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PB0AFK > DAMA 13.01.99 22:15l 260 Lines 11081 Bytes #-9552 (0) @ WW
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To : DAMA@WW
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* Msg:43443 Bid:22198-PB0AFK
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄĶToplogo creator (c) 1997-1998 by PD0OLNºÄÄÄÄÄÄ
Reply to to respective writers!
Downloaded from ON4CP-8 - DOS server - directory c:\packet\dama :
-----------------------------------------------------------------
Correct parameter setting on a DAMA node :
==========================================
Following information have been written to guide the user to set his
parameters in order to get the most of the DAMA TheNetNode. We stress the
users to use as much as possible the TF24a eprom and one of the suitable
terminal programs. But for those who can not (or "will not" ? ) use a DAMA
eprom, we will explain a way to still use a TAPR type eprom BUT with revised
parameters.
1. For the DAMA users :
-----------------------
For those of you who use the TheFirmware version 2.4a, there is nothing
special to do as the software automatically switch in the DAMA mode as soon as
a DAMA frame is detected. Nevertheless following parameters implemented in
version 2.4a (24 SEPT 92) are important for the DAMA mode:
<esc> B n time out (in seconds) for the DAMA mode. After this time out,
the software switch back to the non DAMA mode (default value
= 120 = 2 minutes)
<esc> F n - if the DAMA mode is NOT used this parameter is the FRACK
(in 10 msec)
- if the DAMA mode active, this parameter is the initial
SRTT in 10 msec steps (default value = 700)
- if values lower than 15 are given, the value is
automatically multiplied by 100 !
<esc> @T2 n timer T2 (0-65535, in 10 ms increments). To allow to
acknowledge more than one frame, it is necessary to set @T2
slightly longer than one frame. One frame is 1+14+1+256+2+1 =
275 bytes or 2200 bits and at 1200 Bd this is 1.83 sec, so we
recommend to use 220 (= 2.2 sec) for @T2.
<esc> @T3 n timer T3 (0-65535, in 10 ms increments). As the DAMA node test
the link permanently you can set @T3 at 0. Nevertheless, if you
want to check the link take a large value as 18000 (= 3 min).
<esc> @A1 Alpha1 is a scale factor to compute the SRTT (smoothed RTT)
for decreasing values (default = 7)
<esc> @A2 Alpha2 is a scale factor to compute the SRTT (smoothed RTT)
for increasing values (default = 15)
For each frame, the TNC measures the RTT (Round Trip timer),
that is the time between the beginning of the last frame and
the reception of the ACK. Then the TNC computes the SRTT as
a function of the old SRTT, the last measured (RTT) and the
Alpha1 or Alpha2 factors.
(SRTT x Alpha2) + RTT (SRTT x Alpha1) + RTT
SRTT = --------------------- or SRTT = ---------------------
Alpha2 + 1 Alpha2 + 1
Example 1 : SRTT = 300 and RTT = 200 (than is 33% faster) :
As the RTT decreases, we must use the Alpha1 parameter and the
TNC will compute the new value of SRTT = 288 or 4 % faster
Example 2 : SRTT = 300 and RTT = 400 (that is 33% slower) :
As the RTT increase, we must use the Alpha2 parameter and the
TNC will compute the new value of SRTT = 306 or 2 % slower
In other words, the adaptation of the SRTT to the current RTT
is slower for increasing value than for decreasing value ...
At the beginning of the connection there is not previous value
of SRTT, the the TNC takes the IRTT ( Initial RTT ) (see also
<esc>F ).
<esc> @A3 Beta : factor (default value = 3) to compute the FRACK
following the formula :
FRACK = (Beta x ((number of digipeater x 2 ) + 1) x SRTT)
Example : SRTT = 288 no digipeater :
then FRACK = (3 x ((0 x 2) + 1) x 288) = 864 = 8.64 sec
<esc> @ I n PACLEN for the IPOLL frames (default = 60)
<esc> @ M If set at 0, removes the 7th bit.
(for the other parameters, please refer to the official documentation)
If you are using a TF24a eprom we highly recommend to use either :
- ESKAY PACKET ("SP") version 7 from DL1MEN
(Sigi Kluger ex DL1MEN , Richard Strauss Str. 19 , D-8000 Munchen 80)
- Graphic Packet ("GP") from DH1DAE
(Ulf Saran DH1DAE , Veit-Stoss-Strasse 36 , D-5900 Siegen)
- or Turbo Packet from DL1BHO
(Reiner Schmidt DL1BHO , Arminiustrasse 11 , D-4550 Bramsche 8)
2. For TAPR users :
-------------------
For those of you who use a TNC who do not have the DAMA mode , for those of
you who use a TAPR 1.1.6 eprom, for those of you who use a KAM, for those of
you who use a "multimode controllers") , and waiting till those manufacturers
understand that DAMA is "THE solution", waiting they produce DAMA eproms and
waiting they will sell it to you, we suggest to use the following parameters:
"Pseudo DAMA Parameters" for non DAMA stations :
-----------------------------------------------
TAPR or KAM Digicom and BAYCOM WA8DED DAMA mode Normal use
----------- ------------------ --------- ------------- --------------
FRack FRACK <esc> F >=150 (>15s) 6 (= 6 sec)
PERSist - <esc> P 255 64
SLottime - <esc> W 5 10
DWait DWAIT - 0 0
RESPtime RESPTIME <esc> @T2 0 22 (= 2.2 sec)
CHeck LINKTIME <esc> @T3 0 30 (= 5 min)
Please note the two columns :
- "DAMA mode" to access a DAMA node, and,
- "Normal use" to connect another station and we stress to switch back to
these parameters if you do not connect a DAMA node !
Explanations for DAMA mode :
1. The FRACK must be large because the user has to wait that the DAMA node
polls him. If your FRACK is too low, the DAMA node will inform the user
(with a "UI" frame) that his FRACK is too low. After "n" warnings, the
user will be disconnected.
2. PERSIST and SLOTTIME must be set so that the TNC IMMEDIATELY answer to a
poll request. If the user do not reply IMMEDIATELY, he will lose his turn,
and should feel that the node forgot him ...
3. RESPTIME must be at 0 to answer IMMEDIATELY a polling request
4. CHECK may be at 0 because the node already make a check
Explanations for Normal use :
1. PERSIST and SLOTTIME must be set to allow other station to share the
channel (please share the channel, do not stole it !).
2. RESPTIME must be longer than one frame. As one frame is 275 bytes or 2200
bits, this represents 1.83 sec and RESPTIME must be slightly greater than
this time let's say 2.2 sec at 1200 Baud. With this value your TNC is able
to acknowledge a block of "n" frames instead of acknowledge the frames
individually. ("n"= the MAXFRAME used).
3. ESKAY or Graphic Packet with TAPR, KAM, PK232, ... controllers
------------------------------------------------------------------
Another solution is to use a resident software (TFKISS) that emulates
TheFirmware software in KISS mode :
computer \|/
+-----------+----------+ +----------------------------+ +------+ |
| | | | Whatever TNC in KISS mode | | | |
| GP or SP | TFKISS |---| (KAM, PK232, ... |---| TCVR |--+
| |(resident)| | TNC2 with TAPR 1.1.6 | | |
| | | | or even TNC2 with TF 2.6 ) | | |
+-----------+----------+ +----------------------------+ +------+
For more information, please read the manual of TFKISS ...
Remember that the DAMA target will only be reached, if ALL users use a DAMA
eprom !
----------------------------------------------------------------------------
references : ARRL AX.25 Amateur Packet Radio Link Layer Protocol, Oct 1984
DL1EKC
ON5ZS
----------------------------------------------------------------------------
DRAMA INFO ON4CP :
Those amongst you who use either a TNC which does not have DAMA mode, or
use a TAPR 1.1.6 eprom, or use a KAM, or use a "multimode controller", and
are waiting till the manufacturer understands that DAMA is "THE solution",
and produce/sell to you DAMA EPROMS, we suggest you use the following
parameters settings:
"Pseudo DAMA Parameters" for non DAMA stations :
-----------------------------------------------
TAPR or KAM Digicom and BAYCOM WA8DED DAMA mode Normal use
----------- ------------------ ------ --------- ----------
FRack FRACK <esc> F >=150 (>15s) 6 (= 6 sec)
PERSist - <esc> P 255 64
SLottime - <esc> W 5 10
DWait DWAIT
RESPtime RESPTIME <esc> @T2 0 22 (= 2.2 sec)
CHeck LINKTIME <esc> @T3 0 30 (= 5 min)
Please note the two columns : "DAMA mode" to access a DAMA node, and,
"Normal use" to connect another station and we
stress to switch back to these parameters if
you do not connect a DAMA node !
Explanations for DAMA mode :
============================
1. FRACK must be large because the user has to wait till the DAMA node
polls him. If your FRACK is too low, the DAMA node will inform the user
(with a "UI" frame) that his FRACK is too low. After "n" warnings, the
user will be disconnected.
2. PERSIST and SLOTTIME must be set so that the
TNC IMMEDIATELY answers to a poll request. If the user does not reply
IMMEDIATELY, he will lose his turn, and should feel that the node forgot him
3. RESPTIME must be at 0 to answer IMMEDIATELY a polling request
4. CHECK may be at 0 because the node already make a check
Explanations for Normal use :
=============================
1. PERSIST and SLOTTIME must be set to allow other stations to share the
channel (please avoid OWNERSHIP of the channel !).
2. RESPTIME must be longer than one frame. As one frame is 275 bytes or 2200
bits, this represents 1.83 sec and RESPTIME must be slightly greater than
this time, let's say 2.2 sec at 1200 Baud. With this value your TNC is able
to acknowledge a block of "n" frames instead of acknowledging the frames
individually. ("n"= the MAXFRAME used).
Remember that the DAMA target will only be reached provided ALL users have
their TNC equipped for DAMA i.e. with a DAMA EPROM installed or running DAMA
as in the case of BAYCOM!
DAMA = The SOLUTION or a DrAMA ???
The Future will bring some New and better Protokoll ???
---
This second MSG was from Karl , OE3KLU @ OE3XKR.AUT.EU
73 de Henk
Pc :486Dlc/40MHz
Tnc:AEA Pk-88
Trx:Bosch Kf-161
Ant:Dualband 2m/70cms
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