** Also affects: nova (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1554227
Title:
DHCP unicast requests are not responded to
Status in OpenStack Compute (nova):
New
Status in nova package in Ubuntu:
New
Bug description:
Issue:
We run nova-network in VLAN+multi_host mode on Kilo and notice that only one
dnsmasq process (either the oldest or newest) on the hypervisor responds to
unicast BOOTPREQUESTS. dhclient on VMs will retry until it eventually gives up
and broadcasts the request, which is then responded to. Depending on the timing
of the DHCP broadcast request, VMs can briefly lose connectivity as they
attempt rebinding.
According to
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=9380ba70d67db6b69f817d8e318de5ba1e990b12,
it seems that passing "--interface" argument, in addition to "--bind-
interfaces" is necessary for dnsmasq to work correctly in VLAN mode.
Reproduce steps:
1. Create two tenants
2. Create a VM under each tenant, forcing the VMs to run on a single
hypervisor. I tested with a vanilla Ubuntu cloud image, but any other image
that uses dhclient should also work.
3. On the hypervisor, run dhcpdump -i <bridge interface> for each tenant's
bridge interface. On at least one of them, you should see unicast BOOTPREQUEST
with no corresponding BOOTPREPLY. dnsmasq will reply when the request
eventually hits 255.255.255.255.
Nova/Openstack/dnsmasq versions:
ii nova-api 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - API frontend
ii nova-common 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - common files
ii nova-compute 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - compute node base
ii nova-compute-libvirt 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - compute node libvirt support
ii nova-compute-qemu 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - compute node (QEmu)
ii nova-network 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - Network manager
ii nova-novncproxy 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute - NoVNC proxy
ii python-nova 1:2015.1.2-0ubuntu2~cloud0
all OpenStack Compute Python libraries
ii python-nova-adminclient 0.1.8-0ubuntu2
amd64 client for administering Openstack Nova
ii python-novaclient 1:2.22.0-0ubuntu2~cloud0
all client library for OpenStack Compute API
ii dnsmasq-base 2.68-1ubuntu0.1
amd64 Small caching DNS proxy and DHCP/TFTP server
ii dnsmasq-utils 2.68-1ubuntu0.1
amd64 Utilities for manipulating DHCP leases
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