USER DOCUMENTATION
FPAC is a network manager developed by French hams within the ATEPRA. The ATEPRA is a radio amateur association which is providing support to packet radio experimentation.
The FPAC system works in connected mode, that means the system establishes the connection and maintains it during the whole communication.
FPAC provides transparent routing of AX25 data packets for the user. It routes packets from one point of the network to another one.
FPAC is based on ROSE system imagined and realized by Tom MOULTON W2VY. ROSE follows the OSI model and uses a hierarchical addressing scheme.
A huge development work has been provided by F6DWJ to first port the ROSE system, running on a Z80 based TNC, to a PC environment, and then to add new functionality based on proposals from the first users: F6FBB, F6ABJ, F1ONT, F1TE, F6DEG...
FPAC while keeping the original ROSE philosophy, takes advantage of the PC platform (powerful processor, large memory). The PC with powerful development tools, simplifies the software design and allows more complex software.
With the help of F6ABJ, F6DEG, F1TE, F1AAV have designed a 4 channels SCC board and modems. F1TE, F6FBB, F6DEG, ..., have tested these hardwares. F1EDH has written the final French documentation based on preliminary one by F6DWJ, F6BEX, F1TE, F6CSS, F5CDC... F5PBX and F6ABJ have checked the documentation. W5/F6CNB has translated it.
Thanks to all hams who have given their time for this project. When you are using FPAC, think to the large number of days spent to complete this project.
Thanks again to F6DWJ, the main contributor of the project.
A network consists of nodes linked together. The network users connect each others through these NODES.
The data are transmitted from NODE to NODE from the input node to the output one. The answers follow the reverse path.
FPAC network implements the level 3 of the OSI model (see appendix)
FPAC reliability improves with the number of links between nodes. Because the nodes and links are not 100% reliable, the network establishes the connection based on available nodes and links.
Each node only knows adjacent nodes and addresses routed by these nodes. When the network establishes a connection, each node tries to connect one of its neighbors. It knows which node it should try based on the destination address. If the connection failed, it'll try another alternate node which can also provide a route to the final destination. There is no need to transmit out of date routing tables, each node only handles connections with its neighbors based on the destination address. The network reliability and status is tested in real-time.
But it is obvious that the network reliability largely depends on the number of links. It is very important to increase the number of nodes and the number of alternate routes.
The above network is derived from the French FPAC/ROSE network around Paris.
Each node is identified by a callsign: e.g. F6KDS-11, and a FPAC routing address: 193201. The callsign is used for the input connection, the address is used for determining the output node.
The nodes are linked together by dedicated transport links.
The network provides the transport of data from an input NODE to an output NODE. To use the network, you need to know the callsign of the input NODE and the address of the output NODE. (and obviously the callsign you want to connect).
An ham can connect to another ham through the network indicating:
- the callsign of the ham to connect
- the callsign of the input FPAC NODE
- the address of the output FPAC NODE :
Ex: I wish to connect F5LXS which station is on the F6PTT-11 VHF user frequency (145.275). I am on one of the F6KDS-11 user frequencies (144.625 or 432.650). I type the following connection request:
C F5LXS V F6KDS-11,191201
The F6KDS-11 node answers: Connecting F5LXS
The F6KDS-11 NODE connects the F6ABJ-11 NODE (on a reserved transport radio channel). Then F6ABJ-11 connects either F6PTT-11 directly or F6PRA-9 (depending of the table defined by the sysop based on the radio links quality). And so on until the output NODE (which address is 191201) is connected. In this case, the main route is directly to F6PTT-11 that starts a connection request to F5XLS on its VHF user frequency.
When F5LXS answers (to F6PTT-11), a connection acknowledge is sent back in the opposite direction and F6KDS-11 answers me: Connected to F5LXS-0 @ 2080191201.
Now, I am really connected to the called station.
For the users, the FPAC network appears like two Level 2 stations: the input NODE identified by its callsign and the output NODE identified by its address.
The traffic is using the TPK packet program and a TNC2 packet controller:
(Lines numbers have been added as references for the explanations)
- C F5LXS V F6KDS-11,191201
- Connection : F5LXS V F6KDS-11,191201
- cmd:
- *** CONNECTED to F5LXS VIA F6KDS-11,191201 [15-02-94 10:27:46]
- Connecting...
- Connected to F5LXS-0 @ 2080191201
Line 1: I type the command C F5LXS V F6KDS-11,191201
Line 2: my TNC2/TPK answers : Connection : F5LXS V F6KDS-11,191201
Line 3: my TNC2 is waiting
Line 4: my TNC2 informs me of the connection :
*** CONNECTED to F5LXS VIA F6KDS-11,191201 [15-02-94 10:27:46]
WARNING you are only connected to F6KDS-11 and not yet to F5LXS !!!
Line 5: the FPAC input NODE (F6KDS-11) indicates that it is trying to establish the connection.(virtual circuit establishment) : Connecting...
Line 6: I am now connected to: Connected to F5LXS-0 @ 2080191201Remarks: The five first lines appear very quickly. Because the connection is direct, the speed will depend only on the local traffic.
The waiting time for the effective connection (apparition of line 6) depends on each network links load. It should be between 15 and 30s.
This type of connection is similar to a connection to a ham station. You need to indicate the BBS callsign (SSID included) and its FPAC address. Ex:
C F6PTT-1 V F6KDS-11,191201
then the traffic is similar to a ham connection. Ex:
Connection : F6PTT-1 V F6KDS-11,191201 cmd: *** CONNECTED to F6PTT-1 VIA F6KDS-11,191201 [03-06-94 18:14:09] Connecting... Connected to F6PTT-1 @ 2080191201 [FBB-5.15-AB1FHMR$] F6PTT BBS. JN18DR. channel 2 - 11 active channel(s). Hi DOMINIQUE. Type ? <CR> for help. 11:F1EDH de F6PTT (A,B,C,D,F,G,I,J,K,L,M,N,O,P,R,S,T,U,V,W,X,Y,Z,?) > LL 3 Msg # TSD Dim to @ BBS From Date/Time Subject Selection = [*] 282251 B$ 2181 UNIX @WW DK3HG 0311/1911 Re: XTREE type prog for Linux? 282249 B$ 1895 ALL @WW IK7NXM 0311/1909 *W.A.A.C.*AWARD 282245 B$ 2845 WINDOW@WW DB7DB 0311/1901 Neues von Winlog. 10:F1EDH de F6PTT (A,B,C,D,F,G,I,J,K,L,M,N,O,P,R,S,T,U,V,W,X,Y,Z,?) > B Connected time 2mn 08s - CPU Time : 6s 73 de F6PTT. *** Disconnect at F6PTT-11 2080175201 ****** 0000 Disconnection by remote station
Note that there is a reduction of the speed during the initialization of a YAPP transfer due to YAPP negotiation (file name, file size, remaining part to transfer, ...) between your station and the BBS. After this phase, the speed only depends on the network load.
The previous examples use the French addressing scheme based on regions and subregions. The American one is based on telephone area codes. The addressing scheme should be defined at the country level based on the following address format.
[2080] xxxxxx [Country Node address ] address2080 : address for France (optional) xxxxxx : 6 digits node address. The address should be organized on an hierarchical way from left to right.The address coding should be hierarchical. Each node uses the hierarchical structure to establish the virtual link. Each NODE only knows its neighbors and the hierarchical addresses they can handle.
In France, the general rule affects SSID 10 et 11 to a node located at a server site (BBS, DXC, ...) and SSID 8 et 9 to stand-alone NODES.
Ex:
F6KDS-11 is the input callsign of a FPAC node associated with the F6KDS-1 BBS. F6KDS-10 is the callsign of the digipeater associated with F6KDS-11.
F6PRA-9 is the callsign of a stand-alone FPAC NODE, F6PRA-8 is the callsign of the digipeater associated with F6PRA-9.
In this case, the FPAC NODE is completely transparent. Alias 1 (see thereunder) allows a repetition of the frames to the BBS without modifications, frames from the BBS are repeated to the user.
For the user, the connection to the BBS is similar to the one without FPAC NODE except for the "Broadcast" .
FPAC provides additional advanced functions:
It is possible to connect a "NODE" and to get information on its configuration and on the local traffic.
For the user, the NODE has two callsigns :
The "DIGI" : (digipeater callsign) It is the callsign with the lowest SSID ex : F6KDS-10
The "NODE" : You can connect it by requesting a connection to NODE through a standard FPAC request ex : C NODE V F6KDS-11,193201 which connects the F6KDS NODE (address 193201)
Connections to NODE or to the DIGI callsign provide the same functionality.
The connection uses the NODE address which allows to connect any NODE of the network by using its address.
The connection to DIGI is only possible from one of the user frequencies or from a neighbor node. This second possibility provides one way to explore the network without knowing the NODE addresses.
The connection to the NODE input callsign provides a limited information after either a <CR> or a 1 minute time-out. In both cases, the NODE will disconnect you after the information message. The connection request is a natural reflex but provides very few information. ex:
C F6KDS-11 FPAC/ROSE system node QTH : Les LILAS ************************** LOCATOR JN18FV * FPAC DPS93 * ADDRESS : 193201/193301 * Under testing * Level 2 digipeater CALLSIGN : F6KDS-10 ************************** Use C F6XXX Via F6KDS-11,destination address where "destination address" is the address of the node near F6XXX For more information on the FPAC network, check the F6KDS-1 BBS 73 and good QSOs for more information on this node use: C NODE V F6KDS-11,193201 or C F6KDS-10Now, we can check the information available using the described procedure.
Type the connection request to the FPAC DIGI callsign. It is similar to the NODE one but you don't need to know its FPAC address.
Ex:
C F6KDS-10
Connection : F6KDS-10 *** CONNECTED to F6KDS-10 [28-05-94 09:30:29] Connecting... Connected to NODE-0 @ 2080193201 [FPAC-DWJ-1.2d1-C$] NODE : F6KDS-11 Type <CR> to get information. FPAC (A,B,C,H,I,L,M,S,T,U,?) >
or to connect the node itself, use:
C NODE V F6KDS-11,191201
The address is the one of the NODE you want to connect (either the local one or a remote one). In this case 191201 is the address for F6PTT-11 node:
- Connection : NODE V F6KDS-11,191201
- cmd:
- *** CONNECTED to NODE VIA F6KDS-11,191201 [15-02-94 10:15:33]
- Connecting...
- Connected to NODE-0 @ 2080191201
[FPAC-DWJ-1.2d1-C$]- NODE : F6PTT-11
Type <CR> to get information.
F6PTT-9 /2080177203
F6PRA-9 /2080192205
F6ABJ-11 /2080175201
F6KDS-11 /2080193201- FPAC (A,B,C,H,I,L,M,S,T,U,?) >
Line 1 : The TNC2/TPK acknowledges the connection request.
Line 2 : The TNC2 is waiting.
Line 3 : The TNC2 acknowledges the connection with F6KDS-11
Line 4 : FPAC network tries to establish the connection.
Line 5 : The connection request succeeds with NODE 191201.
Line 6 and following : The network displays the route used by the connection. First F6KDS-11 (complete address 2080193201) then F6ABJ-11 (address 2080175201) then F6PRA-11 (address 2080192205) finally F6PTT-11 (address 2080177203).
Line 7 : FPAC menu
The node menu is :
FPAC (A,B,C,H,I,L,M,S,T,U,?) >
The meaning of the letters is the following and can be displayed by typing "?<CR>" or just "<CR>"
- A = Alias
- B = Bye
- C = local Connection
- H = Heard list
- I = Information
- L = Links list
- M = used Memory
- S = Statistics
- T = Traffic
- U = NODE Users list
- ? = this menu
Display the ALIAS list:
An alias is a short-cut to avoid to type the full route of station. For example, on F6KDS, the alias 2 allows the connection to F6ABJ-1 (BBS). The alias is the node callsign followed by a SSID between 1 and 6. To connect F6ABJ-1, through F6KDS-11, you can use either:
C F6ABJ-1 V F6KDS-11,175201
or C F6KDS-2
In France, Alias "1" is reserved to the BBS associated with the node because the French BBSs generally use SSID 1. If you request a connection to alias 1 the node is completely transparent for the user.
An alias can only be used from an user frequency.
Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) >A ALIAS USE --------- To use alias : C F6PTT-n n = 0 NODE-0 n = 1 F6PTT-1 n = 2 F6ABJ-1 n = 3 FF6RAC-1 n = 4 F5LO-0 n = 5 F5MSQ-1
To disconnect the NODE.
Allow to connect a station heard directly by the NODE.
You can specify the port used for the connection by "c 2 f5xyz".
The disconnection will be in two steps: disconnection from the station then disconnection from the NODE.
Ex:
Connection : NODE V F6KDS-11,175201 Connection request to F6ABJ NODE *** CONNECTED to NODE VIA F6KDS-11,175201 [29-05-94 07:41:28] Connected to F6KDS-11 Connecting... FPAC is establishing the connection Connected to NODE-0 @ 2080175201 You are connected to NODE 175201 [FPAC-DWJ-1.2f1-C$] FPAC prompt NODE : F6ABJ-11 ... Type <CR> to get information. ... F6KDS-11 /2080193201 ... FPAC (A,B,C,H,I,L,M,S,T,U,?) > ... C F6BVP-1 Connection request to F6BVP-1 Connecting... FPAC is establishing the connection *** Local Connected *** You are connected [FBB-5.15-AB1FHMR$] BBS prompt ... Howdy DOMINIQUE, ... Welcome to Paris, France. ... 2:F6BVP (A,B,C,D,F,G,I,J,K,L,M,N,O,P,R,S,T,U,V,W,X,Y,Z,?) > ... B You request a disconnection from BBS Connected time 1mn 23s - CPU Time : 1s ... 73 de F6BVP. ... *** Local Disconnected *** You are disconnected from the BBS FPAC (A,B,C,H,I,L,M,S,T,U,?) > back to FPAC prompt B You request a disconnection from FPAC NODE Bye and 73 You are disconnected FPAC *** Disconnect at F6ABJ-11 2080175201 *** ... *** 0000 Disconnection by the remote station
Display the list of stations heard by the NODE. Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) >H Heard list for F6PTT-11 2080191201 --------------------------------------------------------------------------- last first Port Station Destination heard heard RXCnt FType Path --------------------------------------------------------------------------- 3 F6ABJ-11 F6PTT-11 00:00 24:48 15413 I 0 F6PTT-1 F6ABJ-1 00:00 22:11 6503 I F6PTT-11,175201 2 F1THZ F1THZ-1 00:00 00:00 3 I F6PTT-10 4 F6PTT-9 F6PTT-11 00:00 24:52 21265 RR 0 F6PTT-1 F5MSQ-1 00:00 05:05 1697 I F6PTT-11,441201Column 1: used ports (from 0 to 9 in the present version, It is the number of the physical line attached to the PC (SCC, DRSI, KISS,...)
Column 2: heard station callsigns.
Column 3: station in QSO with the one in the second column
Column 4: time since last heard
Column 5: time since first heard
Column 6: number of exchanged packets
Column 7: type of the last exchanged frame
Column 8: path used by the packet through the network (if QSO uses the network)
Display information set up by the NODE sysop.
Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) > I FPAC/ROSE NODE QTH : Les LILAS ************************** LOCATOR JN18FV * FPAC DPS93 * ADDRESS : 193201/193301 * Tests en cours * level 2 digipeater callsign: F6KDS-10 ************************** Use C F6XXX Via F6KDS-11,destination address where "Destination address" is the node address close to F6XXX For more information on FPAC network, check on F6KDS-1 BBS.73 and good QSOs
To get traffic information, connect NODE V F6KDS-11,193201
Display links and their parameters. A link is a level 2 connection.
The nodes are the names of the neighbor nodes, the port number to connect them and their check.
The listed USERS have the following functions:
During a connection request to a callsign, FPAC starts the request on one of its user ports depending of the specified address. But if the callsign is a "user" one, FPAC starts the request on the port indicated by the USER word. In the following example: C F6HNV-8 V F6KDS-11,191201, will connect to F6HNV-8 (through port 2 of F6PTT-11).
All FPAC NODES should be configured with the DIGIs of the neighbor NODES setup as USER. Then it is possible to connect from DIGI to DIGI when you want to explore the network.
The ALIAS list is also displayed. The R at the end of the line means that the alias is used in both directions. This is the case for the local BBS which needs a transparent node.
Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) >L LINKS LIST ---------- F6PTT-11 2080191201 Port 2 2080191201 ---------------------------------------- Port Delay ---------------------------------------- Node 1 : F6PTT-9 4 900 Node 2 : F6ABJ-11 3 900 User 1 : F6ABJ-1 3 User 2 : F6HNV-8 4 User 3 : F6PTT-8 4 User 4 : F6PTT-1 0 Alias n = 0 NODE - 0, 191201- 0 n = 1 F6PTT - 1, 191201- 0, R n = 2 F6ABJ - 1, 175201- 0 n = 3 FF6RAC- 1, 175201- 0 n = 4 F5LO - 0, 177203- 0 n = 5 F5MSQ - 1, 445201- 0Remarks:
The port 4 provides the link with F6PTT-9 (link 7 on the network drawing page 2),
The port 3 provides the link with F6ABJ-9 (link 4 p1).
The port 0 provides the local link with the BBS.
The port 2 is the user port.
It is possible to define several user ports on different frequencies:Il est possible que plusieurs ports soient définis sur des QRG différentes.
Ex: on F6KDS, port 2 (193201) is on VHF, port 3 on UHF(193301)
(A,B,C,H,I,L,M,S,T,U,?) >L LINKS LIST ---------- F6KDS-11 2080193201 Port 2 2080193201Port 3 2080193301
Display the memory size and usage. (useful for SYSOP)
Ex :
FPAC (A,B,C,H,I,L,M,S,T,U,?) >M MEMORY STATUS ------------- Low memory size : 28252 Bytes Used memory : 7734 Bytes I/O memory size : 65000 Bytes Used memory : 15538 Bytes
Display the NODE statistics:
The user port is default one.
The test port is the beacon one.
In general, the monitor and the log are disable, to minimize processor load.
The beacon period is in seconds.
The threshold is the minimum size, in bytes, of the buffer. Below this value, the node starts to slow down.
Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) >S STATISTICS [FPAC-DWJ-1.2d1-C$] ------------------------------- Starting date : 01/01/94 a 00:00:19 Current date : 01/02/94 a 01:39:33 User port : 2 Test port : 2 Monitor : 0 Log : 0 Beacon : 900 Threshold : 8000 Max size : 990 Panic : 0 Options : No network supervisor
Display the cumulated NODE traffic since the last reset.
For each neighbor, the number of in/out bytes is displayed.
For each port, the number of in/out frames is shown.
Ex :
FPAC (A,B,C,H,I,L,M,S,T,U,?) >T TRAFFIC ------ Bytes Callsign Digipeater Port in out Delay Tried Failed -------------------------------------------------------------------------- Nodal 1:F6PTT-9 4 1184918 454112 900 0 0 Nodal 2:F6ABJ-11 3 709685 391884 900 0 2 -------------------------------------------------------------------------- Port : 0 1 2 3 4 5 6 7 8 9 ------------------------------------------------------------------------------ Msg in : 38919 0 12738 15599 21523 0 0 0 0 0 Msg out: 38348 0 17284 17595 24109 0 0 0 0 0 Frm Err: 105 20631 20368 25791 13959 0 0 0 0 0 RX Ovfl: 0 0 0 0 0 0 0 0 0 0 TX Unfl: 0 0 0 0 0 0 0 0 0 0
Display the NODE users list. Only the current one.
The symbol groups between parenthesis show the level 3 status.
The first group show the virtual circuit number.
The second group shows the status of the call P1=ready, P2=DTE call request, P3=DXE incoming call, P4=Data transfer, P5= call collision, P6= DTE clear request, P7=DXE clear indication.
The last one (if the second one is P4): D1=flow control ready, D2=DTE reset request, D3=DXE reset indicator.
Ex:
FPAC (A,B,C,H,I,L,M,S,T,U,?) >U USERS LIST for F6PTT-11 NODE 2080191201 ------------------------------------------------------ Low Memory Size : 28252 Bytes Used Low Memory : 6696 Bytes I/O Memory Size : 65000 Bytes Used I/O Memory : 13958 Bytes F6PTT-1 AX25L2 linked to : F5PKV @ 2080191201 F5PKV AX25L2 linked to : F6PTT-1 @ 2080191201 F6PTT-1 AX25L2 linked to : F6KBK-1 @ 2080177201 F6PTT-1 AX25L2 linked to : F5MSQ-1 @ 2080441201 F6ABJ-11 X.25 Trunk (R1) with the following connections: F1EDH @ 2080193201 ( 30 P4 D1) --> NODE @ 2080191201 F6PTT-9 X.25 Trunk (R1) with the following connections: F5MSQ-1 @ 2080441201 ( 2 P4 D1) --> F6PTT-1 @ 2080191201 F6KBK-1 @ 2080177201 ( 20 P4 D1) <-- F6PTT-1 @ 2080191201 There is no waiting connection. The following X25 routes are not operational: None, all links are operationalIn the previous example, there are 6 level 2 users. 3 QSO are using the network.
- F1EDH via F6ABJ connected toNODE
- F5MSQ-1 in QSO with F6PTT-1 via F6PTT-9
- F6PTT-1 connected to F6KBF-1 via network
A NODE provides three main functions :
If you are using TPK terminal program and the broadcast function with your F6FBB BBS. In this case, the BBS transmits (broadcasts) the messages lists in a unconnected mode.
i le numéro du message dont le titre est actuellement diffusé par le BBS est plus grand que le numéro suivant de votre liste, votre programme TPK demande une resynchronisation.
Because FPAC uses the connected mode, a special trick has been implemented.
The non-connected frames (Unproto "UI") should include addresses in the following format:
DESTIN V INDIC_FPAC-n
where "n" is the port number used to repeat the frame. Ex :
Your TPK sends an UI frame on the VHF user frequency :
F6KDS-1 V F6KDS-0 In this case the frame will be received on port 2 (the user one) and repeat on port 0 (the BBS one) and will be received by F6KDS-1 (the BBS).
The BBS will answer with the following format :
FBB V F6KDS-2 The frames will be repeated on the port 2 (F6KDS-2) and will be received by you TPK
Here is an example of connection from NODE to NODE through the French FPAC network.
Connection : F6KDS-10 Connection request to F6KDS-10 *** CONNECTED to F6KDS-10 [29-05-94 08:07:41] You are connected to DIGI F6KDS-10 Connecting... ... Connected to NODE-0 @ 2080193201 ... [FPAC-DWJ-1.2f1-C$] FPAC prompt NODAL : F6KDS-11 ... Type <CR> to get information. ... FPAC (A,B,C,H,I,L,M,S,T,U,?) > ... C F6ABJ-10 Connection request to DIGI F6ABJ-10 connecting... FPAC is connecting *** Local Connected *** You are connected to DIGI F6ABJ-10 Connecting... .. Connected to NODE-0 @ 2080175201 ... [FPAC-DWJ-1.2f1-C$] FPAC prompt NODAL : F6ABJ-11 ... Type <CR> to get information. ... FPAC (A,B,C,H,I,L,M,S,T,U,?) > ... C F6PTT-10 Connection request to DIGI F6PTT-10 connecting FPAC is connecting *** Local Connected *** You are connected to DIGI F6PTT-10 Connecting... ... Connected to NODE-0 @ 2080191201 ... [FPAC-DWJ-1.2f1-C$] FPAC prompt NODAL : F6PTT-11 ... Type <CR> to get information. ... FPAC (A,B,C,H,I,L,M,S,T,U,?) > ... B Disconnection request from DIGI F6PTT-10 Bye and 73 You are disconnected from DIGI F6PTT-10 *** Disconnect at F6PTT-11 2080191201 *** ... *** 0000 Disconnection by remote station ... *** Local Disconnected *** F6ABJ-10 DIGI suppresses the link FPAC (A,B,C,H,I,L,M,S,T,U,?) > FPAC prompt from F6ABJ-10 DIGI B Disconnection request from F6ABJ-10 DIGI Bye and 73 You are disconnected from F6ABJ-10 DIGI *** Disconnect at F6ABJ-11 2080175201 *** ... *** 0000 Disconnection by the remote station ... *** Local Disconnected *** F6KDS-10 DIGI suppresses the link FPAC (A,B,C,H,I,L,M,S,T,U,?) > FPAC prompt from F6KDS-10 DIGI B Disconnection request from F6KDS-10 DIGI Bye and 73 You are disconnected from F6KDS-10 DIGI *** Disconnect at F6KDS-11 2080193201 *** ... *** 0000 Disconnection by remote station No more connection !
Level 1: The PHYSICAL layer
It is concerned with the "real world" part of sending and receiving data. It includes Modems, TX/RX, ...
Level 2: The LINK layer
It provides an error free transmission and reception of data for the upper layers.
Level 3: The NETWORK layer
Simple Routing:
The data will always take the same route. If one node on the route is down, the data will never arrive.
Broadcast Routing (or flood):
The routing information are broadcasted by each node. This method generates a large traffic.
Centralized adaptive routing:
Each node transmits its status to a central one which recomputes routing tables and transmits them to each node.
Distributed adaptive routing:
Each node receives the information from its neighbors and updates its tables.
Hierarchical Routing:
The network is split in small sub-network. The routing is performed for each regions. This is the routing used by ROSE/FPAC.
Level 4: The TRANSPORT layer
It adapt the size of the data between different networks and guarantees that the data are received in the right order.
Level 5: The SESSION layer
It provides the control of links between users or programs
Level 6: The PRESENTATION layer
It provides the presentation of the data to easy their use. It can also provide code conversion or data compression.
Level 7: The APPLICATION layer
It provides the requested service like DXC, BBS, ...
