Data Network Planning¶
Data networks are the payload-carrying networks used implicitly by end users when they move traffic over their project networks.
You can review details for existing data networks using OpenStack Horizon Web interface or the CLI.
When planning data networks, you must consider the following guidelines:
From the point of view of the projects, all networking happens over the project networks created by them, or by the admin user on their behalf. Projects are not necessarily aware of the available data networks. In fact, they cannot create project networks over data networks not already accessible to them. For this reason, the system administrator must ensure that proper communication mechanisms are in place for projects to request access to specific data networks when required.
For example, a project may be interested in creating a new project network with access to a specific network access device in the data center, such as an access point for a wireless transport. In this case, the system administrator must create a new project network on behalf of the project, using a VLAN ID in the project’s segmentation range that provides connectivity to the said network access point.
Consider how different offerings of bandwidth, throughput commitments, and class-of-service, can be used by your users. Having different data network offerings available to your projects enables end users to diversify their own portfolio of services. This in turn gives the StarlingX OpenStack administration an opportunity to put different revenue models in place.
For the IPv4 address plan, consider the following:
Project networks attached to a public network, such as the Internet, have to have external addresses assigned to them. You must therefore plan for valid definitions of their IPv4 subnets and default gateways.
As with the OAM network, you must ensure that suitable firewall services are in place on any project network with a public address.
Segmentation ranges may be owned by the administrator, a specific project, or may be shared by all projects. With this ownership model:
A base deployment scenario has each compute node using a single data interface defined over a single data network. In this scenario, all required project networks can be instantiated making use of the available VLANs or VNIs in each corresponding segmentation range. You may need more than one data network when the underlying physical networks demand different MTU sizes, or when boundaries between data networks are dictated by policy or other non-technical considerations.
Segmentation ranges can be reserved and assigned on-demand without having to lock and unlock the compute nodes. This facilitates day-to-day operations which can be performed without any disruption to the running environment.
In some circumstances, data networks can be configured to support VLAN Transparent mode on project networks. In this mode VLAN tagged packets are encapsulated within a data network segment without removing or modifying the guest VLAN tag(s).
