Austin Road Runner
by Time Warner Cable

Austin RR User's FORUMS

Go 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.

Austin RR User's SURVEY

Austin RR E-Groups e-mail list

Marc Petrick setup an e-groups message board for Austin RR users. There is a lot of discussion related to Austin RR.

General Information

The Modem -- 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.

Actual throughput

You might 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 Protocol).

Registry Tweaks

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.

Registry Tweaks for Windows 95/98

These tweaks are courtesy of Philip Philipov. Open 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)

HKey_Local_Machine\System\CurrentControlSet\Services\VxD\MS TCP
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.

HKey_Local_Machine\System\CurrentControlSet\Services\VxD\MS TCP
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)
HKey_Local_Machine
\System\CurrentControlSet\Services\VXD\MSTCP\Parameters
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.

Patch95 - Generic Registry patch for Windows 95

Patch98 - Generic Registry patch for Windows 98

Patch2000 - Generic Registry patch for Windows 2000 (see below).

Windows NT Registry Tweaks

Reprint from Philip Philipov: 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.

HKEY_LOCAL_MACHINE
\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
"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)
EnablePMTUBHDetect="0" (DWORD decimal var, boolean, 0-false or 1-true. Set to 1 if you decide to set "EnablePMTUDiscovery" to 1)

HKEY_LOCAL_MACHINE
\SYSTEM\CurrentControlSet\Services\<Adapter Name>\Parameters\Tcpip
MTU="1500" (DWORD 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)

Windows 2000 Registry Tweaks

There are three places in the Windows 2000 Registry where you can add the TCP Window parameter.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ GlobalMaxTcpWindowSize="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.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ 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. TcpWindowSize can 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 to 64K.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ Tcp1323Opts="3" (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.)
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ DefaultTTL="64" (DWORD, recommended setting is 64. Other settings that are widely used are 128 and 32)
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ 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.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ 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.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ SackOpts="1" (DWORD - boolean, recommended setting is 1. Possible settings are 0 - No Sack options or 1 - Sack Option enabled).
HKLM\SYSTEM\CurrentControlSet\Services \Tcpip\Parameters\Interfaces\ MTU="1500" (DWORD, valid range is from 68 to MTU of Network).

RR Web Proxy

Speed 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.

RR Business Services

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.

Road Runner 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 information.

Other Austin Road Runner Links

Marc´s Austin RR Info

Official Austin Road Runner Home Page

Official Road Runner Online Support

General Links

Joe McDonald's Unofficial RR FAQ

Phil Karn's RR Info

Cable Modem Info

MapNet -- trace your Internet backbone.

DHS.ORG -- get a free domain name

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