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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

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Presented by betsey doane k1eic

Presented By Betsey Doane, K1EIC

Chuck Rexroad, AB1CR


Objectives
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
Types of Connections

  • Two stations connect directly

  • Two stations connect through a digipeater

  • Two stations connect through a packet network


What is a digipeater
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

Connect Through 2 Digipeaters

W1HAD

Orig node

N4GAA

Digi node

Inter-node link

Inter-node link

End-to-end connection

N1URO

Digi node

AB1CR

Dest node

Inter-node link


Network terminology
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
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
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
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
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
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
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 ports using 6pack driver
FlexNet w/multiple RS-232 portsusing 6PACK driver

PC

TNC 0

COM 1

< 6PACK interface>

TNC 1

COM 2

< 6PACK interface>

TNC 2

COM 3

< 6PACK interface>

O

O

O

O

O

O

O

O

COM 9

TNC 8

< 6PACK interface>

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


The supplemental station identifier
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
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
Partial Destination Table

W1HAD 0-15 76 W1QI 0-0 55 W1TOM 0-4 666 W1TOM 10-14 532

W2CRA 0-15 1299 W2CXN 0-15 252 W2JT 0-15 74 W2LV 0-14 46

W2PAT 8-8 560 W2QW 0-15 831 W3AVK 6-6 176 WA1ZYX 9-9 721

WA2FNQ 0-15 267 WA2NDV 2-2 225 WA2PNU 0-15 42 WA2SNA 0-13 28

WA2SNA 14-14 58 WA2TOW 2-2 58 WA2UMX 2-2 331 WA2UMX 9-9 227

WA2UMX 13-13 263 WA2UMX 14-14 311 WA2WNI 0-14 128 WA2YSM 7-7 1014

WA2ZWP 0-15 280 WA3LWR 0-14 76 WB1CQO 0-6 471 WB1CQO 4-4 456


Find the route
Find the Route

  • Syntax: D {call sign} shows route

    =>d wb2cik

    *** WB2CIK (0-14) T=109

    =>

    *** route: W1HAD WX1CT-7 WB2CIK

    AB1CR 2-4 388

    =>d ab1cr-2

    AB1CR 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
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
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, NY

Port 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 9k6

Port 4 Link to: WX1CT-7 Bridgeport, Fairfield Cty, CT 9k6

Link to: WB2CIK West Hills, Suffolk Cty, NY

Port 5 Link to: Future 223.58 MHz. 1k2

Port 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
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: [email protected]

PBBS: K1EIC @ W1HAD.CT.USA.NOAM



Credits and resources
Credits and Resources

  • Workshop Presenters

    Betsey Doane, K1EIC [email protected]

    Chuck Rexroad, AB1CR [email protected]

  • Packet SYSOPS

    Frank Van Cleef (Van), W1WCG [email protected]

    Bob Anderson, K2BJG [email protected]

    John Papson, WB2CIK, [email protected]

  • Author Dr. John A. Allocca, WB2LUA [email protected]

  • Web Sites

    http://www.northeastflexnet.org

    http://www.packetradio.com


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