The College of Packet Radio Knowledge

What is Flexnet

Presented By Betsey Doane, K1EIC

Chuck Rexroad, AB1CR

Objectives

Explain the meaning of: A digipeater A packet network The backbone Network protocol Flexnet protocol

Use Flexnet commands Articulate the advantages of Flexnet over other

protocols

Types of Connections

Two stations connect directly Two stations connect through a digipeater Two stations connect through a packet

network

What is a Digipeater

A digipeater is A store and forward "digital repeater" which will receive and transmit a data packet on the same frequency.

All amateur packet stations are capable of digital repeating in a simplex environment.

Connect Through 2 Digipeaters

C AB1CR V N4GAA N1URO

W1HADOrig node

N4GAADigi node

N1URODigi node

AB1CRDest node

Inter-node link

Inter-node link

Inter-node link

End-to-end connection

Network Terminology

A packet network is a set of stations logically linked together to route data from one user to another

Each station is called a node or digi. Communication among the stations in the network is done

through software which specifies how data is routed and how the stations will talk to each other.

Call this software a network protocol. Flexnet is a network protocol.

Types of Nodes

Users connect to user nodes presently at 1200 baud

The forwarding of information through the network is done through a system of linked nodes at higher speeds on frequencies not open to users.

The backbone is carefully planned and must be kept free of interference.

Advantages of Flexnet

Routing is fully automatic

No SysOp intervention is needed or allowed

FlexNet will continuously select fastest path FlexNet will automatically route around an

intermittent , one way or failed links

More Advantages

Flexnet is fair SysOp/NodeOp ego’s don’t enter into

network routing No more one way links, phantom nodes !!

How It Works

K1EIC connects to AB1CR through the network:

C W1HAD—ack is completed W1HAD connects to N1URO on backbone [ 1

hop] ack is completed N1URO connects to AB1CR-4 BBS [another

hop] ack is completed

Trouble With Link!

Flexnet tests the round trip times of links every 4 minutes

Failure is noticed fm HAD to URO!

What to do?

How we Got Connected

Link RTTs are checked every 4 minutes The lower the roundtrip time, the better the path Network rerouted us:

K1EIC to W1HAD W1HAD routed to N4GAA N4GAA to N1URO N1URO to W1EDH W1EDH to AB1CR-4

FlexNet w/multiple RS-232 portsusing 6PACK driver

PC

TNC 0

TNC 8

TNC 2

TNC 1

COM 1

COM 2

COM 3

COM 9

OOOOO

Advantage: Easy to troubleshoot, high speed Disadvantage: Cost of multiple port RS-232 cards.

OOO

< 6PACK interface>

< 6PACK interface>

< 6PACK interface>

< 6PACK interface>

The Supplemental Station Identifier The SSID is an optional number ranging from 0 to 15 appended

to a call sign that allows that call to be used in 16 different ways. Syntax. Call sign }-SSID} Example. W1HAD-4 is the call of the PBBS at Shelton. Nodes are shown with a range of SSIDs available. EX. WX1CT 0-15 AB1CR 2-5 Call signs of bulletin boards have SSID -4 C W1HAD-4 Always connect to a node using the lowest number in the SSID

range. Ranges beginning with 0 need no SSID to connect.

Where to Go

Each node maintains a destination table listing all nodes that can be reached.

Use the D command to get the list. Call is followed by range of SSID’s followed by

the round trip time (RTT) of the current route to the destination node. This RTT is the average of the RTT’s of each link in the route.

The lower the RTT the better the path.

Partial Destination Table

W1HAD 0-15 76 W1QI 0-0 55 W1TOM 0-4 666 W1TOM 10-14 532W2CRA 0-15 1299 W2CXN 0-15 252 W2JT 0-15 74 W2LV 0-14 46W2PAT 8-8 560 W2QW 0-15 831 W3AVK 6-6 176 WA1ZYX 9-9 721WA2FNQ 0-15 267 WA2NDV 2-2 225 WA2PNU 0-15 42 WA2SNA 0-13 28WA2SNA 14-14 58 WA2TOW 2-2 58 WA2UMX 2-2 331 WA2UMX 9-9 227WA2UMX 13-13 263 WA2UMX 14-14 311 WA2WNI 0-14 128 WA2YSM 7-7 1014WA2ZWP 0-15 280 WA3LWR 0-14 76 WB1CQO 0-6 471 WB1CQO 4-4 456

Find the Route

Syntax: D {call sign} shows route

=>d wb2cik*** WB2CIK (0-14) T=109=>*** route: W1HAD WX1CT-7 WB2CIKAB1CR 2-4 388

=>d ab1cr-2AB1CR 2-4 394 WC2ABG 0-15 842

=>d wc2abg*** WC2ABG (0-15) T=842=>*** route: W1HAD WX1CT-7 WB2CIK KC2COJ WB2SNN W2JT WC2ABG=>

Why It Works

Each Flexnet/digi node with links to its network neighbors uses regular polling to verify that the nodes are operational.

An autorouter at each node exchanges network-wide routing data with Flexnet digi/node neighbors whenever link conditions change.

Routing data is updated throughout the network very quickly. A destination table with current network status info is maintained

by each Flexnet digi/node. Display destination table using the D command.

Use I to Get Info

System info: This FlexNet-Digi node, W1HAD, is located at Shelton, Fairfield County, Connecticut, USA. The Grid locator is [FN31jh]. It is operating on a 486 PC (lists software)

Ident: W1HAD responding to ssid in the range 0 thru 7 This is the Club call of the Mohegan Amateur Radio Club.

Port 0 -2 VHF Local User Channel. 145.05 MHz. 1k2 Port 1 -3 SCT/LINY Multi Channel. 223.46 MHz. 1k2 Link to W1WCG-2 North Haven, New Haven Ct, CT Link to: NY2LI Yaphank, Suffolk County, NYPort 2 -7 SCT/LINY UHF Multi Channel. 441.050 MHz. 1k2 Link to: N4GAA-7 West Haven, New Haven Cty, CT Link to WX1CT-7 Bridgeport, Fairfield Cty, CT Port 3 -6 Link to: N1URO-6 Burlington, Hartford Cty, CT 9k6Port 4 Link to: WX1CT-7 Bridgeport, Fairfield Cty, CT 9k6 Link to: WB2CIK West Hills, Suffolk Cty, NYPort 5 Link to: Future 223.58 MHz. 1k2Port 15 Link to: W1HAD-4 Local PBBS Host Interface

The <S>earch command is set via all FlexNet-Digi User ports within the state of Connecticut. The <M>ail command is set to W1HAD-4 at Shelton, CT******

Info con’t

Call: W1HAD was adopted as the Club call of the Mohegan Amateur

Radio Club. Trustee K1EIC. It is dedicated in memory of one of Connecticut's Amateur Radio pioneers the late

Paul M. Doane, W1HAD 1939 - 1994

Sponsor: Mohegan Amateur Radio Club

Sysop: Elizabeth L, Doane, K1EIC Phone: 203-929-7759 92 Mohegan Road .

Shelton, CT 06484-2448

Internet: k1eic@arrl.org

PBBS: K1EIC @ W1HAD.CT.USA.NOAM

Some Useful CommandsCommand Meaning<A>ll Lists all nodes, reachable or not

<C>onnect Connect to a station

<D> List of reachable nodes

<F>ind Find a node within the ARRL Section of the node user is connected to; F {call}

<H> Help

<I> Info about the node

<M> Connects station to mailbox associated with that node

<Q> Quit disconnects station from node

<U> Current users

Credits and Resources Workshop PresentersBetsey Doane, K1EIC k1eic@arrl.orgChuck Rexroad, AB1CR ab1cr@arrl.net Packet SYSOPSFrank Van Cleef (Van), W1WCG w1wcg@snet.netBob Anderson, K2BJG K2BJG@cfl.rr.comJohn Papson, WB2CIK, wb2cik@bythebays.com Author Dr. John A. Allocca, WB2LUA john@allocca.com Web Siteshttp://www.northeastflexnet.orghttp://www.packetradio.com