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SubjectRe: 2.1.129-ac3 severe RX errors in PPP
Hiho

I've seen similar problems. For me the pppsession starts very slow (~300
bytes/sec) and sometimes gets a bit faster in average (~2.5Kb/sec) for small
files. Sometimes it stays that slow all the time.
With "big" (>~10Kb) files I see the connection starting nearly reasonably fast
for my connect speed and then suddenly stopping for many seconds
resulting in a very bad average transfer rate. During these hangs the
recieve/transmit leds of my modem are both off.

With the tcpdump output found at
http://www.unix-ag.uni-kl.de/~sattler/ppptcpdump
you can observe both the slow start at the very beginning and the stalled
transfer at the very end. The middle part is just a typical session.

Lets have a look at my setup to find out what we have in common.

My machine:
- dual P100 on gigabyte board with intel HX chipset.
- ide harddisc: (hdparm -u /dev/hda -> unmaskirq = 1 (on))
- scsi harddisc and other stuff (adapec 2940UW on board)
But there is usually not much hd activity during the ppp connection.
- PS/2 mouse (generates MANY interrupts)
- ne2k ISA that is set up (correctly), but not connected to a network.
- 3Com (U.S. Robotics) voice modem with recent firmware.
Connected to the on board serial port (16550 compatible) with 115kbit/sec.
- SMP 2.1.130-pre3 with devfspatch and earlier kernels (without devfs)
- ppp built as module loaded by kmod.
- pppd --version -> pppd version 2.3 patch level 5
- the ppp session is started with kppp (KDE ppp frontend).
- gcc --version -> egcs-2.91.55

The ppp reciever is a Livingston portmaster 3 and the www-server in the
example is a sun supersparc running solaris 2.5.1 but it happens with
all hosts I've found.


Here come some additional details...

My connect string is:
CONNECT 45333/ARQ/V90/LAPM/V42BIS


/sbin/ifconfig
ppp0 Link encap:Point-to-Point Protocol
inet addr:131.246.94.16 P-t-P:131.246.119.5 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:4866 errors:3 dropped:0 overruns:0 frame:3
TX packets:5266 errors:0 dropped:0 overruns:0 carrier:0
Collisions:0


/sbin/route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
pm.rhrk.uni-kl. * 255.255.255.255 UH 0 0 0 ppp0
192.16.1.0 * 255.255.255.0 U 0 0 0 eth0
192.16.1.0 * 255.255.255.0 U 0 0 0 eth0
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default pm.rhrk.uni-kl. 0.0.0.0 UG 0 0 0 ppp0


traceroute www.unix-ag.uni-kl.de
traceroute to pizza.unix-ag.uni-kl.de (131.246.89.1), 30 hops max, 40 byte
packets
1 pm.rhrk.uni-kl.de (131.246.119.5) 147.838 ms 133.856 ms 139.301 ms
2 vgw6-s119-b34-3-3.rhrk.uni-kl.de (131.246.119.253) 142.958 ms 135.239
ms 138.681 ms
3 pizza.unix-ag.uni-kl.de (131.246.89.1) 139.47 ms 138.117 ms *


Matthias


PS: Do I have forgotten something important?

PPS: I've just found out, that seyon crashes the computer instantly.
Could this be devfs???

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