VPN

For the VPN soultion a Virtual Private Network is set up between the satellite modem and the S-ISP (Satellite Internet Service Provider) on connection. This way the satellite modem will be connected to the LAN of the S-ISP. The VPN connection is automatically established when the satellite modem goes online.

Usage scenario for VPN

This scenario assumes that the end user has the satellite modem online.

  1. An end user types in www.google.com in a browser on their computer connected to the satellite modem.
  2. The modem receives the request for the www.google.com page
  3. The modem forwards the request for the webpage through the return channel to the S-ISP server.
  4. The S-ISP server downloads the pageand embeds it in a MPEG-2 transport stream inside MPE data which is sent to a satellite
  5. The satellite sends the MPEG-2 stream down to earth
  6. The frontend on the satellite modem downconverts and demodulates the transport stream
  7. The transport stream is passed through the frontend driver which filters out the MPE data packets based on which PID to filter on
  8. The filtered MPE data packets are sent to the IP over DVB module which extracts the IP packet and inserts it into the Linux network stack
  9. The Linux network stacks checks the routing table and outputs the IP packet through the correct interface, in this case the interface for the local LAN where the end users PC sits.
  10. The end user's computer receives the packet and sends a ACK for the packet back to the satellite modem

The VPN variant supports both PPTP and L2TP.