Transcript The College of Packet Radio Knowledge

The College of Packet Radio
Knowledge
What is Flexnet
Presented By Betsey Doane,
K1EIC
Chuck Rexroad, AB1CR
Objectives
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Explain the meaning of:
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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
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Two stations connect directly
Two stations connect through a digipeater
Two stations connect through a packet
network
What is a Digipeater
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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
W1HAD
Inter-node link
Orig node
Digi node
N1URO
Digi node
N4GAA
AB1CR
Inter-node link
Dest node
Network Terminology
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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
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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
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Routing is fully automatic
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No SysOp intervention is needed or allowed
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FlexNet will continuously select fastest path
FlexNet will automatically route around an
intermittent , one way or failed links
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More Advantages
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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!
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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
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Link RTTs are checked every 4 minutes
The lower the roundtrip time, the better the path
Network rerouted us:
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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
COM 1
COM 2
< 6PACK interface>
< 6PACK interface>
TNC 0
TNC 1
PC
COM 3
O
O
O
COM 9
< 6PACK interface>
TNC 2
O
O
O
O
O
< 6PACK interface>
TNC 8
Advantage: Easy to troubleshoot, high speed Disadvantage: Cost of multiple port RS-232 cards.
The Supplemental Station Identifier
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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
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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
W2CRA 0-15 1299 W2CXN 0-15 252
W2JT 0-15 74
W2PAT 8-8 560
W2QW 0-15 831
W3AVK 6-6 176
WA2FNQ 0-15 267 WA2NDV 2-2 225
WA2PNU 0-15 42
WA2SNA 14-14 58 WA2TOW 2-2 58
WA2UMX 2-2 331
WA2UMX 13-13 263 WA2UMX 14-14 311 WA2WNI 0-14 128
WA2ZWP 0-15 280 WA3LWR 0-14 76
WB1CQO 0-6 471
W1TOM 10-14 532
W2LV 0-14 46
WA1ZYX 9-9 721
WA2SNA 0-13 28
WA2UMX 9-9 227
WA2YSM 7-7 1014
WB1CQO 4-4 456
Find the Route
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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
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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
Port 1
-2 VHF Local User Channel.
145.05 MHz. 1k2
-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
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
Some Useful Commands
Command
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 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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