History of FlexNet in The Northeast

FlexNet, the "RF Data Pipeline"

by John C. Papson  WB2CIK

August 1998 three TheNet X.1J4 Nodes on Long Island switched over to a new (in the USA) networking protocol called FlexNet for a short weekend test!

Once we saw how well it worked, it stayed.

What is it?

FlexNet is a different networking protocol (NETROM/TheNET/BPQ/MSYS all use the same protocol, ROSE and TCP/IP are two different protocols) used extensively used in Europe.  Originally, FlexNet needed a special controller called the Rein Main Network Controller (RMNC), available only in Germany.

A few years ago, the authors compiled the software to run in an IBM PC and called it "PC FlexNet".

What are its advantages?

FlexNet incorporates the best features of all existing protocols (NETROM/TheNET/BPQ-ROSE-TCP/IP) and many improvements.

It has the "auto routing" of NETROM/TheNET/BPQ, (ROSE and TCP/IP routing is manually hard coded) The "transparency" to protocol of ROSE, (none of the others are) The measurement of round trip time (PING) and adaptive parameters (back off) of TCP/IP.

And the FlexNet Group in Darmstadt Germany made vast improvements too.

There is a periodic test of each Link, which occurs ever 4 minutes or so.  The autorouter employ's the measured round trip time data, not just broadcasts from neighbor nodes.

In the past, NETROM autorouted solely on what it has heard.  One way, poor and intermittent paths, inconsistent parameter settings and differing network standards all resulted in nodes listed in the table, which users just could not connect to.

With FlexNet, if a "Digi" appears in the "<Destination Table>", the user can reach it !

FlexNet rapidly adapts to traffic load, equipment failures, weather induced path degradation and propagation effects, as it adjusts all of the TNC parameters automatically, and continuously adapts them to the path conditions.

If the path is very marginal, FlexNet sends single frames of very short packets, and if excellent, it will send strings of 7 frames, each with a maximum length packet.

And if a path fails, it will automatically route around it, even if it take a dozen hops!!   Traffic keeps flowing while the link is repaired...

FlexNet is consistent, as there are no SysOp adjustments to configure... It is fair and just to all users and neighbor nodes...  All path qualities are solely based on measurements; there is nothing that can be altered... This eliminates any and all "political" or "ego" problems from entering into the selection of the best possible route a packet should take...

Oh, did I say that it is FAST.... a 1200 baud link will almost look like a 9600 link, and the 9600 links fly!!!!!

How do I use it?

FlexNet appears different and very confusing at first glance, but it isn't that different...

FlexNet only uses Callsign-SSID; there are no Mnemonics (NETROM) or InterNet Addresses (TCP/IP) nor Telephone Numbers (ROSE).

Some familiar items have new names.  A "Node" is now called a "Digi"; a "<Node Table>" is now a "<Destination Table>"; a "<Route>" is now a "<Link>", "<Bye>" is now "<Quit>"...

A few are the same. "<Users>, "<MHeard>", "<STats>", "<Ports>", "<Information>", "<Help>".

And some new ones: "<Mailbox>", "<A>" "<Conference>" "<Find>"

You can connect to the "Digi" or the "BBS" direct from 144.99 simply by "C WA2PNU-2" or "C WA2PNU-4" respectively.   The connection to the BBS will be transparent to the FlexNet, so you will avoid the connect text from the Digi, and when you exit the BBS you will be totally disconnected.

Or you can connect to the Dig first using "C WA2PNU-2" receive the connect text, and then connect further on...  If you then want the BBS, you can either "C WA2PNU-4" or simply "M", while connected to WA2PNU-2 Digi.  When you disconnect from the BBS, you then will be returned to the Digi WA2PNU-2.

Going a little further, you can connect to a distant BBS by either method.

For example, to get to Bob's WA2SNA-4 BBS, you can do it in one step "C WA2SNA-4 V WA2PNU-2" or in two steps "C WA2PNU-2" then "C WA2SNA-4".

Ooooops, what was the "V”???

The "V" equals "Via", which means that you are connecting to WA2SNA-4 thru WA2PNU-2. You can connect to any station in the <D> table this way, no matter how distant they are.  (As the network grows, there will be stations in 4 or 5 states in the table).

At present (6/99), we only have over 30 sites running FlexNet, with a total <D> list of over 80 FlexNet Digi's and neighboring NETROM/TheNet Nodes.

FlexNet is also self-learning, as it will remember the way back to the last 200 callsigns that have used a Digi. If you have talked to W3XYZ off of the WA3LWR Digi, the next time you want to connect to W3XYZ, most likely you will only have to "C W2XYZ V WA2PNU", dropping the "LastDigiCallsign" from the command string.

And Smart too!   The <Find command will allow you to locate a user wherever he is located throughout the FlexNet Network.

How Do I connect to the old network?

The problem is that FlexNet does not exchange networking information with NETROM.

So you have to manually step across the boundary. (This disappears as FlexNet network grows)

Initially, connect text listed the Callsign and SSID of the NETROM Node at each Flex -- NR border crossing. You simply C <Callsign-SSID> and you are in the old NETROM network.

In the reverse direction, look for a node with FLEX, FLX or FX in it's Mnemonic, they are the NR -- Flex border crossing points.

Locally we have used the <A text for a very detailed cross reference of the "callsign ssid range" that FlexNet's displays to the exact geographic location of each Digi or Node...

And much more...

We now have many sites, which have a FBB BBS running on top of FlexNet in the same PC... The combination works flawlessly, running unattended for months on end...  The combination of FlexNet 3.3g and FBB 7.00g (DOS) is dead reliable, even working on several remote mountain top sites. FlexNet links to FBB using the TFEMU interface.

Pavilion DX Cluster can also run on top of FlexNet, and is in use in a couple of sites....  FlexNet links to DX Cluster also using the TFEMU interface.

And we have MFNOS IP Routers in place at major FlexNet Digi's, providing the same or better coverage we had before the conversion to FlexNet.  We accomplish this by linking to a second PC, using the KISS interface via a serial port.

Where do I get it?

FlexNet Group Darmstadt, source of all FlexNet software:

http://www.afthd.tu-darmstadt.de/~flexnet/

(they will require you to register for the "digi" module, all other pieces can be simply downloaded...)

Thomas Sailor's FlexNet Drivers:

http://www.ife.ee.ethz.ch/~sailer/pcf/pcfindex.html

Charles Brabham, N5PVL, many good FlexNet set-up examples, in American

English: http://home.texoma.net/~n5pvl/

Where's it in use?

The current NY Metro FlexNet coverage area extends south to K2UL outside of Trenton NJ, west to K3YTL in Wilkes-Barre PA, north to KA2MSL in Stewart Airbase NY, east to K1IMD in Jamesport LI NY.

K2UL's immediate NETROM neighbor to the south is K2ADJ...  There's also a group of FlexNet Digi's in Quebec Providence, Canada.

Presently many additional Node sites in the process of converting to FlexNet, with the prospect of NY Metro FlexNet linking to Quebec FlexNet.

I should add that there is no limit on the size of the <Destination> Table, because a PC is not memory limited; TNC's have only 32 KB of RAM!!!   In Germany, the <D> Table now has over 600 entries, listing Digi's from Spain to the Baltic States, all of which are reachable! This is about the size of the USA east of the Mississippi!

Thank you for reading....   73...

John C. Papson    WB2CIK@WA2PNU.#NLI.NY.USA.NOAM