The Packet Radio
“
2 N 1
”
Handbook
by
Buck Rogers
K4ABT
Section 1
;
Packet Radio “The Basics
”
Section 2
;
The X1J4 System Node Operator’s (SNO) Handbook
Section II
;
TheNET X1J4 System Node Operators Handbook
__ Page 23
Chapter Seven
Understanding theNET X-1J 4 Node
TheNET
X1
supports multi-frequency operation without
the need for unconventional multi-port digipeater
hardware. A dual-frequency node, for example, consists
of a two TNC2 (with
X1
in each) connected together with
an RS232 interface cable.
Configuring a TheNET
X1
node for three or four
frequencys is just as easy; A TNC2 is used for each
frequency (or baud/speed), and the multiple TNCs are
interconnected via their RS232 ports using a diode-
matrix interface.
In addition, it is possible to configure a dual-frequency
TheNET
X1
node in
which the two TNC2s are not co-located. Instead of an
RS232 cable, the TNC interconnect can employ a
dedicated telephone line, fiber optics or other media as a
high-data rate backbone.
TheNET
X1
uses an asynchronous variant of AX.25 over
the interconnect, it is not necessary that it be an error-
free connection. This opens up fascinating possibilities,
such as a fiber-optic or satellite linked dual-frequency
node which may be accessed from any point coast to
coast.
AUTOMATIC ROUTING:
TheNET
X1
automatically takes care of the routing of
traffic between one node and another. A user needs to
specify just the desired destination, not the route.
Each node keeps track of the other nodes in the network
and the various possible paths that may be used to reach
them. If a node or path becomes unusable due to
equipment failure or poor propagation, TheNET
X1
automatically switches to an alternate route (if available)
to circumvent the outage. Conversely, when a new node
is placed on-line, other nodes automatically incorporate
the new node into the network routing structure. Such
routing changes are handled dynamically, without
disrupting user connections in progress.
TheNET
X1
supports three methods of updating its
routing information: local, remote, and automatic. Initial
routing information may be entered manually by an on-
site operator using a local terminal.
Routing changes may be made remotely by a SYSOP or
network manager over an ordinary packet radio
connection randomized verification algorithm effectively
prevents changes by unauthorized operators. In addition,
TheNET
X1
nodes broadcast routing information to each
other as defined in the Param and Mode settings.
Furthermore the nodes can be set to "locked-path"
settings, thus eliminating the need for any broadcast at
all. In any case, the node(s) may be enabled to
incorporate new nodes and to bypass outages in real-time
without manual control.
THE "CQ" FEATURE
:
TheNET
X1
allows a user to broadcast a CQ from a local
or distant node, and enables other stations to replay to the
CQ using the high-level facilities of the network. A
user's CQ request remains active for up to 15 minutes,
during which time it appears in the node's user directory.
NODE IDENTIFIERS:
Each TheNET
X1
node is identified in two ways: by a
valid amateur callsign
permanently encoded into each copy of TheNET
X1
, and
by an arbitrary node identifier established by the node's
sysop. Identifiers may be up to six characters long or
three-letter city designators similar to those used by
airports to identify the neighboring city or location.
Some examples of these are ATL for Atlanta, MCN for
Macon, CHI for Chicago, or JVLfor Jacksonville, etc.
Node identifiers appear in node station identification
beacons, and are passed to other nodes during the
periodic routing broadcasts (PARAMS Parameter
number 7).
Despite its internal advanced networking capabilities,
TheNET
X1
is exceptionally easy to use. A new user
needs to learn only one command, CONNECT, to
establish cross links to other nodes or downlinks to other
user stations.
More sophisticated users may wish to use the NODES
command to list the callsigns and identifiers of other
network nodes, and the USERS command to find out
who else is using the node.
