satcom topology

Satcom Topology

Table of content

• Satcom Topology
  • Star topology
  • Mesh topology
  • OpenSAND exploitation

OpenSAND features two types of system topologies depending on the type of satellite used: a star topology, with a transparent satellite; and a mesh topology, with a regenerative satellite with on-board switching capabilities.

The choice of the topology used impacts on the RTT between different terminals, and defines the type of standard to use on each link, the available encapsulation protocols. It also affects the way the physical attenuation values are transmitted in OpenSAND.

Star topology

The star topology has the gateway as the centre: all traffic from and to the terminals must pass through the gateway for routing purposes. This topology uses a transparent satellite, with no processing on-board.

For more information about the star topology in OpenSAND, refer to the star topology page.

Mesh topology

The mesh topology allows direct communication between terminals without needing the data to pass through the gateway: the switching is performed on board of the satellite, which produces smaller RTTs.

For more information about the mesh topology in OpenSAND, refer to the mesh topology page.

OpenSAND exploitation

The type of topology used can be changed from the OpenSAND manager. To do so, the Advanced mode must be activated, in the Simulation section of the menu bar.

In the Configuration tab, at the top left corner, a section Satellite payload type will appear. By default, a Transparent satellite is used (star topology). By choosing a Regenerative satellite, the topology used will be of type Mesh.

When switching the type of payload to use, the available Encapsulation options will also change. Be careful, each mode may have some constraints on the allowed types of encapsulation.

Regenerative satellite mode (mesh topology) has not been exhaustively tested with DVB-RCS2, and its correct functioning is not guaranteed.