Learning OpenStack Networking - Third Edition

Setting the agent mode

When using distributed virtual routers, a node can operate in one of two modes: dvr or dvr_snat. A node configured in dvr_snat mode handles north-south SNAT traffic, while a node in dvr mode handles north-south DNAT (for example, floating IP) traffic and east-west traffic between instances.

Compute nodes running the Open vSwitch agent run in dvr mode. A centralized network node typically runs in dvr_snat mode, and can potentially acts as a single point of failure for the network for instances not leveraging floating IPs.

Neutron supports deploying highly-available dvr_snat nodes using VRRP, but doing so is outside the scope of this book.

In this book, the snat01 node will be dedicated to handling SNAT traffic when ...