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>From: steve@matt.ksu.ksu.edu (Steve Schallehn)
>Newsgroups: rec.radio.amateur.packet
>Subject: packet radio FAQ 3 of 3
>Message-ID: <1991Jul10.123341.25474@maverick.ksu.ksu.edu>
>Date: 10 Jul 91 12:33:41 GMT
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Frequently Asked Questions
for
Amateur Packet Radio
Part 3 of 3

Version 1.0
9 Jul 1991

This document is for unlimited distribution.

Please send corrections and additions to Steve Schallehn
(steve@matt.ksu.ksu.edu).  This posting will be made on a monthly
basis, posted to rec.radio.amateur.packet.



3.0 Networking and special packet protocols. . . . . . . . . .  1
     3.1 Are there any other protocols in use other than
          AX.25? . . . . . . . . . . . . . . . . . . . . . . .  1
     3.2 What is TCP/IP? . . . . . . . . . . . . . . . . . . .  1
     3.3 Networking Schemes. . . . . . . . . . . . . . . . . .  2
          3.3.0 What are some of those other networking
               schemes?. . . . . . . . . . . . . . . . . . . .  2
          3.3.1 Digipeaters. . . . . . . . . . . . . . . . . .  2
          3.3.2 KA-Nodes . . . . . . . . . . . . . . . . . . .  2
          3.3.3 NET/ROM. . . . . . . . . . . . . . . . . . . .  2
          3.3.4 ROSE . . . . . . . . . . . . . . . . . . . . .  3



3.0 Networking and special packet protocols

This is a sample of some of the more popular networking schemes
available today.  By far, there are more customized networking
schemes used than listed.  Consult your local packet network guru
for specific network information.


3.1 Are there any other protocols in use other than AX.25?

AX.25 is considered the defacto standard protocol for amateur
radio use and is even recognized by many countries as a legal
operation mode.  However, there are other standards.  TCP/IP is
used in some areas for amateur radio.  Also, some networking
protocols use other packet formats than AX.25.


3.2 What is TCP/IP?

TCP/IP stands for Transmission Control Protocol/Internet
Protocol.  This is commonly used over the Internet wired computer
network.  The TCP/IP suite contains different transmission
facilities such as FTP (File Transfer Protocol), SMTP (Simple
Mail Transport Protocol), Telnet (Remote terminal protocol), and
NNTP (Net News Transfer Protocol)

The KA9Q NOS program (also called NET) is the most commonly used
version of TCP/IP in packet radio.  NOS originally was written
for the PC compatible.  However, NOS has been ported to many
different computers such as the Amiga, Macintosh, Unix System V,
and others.  Smaller computers like the Commodore 64 and the
Timex-Sinclar do not currently have version of NOS available.



3.3 Networking Schemes

3.3.0 What are some of those other networking schemes?

During the early days of amateur packet radio, it became apparent
that a packet network was needed.  To this end, the following
packet network schemes were created.


3.3.1 Digipeaters

The first networking scheme with packet radio was Digipeaters.
Digipeaters would simply look at a packet, and if it's call was
in the digipeater field, it would resend the packet.  Digipeaters
allow the extension of range of a transmitter by retransmitting
any packets addressed to the digipeater.

This scheme worked well with only a few people on the radio
channel.  However, as packet became more popular, digipeaters
soon were clogging up the airwaves with traffic being repeated
over long distances.  Also, if a packet got lost by one of the
digipeaters, the originator station would have to retransmit the
packet again, forcing every digipeater to transmit again and
causing more congestion.


3.3.2 KA-Nodes

Kantronics improved on the digipeater slightly and created KA-
Nodes.  As with digipeaters, KA-Nodes simply repeat AX.25 frames.
However, a KA-Node acknowledges every transmission each link
instead of over the entire route.  Therefore, instead of an end-
to-end acknowledgement, KA-Nodes allow for more reliable
connections because acknowledgments only carried on one link.
KA-Nodes therefore are more reliable than digipeaters, but are
not a true network.  It is similar like having to wire your own
telephone network to make a phone call.


3.3.3 NET/ROM

NET/ROM was one of the first networking schemes to try to address
the problems with digipeaters.  A user connects to a NET/ROM as
if connecting to any other packet station.  From there, he can
issue the NET/ROM commands to instruct it to connect to another
user locally or connect to another NET/ROM.  This connect then
connect again means that to a user's TNC, you are connected to a
local station only and it's transmissions does not have to be
digipeated over the entire network and risk loosing packets.
This local connection proved to be more reliable.

NET/ROM don't use all of the AX.25 protocol.  Instead, they use
special AX.25 packet called Unnumbered Information (UI) packets
and then put their own special protocol on top of AX.25.  This is
again used to increase efficiency of it's transmissions.

NET/ROM is a commercial firmware (software put on a chip) program
that is used as a replacement ROM in TAPR type TNC's.  Other
programs are available to emulate NET/ROM.  Among them are
TheNet, G8BPQ node switch, and some versions of NET.

NET/ROM nodes, at regular intervals, transmit to other nodes
their current list of known nodes.  This is good because as new
nodes come on-line, they are automatically integrated in the
network, but if band conditions such as ducting occur, often
unreachable nodes are entered into node lists.  This causes the
NET/ROM routing software to choose routes to distant nodes that
are impossible.  This problem requires users to develop a route
to a distant node manually defining each hop instead of using the
automatic routing feature.


3.3.4 ROSE

Rose is another networking protocol derived from X.25.  Rose
nodes have a static list of the nodes it can reach.  For a user
to use a ROSE switch, he issues a connect with the destination
station and in the digipeater field places the call of the local
rose switch and the distant rose switch the destination station
can hear.  Other then that, the network is completely transparent
to the user.

The static routing tables ROSE uses ensures that packet routing
does not use unreliable links such as NET/ROM suffers from.
However, ROSE suffers from it's inability to change it's routing
table as new nodes come on line.  The operator must manually
change every routing table, thus ROSE networks require greater
maintenance times.
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