Small update: I have installed the latest OVS from git master (following this https://github.com/openvswitch/ovs/blob/master/INSTALL.Debian.md <https://github.com/openvswitch/ovs/blob/master/INSTALL.Debian.md> - option 2: build packages -> then installed openvswitch-datapath-dkms). After increasing the MTU on the physical link between the boxes / hypervisors, the iperf tests are still very bad: 3.21 Mbits/sec
Thanks, DC > On Jul 4, 2016, at 9:34 PM, D3c3 Balus <d3c3ba...@gmail.com> wrote: > > Hello, > > I’m using 2 Ubuntu Xenial 16.04 LTS with the following: > - kernel: 4.4.0-28-generic > - OVS version: 2.5.0 (installed from ubuntu packages: openvswitch-common & > openvswitch-switch) > > I’m configuring a GRE tunnel between OVS bridges running on each of the > machines with: > > ovs-vsctl add-port br0 tun0 -- set Interface tun0 type=gre > options:remote_ip=x.x.x.x > > and I achieve connectivity between VMs, as desired, via the GRE tunnel. > > > Problem: iperf test show really low performance (734 bits/sec !!) > considering a baseline that shows almost 1G over the direct link. > > Troubleshooting performed: > 1. increased MTU of the physical link on both sides: `ip link set dev enp0s8 > mtu 2000` => same poor perf > 2. increased MTU of the br0 on both OVS bridges: `ip link set dev br0 mtu > 1700` => same poor perf > > [FYI: I performed the same operations on an older version of Ubuntu = > Trusty 14.04 LTS, kernel 3.13.0-86, and after adjusting the MTU as above, the > GRE performance was satisfactory ~ 414 Mbps !! ] > > I continued troubleshooting my Ubuntu Xenial 16.04 (kernel 4.4.0-28): > 3. I noticed that this system has these interfaces gre0@NONE, gretap0@NONE, > gre_sys@NONE (which did not appear on Ubuntu Trusty 14.04, kernel 3.13.0-86) > and realized that Ubuntu Xenial 16.04 uses the linux kernel module ip_gre > instead of the one provided by Open vSwitch: > > SNAPSHOT from Ubuntu Xenial 16.04 (kernel 4.4.0-28): > ``` > root@xenial ~$ lsmod | grep gre > vport_gre 16384 1 > ip_gre 20480 1 vport_gre > ip_tunnel 28672 1 ip_gre > gre 16384 1 ip_gre > openvswitch 98304 3 vport_gre > > root@xenial ~$ dmesg | grep gre > .. > [ 379.947836] gre: GRE over IPv4 demultiplexor driver > [ 379.955295] ip_gre: GRE over IPv4 tunneling driver > [ 379.960352] device gre_sys entered promiscuous mode > ``` > > SNAPSHOT from Ubuntu Trusty (kernel 3.13.0-86): > ``` > root@trusty ~$ lsmod | grep gre > gre 13796 1 openvswitch > > root@trusty ~$ dmesg | grep gre > [ 9.270743] gre: GRE over IPv4 demultiplexor driver > root@box-0 ~$ > ``` > > 3. It seems that latest OVS version uses vport_gre kernel module for GRE and > this one depends on Linux GRE module (ip_gre): > > ``` > root@xenial ~$ modinfo vport_gre > filename: > /lib/modules/4.4.0-28-generic/kernel/net/openvswitch/vport-gre.ko > alias: vport-type-3 > license: GPL > description: OVS: GRE switching port > srcversion: A4455AB407AE7569E81E791 > depends: openvswitch,ip_gre > intree: Y > vermagic: 4.4.0-28-generic SMP mod_unload modversions > ``` > > > > Questions: > 1. is this intended - that the latest versions of OVS uses the linux GRE > module (instead of its own, as it seem it was the case in the past)? > 2. I tried stopping OVS and unloading the Linux GRE module - but that was > unsuccessful. How should I fix my problem in order to achieve satisfactory > level of performance over GRE ? > > > Thank you, > > > DC
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