KA-Node
Overview
Most Kantronics TNCs (e.g., KPC-3 Plus, KPC-9612 Plus) include, as a part of
their firmware, the Kantronics KA-Node, a packet networking node. If you turn
this node on, others may use your station (unattended) not only as a digipeater
but as a node, enabling them to find pathways to other stations and making those
pathways more efficient.
KA-Nodes, like other networking nodes such as NET/ROM, operate more effi
-
ciently than do digipeaters as a link between two stations. End-to-end acknowl
-
edgement of received packets is not required with the nodes; instead they handle
errors beween each other, rather than from end to end (which can cause extra
traffic when errors or interference occurs). A KA-Node, however, is “silent” in
that it does not automatically connnect to and exchange routing data with adja-
cent nodes, as do fully-features nodes such as NET/ROM, X1J, or Kantronics op-
tional K-Net. Consequently, users cannot issue a connect to a distant station
without knowing the path - as they sometimes can with a fully-featured node. At
the same time, KA-Nodes are useful in that they are more efficient than
digipeaters in using channel time, while not requiring the effort and time required
to maintain a full node.
When packet got started in the early 1980s, the initial packet units - terminal
node controllers (TNCs) - were designed and coded not only to accept sta
-
tion-to-station connects, but to act as digipeaters for other stations. It was the
first
attempt at packet radio networking, linking two stations together via several oth
-
ers. It soon became evident, however, that digipeating, particularly through busy
channels, was an inefficient method of linking two stations via others. First of all,
the station initiating the “connect” had no way to know ahead of time whether or
not the digipeating stations were available. Second, the AX.25 protocol called for
the station being connected to - at the end of several digipeaters - to acknowledge
each packet of the initiating station. Packets not acknowledged (due to collisions)
had to be retransmitted by the initiating station AND ALL DIGIPEATERS in the
communications chain. As a result, communication often ground to a halt when
channels were busy.
KA-Node Packet Modes of Operation
KAM’98 v 8.3 199 User’s Guide
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