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 Limitations

  • No equivalent for nova-network --multi_host option. Nova-network has a model where the L3, NAT, and DHCP processing happen on the compute node itself, rather than a dedicated networking node. OpenStack Networking now support running multiple l3-agent and dhcp-agents with load being split across those agents, but the tight coupling of that scheduling with the location of the VM is not supported in Icehouse. The Juno release is expected to include an exact replacement for the --multi_host option in nova-network.

  • Linux network namespace required on nodes running neutron-l3-agent or neutron-dhcp-agent if overlapping IPs are in use. To support overlapping IP addresses, the OpenStack Networking DHCP and L3 agents use Linux network namespaces by default. The hosts running these processes must support network namespaces. To support network namespaces, the following are required:

    • Linux kernel 2.6.24 or later (with CONFIG_NET_NS=y in kernel configuration)

    • iproute2 utilities ('ip' command) version 3.1.0 (aka 20111117) or later

    To check whether your host supports namespaces, run these commands as root:

    # ip netns add test-ns
    # ip netns exec test-ns ifconfig

    If these commands succeed, your platform is likely sufficient to use the dhcp-agent or l3-agent with namespaces. In our experience, Ubuntu 12.04 or later support namespaces as does Fedora 17 and later, but some earlier RHEL platforms do not by default. It might be possible to upgrade the iproute2 package on a platform that does not support namespaces by default.

    If you must disable namespaces, make sure that the neutron.conf file that is used by neutron-server has the following setting:

    allow_overlapping_ips=False

    Also, ensure that the dhcp_agent.ini and l3_agent.ini files have the following setting:

    use_namespaces=False
    [Note]Note

    If the host does not support namespaces, the neutron-l3-agent and neutron-dhcp-agent should run on different hosts because there is no isolation between the IP addresses created by the L3 agent and by the DHCP agent. By manipulating the routing, the user can ensure that these networks have access to one another.

    If you run both L3 and DHCP services on the same node, you should enable namespaces to avoid conflicts with routes:

    use_namespaces=True
  • No IPv6 support for L3 agent. The neutron-l3-agent, used by many plug-ins to implement L3 forwarding, supports only IPv4 forwarding. Currently, there are no errors provided if you configure IPv6 addresses via the API.

  • ZeroMQ support is experimental. Some agents, including neutron-dhcp-agent, neutron-openvswitch-agent, and neutron-linuxbridge-agent use RPC to communicate. ZeroMQ is an available option in the configuration file, but has not been tested and should be considered experimental. In particular, issues might occur with ZeroMQ and the dhcp agent.

  • MetaPlugin is experimental. This release includes a MetaPlugin that is intended to support multiple plug-ins at the same time for different API requests, based on the content of those API requests. The core team has not thoroughly reviewed or tested this functionality. Consider this functionality to be experimental until further validation is performed.

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