This web site has been established to be a concise repository for AX.25 layer
2 design activities. AX.25 is a protocol originally developed for amateur
radio in the late 1970's and standardized on in 1984 with the release of the
Amateur radio enthusiasts quickly developed many diverse network architectures
using AX.25 as a basis. Unfortunately, AX.25 was released as a link layer
protocol not a network or application layer protocol. As was common in
those days, a "tower of Babel" was created with all the different network
architectures. Many of the networks were also based on single frequencies
causing extensive collisions between repeated packets.
When the Internet came along, amateurs quickly began to lose interest in the
different AX.25 networks. While the Internet at that time was slow (14.4
kbps modems and expensive ($25 per month for local access if available), it
offered worldwide connectivity and an emerging application portfolio.
AX.25, on the other hand, provided limited reliability on a local level with few
applications other than keyboard-to-keyboard or keyboard-to-BBS. There was
some adaptation of IP over AX.25 with some success but these networks were
normally UI networks without repeater coverage.
Today, there are very few applications utilizing AX.25 networks. DX
clusters have significantly more users on telnet than on RF. Winlink 2000
supports packet by way of Paclink and Telpac, but primarily in point-to-point
operation (repeater use requires network topology knowledge by the user).
Europe has standardized on FlexNet to implement their backbone network.
APRS uses specially configured digipeaters, which in the tradition of previous
AX.25 networks, are not compatible with non-APRS applications. All of
these networks require the end user to modify their software or hardware to use
the various local environments. The prerequisite of network topology
knowledge is daunting at best and leads to either disuse or misuse.
The goal of this web site and, more importantly, the
AX.25 Layer 2 Special Interest Group is to define and develop a generic AX.25 layer 2
implementation that can be used by any of the above applications along with
supporting layer 3 protocols without requiring prior knowledge of the local
network topology by those users, applications, and protocols. Also, a
generic layer 1/2 interface would be beneficial as well.
Unfortunately, TAPR has reorganized their forums and this SIG is no longer available.