When a SCADAPack E outstation routes a TCP/IP packet to another TCP/IP host, the following rules are applied in order, until the packet has been sent or discarded:
- If only one TCP/IP interface is configured and that interface is PPP, the outstation routes each TCP/IP packet via that interface.
- If the TCP/IP packet has a destination address that matches a host on the same subnet as one of the Ethernet interfaces, the outstation routes the TCP/IP packet directly via that ethernet interface.
- If the packet has not been sent in step 1 or step 2, above, the outstation looks up the destination address of the packet in the IP Route table. It searches the entries in the route table in Host, Network, Gateway, and finally Default-Gateway order (see Types of IP Route). If a match is found, the outstation routes the packet to the corresponding gateway via the corresponding port.
- The packet is discarded.
A SCADAPack E outstation does not differentiate between TCP/IP packets that it generates itself and TCP/IP packets that it receives from another host. It applies the same routing rules to every packet.
If you create and configure an IP Route Table in Geo SCADA Expert, you can use that table to specify up to 20 route entries for outbound TCP/IP packets. You can add entries to the table to allow a SCADAPack E outstation to:
- Route TCP/IP packets that the outstation generates, to any host that is not on a local subnet.
- Act as a TCP/IP router, enabling the outstation to forward packets between subnets.
Further Information