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SEVENSTAX Routing

Services for routing of data packets are required for transfer of data between multiple communication interfaces (e.g. Ethernet, WIFI, GSM/UMTS, etc.) of multi-homed hosts. This routing takes place on the network layer (internet protocol layer) of communication systems. SEVENSTAX Routing extends the SEVENSTAX TCP/IP-Multidevice stack with this service for routing of IP packets.

The following processes are supported:

  • IP forwarding (static routing)

  • Network Address Translation (NAT)

    • Traditional Outbound NAT according to RFC 3022

    • Port Restricted Cone NAT

    • Source NAT

    • Destination NAT

    • Freely definable maximum number of simultaneous connections

    • Twice NAT according to RFC 2663

A Layer 2 software switch is included in SEVENSTAX Routing to provide a transparent connection between two Ethernet based networks (e.g. USB CDC/ECM and Ethernet/WIFI). In this way, packets can be spread on MAC level. Thus a PC which is connected via USB can not only access services of embedded systems but is also able access embedded systems via networks that are connected to it by Ethernet. Thereby USB can be used e.g. as a maintanance interface for embedded systems which are stationary linked on the Ethernet side.

Technical details of the SEVENSTAX L2-Switch:

  • Packet forwarding according to „Store-and-Forward“
  • Handling of multicast and broadcast

A further component of SEVENSTAX Routing is the RCP (Router Control Protocol) developed by SEVENSTAX. RCP controls the dial-in procedure of the router. As it is designed for embedded systems it is much more efficient and secure in comparison to other control protocols (e.g. UPnP). Dial-in routers are routers that are not supposed to be permanently online (e.g. GSM/GPRS/UMTS/LTE interfaces).

SEVENSTAX RCP has the following features:

  • Negotiation of permanent and temorary gateway addresses

  • Arbitrary number of hosts

  • Dynamic distribution of router load between the hosts

  • Control of dial-in behavior of the router

  • Router extension with "hot-plug" ability

  • Support of multiple routers in a network