Text 1870, 237 rader
Skriven 2004-06-12 18:54:12 av Henri Derksen (2:280/1208.1)
Kommentar till text 1839 av David Drummond (3:640/305)
Ärende: Modem speeds
====================
Hello David and others,
In a message on Tue. 08 Jun 2004, 19:34:14,
subject: modem speeds
on area FTSC_Public (FTSC_PUBLIC),
David Drummond wrote to All:
DD> I note that a modem speed of 33600 is used by a number of nodes in
DD> Zones 1,2 and 4, but not by the rest (who still use 9600).
DD> Is there an FTSC doc regarding this?
FTS 5000 I think, but there are errors in too ;-(.
FTS 5000> Field 7 - Baud rate
FTS 5000>
FTS 5000> This field contains the maximum baud rate supported by the node.
FTS 5000> (eg: 9600, 14400, 38400, etc)
* First of all the term BAUD is misused very many times.
We must use BITrate, because a BAUD can hold many bits today!
* Second problem is the question wich bitrate we mean?
That of the Node's computer system serial port (DTE),
or that of his modem to modem connection (DCE)
* Third problem is that there are serial port speeds that do not exist
as a modem speed, for instance:
134.5, 1800, 38400, 57600, 115200, 230400 bps.
Otherwise there are modemspeeds that are not a serial port speed,
for instance:
14400, 21600, 26400, 28800, 31200, 33600
* Fourth problem is old software (Makenl) that does not accept higher speeds
than 19200 bps.
Or Mailer software that does not support fixed DTE speeds, and want to
dial out which the same DTE speed as modem-speeds,
i.e. up to max 9600 bps V32, or ZyX19200
even if you have an newer modem wich has an interspeeder.
The software is the bottleneck in that case.
* Fifth problem are old modems that do not have an interspeeder.
Mostly they can not connect at higher modem speeds than 9600 bps V32.
Higher speed modems with at least 14400 bps V32bis must have an
interspeeder, because 14400 bps is not a DTE-serial port speed.
The solution is very simple:
Use this Bitrate field voor DTE-speeds only!
And set that speed to the highest fixed DTE speed you are using,
i.e. 19200, 57600 or 115200 bps, depending on your uart.
There are programs to find out what kind of uart your system uses.
The modem speeds can be derived from the modem flags, or see below.
The DTE speeds are:
300, 600, 1200, 2400, 4800, 7200, 9600, 19200, 38400, 57600, 64000, 115200,
128000, 230400 bps
All other bitrates are not allowed. Some are even very wrong, because they are
not serial port values (but DCE-modem values) and cannot be selected by most
DTE's such as 14400, 21600, 26400, 28800, 31200 and 33600 bps.
Also the FSP-1003 is *wrong* in this case, bacause the Baudrate field was used
for old modems with no InterSpeedingBuffer, i.e. DTE-speed = DCE-speed.
I think we must consider this field for the DTE-speed (most useful is the
maxumim bitrate multiplied by the maximum compression rate. So V34 28800 bps
combined with V42bis OnLine DataCompression over V42 OnLine ErrorCorrection
(max 4 times) would result in an optimum DTE-speed of 115200 bps.
The Modem (DCE) OnLine speed can be read of from the ITU-T modem flags.
And the rates from 300 up to 460800 for DTE speeds are relevant. Then you can
see if the node has set up his DTE-speed efficiently according to the highest
carrier speed combined with OnLine ErrorCorrection and OnLine DataCompresssion
(carrier+EC+DC).
So when some system has the Z19 flag (= 19200 bps ZyXEL), but he has no
16c550an uart in his serial port, his bitrate is 19200 and can not be 57600 nor
115200.
There is no reason to limit the bitrate to 9600 bps.
Old modems with no interspeed buffer (DTEspeed=DCEspeed) can not answer with
CONNECT 14400, because that kind of modems does not have a higher protocol than
V32 (9600).
All V32Bis (14400) and higher protocol modems have an InterSpeedBuffer and than
you can lock the DTE rate to at least 19200 bps for a 8250 uart and to 115200
bps for a 16c550an uart.
All the possible FidoNet (TechNology) Node- and Point-List MODEM Flags:
;S V17 ITU-T V17 14400/14400 bps Half Duplex (also Fax)
;S V19 ITU-T V19 DTMF (*#0123456789ABCD) Full Duplex
;S V21 ITU-T V21 300/300 bps Full Duplex
;S V21C ITU-T V21ch2 300/300 bps Half Duplex (also Fax)
;S B103A Bell 103A 300/300 bps Full Duplex
;S V22 ITU-T V22 1200/1200 bps Full Duplex
;S B202C Bell 202C 1200/1200 bps Half Duplex
;S B212A Bell 212A 1200/1200 bps Full Duplex
;S B201C Bell 201C 2400/2400 bps Half Duplex
;S V22B ITU-T V22B 2400/2400 bps Full Duplex
;S V23 ITU-T V23 1200/75 bps Full Duplex Rx/Tx or Tx/Rx
;S V26 ITU-T V26 2400/2400 bps Half Duplex
;S V26B ITU-T V26BIS 2400/75 bps Full Duplex (implies V26)
;S V26T ITU-T V26TER 2400/75 bps Full Duplex (implies V26B)
;S V27 ITU-T V27 4800/4800 bps Half Duplex (implies V26)
;S V27B ITU-T V27BIS 4800/75 bps Full Duplex (implies V27)
;S V27T ITU-T V27TER 4800/75 bps Full Duplex (implies V27B)
;S V29 ITU-T V29 9600/9600 bps Half Duplex (also Fax)
;S V32 ITU-T V32 9600/9600 bps Full Duplex
;S V32b ITU-T V32BIS 14400/14400 bps Full Duplex
;S V32T V.32 Terbo mode (implies V.32Bis) 19200 bps Full Duplex
;S V33 ITU-T V33 14400/14400 bps Half Duplex
;S V34 ITU-T V34 33600/33600 bps Full Duplex
;S V42 LAP-M OnLine Error Correction w/fallback to MNP 1-4
;S V42B LAP-M OnLine EC+Data Compression w/fallback to MNP 1-5
;S V44 LAP-M OnLine EC+Data Compression w/fallback to V42B
;S V90C ITU-T V.90 modem Client, 56000/33600 (isdn2ana)
;S Destination has analogue answer modem.
;S isdn2ana 56000/33600 or ana2ana (33600/33600)
;S V90S ITU-T V.90 Server, 64000/56000/33600 Rx and Tx
;S Destination has isdn answer modem.
;S isdn2isdn 64000/64000 or ana2isdn (33600/56000)
;S V92C ITU-T V.92 modem Client, 56000/44000 (isdn2ana)
;S Destination has analogue answer modem.
;S isdn2ana 56000/44000 or ana2ana (33600/33600)
;S V92S ITU-T V.92 Server, 64000/56000/440000 Rx and Tx
;S Destination has isdn answer modem.
;S isdn2isdn 64000/64000 or ana2isdn (44000/56000)
;S V54 Remote Digital LoopBack Tests accepted.
;S V110L ITU-T V.110 19k2 async ('low').
;S V110H ITU-T V.110 38k4 async ('high').
;S V120L ITU-T V.120 56k async,
;S layer 2 framesize 259, window 7, modulo 8.
;S V120H ITU-T V.120 64k async,
;S layer 2 framesize 259, window 7, modulo 8.
;S X75 ITU-T X.75 SLP (single link procedure) with 64kbit/s
;S B channel; layer 2 max.framesize 2048, window 2,
;S non-ext.mode (modulo 8);
;S layer 3 transparent (no packet layer).
;S MNP Microcom Networking Protocol OnLine Error Correction
;S H96 Hayes V9600
;S HST USR Courier HST ? bps ?
;S H14 USR Courier HST up to 14.4Kbps
;S H16 USR Courier HST up to 16.8Kbps
;S MAX Microcom AX/96xx series (9600 bps ?)
;S PEP Packet Ensemble Protocol (19200 bps ???)
;S CSP Compucom Speedmodem ? bps ?
;S VFC Rockwell's V.Fast Class 28800/28800 bps Full Duplex
;S ZYX Zyxel 16.8 Kbps (implies V.32Bis & V.42Bis)
;S Z19 ZyXEL 19k2 (Implies ZYX)
;S X2C US Robotics x2 client, 56000/33600 (isdn2ana)
;S Destination has analogue answer modem.
;S isdn2ana 56000/33600 or ana2ana (33600/33600)
;S X2S US Robotics x2 server, 64000/56000/33600 Rx and Tx
;S Destination has isdn answer modem.
;S isdn2isdn 64000/64000 or ana2isdn (33600/56000)
;S FAX ITU-T V29,V27ter,V21ch2 ITU-T Group 3 Fax T30 protocol.
;S F17 ITU-T V17 14400 bps HD Fax G3T30 (Implies FAX flag)
;S
;S NOTE: Many V22 modems also support Bell 212A.
;S No modem flag at all means ISDN/InterNet TCP/IP
;S (i.e. *not* connectable via PSTN analogue modems)
Although there are very many Modem flags, there is much redundancy when the
higher speed modems are used. So only the highest possible flag should be
enough.
As most "AlterNets" also use "FidoNet Technology Networking", they also have to
support all these flags. Otherwise they must noy apply to FTN ;-).
To reduce redundancy, remove flags in the NodeList when they are implied by a
higer flag.
;S Redundant Node-/Point-List modemflags:
;S
;S V22B implies V22
;S V32 implies V22 V22B
;S V32B implies V22 V22B V32
;S V32T implies V22 V22B V32 V32B
;S VFC implies V22 V22B V32 V32B
;S V34 implies V22 V22B V32 V32B MNP V42 V42B
;S X2C implies V22 V22B V32 V32B V34
;S X2S implies V22 V22B V32 V32B V34 X2C
;S V90C implies V22 V22B V32 V32B V34
;S V90S implies V22 V22B V32 V32B V34 V90C
;S V92C implies V22 V22B V32 V32B V34 V90C
;S V92S implies V22 V22B V32 V32B V34 V90C V90S V92C
;S
;S HST implies MNP
;S H14 implies HST MNP
;S H16 implies H14 HST MNP V42 V42B
;S
;S V42 implies MNP
;S V42B implies MNP V42
;S V44 implies MNP V42 V42B
;S ZYX implies V22 V22B V32 V32B MNP V42 V42B
;S Z19 implies V22 V22B V32 V32B MNP V42 V42B ZYX
;S VFC implies V22 V22B V32 V32B MNP V42 V42B
;S
;S V26B implies V26
;S V26T implies V26 V26B
;S V27 implies V26
;S V27B implies V26 V26B V27
;S V27T implies V26 V26B V27 V27B
;S V29 implies V26 V27
;S
;S More redundant NodeList flags (ISDN/InterNet)
:S
;S IP implies IBN IFC ITN IVM
;S IBN implies IP
;S IFC implies IP
;S ITN implies IP
;S IVM implies IP
;S More redundant NodeList flags (fileRequesting):
;S XA implies XW XR XP XB XC XX
:S XB implies XW XR XP
;S XC implies XW XR XX
;S XR implies XW
;S XX implies XW
;S More redundant NodeList flags (IFZMH)
;S CM implies T??
;S #@@ implies !@@
Hopefully all nodelist segments will be cleaned from redundancy?
I hope you appreciate my comments?
Many success and good luck.
Greetings from: |_| |\
| |enri |/erksen, SysOp UniCorn BBS, Arnhem NL +31-26 4425506.
Also for teleFAX.
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* Origin: Do you see the CONNECTion ? UniCorn BBS (2:280/1208.1)
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