2boxers_at_comcast_dot_net wrote:
> Maybe somebody else has experienced similar problems and can make
> suggestions that pertain to what is happening to me.
>
> I was running Mandrake 9. The system basically performed flawlessly.
> I was able to PPP with a modem from the linux box, ftp over that
> connection, as well as set up the linux box to be an IPTABLES NAT so
> that workstations on the network could have Internet connectivity as
> well. The modem line was a backup to the Cable Modem interface, which
> also worked well under Mandrake.
>
> I recently installed RH9 on this pc. I did this because I bought a
> new RAID5 controller (S150SX4) from promise and it has specific kernel
> requirements- one of them being 2.4.20-8 or 2.4.20-8smp. The
> controller card is working fine and performance is acceptable.
>
> Here is the problem:
> PPP is performing poorly. There are 10 - 20% RX errors as well as 10
> - 20% packet loss with simple pings.
>
> This very same modem and phoneline when plugged into a system running
> Windows XP performs fine.
>
> This very same modem and phoneline also performed fine with the
> previous Mandrake configuration .
>
> Regardless of connect speeds which are either 28800 or 49333,
> depending on whether or not I enable V90, I get 1.4 - 1.6KB/sec avg
> speed over FTP. Note: this is a USR Courier V.everything modem.
>
> I used to get over 4k on average with bursts of 5-6KB/sec.
>
> With the packet loss and RX errors, needless to say, this PPP
> interface is worthless as a NAT.
>
> Here is my system:
> Dual P2 400's. (Not a powerhouse, but it has been reliable for a
> couple years now)
> 1GB pc-133 RAM
> 400GB RAID5
> Intel Gigabit Ethernet
> 3Com 10/100 Ethernet
> Adaptec 2940 w/Tandberg SLR5 tapedrive and NEC Cd-Rom
> Panasonic IDE Cd-Rom
> USR Courier v.everything modem
>
> RH9
> kernel-2.4.20-8smp
> iptables v1.2.7a
>
> So far I have tried:
> connecting to a different ISP
> using a different modem
> lowering baud rates and line speeds
> verified correct modem init string
> asyncmap 0
>
> None of this made much of a difference if at all.
>
> During FTP transfers, both CPUs are virtually idle. 2-3% intermittent
> utilization and yet the ftp performance is poor.
>
> I tried using mru 576 and mtu 576 and there was a slight throughput
> improvement. 1.9KB/sec, but nothing great. Packet loss and RX errors
> still were at 10-20%.
>
> Also, with mru and mtu at 576, workstations fail to transfer through
> the NAT. It seems that the minimum that works over the NAT is 1500.
>
> Can somebody suggest some things to test to help narrow down this
> problem?
>
> Thanks in advance,
> Charles

Here are some comments / suggestions:

*) Various people have reported poor performance issues with various FTP
programs (clients and/or servers) on various releases of <pick your
favorite Linux distro>. So you might want to run some "Google Groups"
searches on the Linux/Redhat newsgroups using keywords like "poor ftp
performance" to see if you can locate some of these message threads.
(
http://www.google.com/advanced_group_search
Newsgroups: *linux* *redhat*
)

*) Even though the manufacturer of your RAID5 controller states that the
"required" kernel version as '2.4.20-8', chances are that other kernel
versions - and particularly later kernel versions - will work as good
as, or even better than, the 2.4.20-8 release.

*) Multiple RH9 Linux 'kernel' RPMs can be installed on a single system
at the same time, giving you the option to boot the computer into one of
several different kernel versions. So you might consider downloading and
installing the latest 'update' release of the RH9 'kernel' RPM.
(ftp://ftp.redhat.com/pub/redhat/linux/updates/9/en/os)

*) The Linux kernels that Red Hat provides contain Red Hat-specific
"fixes" in the kernel code. So you might want to try downloading,
building, and installing a stock Linux 2.4.20 (or later) kernel - i.e.,
a kernel that hasn't been "fixed" by Red Hat - to see if a stock kernel
works better. (http://www.kernel.org)

*) The 'netfilter' firewall software (in the Linux kernel) has some
kernel modules that provide protocol-specific support for connection
tracking (ip_conntrack_*) and NAT (ip_nat_*). FTP is one of the
protocols that requires these special connection tracking and NAT kernel
modules - i.e., 'ip_conntrack_ftp' and 'ip_nat_ftp', respectively.

[root]# modprobe ip_conntrack_ftp
[root]# modprobe ip_nat_ftp
[root]# lsmod | grep ^ip | sort
[root]# find /lib/modules/ -name "ip_conntrack*"
[root]# find /lib/modules/ -name "ip_nat_*"

*) Are you using the latest-and-greatest release of the 'ppp' RPM? FWIW,
here's the version that's currently installed on my RH9 Linux box:

[root]# rpm -q ppp
ppp-2.4.1-10

(n.b. I don't use PPP. So I can't offer any advice as to whether this is
a stable/good release of the 'ppp' RPM or not.)

FWIW, if the 'Fedora Core 1' distro has a newer version/release of the
'ppp' RPM, you might consider downloading and then building the *SOURCE*
RPM (SRPM) (.src.rpm) for the new release. You should be able to find
the 'ppp' SRPM on Red Hat's FTP site (which seems to be off line today,
along with Red Hat's web server <?>).

--
Jim

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