Book Image

Learning OpenStack Networking (Neutron)

By : James Denton
Book Image

Learning OpenStack Networking (Neutron)

By: James Denton

Overview of this book

OpenStack Neutron is an OpenStack component that provides networking as a service for other OpenStack services to architect networks and create virtual machines through its API. This API lets you define network connectivity in order to leverage network capabilities to cloud deployments. Through this practical book, you will build a strong foundational knowledge of Neutron, and will architect and build an OpenStack cloud using advanced networking features. We start with an introduction to OpenStack Neutron and its various components, including virtual switching, routing, FWaaS, VPNaaS, and LBaaS. You’ll also get hands-on by installing OpenStack and Neutron and its components, and use agents and plugins to orchestrate network connectivity and build a virtual switching infrastructure. Moving on, you’ll get to grips with the HA routing capabilities utilizing VRRP and distributed virtual routers in Neutron. You’ll also discover load balancing fundamentals, including the difference between nodes, pools, pool members, and virtual IPs. You’ll discover the purpose of security groups and learn how to apply the security concept to your cloud/tenant/instance. Finally, you' ll configure virtual private networks that will allow you to avoid the use of SNAT and floating IPs when connecting to remote networks.
Table of Contents (21 chapters)
Learning OpenStack Networking (Neutron) Second Edition
About the Author
About the Reviewers

Centralized SNAT

Source NAT, or SNAT for short, is the method of changing the source address of a packet as it leaves the interface of a router. When a Neutron router is allocated an IP address from an external network using the router-gateway-set command, the IP is used in source NAT operations. The source IP of traffic from virtual machine instances to external networks will be translated as the router's address when the instances do not have 1-to-1 floating IPs configured. All routers in Neutron, whether they are standalone, HA, or distributed, support SNAT.


As of the Kilo release of OpenStack, routers that handle SNAT are centralized on a single node and are not highly available. As a workaround, multiple nodes may be configured in dvr_snat mode.

Reviewing the topology

In this demonstration, the following provider and tenant networks are created:

Figure 9.20

Using the --distributed=true option, a distributed virtual router is created:

Figure 9.21

In this environment, the L3 agent on the...