On 9/16/21 4:18 PM, Vladislav Odintsov wrote: > Sorry, by OOT I meant non-inbox kmod. > I’ve tried to use inbox kernel module (from kernel package) and problem > resolved. > > Regards, > Vladislav Odintsov > >> On 16 Sep 2021, at 17:17, Vladislav Odintsov <[email protected]> wrote: >> >> Hi Dumitru, >> >> I’ve tried to exclude OOT OVS kernel module. >> With OVN 20.06.3 + OVS 2.13.4 the problem solved. >> >> Could you please try with OOT kmod? For me it looks like a bug in OOT OVS >> kernel module code.
You're right, this seems to be a missing patch in the OOT openvswitch module. I could replicate the problem you reported with the OOT module. Regards, Dumitru >> >> Thanks. >> >> Regards, >> Vladislav Odintsov >> >>> On 16 Sep 2021, at 11:02, Dumitru Ceara <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> On 9/16/21 2:50 AM, Vladislav Odintsov wrote: >>>> Hi Dumitru, >>>> >>>> thanks for your reply. >>>> >>>> Regards, >>>> Vladislav Odintsov >>>> >>>>> On 15 Sep 2021, at 11:24, Dumitru Ceara <[email protected]> wrote: >>>>> >>>>> Hi Vladislav, >>>>> >>>>> On 9/13/21 6:14 PM, Vladislav Odintsov wrote: >>>>>> Hi Numan, >>>>>> >>>>>> I’ve checked with OVS 2.16.0 and OVN master. The problem persists. >>>>>> Symptoms are the same. >>>>>> >>>>>> # grep ct_zero_snat /var/log/openvswitch/ovs-vswitchd.log >>>>>> 2021-09-13T16:10:01.792Z|00019|ofproto_dpif|INFO|system@ovs-system: >>>>>> Datapath supports ct_zero_snat >>>>> >>>>> This shouldn't be related to the problem we fixed with ct_zero_snat. >>>>> >>>>>> >>>>>> Regards, >>>>>> Vladislav Odintsov >>>>>> >>>>>>> On 13 Sep 2021, at 17:54, Numan Siddique <[email protected]> wrote: >>>>>>> >>>>>>> On Mon, Sep 13, 2021 at 8:10 AM Vladislav Odintsov <[email protected] >>>>>>> <mailto:[email protected]>> wrote: >>>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> we’ve encountered a next problem with stateful ACLs. >>>>>>>> >>>>>>>> Suppose, we have one logical switch (ls1) and attached to it a VIF >>>>>>>> type logical ports (lsp1, lsp2). >>>>>>>> Each logical port has a linux VM besides it. >>>>>>>> >>>>>>>> Logical ports reside in port group (pg1) and two ACLs are created >>>>>>>> within this PG: >>>>>>>> to-lport outport == @pg1 && ip4 && ip4.dst == 0.0.0.0/0 allow-related >>>>>>>> from-lport outport == @pg1 && ip4 && ip4.src == 0.0.0.0/0 allow-related >>>>>>>> >>>>>>>> When we have a high-connection rate service between VMs, the tcp >>>>>>>> source/dest ports may be reused before the connection is deleted from >>>>>>>> LSP’s-related conntrack zones on the host. >>>>>>>> Let’s use curl with passing --local-port argument to have each time >>>>>>>> same source port. >>>>>>>> >>>>>>>> Run it from VM to another VM (172.31.0.18 -> 172.31.0.17): >>>>>>>> curl --local-port 44444 http://172.31.0.17/ >>>>>>>> >>>>>>>> Check connections in client’s and server’s vif zones (client - >>>>>>>> zone=20, server - zone=1): >>>>>>>> run while true script to check connections state per-second, while >>>>>>>> running new connection with same source/dest 5-tuple: >>>>>>>> >>>>>>>> while true; do date; grep -e 'zone=1 ' -e zone=20 >>>>>>>> /proc/net/nf_conntrack; sleep 0.2; done >>>>>>>> >>>>>>>> Right after we’ve succesfully run curl, the connection is getting >>>>>>>> time-closed and next time-wait states: >>>>>>>> >>>>>>>> Mon Sep 13 14:34:39 MSK 2021 >>>>>>>> ipv4 2 tcp 6 59 CLOSE_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=1 use=2 >>>>>>>> ipv4 2 tcp 6 59 CLOSE_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=20 use=2 >>>>>>>> Mon Sep 13 14:34:39 MSK 2021 >>>>>>>> ipv4 2 tcp 6 119 TIME_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=1 use=2 >>>>>>>> ipv4 2 tcp 6 119 TIME_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=20 use=2 >>>>>>>> >>>>>>>> And it remains in time-wait state for nf_conntrack_time_wait_timeout >>>>>>>> (120 seconds for centos 7). >>>>>>>> >>>>>>>> Everything is okay for now. >>>>>>>> While we have installed connections in TW state in zone 1 and 20, lets >>>>>>>> run this curl (source port 44444) again: >>>>>>>> 1st SYN packet is lost. It didn’t get to destination VM. In conntrack >>>>>>>> we have: >>>>>>>> >>>>>>>> Mon Sep 13 14:34:41 MSK 2021 >>>>>>>> ipv4 2 tcp 6 118 TIME_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=1 use=2 >>>>>>>> >>>>>>>> We see that TW connection was dropped in source vif’s zone (20). >>>>>>>> >>>>>>>> Next, after one second TCP sends retry and connection in destination >>>>>>>> (server’s) zone is dropped and a new connection is created in source >>>>>>>> zone (client’s): >>>>>>>> >>>>>>>> Mon Sep 13 14:34:41 MSK 2021 >>>>>>>> ipv4 2 tcp 6 120 SYN_SENT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 [UNREPLIED] src=172.31.0.17 dst=172.31.0.18 >>>>>>>> sport=80 dport=44444 mark=0 zone=20 use=2 >>>>>>>> >>>>>>>> Server VM still didn’t get this SYN packet. It got dropped. >>>>>>>> >>>>>>>> Then, after 2 seconds TCP sends retry again and connection is working >>>>>>>> well: >>>>>>>> >>>>>>>> Mon Sep 13 14:34:44 MSK 2021 >>>>>>>> ipv4 2 tcp 6 59 CLOSE_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=1 use=2 >>>>>>>> ipv4 2 tcp 6 59 CLOSE_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=20 use=2 >>>>>>>> Mon Sep 13 14:34:44 MSK 2021 >>>>>>>> ipv4 2 tcp 6 119 TIME_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=1 use=2 >>>>>>>> ipv4 2 tcp 6 119 TIME_WAIT src=172.31.0.18 dst=172.31.0.17 >>>>>>>> sport=44444 dport=80 src=172.31.0.17 dst=172.31.0.18 sport=80 >>>>>>>> dport=44444 [ASSURED] mark=0 zone=20 use=2 >>>>>>>> >>>>>>>> I guess, that it could happen: >>>>>>>> 1. Run curl with an empty conntrack zones. Everything is good, we’ve >>>>>>>> got http response, closed the connection. There’s one TW entry in >>>>>>>> client’s and one in server’s zonntrack zones. >>>>>>>> 2. Run curl with same source port within >>>>>>>> nf_conntrack_time_wait_timeout seconds. >>>>>>>> 2.1. OVS gets packet from VM, sends it to client’s conntrack zone=20. >>>>>>>> It matches pre-existed conntrack entry in tw state from previous curl >>>>>>>> run. TW connection in conntrack is deleted. A copy of a packet is >>>>>>>> returned to OVS and recirculated packet has ct.inv (?) and !ct.trk >>>>>>>> states and got dropped (I’m NOT sure, it’s just an assumption!) >>>>>>>> 3. After one second client VM resends TCP SYN. >>>>>>>> 3.1. OVS gets packet, sends through client’s conntrack zone=20, a new >>>>>>>> connection is added, packet has ct.trk and ct.new states set. Packet >>>>>>>> goes to recirculation. >>>>>>>> 3.2. OVS sends packet to server’s conntrack zone=1. It matches >>>>>>>> pre-existed conntrack entry in tw state from previous run. Conntrack >>>>>>>> removes this entry. Packet is returned to OVS with ct.inv (?) and >>>>>>>> !ct.trk. Packet got dropped. >>>>>>>> 4. Client’s VM again sends TCP SYN after 2 more seconds left. >>>>>>>> 4.1 OVS gets packet from client’s VIF, sends to client’s conntrack >>>>>>>> zone=20, it matches pre-existed SYN_SENT conntrack entry state, >>>>>>>> packets is returned to OVS with ct.new, ct.trk flags set. >>>>>>> >>>>>>> >>>>>>>> 4.2 OVS sends packet to server’s conntrack zone=1. Conntrack table for >>>>>>>> zone=1 is empty, it adds new entry, returns packet to OVS with ct.trk >>>>>>>> and ct.new flags set. >>>>>>>> 4.3 OVS sends packet to server’s VIF, next traffic operates normally. >>>>>>>> >>>>>>>> So, with such behaviour connection establishment sometimes takes up to >>>>>>>> three seconds (2 TCP SYN retries) and makes troubles in overlay >>>>>>>> services. (Application timeouts and service outages). >>>>>>>> >>>>>>>> I’ve checked how conntrack works inside VMs with such traffic and it >>>>>>>> looks like if conntrack gets a packet within a TW connection it >>>>>>>> recreates a new conntrack entry. No tuning inside VMs was performed. >>>>>>>> As a server I used apache with default config from CentOS distribution. >>>>> >>>>> I don't have a centos 7 at hand but I do have a rhel 7 >>>>> (3.10.0-1160.36.2.el7.x86_64) and I didn't manage to hit the issue you >>>>> reported here (using OVS and OVN upstream master). The SYN matching the >>>>> conntrack entry in state TIME_WAIT moves the entry to NEW and seems to >>>>> be forwarded just fine, the session afterwards go to ESTABLISHED. >>>>> >>>>> Wed Sep 15 04:18:35 AM EDT 2021 >>>>> conntrack v1.4.5 (conntrack-tools): 7 flow entries have been shown. >>>>> tcp 6 431930 ESTABLISHED src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=6 use=1 >>>>> tcp 6 431930 ESTABLISHED src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=3 use=1 >>>>> -- >>>>> Wed Sep 15 04:18:36 AM EDT 2021 >>>>> conntrack v1.4.5 (conntrack-tools): 7 flow entries have been shown. >>>>> tcp 6 119 TIME_WAIT src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=6 use=1 >>>>> tcp 6 119 TIME_WAIT src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=3 use=1 >>>>> -- >>>>> Wed Sep 15 04:18:38 AM EDT 2021 >>>>> conntrack v1.4.5 (conntrack-tools): 7 flow entries have been shown. >>>>> tcp 6 431999 ESTABLISHED src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=6 use=1 >>>>> tcp 6 431999 ESTABLISHED src=42.42.42.2 dst=42.42.42.3 sport=4141 >>>>> dport=4242 src=42.42.42.3 dst=42.42.42.2 sport=4242 dport=4141 [ASSURED] >>>>> mark=0 secctx=system_u:object_r:unlabeled_t:s0 zone=3 use=1 >>>>> -- >>>>> >>>>> DP flows just after the second session is initiated also seem to confirm >>>>> that everything is fine: >>>>> >>>>> # ovs-appctl dpctl/dump-flows | grep -oE "ct_state(.*),ct_label" >>>>> ct_state(+new-est-rel-rpl-inv+trk),ct_label >>>>> ct_state(-new+est-rel-rpl-inv+trk),ct_label >>>>> ct_state(-new+est-rel+rpl-inv+trk),ct_label >>>>> ct_state(+new-est-rel-rpl-inv+trk),ct_label >>>>> ct_state(-new+est-rel+rpl-inv+trk),ct_label >>>>> ct_state(-new+est-rel-rpl-inv+trk),ct_label >>>>> >>>>> I also tried it out on a Fedora 34 with 5.13.14-200.fc34.x86_64, still >>>>> works fine. >>>>> >>>>> What kernel and openvswitch module versions do you use? >>>>> >>>> On my box there is CentOS 7.5 with kernel 3.10.0-862.14.4.el7 and OOT >>>> kernel module. >>>> I’ve tested two versions, in both the problem was hit: >>>> openvswitch-kmod-2.13.4-1.el7_5.x86_64 >>>> openvswitch-kmod-2.16.0-1.el7_5.x86_64 >>>> >>>> Do you think the problem could be related to kernel (conntrack) and kernel >>>> must be upgraded here? >>>> Or, maybe I should try master OVS, as you did? >>> >>> I just tried with OVS v2.13.4, OVN master and it all worked fine (both >>> on Fedora 34 and rhel 7). I don't think the problem is in user space. >>> >>> Regards, >>> Dumitru >>> >>> _______________________________________________ >>> dev mailing list >>> [email protected] <mailto:[email protected]> >>> <mailto:[email protected] <mailto:[email protected]>> >>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >>> <https://mail.openvswitch.org/mailman/listinfo/ovs-dev> >>> <https://mail.openvswitch.org/mailman/listinfo/ovs-dev >>> <https://mail.openvswitch.org/mailman/listinfo/ovs-dev>> >> _______________________________________________ >> dev mailing list >> [email protected] <mailto:[email protected]> >> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >> <https://mail.openvswitch.org/mailman/listinfo/ovs-dev> > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
