Frequently Asked Questions
- Does IPNetTuner permanently change my Open
Transport files?
- I use IPNetRouter to share my Internet
connection. Do I only need to run IPNetTuner on my IPNetRouter
machine OR do I need to also run IPNetTuner on all my client Macs?
- I am using a hardware router to share
my Internet connection. Can IPNetTuner still help me increase
the performance of my Macs behind my hardware router?
- What is the difference between a
Link Rate test and a TCP Rate test?
- Why when I perform a TCP Test against
some servers I do not note a performance increase?
- Why are the Open Transport default values restored
when I wake up my tuned Mac?
- I opened one of the preconfigured IPNetTuner
files and IPNetTuner quit — what's happening?
- How can I easily view the settings in a
configuration file?
- What parameters should I modify to improve
performance with my connection?
- How do I set the RWIN value in Open Transport?
- What is the default value for the "tcp_RWIN_mss_multiplier"
parameter?
- Where is the Selective Ack option?
Does IPNetTuner permanently change my
Open Transport files?
No. IPNetTuner only modifies Open Transport IP parameters stored
in RAM memory. IPNetTuner cannot permanently modify any Open Transport
files. If you restart your Mac then all Open Transport settings
are reset to their defaults. Alternatively, you can also reset individual
parameters using IPNetTuner if you wish.
Most users find a set of settings which work best for them. Then
they put a copy (or alias) of this IPNetTuner settings document
in their Startup Items folder. This way IPNetTuner is automatically
launched when the machine is restarted, the chosen settings are
invoked, and IPNetTuner quits.
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I use IPNetRouter to share my Internet
connection. Do I only need to run IPNetTuner on my IPNetRouter machine
OR do I need to run IPNetTuner on all my client Macs?
You should run IPNetTuner on ALL your Macintoshes (both the IPNetRouter
machine and each Macintosh client). When you run TCP Tests on each
machine, you will clearly see this.
Open Transport's TCP Parameters influence each and every TCP connection.
A router, such as IPNetRouter, only forwards datagrams. It does
not modify or have any effect on the reliable end-to-end delivery
and receipt of datagrams associated with connection oriented services
such as TCP. Hence we must modify the TCP stack of every machine
in order to affect the machine's performance.
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I am using a hardware router
to share my Internet connection. Can IPNetTuner still help me increase
the performance of my Macs behind my hardware router?
Absolutely! As mentioned above, Open Transport's TCP Parameters
influence each and every TCP connection. Any router, even a hardware
router, only forwards datagrams. It does not modify or have any
effect on the reliable end-to-end delivery and receipt of datagrams
associated with connection oriented services such as TCP. Hence
we must modify the TCP stack of every machine in order to affect
the machine's performance.
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What is the difference between
a Link Rate test and a TCP Rate test?
Please see our Test
descriptions for more information on these two tests and how
they differ.
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Why when I perform a TCP Test against
some servers I do not note a performance difference between the
default OT settings and my tuned OT settings?
The throughput from some servers can be limited by other things
other than TCP transport parameters. Specifically:
- the server may be overloaded (not enough CPU power)
- the server may be limited by the speed of its Internet connection
- the page you are downloading (testing) is too small. You should
test against a page at least 20 Kbytes if possible.
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Why are the Open Transport default values
restored when I wake up my tuned Mac?
Since IPNetTuner only modifies OT parameters in RAM, if Open Transport
is reloaded then the parameters modified by IPNetTuner will be reset
to default values. This would typically occur if you turn Open Transport
on or off or your Mac reloads the networking stacks coming out of
sleep mode. If this occurs, you can reload the desired parameters
by double-clicking on a saved configuration file containing the
appropriate settings.
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I opened a configuration file and IPNetTuner
quit &emdash; what's happening?
Although IPNetTuner has quit, the parameters in the configuration
file have modified your Mac's Open Transport IP networking settings.
The observed behavior occurs if the configuration file was saved
with the "Auto Configure" option checked in IPNetTuner.
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How can I easily see the settings in
a configuration file?
The easiest method is to open the file in a text editor, such as
Simpletext; IPNetTuner documents are really text documents. To see
the parameters of "Auto Configure" saved documents directly
in IPNetTuner use the "Load Settings" button. If you use
the "Open..." file function, the settings will be loaded,
made active, and IPNetTuner will automatically quit.
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What parameters should I modify to
improve performance with my connection?
There are two parameters which, when modified, seem to show marked
download improvements for all types of connections:
tcp_deferred_ack_interval=1
tcp_mss_min=536
Specific Cable/DSL/ADSL Connection Settings:
tcp_rwin_mss_multiplier=36
tcp_dupack_fast_retransmit=4
tcp_mss_def=536
tcp_rexmit_interval_max=2000
tcp_rexmit_interval_min=2000
tcp_rexmit_interval_initial=2000
Specific PPP Analog Modem Connection Settings:
tcp_mss_max=536
tcp_mss_def=536
tcp_rwin_mss_multiplier=6
tcp_rexmit_interval_initial=3000
tcp_rexmit_interval_min=3000
tcp_conn_grace_period=3000
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How do I set the RWIN value in Open Transport?
To set the RWIN value with IPNetTuner, use the "tcp_mss_max"
and "tcp_rwin_mss_multiplier" parameters. The product
of these two values is the maximum RWIN size. For example, if the
"tcp_mss_max" value is 2048 bytes and the other parameter
is 16, the RWIN size would be
16 * 2048 bytes = 32768 bytes
The proper settings for either parameter can vary depending on
the unique properties of your network connection and the remote
site(s) you are tuning performance with. See the IPNetTuner
documentation for more information.
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What is the default value for the "tcp_RWIN_mss_multiplier"
parameter?
It is 0 (zero). This actually results in a RWIN size of about 16K
(zero is a special case defined by Open Transport).
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Where is the Selective Ack option?
According to one of Apple's senior Open Transport engineers, Open
Transport (all versions) does not support selective ack. If you
have information from a non-Apple web site that indicates that Open
Transport does support selective ack, please request the webmaster
of that site confirm the information with Apple.
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