Basic Terminology

The following definitions describe key concepts and terminology that are commonly used in the StarlingX community and in this documentation.

All-in-one Controller Node

A single physical node that provides a controller function, compute function, and storage function.

Bare Metal

A node running without hypervisors (for example, application workloads run directly on the operating system which runs directly on the hardware).

Compute or Worker

A node within a StarlingX edge cloud that is dedicated to running application workloads. There can be 0 to 99 compute nodes in a StarlingX edge cloud.

  • Runs virtual switch for realizing virtual networks.

  • Provides L3 routing and NET services.

Controller

A node within a StarlingX edge cloud that runs the cloud management software (control plane). There can be either one or two controller nodes in a StarlingX edge cloud.

  • Runs cloud control functions for managing cloud resources.

  • Runs all OpenStack control functions, such as managing images, virtual volumes, virtual network, and virtual machines.

  • Can be part of a two-node HA control node cluster for running control functions either active/active or active/standby.

Data Network(s)

Networks on which the OpenStack / Neutron provider networks are realized and become the VM tenant networks.

Only compute type and all-in-one type nodes are required to be connected to the data network(s). These node types require one or more interface(s) on the data network(s).

Infra Network

A deprecated optional network that was historically used for access to the storage cluster.

If this optional network is used, all node types are required to be connected to the INFRA network.

IPMI Network

An optional network on which Intelligent Platform Management Interface (IPMI) interfaces of all nodes are connected. The network must be reachable using L3/IP from the controller’s OAM interfaces.

You can optionally connect all node types to the IPMI network.

Management Network

A private network (that is, not connected externally), typically 10GE, used for the following:

  • Internal OpenStack / StarlingX monitoring and control.

  • VM I/O access to a storage cluster.

All nodes are required to be connected to the management network.

Node

A computer that is usually a server-class system.

Node Interfaces

All nodes’ network interfaces can, in general, optionally be either:

  • Untagged single port.

  • Untagged two-port LAG and optionally split between redundant L2 switches running vPC (Virtual Port-Channel), also known as multichassis EtherChannel (MEC).

  • VLAN on either single-port ETH interface or two-port LAG interface.

OAM Network

The network on which all external StarlingX platform APIs are exposed, (that is, REST APIs, Horizon web server, SSH, and SNMP), typically 1GE.

Only controller type nodes are required to be connected to the OAM network.

PXEBoot Network

An optional network for controllers to boot/install other nodes over the network.

By default, controllers use the management network for boot/install of other nodes in the OpenStack cloud. If this optional network is used, all node types are required to be connected to the PXEBoot network.

A PXEBoot network is required for a variety of special case situations:

  • Cases where the management network must be IPv6:

    • IPv6 does not support PXEBoot. Therefore, you must configure an IPv4 PXEBoot network.

  • Cases where the management network must be VLAN tagged:

    • Most server’s BIOS do not support PXEBooting over tagged networks. Therefore, you must configure an untagged PXEBoot network.

  • Cases where a management network must be shared across regions but individual regions’ controllers want to only network boot/install nodes of their own region:

    • You must configure separate, per-region PXEBoot networks.

Storage

A node within a StarlingX edge cloud that is dedicated to providing file and object storage to application workloads. There can be 0 or more storage nodes within a StarlingX edge cloud.

  • Runs CEPH distributed storage software.

  • Part of an HA multi-node CEPH storage cluster supporting a replication factor of two or three, journal caching, and class tiering.

  • Provides HA persistent storage for images, virtual volumes (that is, block storage), and object storage.

Virtual Machines (VM)

An instance of a node provided by software (a hypervisor), which runs within the host operating system and hardware.