From the User's Point of View

OpenStack combines many technologies in the background – and that seems to work. Users click their virtual networks together via a web interface (Figures 4 and 5) and do not need to worry about unauthorized third parties seeing the traffic from their systems. The most important aspects in terms of Internet access are covered by virtual routers (Figure 6) and floating IP addresses.

Figure 4: Users see the topology of the networks and routers in the web interface.

Figure 5: There are virtually no limits to the user's imagination when creating SDN networks: Because the networks are separated, even multiple networks with the same address space are possible.

Figure 6: Virtual routers connect a virtual network in OpenStack directly to the outward-facing gateway of the SDN solution.

The solution is also fun from the provider's perspective: Although the learning curve is steep and it takes some time before the SDN works, after doing so, the network does not cause admins very much effort. Because the whole physical infrastructure at switch level is a flat hierarchy and the entire network configuration is possible directly from within the cloud, configuring switches is a thing of the past.

Neutron's modular architecture allows providers new features with little overhead. X as a service (X aaS) in Neutron, for example, lets the developer implement load balancers as a service, via an agent that installs an HA-proxy instance on a previously defined host. The load balancer configuration is carried out centrally in the Neutron CLI or via the OpenStack dashboard.

The same is true for firewall as a service (FWaaS) and VPN as a service (VPNaaS): Developers have no problem to accessing the existing Neutron infrastructure and using agents to provide the desired services. In the example of VPNaaS, the customer can connect to their virtual cloud network directly via VPN.

Which SDN Solution?

Neutron does not make any decisions for the admin when it comes to choosing the right SDN technology. The Neutron developers consider Open vSwitch unsuitable for a variety of scenarios; especially for large environments that provide hundreds of computing nodes.

If you want to roll out OpenStack on a large scale, you will need to consider solutions such as MidoNet, Plumgrid, or OpenContrail sooner or later. Each of these options has strengths and weaknesses. If you are in doubt, only extensive evaluation will help you decide the best solution for your network.