Book Image

Learning OpenStack Networking - Third Edition

By : James Denton
Book Image

Learning OpenStack Networking - Third Edition

By: James Denton

Overview of this book

OpenStack Networking is a pluggable, scalable, and API-driven system to manage physical and virtual networking resources in an OpenStack-based cloud. Like other core OpenStack components, OpenStack Networking can be used by administrators and users to increase the value and maximize the use of existing datacenter resources. This third edition of Learning OpenStack Networking walks you through the installation of OpenStack and provides you with a foundation that can be used to build a scalable and production-ready OpenStack cloud. In the initial chapters, you will review the physical network requirements and architectures necessary for an OpenStack environment that provide core cloud functionality. Then, you’ll move through the installation of the new release of OpenStack using packages from the Ubuntu repository. An overview of Neutron networking foundational concepts, including networks, subnets, and ports will segue into advanced topics such as security groups, distributed virtual routers, virtual load balancers, and VLAN tagging within instances. By the end of this book, you will have built a network infrastructure for your cloud using OpenStack Neutron.
Table of Contents (16 chapters)

Integrating load balancers into the network

When using the HAProxy driver, load balancers are implemented in one-arm mode. In one-arm mode, the load balancer is not in the path of normal traffic to the pool members. The load balancer has a single interface for ingress and egress traffic to and from clients and pool members.

A logical diagram of a load balancer in one-arm mode can be seen here:

In the preceding diagram a load balancer is configured in one-arm mode and resides in the same subnet as the servers it is balancing traffic to.

Because a load balancer in one-arm mode is not the gateway for pool members it is sending traffic to, it must rely on the use of source NAT to ensure return traffic from the members to the client is sent back through the load balancer. An example of the traffic flow can be seen in the following diagram:

In the preceding diagram, the load balancer...