** Also affects: neutron (Ubuntu)
** Also affects: neutron (Ubuntu Xenial)
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to neutron.
intermittent dhcp failures
Status in neutron:
Status in neutron package in Ubuntu:
Status in neutron source package in Xenial:
We have observed instances failing to get a DHCP reply, either when booting
for the first time, or after a reboot.
By tcpdumping the traffic on the tap, then qvb and qvo interfaces, we can see
the DHCP request leaving, but it doesn't reach the neutron-gateway node where
the dhcp agent for the network runs.
If we remove and then re-add the network to the dhcp agent, it starts
working fine again.
I have dumped the output of `ovs-ofctl dump-flows br-tun` on the
neutron-gateway side, before and after doing the remove/add.
One difference I noted, was a rule appearing, with the mac of the VM which
had the issue:
cookie=0xb42e8d404b989e72, duration=13.344s, table=20, n_packets=0,
n_bytes=0, hard_timeout=300, idle_age=13,
However, this is a rule for packets from the dhcp agent to the VM, so
its absence doesn't explain why DHCP requests don't arrive to
The cloud is running neutron 8.4.0 (Mitaka), on ubuntu (16.04)
Most of the time it works, but this problem comes back often enough
that it impacts users.
To manage notifications about this bug go to:
Mailing list: https://launchpad.net/~yahoo-eng-team
Post to : firstname.lastname@example.org
Unsubscribe : https://launchpad.net/~yahoo-eng-team
More help : https://help.launchpad.net/ListHelp