HI JULIAN,
YOUR PARAMETERS ARE MADE THE SNOWS BALL
YOU HAVE NOT CHANCE WITH A IRTT TOO SLOW IS 1.1 SEC.
AND YOUR WINDOW SIZE 4320 IS THAN OR LESS EQUIV TO 16 FRAMES
WITH THE PACLEN DE 256
IF YOU MULTIPLIC 256 X 16 = 4096
ON AX25 THE MAXFRAMES IS 7
I SUGGEST YOU THAT MAKE SOME CHANGE ON YOUR SETUP
LIKE THIS:
IRTT = 4000 or 5000 "4 or 5 seconds"
MTU = 256
MSS = 216
WINDOWD = 2048
i hope this help you
73's Jose Ramon (hi8gn) Powered By Linux Slackware
[EMAIL PROTECTED] wrote:
>
> Hello,
>
> I have changed the software of Madrid gateway, from jnos to Linux
> (latest kernel (2.0.36) and axutils, RedHat 5.2).
>
> A problem that I observed with my own station is now much more obvious.
>
> When the traffic goes up, a "snow ball" effect happens with the ax25
> polling procedure.
>
> The cause of the problem is that the gateway receives _several_ RR(f)
> "desincronized" responses ("desincronized"= it is not ackowledging the
> last frame sent by the gateway), wich causes the retransmition of the frames.
>
> If X desincronized RR(f) are received, Linux retransmit X times the
> remaining frames (from the next frame ackowledged by this RR to the last
> frame that the protocol has in its window), without releasing the ptt.
>
> That only happens with the Linux gateway, did not happen before with the
> Jnos; this gateway is only a router/firewall to access to radio ports,
> the tcp server is the same than before, another computer wich is routed
> via this router; that's problem of ax25, not tcp/ip.
>
> My thoery is:
>
> Linux mark always the last packet with (p), but when the traffic goes up
> (wich happens very quickly at 1200 bps) the retransmition timer expires
> and an RR(p) is generated, when in fact the station is still transmiting.
> To the receivers listen the last information packet with (p) and the
> RR(p), generating another RR(p).
>
> I also remark that the X retransmited blocs of packets are not the same,
> the transmition window is moving; thats maybe related with the fact that
> the retransmition of packets also causes the sending of REJ from
> receiving station.
>
> I have tried to increment the t1 timer, and put the exponential backoff,
> without no better results.
> I think that the origin of the problem is that Linux mark always the last
> packet with (p); or that maybe a bad configuration which causes that ?
>
> Here is the config:
>
> #!/bin/sh
> # Puerto de VHF en com2
>
> IRTT=1100
> MTU=256
> MTU_TEST=256
>
> echo "Configurando tnc a 1200 baudios ..."
>
> insmod mkiss
> # -i ip -m mtu tty puerto_ax25
> kissattach -i 44.133.228.1 -m 256 /dev/ttyS1 1200
>
> sleep 2
>
> # -p puerto_ax2 -l txtail(ms) -r persist -s slottime(ms) -t txdelay(ms)
> kissparms -p 1200 -l 0 -r 32 -s 160 -t 300
>
> /sbin/ifconfig ax0 mtu $MTU_TEST netmask 255.255.255.192 broadcast
> 44.133.228.63 44.133.228.1
> /sbin/route add -net 44.133.228.0 netmask 255.255.255.192 window 4320 mss
> $MTU_TEST irtt $IRTT dev ax0
> /sbin/route add -net 44.133.0.0 netmask 255.255.0.0 window 4320 mss
> $MTU_TEST irtt $IRTT dev ax0
> /sbin/route add -net 44.128.0.0 netmask 255.255.0.0 window 4320 mss $MTU
> irtt $IRTT dev ax0
> /sbin/route add -net 44.133.28.0 netmask 255.255.255.0 window 4320 mss
> $MTU_TEST irtt $IRTT dev ax0
>
> # Configuracion de parametros ax25
>
> # Modo conectado=1, datagram=0
> /bin/echo "1" > /proc/sys/net/ax25/ax0/ip_default_mode
> # Ventana de 4
> /bin/echo "4" > /proc/sys/net/ax25/ax0/standard_window_size
> # frack tope = 25 segundos
> /bin/echo "250" > /proc/sys/net/ax25/ax0/t1_timeout
> # resptime = 1,5segundo
> /bin/echo "15" > /proc/sys/net/ax25/ax0/t2_timeout
> # Se comprueba el enlace cada 20 minutos
> /bin/echo "12000" > /proc/sys/net/ax25/ax0/t3_timeout
> # Enlace sin actividad se desconecta a los 30 minutos ( 1800 segundos )
> /bin/echo "18000" > /proc/sys/net/ax25/ax0/idle_timeout
> # Timer lineal=0 exponencial=1
> /bin/echo "1" > /proc/sys/net/ax25/ax0/backoff_type
> /bin/echo "131" > /proc/sys/net/ax25/ax0/maximum_packet_length
>
> # Parametros arp
> # Maximo 7 arps
> /bin/echo "7" > /proc/sys/net/ipv4/arp_max_tries
> # Los arp quedan 1 hora en memoria
> /bin/echo "360000" > /proc/sys/net/ipv4/arp_timeout
> # Los arps requests se hacen cada 15 segundos
> /bin/echo "1500" > /proc/sys/net/ipv4/arp_res_time
> # Se comprueba aproximadamente cada 3500 segundos.
> /bin/echo "350000" > /proc/sys/net/ipv4/arp_check_interval
>
> # arp Publish
> arp --hw-type ax25 -Ds 44.133.228.24 ax0 pub
> arp --hw-type ax25 -Ds 44.133.228.8 ax0 pub
>
> I would like to have help, because in this moment it's dificult to share
> the qrg with nobody and the thoughput is very bad.
>
> Thanks,
> Julian, ea4acl
> -.-
