by Time Warner Cable
RR User's FORUMS
here to discuss cable modem and xDSL technology. Check out the
forums to see a head to head comparison of Austin RR and Verio SDSL.
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RR E-Groups e-mail list
Petrick setup an e-groups
message board for Austin RR users. There is a lot of discussion
related to Austin RR.
Timer Warner is in full swing installing cable modems all over Austin.
Until very recently, the modem that RR installed is the Motorola
Cyber SURFR Wave Cable Modem.
This model is about two years old as of May of 2000, but it is still
a solid preformer with 10Mbps/1.536Mbps download/upload throughput
(data upstream is transmitted at 768Kbps using DQPSK modulation
or 1.5Mbps using 16-ary QAM). At this time, "general use"
accounts use only DQPSK with error correction. The actual throughput
after error correction is 27Mbps downsteam and 680kbps upstream
with 1500 byte MTU. Even though this modem is not the latest technology,
it is still a very nice modem.
In March of 2000, Austin
RR started beta testing a new Toshiba PCX1000 DOCSIS cable modem,
which is on a new network. At this point in time, there seems to
be a slight advange of getting the Toshiba DOCSIS modem over the
Motorola modem. Although RR promises that bandwidth will be identical
on both networks, nevertheless, there are less people on the new
network, and some have reported slightly faster ping times on the
new network. But, for most users, the difference between the two
modems and the two networks in terms of performance will be imperceptable.
be surprised to learn that you may only get download speeds
of 30 to 70 Kbytes/sec (when using your browser to download a file)
without tweaking your Windows Registry. After registry tweaks, you
can expect between 80 and 120 Kbytes/sec. And that means that you
can download a 10 megabyte file from a fast server in about ninety
seconds. Internet traffic will significantly reduce download speed.
Also, it is important
to note that RR trottles down the modem to about 1/10 of the peak
download performance and about 1/3 of peak upload performance. So,
the best possible performance that you can expect from your modem
is approximately 2.7 Mbps download and 300 Kbps upload. After tweaking
my registry, I have seen these numbers using FTP (File Transfer
Some people argue that
there is only one setting that will improve cable modem and DSL
modem performance, namely, increasing the DefaultRcvWindow in the
Windows 95/98 registry and increasing the TcpWindowSize in the Windows
NT/2000 registry (or increasing the TCP Receive Window or RWIN).
The default in Win95/98/NT is 8K, and in Win2000 the default is
16K. Moreover, there is a dispute about whether to increase the
DefaultRcvWindow above 64K in Windows98. But, aside from these disputes,
the registry tweaks below for Microsoft Windows are safe and effective.
I would suggest that you experiment with these settings yourself
in order to determine if you gain any improvement in performance
by increasing their values. In my experience tweaking your registry
will improve Windows peformance considerably. Don't
forget to Backup your Registry, before editing.
Tweaks for Windows 95/98
These tweaks are courtesy
the Registry ( START-RUN-Regedit ) and modify all the following
parameters. If the keys don't exist, you'll have to create them.
The best value for each variable is in RED.
HKey_Local_Machine\System\CurrentControlSet\Services\Class\Ne tTrans\000n (Where "000n" is your TCP/IP protocol. It contains "TCP/IP" assigned to the "DriverDesc" Value)
MaxMTU="1500" (string var, can be 552, 576 or 1500)
MaxMSS="1460" (string var, power of 2, 40 less than MTU)
DefaultRcvWindow="64240" (DWORD decimal var, or string var, 4xMSS, 8xMSS or more...Can also be 4xMTU+24. Best settings to try are 64240 , 46720, 32120, 17520, 11680 and 8760 , in that order)
Note: If you're using Windows 98, you can try a larger value, however
you'll have to experiment to find out whether you get any improvement
with those ( you might want to try 372300, 186880 and 93440
). If you're using Windows 95, stick to the previous recommendations,
the maximum RWin should be a multiple of MSS, not exceeding 64K.
DefaultTTL="128" (string var, 32, 64 or 128)
PMTUDiscovery="0" (DWORD decimal var, zero for optimal performance)
PMTUBlackHoleDetect="0" (DWORD decimal var, zero for optimal performance)
Windows 98 Registry Tweaks
Windows 98 has some improvements in the TCP/IP, including Large Window support ( the 'DefaultRcvWindow' has a maximum value of 2**30 rather than 64K), support for Selective Acknowledgments (SACK) and support for Fast Retransmission and Fast Recovery. The additional setting you should implement are listed below. Note: Don't forget to also add all the other recommended registry settings for MTU, MSS and so on. These tweaks are courtesy of Philip Philipov.
DefaultRcvWindow="372300" (DWORD decimal var, or string var, 4xMSS, 8xMSS or more...Can also be 4xMTU+24. Recommended settings to try are 372300, 186880, 93440, 64240, 32120 and 8760 , in that order)
Tcp1323Opts="3" (string var, recommended setting is 3. The possible settings are 0 - No Windowscaling and Timestamp Options, 1 - Window scaling but no Timestamp options, 3 - Window scaling and Time stamp options.)
SackOpts="1" (string var, recommended setting is 1. Possible settings are 0 - No Sack options or 1 - Sack Option enabled)
MaxDupAcks="3" (DWORD decimal var, taking integer values from 2 to N. Recommended setting is 3)
Generic Registry Patches
If you don't have time to tweak your registry yourself, you can just download these patches, provided by Philip Philipov.
- Generic Registry patch for Windows 95
- Generic Registry patch for Windows 98
- Generic Registry patch for Windows 2000 (see below).
These patches are generic, they use the most aggressive settings,
adding some unnecessary lines for compatibility reasons. Use these
at your own risk. Back up your registry (go to START > RUN, type
'scanregw' and choose YES to the prompt to back up the Registry)
before applying the patch, just to be safe.
NT Registry Tweaks
Windows NT is slightly different in handling TCP/IP than Windows
9x. Keep in mind that even if you apply the Windows NT tweaks, you'll
see smaller performance increase than with Windows 9x, simply because
NT is better optimized for networking. I strongly recommend backing
up your Registry before applying these settings.
"TcpWindowSize"="64240" (DWORD decimal var, range 0-65535. Recommended settings to try are 64240, 32120 and 8760 , in that order)
DefaultTTL="128" (DWORD decimal var, range 1-255 )
EnablePMTUDiscovery="0" (DWORD decimal var, boolean, 0-false or 1-true)
decimal var, boolean, 0-false or 1-true. Set to 1 if you decide
to set "EnablePMTUDiscovery" to 1)
decimal var, Range 68 - <Value of the Network>. Values larger
than the default for the underlying network will result in the transport
using the network default MTU)
2000 Registry Tweaks
There are three
places in the Windows 2000 Registry where you can add the TCP Window
number of bytes) Valid range is from MSS to 2^30. Add the value
as a decimal, for best results it has to be a multiple of MSS.
TcpWindowSize="372300" (DWORD, number of bytes) Valid
range is from MSS to 2^30. Add the value as a decimal, for best
results it has to be a multiple of MSS. Recommended settings to
try are 372300, 186880, 93440, 64240, 32120 and 8760 , in that order.
also exist under \Tcpip\Parameters\Interface\ - if added
at this location, it overrides the global setting for this particular.
The setting below,
namely, Tcp1323Opts, is a necessary setting in order to enable Large
TCPWindow support. Without this parameter, the TCPWindow is limited
(DWORD, recommended setting is 3. The possible settings
are 0 - Disable RFC 1323 options, 1 - Window scaling but no Timestamp
options, 3 - Window scaling and Time stamp options.)
DefaultTTL="64" (DWORD, recommended setting is 64.
Other settings that are widely used are 128 and 32)
EnablePMTUDiscovery="1" (DWORD - boolean, valid settings
are 0-->False and 1-->True. Many connections perform better with
this entry at 1, however, if you prefer to set your upstream to
send fixed 1500 packets, you might want to use 0 instead). When
set at 1, establishing connections and initial transfer speed might
slow down a bit, however you will get better throughput if somewhere
in the path large packets need to be fragmented.
EnablePMTUBHDetect="0" (DWORD - boolean, valid settings
are 0-->False and 1-->True. Recommended setting is 0). When set
to 1 (True), TCP attempts to discover MTU automatically over the
path to a remote host. Setting this parameter to 0 causes MTU to
default to 576.
SackOpts="1" (DWORD - boolean, recommended setting
is 1. Possible settings are 0 - No Sack options or 1 - Sack Option
\Tcpip\Parameters\Interfaces\ MTU="1500" (DWORD,
valid range is from 68 to MTU of Network).
up your web surfing by using the RR Web caching proxy server. Simply
go to "options" in your browser and find "connect to the Internet
through a proxy." Then, enter "proxy-server" on port "8080" (without
the parentheses), and that's it.
At this time,
Austin Road Runner offers what they call "small business accounts"
for $89.95 per month, however, I fail to understand why anyone would
purchase a "small business account," since there appears
to be no difference between "regular" and "business"
accounts, except for the price tag. Tech support says that "we
monitor small business accounts less closely than regular accounts."
But, since there are no bandwidth restrictions on a regular account,
monitoring means very little.
allows you to connect up to eight (8) computers to one cable modem.
They do this by allowing you to plug your modem into a hub, and
they dynamically assign IP addresses (via DHCP) for up to eight
workstations. However, they charge $14.95 for each additional workstation/computer
for regular subscriptions and $44.95 for each additional computer
with the "business" subscription.
In the future,
Austin RR may provide a "Pro LAN" service, which allows
static IP addresses. Other cities are offering "Pro LAN"
or static IP connections (e.g., Memphis RR) for $349 for the first
static IP and $50 for each additional static IP, with a limit of
six or ten. See Memphis
RR for more information.
If you need
static IPs to run servers, my suggestion is "get SDSL."
Cable modems are a shared media. xDSL is a dedicated connection.
See my Austin xDSL Central for more
Austin Road Runner Links
Austin RR Info
Road Runner Home Page
Official Road Runner Online Support
McDonald's Unofficial RR FAQ
Phil Karn's RR Info
Cable Modem Info
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