The DVR is providing direct (vice/versa) access to external network on Compute nodes. For instances with a floating IP addresses routing from project to external network is performed on the compute nodes.Thus DVR eliminates single point of failure and network congestion on Network Node. Agent_mode is set “dvr” in l3_agent.ini on Compute Nodes. Instances with a fixed IP address (only) still rely on the only network node for outbound connectivity via SNAT. Agent_mode is set “dvr_snat” in l3_agent.ini on Network Node. To support DVR each compute node is running neutron-l3-agent,neutron-metadata-agent,neutron-openvswitch-agent. DVR also requires L2population activated and ARP proxys running on Neutron L2 layer. Actually, this setup was carefully tested in regards of Mitaka M1 which hopefully will allow to test solution provided by https://bugs.launchpad.net/neutron/+bug/1365473
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