Terminology
This guide uses the following terminology. (Additional terminology and definitions can be found in an overview of the CORD Ecosystem.)
POD : A single physical deployment of CORD.
Full POD : A typical configuration, used as example in this Guide. A full CORD POD consists of three servers and four fabric switches. This makes it possible to experiment with all the core features of CORD, and it is what the community typically uses for tests.
Half POD : A minimum-sized configuration. It is similar to a full POD, but with less hardware. It consists of two servers (one head node and one compute node), and one fabric switch. It does not allow experimentation with all of the core features that CORD offers (e.g., a switching fabric), but it is still good for basic experimentation and testing.
CORD-in-a-Box (CiaB) : Colloquial name for a Virtual POD.
Development (Dev) Machine : This is the machine used to download, build and deploy CORD onto a POD. Sometimes it is a dedicated server, and sometimes the developer's laptop. In principle, it can be any machine that satisfies the hardware and software requirements.
Development (Dev) VM : Bootstrapping the CORD installation requires a lot of software to be installed and some non-trivial configurations to be applied. All this should happen on the dev machine. To help users with the process, CORD provides an easy way to create a VM on the dev machine with all the required software and configurations in place.
Compute Node(s) : A server in a POD that run VMs or containers associated with one or more tenant services. This terminology is borrowed from OpenStack.
Head Node : A compute node of the POD that also runs management services. This includes for example XOS (the orchestrator), two instances of ONOS (the SDN controller, one to control the underlay fabric and one to control the overlay), MAAS and all the services needed to automatically install and configure the rest of the POD devices.
Fabric Switch : A switch in a POD that interconnects other switches and servers inside the POD.
vSG : The virtual Subscriber Gateway (vSG) is the CORD counterpart for existing CPEs. It implements a bundle of subscriber-selected functions, such as Restricted Access, Parental Control, Bandwidth Metering, Access Diagnostics and Firewall. These functions run on commodity hardware located in the Central Office rather than on the customer’s premises. There is still a device in the home (which we still refer to as the CPE), but it has been reduced to a bare-metal switch.