
	       Using the Wisconsin Network - Part 3
		       By Andy nemec, KB9ALN

      In parts One and Two of this series, we explored what a
 network node is, how they are superior to Digipeaters, what they
 can do, and a little about how they do it. We learned about the
 concept of a Local Area Network (LAN), and how the network nodes
 link them together. Now we will explore more of what a network
 node does, and a little bit of how to effectively use them.

      First, consider what might be needed to do the job of
 connecting one LAN to another. We talked about the fact that nodes
 "Talk" to each other, and that they know that other nodes exist,
 and what other nodes they can "talk" to. How is this done? Well,
 nodes periodically "poll" each other  to determine if a node is
 present, and how good of a communication path exists between them.
 They exchange a series of packets, and take note of the time that
 it takes a given node to respond in this exchange. A formula is
 used to calculate what is known as a "Route Quality" number. The
 higher the number, the better the "Route Quality".

      Different route quality standards are used at different node
 baud rates. For example, a 1200 baud 2-Meter node may have a route
 quality of 192, and this is considered good. A UHF Node operating
 at high speed (9600 baud) may have a good route quality of 225.
 Nodes linked by wire on the same node stack will usually have the
 maximum quality possible of 255.

      Why is this important? Nodes use this information as a means
 to know how to route your packets through the network. How? Each
 node sends out a  "Broadcast" to other nodes letting them know of
 other nodes it can reach, and of the route quality. A typical
 "Nodes Broadcast" may look like this:

 KE9LZ-5>NODES UI Pid = CF
       Nodes Broadcast de WIGRB:
       #446GB     N9CFN-4   via N9CFN-4    255
       #APL4      KB9BYQ-6  via N9CFN-4    222
       IPGB       N9CFN     via N9CFN      150
       IPGRB      KE9LZ     via KE9LZ      150
       IPNOK      N9NOK     via N9NOK      150
       WICRIV     KE9LK-7   via N9CFN-5    185
       WIDC       W9AIQ-1   via N9CFN-5    191
       WIGB       N9CFN-5   via N9CFN-5    255
       
      Now a look at the broadcast in a little detail. The top line
 looks pretty much like most packet "headers" on your monitor
 screen, with one exception. Notice that it says "PID = CF". This
 is the "Protocol Identifier". Remember when we talked about nodes
 speaking to each other in their own language? This is what is
 known as the "Net/Rom Protocol". This explains why most TNC's
 cannot interpret these broadcasts, and why you may have never seen
 them. The above sample came from the Green Bay node with an alias
 of WIGRB. 

      Each route that is broadcast consists of a node alias,
 followed by that node's call-sign, the route it uses to connect to
 it, and the route quality number. The first entry is a node that
 is connected by wire to  the node, because it's route quality is
 255 (the highest it can be). The second entry is connected
 reachable through a high-speed UHF radio link, of good quality,
 222. The third, fourth, and fifth listings are of so-so quality,
 150. The sixth and seventh listings are of medium-to-good quality
 and are reachable by a combination of a wire-linked node, and VHF
 radio. The last listing is - you guessed it - wire linked to this
 node. Note that nodes WICRIV and WIDC are reached by way of WIGB.

      By now you may be wondering why we have bothered to learn
 this information, because you can't normally see the broadcasts.
 The answer to this is simple: You can see a portion of this
 broadcast by issuing the  ROUTES or R command to a node you have
 connected to. You will not see all of the routes on the route
 table, only the ones that can be accessed directly by the node.
 This is useful information. It not only tells you that there is a
 path to a node, but how good it is. Like the rest of radio, not
 all routes are reliable 100% of the time, and this allows you to
 determine how to make a long-distance connection.

      The "Routes" command is one of the more useful that can be
 givien to a node. In the next installment, we will explore more of
 how a node works, and what commands you will find useful when you
 "Surf the Network". 
 
  *End of Part 3*
