[openstack-dev] [devstack] [neutron] Progress, and current problems
Mike Spreitzer
mspreitz at us.ibm.com
Tue Jan 5 08:02:15 UTC 2016
I have been trying to get
http://docs.openstack.org/developer/devstack/guides/neutron.html#using-neutron-with-a-single-interface
working on Ubuntu 14.04 (updated to the latest, which includes kernel
3.19). With the latest sources and a sufficiently recent OVS, the
one-node install pretty much works! I added to local.conf only: (a)
IP_VERSION=4, to avoid issues with v6, and (b) some settings to get logs
saved to files without coloring.
In particular, what I have done regarding OVS is to download 2.4 and build
the .deb packages according to the instructions. I used the kernel
datapath from the linux kernel 3.19. I installed the openvswitch-common
and openvswitch-switch .debs that I built.
I think the doc should be enhanced to discuss IPv6. I tried once without
the `IP_VERSION=4`, and the resulting IPv6 config was not good.
IMHO the default should be to keeps logs in files without coloring,
because that is the most user-friendly. I think that for DevStack the
defaults should be friendly to newbies, since this is where they start.
I then went on to
http://docs.openstack.org/developer/devstack/guides/neutron.html#adding-additional-compute-nodes
, and ran into MTU problems. All MTUs come out to be 1500, which just
does not work (due to the tunneling overhead).
I then tried a fresh DevStack install with a revised local.conf derived
from
https://specs.openstack.org/openstack/fuel-specs/specs/7.0/jumbo-frames-between-instances.html#proposed-change
. Specifically, this is what I added to my local.conf for MTU issues:
[[post-config|$NEUTRON_CONF]]
[DEFAULT]
advertise_mtu=True
network_device_mtu=1450
[[post-config|/$Q_PLUGIN_CONF_FILE]]
[ml2]
physical_network_mtus = public:1450
That got me MTUs of 1450 on the router and DHCP ports but not the VM
plumbing. Perhaps I read too much into the word "keep".
Then I added
network_device_mtu = 65000
to the DEFAULT section of nova.conf, then restarted all the nova
processes. I created a new VM after that. The result was that the
qbr..., qvo..., qvb..., and tap... network interfaces in the main netns
have MTU of 65000 --- and eth0 inside the VM has an MTU of 1500.
So then I changed the network_device_mtu setting in nova.conf to 1450,
restarted all the nova processes again, and made another new VM. Now the
qbr..., qvo..., qvb..., and tap... network interfaces in the main netns
have MTU of 1450 but the VM still got an MTU of 1500 on its eth0.
In my logs directory, `grep 'Running command' *.log | grep set | grep -i
mtu` finds only the setting of the MTUs of the router and DHCP stuff ---
nothing for any of the VMs.
Regards,
Mike
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