Specifications

System Configuration Files
250 025-9035AA
USA will appear as part of the satellite downlink page stream. Usually the pages set to
NetUSA are destined for the same regions as the terminal wishes to receive from the
downlink, so simple routing control will not suffice.
There are two methods of handling this. The first is to use the remapping functions to
change the destination addresses of the incoming Network USA pages to some other set of
addresses. Then these addresses would have their routing set up so that they only go to
Central, for local paging.
The second method is to use the “reject us” and “block us” fields that are part of the “17”
opcode in the TNPP option parameters. These two fields allow control of packet routing
based on the source address of the packets.
Both of these fields are bit-mapped port specifiers, similar to the “accept from” and “route
to” fields for node routing. The “reject us” field allows you to specify ports that will reject
any packet that originated at a node with the same primary node ID as this terminal. The
“block us” field is used to specify which ports will not route packets with this terminal's
source address.
Both of these fields are ignored when the packet is being originated by Central. Thus by
setting the “block us” field to block routing to the port that send packets toward the
Network USA uplink, any packet received at the downlink port that has our node ID as the
source will not be routed back out towards NetUSA. This would be used when the
terminal wishes to treat all NetUSA pages, even those of local origin, in the same fashion.
Alternatively the “reject us” bit could be set for the port connected to the satellite
downlink. In this case no NetUSA page that was sent by this terminal will be processed
and passed back to Central. Thus, these pages originally must have been paged locally if
the terminal is to alert those pagers. This configuration can be used to give quicker service
to locally originated NetUSA pages than to those that come from other nodes.
The following sample displays a very simple example of a terminal that routes pages to the
Network USA uplink, and receives Network USA from a satellite dish downlink. Only a
single destination node address is being used.
0C 01 09 05 03 06 00 00 00 00 00 00 ; Duplex, to NetUSA UpLink
0C 02 09 05 01 01 00 40 00 00 00 00 ; Simplex, NetUSA DownLink
; Route Accept
; node 0502 To From
0C 00 0A 04 00 00 05 02 00 03 00 05 08 ;
; we are 1111, reject at port 2
0C 00 0A 17 11 11 00 04 00 00 00 00 00 ;