Using the Wisconsin Network - Part 2

by Andy Nemec, KB9ALN

In Part one of our series, we discussed what digipeaters and nodes are, the different kinds of nodes, and what makes them so special. In Part Two, we will continue our discussion. Let's review.

A digipeater is a simple repeater of packets. A node is a more sophisticated repeater of packets, it knows if a packet was received, and can often allow you to send your packets over a very long distance. A network node is linked to other nodes and is often capable of doing more than just repeating your packets. We've talked about using nodes to pass our packets a longer distance. However, the need for a network of nodes grew out of another problem closely related to this need for distance.

You may have found that not everybody in the packet community is on the same frequency in different parts of the state. This was done on purpose, so that people would not crowd up on one frequency, making it useless. Different areas of the state are divided up into seperate Local Areas. This is usually done by region, county, or even parts of a city. Each division is called a "LAN", meaning "Local Area Network", having a separate LAN frequency. Some way had to be devised so that different areas could communicate with each other, and that is where the network of nodes comes in.

The Nuts and Bolts of a Node system.

A node in it's physical form is a TNC, a Radio and the antennas it needs to work, similar to other packet stations. The TNC is specially modified with a different set of operating instructions. Some garden variety TNC's have a node built in, like a Kantronics TNC. Network nodes are most often dedicated TNC/Radio Combinations set up specially for the purpose. Network nodes are also connected, by Radio, by wire, or by both. Nodes connected by wire at one location form a "Node Stack". The node radios in a particular stack operate on different frequencies and all "Talk" to each other, and with other node stacks. They exchange information concerning their ability to contact other network nodes. Network Nodes that contact each other over the air usually do so on dedicated frequencies reserved for Node-to-Node commun- ication. This is called a "Backbone", and is devoted to connecting different nodes together so that your packets can be passed a greater distance and to other LAN frequencies. The graphic below will demonstrate a pair of network node stacks that carry packets between 2 LANS by way of a backbone.

(Diagram of a node stack)

If you guessed that the people operating on the Green Bay LAN can connect to the people operating on the Appleton LAN even though they are on different frequencies, you are right. Other LANS can be arranged so that they, too are on the backbone. This is the basis of a packet radio network. In the next part of this series, we will put this knowlege to work. We'll use information you can get from a node in order to explore the network.

On to Part 3 - Node "Broadcasts" and route quality

Back to Part 1 - What is a Node?

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