Open Stack

I am trying to reach 5000. The problem I hit is that northd is
stuck in translating from NB to SB when connect router to external
network.

I assume all your 400 routers connect to the same subnet in that
external network. I am trying another approach where one subnet
is created for each router in external network. That may help to
reduce the ARP flow?

Thanks!
Tony
> -----Original Message-----
> From: Krzysztof Klimonda <kklimonda at syntaxhighlighted.com>
> Sent: Thursday, September 17, 2020 8:57 AM
> To: openstack-discuss at lists.openstack.org
> Subject: [neutron][ovn] Logical flow scaling (flow explosion in
> lr_in_arp_resolve)
> 
> Hi,
> 
> We're running some tests of ussuri deployment with ovn ML2 driver and
> seeing some worrying numbers of logical flows generated for our test
> deployment.
> 
> As a test, we create 400 routes, 400 private networks and connect each
> network to its own routers. We also connect each router to an external
> network. After doing that a dump of logical flows shows almost 800k
> logical flows, most of them in lr_in_arp_resolve table:
> 
> --8<--8<--8<--
> # cat lflows.txt |grep -v Datapath |cut -d'(' -f 2 | cut -d ')' -f1
> |sort | uniq -c |sort -n | tail -10
>    3264 lr_in_learn_neighbor
>    3386 ls_out_port_sec_l2
>    4112 lr_in_admission
>    4202 ls_in_port_sec_l2
>    4898 lr_in_lookup_neighbor
>    4900 lr_in_ip_routing
>    9144 ls_in_l2_lkup
>    9160 ls_in_arp_rsp
>   22136 lr_in_ip_input
>  671656 lr_in_arp_resolve
> #
> --8<--8<--8<--
> 
> ovn: 20.06.2 + patch for SNAT IP ARP reply issue
> openvswitch: 2.13.0
> neutron: 16.1.0
> 
> I've seen some discussion about similar issue at OVS mailing lists:
> https://www.mail-archive.com/ovs-discuss@openvswitch.org/msg07014.html -
> is this relevant to neutron, and not just kubernetes?
> 
> --
>   Krzysztof Klimonda
>   kklimonda at syntaxhighlighted.com