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Current folder name New folder name Book title ---------------------------------------------------------- basic-install DELETE cli-guide DELETE common common NEW admin-guide-cloud Cloud Administrators Guide docbkx-example DELETE openstack-block-storage-admin DELETE openstack-compute-admin DELETE openstack-config config-reference OpenStack Configuration Reference openstack-ha high-availability-guide OpenStack High Availabilty Guide openstack-image image-guide OpenStack Virtual Machine Image Guide openstack-install install-guide OpenStack Installation Guide openstack-network-connectivity-admin admin-guide-network OpenStack Networking Administration Guide openstack-object-storage-admin DELETE openstack-security security-guide OpenStack Security Guide openstack-training training-guide OpenStack Training Guide openstack-user user-guide OpenStack End User Guide openstack-user-admin user-guide-admin OpenStack Admin User Guide glossary NEW OpenStack Glossary bug: #1220407 Change-Id: Id5ffc774b966ba7b9a591743a877aa10ab3094c7 author: diane fleming
88 lines
5.6 KiB
XML
88 lines
5.6 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
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xml:id="ch_limitations">
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<title>Limitations</title>
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<para>
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<itemizedlist>
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<listitem>
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<para><emphasis>No equivalent for nova-network
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--multi_host flag:</emphasis> Nova-network has
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a model where the L3, NAT, and DHCP processing
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happen on the compute node itself, rather than a
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dedicated networking node. OpenStack Networking
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now support running multiple l3-agent and dhcp-agents
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with load being split across those agents, but the
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tight coupling of that scheduling with the location of
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the VM is not supported in Grizzly. The Havana release is expected
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to include an exact replacement for the --multi_host flag
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in nova-network.</para>
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</listitem>
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<listitem>
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<para><emphasis>Linux network namespace required on nodes running neutron-l3-agent
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or neutron-dhcp-agent if overlapping IPs are in use: </emphasis>. In order
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to support overlapping IP addresses, the OpenStack Networking DHCP and L3 agents
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use Linux network namespaces by default. The hosts running these processes must
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support network namespaces. To support network namespaces, the following are
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required:</para>
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<itemizedlist>
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<listitem>
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<para>Linux kernel 2.6.24 or newer (with CONFIG_NET_NS=y in kernel
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configuration) and</para>
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</listitem>
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<listitem>
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<para>iproute2 utilities ('ip' command) version 3.1.0 (aka 20111117) or
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newer</para>
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</listitem>
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</itemizedlist>
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<para>To check whether your host supports namespaces try running the following as
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root:</para>
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<screen><computeroutput>ip netns add test-ns
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ip netns exec test-ns ifconfig</computeroutput></screen>
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<para>If the preceding commands do not produce errors, your platform is likely
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sufficient to use the dhcp-agent or l3-agent with namespace. In our experience,
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Ubuntu 12.04 or later support namespaces as does Fedora 17 and new, but some
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older RHEL platforms do not by default. It may be possible to upgrade the
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iproute2 package on a platform that does not support namespaces by default.</para>
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<para>If you need to disable namespaces, make sure the
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<filename>neutron.conf</filename> used by neutron-server has the following
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setting:</para>
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<screen><computeroutput>allow_overlapping_ips=False</computeroutput></screen>
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<para>and that the dhcp_agent.ini and l3_agent.ini have the following
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setting:</para>
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<screen><computeroutput>use_namespaces=False</computeroutput></screen>
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<note><para>If the host does not support namespaces then the <systemitem class="service"
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>neutron-l3-agent</systemitem> and <systemitem class="service"
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>neutron-dhcp-agent</systemitem> should be run on different hosts. This
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is due to the fact that there is no isolation between the IP addresses
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created by the L3 agent and by the DHCP agent. By manipulating the routing
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the user can ensure that these networks have access to one another.</para></note>
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<para>If you run both L3 + DHCP services on the same node, you should enable
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namespaces to avoid conflicts with routes :</para>
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<screen><computeroutput>use_namespaces=True</computeroutput></screen>
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</listitem>
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</itemizedlist>
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<itemizedlist><listitem>
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<para><emphasis>No IPv6 support for L3 agent:</emphasis> The neutron-l3-agent, used
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by many plugins to implement L3 forwarding, supports only IPv4 forwarding.
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Currently, There are no errors provided if you configure IPv6 addresses via the
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API.</para>
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</listitem>
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<listitem>
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<para><emphasis>ZeroMQ support is experimental</emphasis>: Some agents, including
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neutron-dhcp-agent, neutron-openvswitch-agent, and neutron-linuxbridge-agent use
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RPC to communicate. ZeroMQ is an available option in the configuration file, but
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has not been tested and should be considered experimental. In particular, there
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are believed to be issues with ZeroMQ and the dhcp agent.</para>
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</listitem><listitem>
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<para><emphasis>MetaPlugin is experimental</emphasis>: This release includes a
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"MetaPlugin" that is intended to support multiple plugins at the same time for
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different API requests, based on the content of those API requests. This
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functionality has not been widely reviewed or tested by the core team, and
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should be considered experimental until further validation is performed.</para>
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</listitem>
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</itemizedlist>
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</para>
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</chapter>
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