126Z|00005|odp_util(revalidator45)|WARN|  actions: 
>>>> set(ipv4(src=10.0.1.22,dst=10.0.0.3,ttl=63)),set(eth(src=b8:2a:72:de:1b:e3,dst=00:17:cb:79:2c:01)),push_mpls(label=410384,tc=0,ttl=63,bos=1,eth_type=0x8847),9,set(eth(src=fa:16:3e:33:f7:fe,dst=00:00:5e:00:43:64)),pop_mpls(eth_type=0x800),push_vlan(vid=3,pcp=0),1
>> 
>> push_mpls clears L3/L4, while pop_mpls re-populates them, and then 
>> processing the output to port 1 hits the assert?
> 
> That's what I'm thinking too.
> 
> Jarno, is this something you have time to look into?  It'd be great, if
> you do.  I'm way behind.

I’m looking at this.

Based on the trace given it seems that:
1. Packet is received on br-int port 32, which outputs it via NORMAL action 
over a patch port to another bridge. The only patch-port on br-int is 2 
(patch-tun). The NORMAL action adds dl_vlan=1.
2. br-tun receives the packet on in_port 1 (patch-int), and outputs it on it’s 
port 2 (patch-to-mpls)
3. br-mpls receives the packet on it’s in_port 2 (patch-to-tun), does pop_vlan, 
and outputs to it’s port 21 (ipvpn-pp-out), which is also an patch port.
4. br-mpls (?) receives the packet on it’s in_port 20 (ipvpn-pp-in), does 
dec_ttl,push_mpls:0x8847,load:0x644c0->OXM_OF_MPLS_LABEL[],set_field:b8:2a:72:de:1b:e3->eth_src,set_field:00:17:cb:79:2c:01->eth_dst,output:1

All this generates a megaflow: 
set(ipv4(src=10.0.1.23,dst=10.0.0.3,ttl=63)),set(eth(src=b8:2a:72:de:1b:e3,dst=00:17:cb:79:2c:01)),push_mpls(label=410816,tc=0,ttl=63,bos=1,eth_type=0x8847),9

This is only the beginning part of the trouble-some megaflow, in which br-int 
sends the packet also to another port (vlan 3), and as part of that pops the 
MPLS and restores the original ethernet addresses. Maybe this would happen with 
the trace too, if you flushed MACs before the trace?

The patch ports 21 and 20 appear to be in the same bridge and patched to each 
other. Is this the case?

The crashing megaflow has in_port=5,dl_vlan=3. Is this also on br-int?

Also, OVS 2.6 is a little bit less aggressive about avoiding recirculation 
after mpls operations, and I’d be interested to know if your case fails the 
same way with OVS 2.6?

Thanks,

  Jarno

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