Networking

A SCEPTRE installation includes several networks, including physical host networks and virtual machine (experiment) networks.

Physical Hosts

There are two primary networks on the physical hosts (headnode and compute node).

Control network (CTL)

This network is used to manage the physical hosts and should have access to the internet or an apt-mirror.

Trunked data network (TDN)

This network is used to pass VLAN-tagged experiment traffic between multiple compute nodes.

“Implementation options” - There are two ways to install the network equipment to connect the physical hosts.

1. Two hubs, each dedicated to a specific primary network.

2. A single managed-switch, with a set of ports configured for each primary network.

Experiment

When an experiment is deployed, Open vSwitch (OVS) handles all the internal networking to each virtual machine.

Open vSwitch

Open vSwitch (OVS) is a virtual switch providing advanced networking capabilities including VLAN encapsulation and port-mirroring. It is installed on all compute nodes and controls the networking for an experiment.

• VM to physical network
  • OVS provides the connection from the physical host TDN to each experiment virtual machine.

• Hardware-in-the-loop (HIL).
  • When a virtual experiment needs access to a physical hardware component, OVS acts as a bridge between the two.

Internal experiment networks

There are two internal experiment networks that are handled exclusively by the TDN. Although the two experiment networks traverse the same physical network, they are logically separated via VLAN tagging.

• Experiment (EXP)
  • This network carries packets seen in the ‘experiment’ world such as SCADA protocol traffic. It is normally viewed by operators.
• Management (MGMT)
  • This network is a ‘dark’ network (unseen by normal users). It is used by bennu to move management data between virtual machines.