Free Web Hosting Provider - Web Hosting - E-commerce - High Speed Internet - Free Web Page
Search the Web

Cable/DSL

Navas Cable Modem/DSL
Tuning GuideTM

Cable modem and DSL (e.g., ADSL, G.lite, IDSL, SDSL) tips on increasing speed, enhancing security, fixing problems, sharing a connection, and more.

Copyright 1999-2000 The Navas GroupSM, All Rights Reserved.
Permission is granted to copy for private non-commercial use only.

Posted as <http://Cable-DSL.home.att.net/>. 

Contents

See Also

NOTE: The author has no present connection with any company mentioned herein (other than as a customer), and does not endorse the products of any company. This information was compiled by the author and is provided as a public service. The author does not have the time to give individual technical support, so please do not email requests for assistance. The author is not responsible for any errors or omissions, or for any consequential problems that might result. USE AT YOUR OWN RISK.
  

Before you start

If you are running Windows 95 (rather than Windows 98, Windows NT/2000, or something other than Windows), the first thing you should do is update networking to the latest version by installing:
  1. Windows Socket Update - Kernel 32
  2. Dial Up Networking 1.3 Performance & Security Update (includes general networking fixes, not just dial-up support)
  3. Windows Socket 2 Update
  4. Microsoft DUN 1.3 and Winsock2 Year 2000 Update

[Jump to Contents]

Quick and Easy!

If you want to skip all the discussions and technical explanations, and just cut to the chase, most people only need to do the following to optimize and secure their cable modem or DSL connection:
  1. Before you start
  2. Increasing TCP Receive Window, Method 2
  3. Disable File and Print Sharing (Security on cable modem or DSL, Case A)

[Jump to Contents]

Increasing TCP Receive Window for Microsoft Windows

Q: How do I get the maximum possible DSL or cable modem speed under Windows 95/98/NT/2000? Should I use one of those tweaking programs?

A: The only Windows 95/98/NT/2000 network setting that has any real effect on DSL or cable modem speed is the TCP receive window size, DefaultRcvWindow for Windows 95/98, or TcpWindowSize for Windows NT/2000. Everything else commonly recommended (e.g., TTL) are urban myths that won't help. To modify your TCP receive window size, use one of the following two methods:

Method 1

Save the appropriate four (4) lines of text below to your Desktop in the file name indicated (or just click the accompanying link while holding down the Shift key to download the file), and then double-click on the resulting file to add the setting into your Registry. However, this does not clean out any dial-up modem "tweaks" that might interfere with cable modem/DSL speed -- if you need to do that, use Method 2 (preferred).
Normal Latency*
(e.g., normal DSL or 2-way cable)
32K Window		 Windows 95/98
TCPRW32K.REG		 REGEDIT4

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
"DefaultRcvWindow"="32767"
Windows NT/2000
NTTCP32K.REG		 REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"TcpWindowSize"=dword:00007fff
High latency*
(e.g., poor DSL or 1-way cable)
64K Window		 Windows 95/98
TCPRW64K.REG		 REGEDIT4

[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
"DefaultRcvWindow"="65535"
Windows NT/2000
NTTCP64K.REG		 REGEDIT4

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
"TcpWindowSize"=dword:0000ffff

* Latency: Check latency with 'ping' (or 'traceroute') to a number of distant hosts. (See Important Note below under "Latency") Reasonable rough rules of thumb are that low latency is below 100 ms, and high latency is above 200 ms (with normal latency in the middle).

Method 2 (New!)

As an alternative to the fixed Registry settings above, a single Windows 95/98/NT script is now available that provides not only an adjustable TCP Receive Window size, but also the ICS fix (see Q230116 "Slow Transfer Rates with ICS and High-Bandwidth Devices") and the ability to clean out any dial-up modem "tweaks" that might interfere with cable modem/DSL speed (see Important Note below under "MTU").

Click  while holding down the Shift key to download set_rwin.vbs (Version 1.20). Save the file to your Desktop, and then double-click to run it. Now supports Windows NT (but not yet Windows 2000 -- use Method 1 for Windows 2000)! (Report any problems to cable-dsl@att.net.)

To run this script you must have Windows Script Host/Windows Script 5.0 or higher installed. (If it is installed, you will have WSCRIPT.EXE in the \WINDOWS directory with a version number of 5 or greater.)

This script can also be used to restore all settings to default values (i.e., to remove the Receive Window tweak).

Important Notes:

[Jump to Contents]

Increasing TCP Receive Window for Apple Macintosh

Caveat: The following information has not been tested by this author. USE AT YOUR OWN RISK.

TCP Receive Window can be adjusted with the "tcp_rwin_mss_multiplier" setting of the OT Advanced Tuner from Sustainable Softworks. This author suggests a starting value of 20. You may need to experiment to find your own optimum setting(s). For more information, see:

Note: This author has no connection to Sustainable Softworks.

[Jump to Contents]

Why TCP Receive Window Matters

TCP is a packet-based protocol where data is transmitted in variable-sized blocks, typically with a maximum size of 500-1500 characters. Two important characteristics of the TCP protocol are:

Packet Acknowledgments
In order to insure delivery of each packet, the receiver must acknowledge successful receipt by sending a special acknowledgment packet to the sender. If the sender does not receive the acknowledgment packet within its time limit, it assumes the packet has been lost and will retransmit it (up to its retransmission limit).
Receive Window
If each data packet had to be acknowledged before another could be sent, then performance could suffer due to the delay time needed for the data packet to reach the receiver plus the time needed for the acknowledgment packet to get back to the sender. To avoid this delay, the sender is allowed to keep transmitting data packets prior to receiving acknowledgments up to a maximum "window" size negotiated with the receiver that is normally large enough for several packets. The larger the window, the more packets that can be sent before needing an acknowledgment; however, larger windows can require more packets to be retransmitted when a transmission error occurs. Hence, it's important to have a receive window size that is large enough but not too large.
DefaultRcvWindow (Windows 95/98) and TcpWindowSize (Windows NT/2000) have default values of about 8K bytes (increased to 16K bytes for Windows 2000), which is adequate for relatively slow dialup modems and for high-speed networks with low latency (e.g., less than 20 milliseconds). Increasing DefaultRcvWindow or TcpWindowSize above the default settings (e.g., to 16-64K) can substantially improve throughput on high-speed (e.g., cable modem or DSL) connections where there is higher latency (e.g., 100-200 milliseconds), as is often the case on the Internet, particularly over long network paths.

As an example, consider the case of downloading a file at 100 kilobytes per second from a remote server over a cable modem or DSL connection. The default TCP receive window of about 8K bytes will be consumed in only about 80 milliseconds, which is often less than the latency on the Internet. At this point the sender has to stop sending until an acknowledgment that data was received comes back from the receiver. With a TCP receive window of 64K bytes, the sender can continue for as long as 650 milliseconds without an acknowledgment, which should permit uninterrupted data flow even when latency is 100-200 milliseconds or more.

This TCP receive window tweak is needed because Windows 95/98/NT/2000 do not do a proper job of automatically adjusting the TCP receive window size to accommodate different network speeds and latencies. (Other operating systems may do a better job and not need this kind of tweaking; in this author's tests, for example, Red Hat Linux 6.0 performed as well without tweaking as Windows 98 with tweaking, even though Linux was running on much slower hardware.)

[Jump to Contents]

Microsoft's TCP/IP retransmission bug

Microsoft has confirmed a TCP/IP retransmission bug in Windows 95, 98, and NT that can adversely affect upload (not download) throughput over "high-delay networks (for example, satellite links)." Standard cable modem or DSL service should not be affected by this bug; i.e., the fix is usually not needed. For more information see:

[Jump to Contents]

How to check your connection speed

Speed test sites on the Internet (e.g., BCTEL MultiMedia Gateway) do not provide a reliable measurement of your local link speed. The reason is that no speed test from an arbitrary remote server will tell you much about anything other than that particular route at that particular time under that particular server load, all things that can and do vary widely. (Worse, some speed test sites are so badly implemented that the results are pretty much meaningless.)

To accurately measure the speed of your local link, download a large file (at least one million bytes) from a local server under light load (e.g., Internet software from your ISP in the wee hours) and time how long it takes. When all the various overheads are taken into account, your binary FTP download speed in bytes per second will be about 1/10 of the raw link speed in bits per second (e.g., about 150 KBytes/sec over 1500 Kbits/sec link; about 38 KBytes/sec over 384 Kbits/sec link), assuming optimum configuration of your computer. (See "Increasing TCP Receive Window")

If you are running Windows 98, you can continuously monitor the speed at which data is being sent and received over a network adapter (commonly used to connect a cable or DSL modem) by installing Network Monitor Agent, which is located in the Windows 98 CD directory \Tools\ResKit\NetAdmin\NetMon. Once installed, you will be able to add Network Monitor Performance items to the display in System Monitor. (Network Monitor Agent is also available for Windows 95 in the Windows 95 CD directory \Admin\NetTools\NetMon, and can also be downloaded from Microsoft, but it apparently does not include speed monitoring capabilities.) For more information see Q200910 "How to Install Network Monitor in Windows 95/98".

If you are running Windows NT/2000, you can continuously monitor the speed at which data is being sent and received over a network adapter (commonly used to connect a cable or DSL modem) with Performance Monitor. The Object to use is Network Interface. (For information on Instances, see Q154535 "Multiple Instances of Network Interface in Performance Monitor".)

[Jump to Contents]

Why tweaking TTL won't increase speed

TTL stands for Time To Live, the maximum number of seconds that a packet is allowed to be on the Internet before it is destroyed as undeliverable. However, as a practical matter TTL is really the maximum number of hops that will be followed, since TTL is decreased by at least 1 on every hop, and most hops are less than 1 second (usually much less).

The purpose of TTL is to guard against impossible or erroneous routing (e.g., loops where a packet would otherwise go around and around forever); for example, given an intended route from A to E:

A -> B -> C -> D -> C -> D -> C -> D -> C -> D  ...  

In this case (looping between C and D) the TTL counter would run down to zero and expire, bringing an end to the loop:

32   31   30   29   28   27   26   25   24   23 ... 0

The objective is to have TTL large enough that packets will always reach their destinations over valid routes even with lots of hops, but not so large that excessive resources are wasted when erroneous routing (e.g., looping) is encountered.

In Windows 95 TTL defaults to 32. In almost all cases this is sufficient, since normally the number of hops will be less than 32 (usually much less). However, if and when the number of hops does exceed 32, then packets won't reach the intended destination (and communication won't be possible at all). To guard against unusual cases where the number of hops does exceed 32, default TTL was increased to 128 in Windows 98.

The bottom line is that TTL is not a parameter that increases or decreases speed. If packets are reaching the intended destination, then increasing TTL won't have any effect at all. TTL only matters when packets aren't able to reach the intended destination over a valid route; i.e., when there is no speed at all.

You can check the number of hops on a given route in Windows by using "tracert" (Microsoft-speak for "traceroute") in a command window; e.g.,

>tracert -d www.ibm.com

Tracing route to www.ibm.com [204.146.18.33]
over a maximum of 30 hops:

  1   103 ms    97 ms    96 ms  207.21.104.2
  2   103 ms    99 ms   100 ms  207.21.104.254
  3    97 ms    98 ms    98 ms  208.147.44.1
  4   102 ms    98 ms    97 ms  207.21.177.1
  5   171 ms    99 ms    96 ms  209.157.181.165
  6    99 ms    95 ms    97 ms  209.157.181.162
  7    99 ms   100 ms    99 ms  129.250.15.1
  8   100 ms    97 ms    98 ms  129.250.3.122
  9   100 ms   100 ms    98 ms  129.250.3.77
 10   102 ms   101 ms   103 ms  198.32.136.20
 11   103 ms   104 ms   101 ms  165.87.13.2
 12   175 ms   176 ms   171 ms  165.87.13.58
 13   178 ms   175 ms   174 ms  165.87.35.76
 14   178 ms   178 ms   178 ms  204.146.18.33

Trace complete.

(The trace above was performed over a dialup modem connection. The times in ms would normally be much lower on a cable modem or DSL connection.)

For more information on TTL, see RFC 791.

[Jump to Contents]

Why the System.ini Tweak Doesn't Work

The System.ini Network Card Tweak has its origins in a discussion thread entitled "Slow cable issue????"

The claim is that the tweak (IRQn=4096) improves network performance by allocating 4 megabytes of memory as a buffer for the IRQ (n) used by your network adapter. However:

While it doesn't help, the good news is that (like TTL) this setting doesn't hurt (assuming you don't screw up your SYSTEM.INI file) -- Windows just ignores settings that it doesn't recognize.

Note: This may have gotten its start as confusion over the real SYSTEM.INI settings COMnIrq and COMnBuffer, which are used to control serial port IRQ assignment and buffering (the latter of which can help serial port throughput). But these settings pertain only to the standard Microsoft serial port driver, not to network adapters.

[Jump to Contents]

Security on cable modem or DSL for Microsoft Windows

Security on a full-time cable modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular.

If you are running Windows 95/98, at a minimum you should make sure that the built in capability for File and Print Sharing can't be used against you over the Internet using one of the following methods:

Case A: Disable File and Print Sharing
 You don't want to share files or printers on a local area network. (Your computer and workgroup names will still be visible, but that does not actually make you less secure.)
  1. Open Control Panel - Network.
  2. Disable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. UN-check the two options for files and printer(s).
    3. Click OK twice to close the Network windows.
  3. Restart your computer if prompted to do so.
  4. Close Control Panel.
Case B: Disable NetBIOS over TCP/IP
 You want to conceal your computer and workgroup names from the Internet (even though that does not actually make you more secure), or you do want to share files or printers on a local area network using (only) NetBEUI (which is safe from the Internet, unlike TCP/IP) for File and Print Sharing.
Note: Disabling NetBIOS over TCP/IP may cause connection problems with some Internet Service Providers. If you experience problems, or simply want to avoid any problems, use Case A, Case C, or  Case D, which are equally secure.
  1. Open Control Panel - Network.
  2. If NetBEUI is not installed in the Configuration list:
    1. Click Add.
    2. Select Protocol.
    3. Click Add.
    4. Select Microsoft as the Manufacturer, and then NetBEUI as the Network Protocol.
    5. Click OK twice to close the Network windows.
    6. Restart your computer if prompted to do so, and then reopen Network.
  3. If you do want to share files or printers on a local area network, enable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. Check (enable) the desired options for files and/or printer(s).
    3. Click OK twice to close the Network windows.
  4. Restart your computer if prompted to do so, and then reopen Network.
  5. Unless you normally logon to Microsoft Networks (e.g., Windows NT/2000 servers), Primary Network Logon should be set to Windows Logon.
  6. UN-bind TCP/IP from Microsoft Networking for all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the Bindings tab.
    3. UN-check the option File and Printer Sharing for Microsoft Networks
    4. UN-check the option Client for Microsoft Networks.
    5. Click OK twice to close the Network windows. If you get the message "You have not selected any drivers to bind with. Would you like to select one now?", click No.
  7. Restart your computer if prompted to do so, and then reopen Network.
  8. Make sure that NetBIOS is not enabled on all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the NetBIOS tab.
    3. UN-check (if checked) the option I want to enable NetBIOS over TCP/IP.
    4. Click OK twice to close the Network windows.
  9. Restart your computer if prompted to do so.
  10. Close Control Panel.
Case C: Unbind TCP/IP from File and Printer Sharing
 You do want to share files or printers on a local area network using (only) NetBEUI (which is safe from the Internet, unlike TCP/IP) for File and Print Sharing. (Your computer and workgroup names will still be visible, but that does not actually make you less secure.)
  1. Open Control Panel - Network.
  2. If NetBEUI is not installed in the Configuration list:
    1. Click Add.
    2. Select Protocol.
    3. Click Add.
    4. Select Microsoft as the Manufacturer, and then NetBEUI as the Network Protocol.
    5. Click OK twice to close the Network windows.
    6. Restart your computer if prompted to do so, and then reopen Network.
  3. If you do want to share files or printers on a local area network, enable File and Print Sharing:
    1. Click on File and Print Sharing.
    2. Check (enable) the desired options for files and/or printer(s).
    3. Click OK twice to close the Network windows.
  4. Restart your computer if prompted to do so, and then reopen Network.
  5. Unless you normally logon to Microsoft Networks (e.g., Windows NT/2000 servers), Primary Network Logon should be set to Windows Logon.
  6. UN-bind TCP/IP from File and Printer Sharing for Microsoft Networks for all instances of TCP/IP that point to a network adapter (including Dial-Up Adapter): 
    1. Open TCP/IP Properties by double-clicking on the TCP/IP entry in the Configuration list that points to a network adapter. If you get the long message starting "You have asked to change TCP/IP properties for a dial-up adapter...", click OK.
    2. Click on the Bindings tab.
    3. UN-check the option File and Printer Sharing for Microsoft Networks.
    4. Check (enable) the option Client for Microsoft Networks.
    5. Click OK twice to close the Network windows. If you get the message "You have not selected any drivers to bind with. Would you like to select one now?", click No.
  7. Restart your computer if prompted to do so.
  8. Close Control Panel.
Case D: Set a Scope ID for File and Printer Sharing over TCP/IP
 You do want to share files or printers on a local area network or over the Internet using TCP/IP for File and Print Sharing. (Your computer and workgroup names will not be visible except to other computers with the same Scope ID.)
     See "Increasing NetBIOS Security with Scope ID".

If you are running Windows NT/2000, security is considerably more complex than for Windows 95/98. Start with:

For more information on the real risks of Microsoft Networking, see "File and Printer Sharing (NetBIOS) Fact and Fiction".

For greater security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

* Includes ConSeal Private Links (CPLinks, client-to-client VPN) at no extra charge.

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software (e.g., NetNanny) or hardware (e.g., SonicWALL).

[Jump to Contents]

Security on cable modem or DSL for OS/2

Security on a full-time cable modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular.

For real security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software (e.g., NetNanny) or hardware (e.g., SonicWALL).

[Jump to Contents]

Security on cable modem or DSL for Apple Macintosh

Security on a full-time cable modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular.

For real security, run a "firewall" -- special software that actively works to protect you. You can run firewall software on your own computer:

If you are willing to spend more money, you can get even better protection by using a separate standalone (hardware) firewall. See "Hardware Firewalls".

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software (e.g., NetNanny) or hardware (e.g., SonicWALL).

[Jump to Contents]

Hardware Firewalls

Security on a full-time cable modem or DSL connection to the public Internet is much more important than on a temporary dial-up modem connection. The reason is that there are all too many malicious and/or dishonest people in the world that delight in using Internet connections to wreak harm (e.g., destroy information on your computer, steal your personal financial information). Note that dynamic IP (e.g., DHCP, PPPoE, PPPoA) is not significantly safer that static IP -- that's a dangerous misconception. Dynamic IP just makes you a bit harder to find if someone is looking for you in particular.

You get the best possible protection by using a separate standalone (hardware) firewall. Many of these products also include NAT (network address translation, see RFC 1631) for sharing a single cable modem or DSL connection (see "How to run multiple computers on cable modem or DSL"):

* Products based only on NAT are less effective than true firewalls.

See also "Alternatives to the Alcatel 1000 for DSL" that include packet filtering or firewall.

If you are a "power" user, you can build your own low-cost firewall with:

Not all firewalls are created equal (i.e., some firewalls are better than others). If you want the best possible protection, look for:

If you have children, be warned that there is a lot of dangerous and frightening material on the Internet, so it's also a good idea to install content filtering, based on either software (e.g., NetNanny) or hardware (e.g., SonicWALL).

[Jump to Contents]

Check Your Security

Even if you are scrupulous about security precautions, you still might inadvertently overlook or even create a security risk. You can get good insurance (and peace of mind) by having your system checked. To be thorough and accurate, such checks should be performed from outside your system by a trusted resource using proper tools.

Recommended websites that offer checking services:

Not recommended websites that offer checking services:

For a review of checking services, see ZDNet " Online Security Services".

(HackerWhacker is a claimed trademark of HackerWhacker. "Shields UP!" is a claimed trademark of Gibson Research Corporation.)

[Jump to Contents]

Privacy on the Internet

Although the Internet can be an incredibly valuable resource, it can also be used against your interests, often without your knowledge or consent. Businesses (and other organizations) now routinely use the Internet to gather and compile personal information profiles. All too often these profiles are traded between businesses and aggregated into even more comprehensive profiles, to which just about anyone can get access, even those with bad intentions. In addition to basic information, these profiles can include employment information, financial information (e.g., bank accounts, credit card numbers, brokerage accounts), medical information, personal habits (e.g., what you buy, what you read, what you do), and much more. Here's how this works:

[Jump to Contents]

How to find out what's slowing you down

You've increased your TCP Receive Window, but what if you're still not getting the speed you expect? (1500 Kbits/sec ADSL service is capable of downloading at a bit more than 150 KBytes/sec.) It could just be a matter of a remote server with limited capacity. But it could also be a network under-capacity problem at your ISP (the result of overselling the available capacity to too many subscribers, an all too common problem). No matter what you may have heard or read, "the Internet" is not overloaded.

The usual symptoms of network under-capacity are high latency (the time it takes a packet to cross the network path from one end to the other) and packet loss (where transmitted data is literally lost because of insufficient network capacity). High latency has an adverse effect on interactive use; e.g., real-time gaming over the Internet. Packet loss has an adverse effect on just about everything.

The best way to pinpoint the source of a network problem is to use a standard TCP/IP network tool called 'traceroute', which measures both latency and packet loss at every network "hop" between you and your destination (remote server). Windows 95/98/NT/2000 comes with a free version of traceroute called "tracert". It does a pretty good job, but the output can be hard to understand if you're not into networking. (See Microsoft's Q162326 " Using TRACERT to Troubleshoot TCP/IP Problems in Windows NT" [which also applies to Windows 95/98])

One of the best traceroute alternatives is VisualRoute (shareware: $30) by Datametrics Systems Corporation, available for a variety of platforms, including Windows 95/98/NT/2000, Solaris, and Linux. A fully-functional 30-day demo is available for free download. It combines excellent ease of use with a high level of functionality, notably the ability to analyze the cause of network problems and display the results in English; e.g., (real example, emphasis added):

Analysis: Node 'ftp.cdrom.com' was found in 7 hops (TTL=249). But, problems starting at hop 6 in network "CRL Network Services, Inc" are causing IP packets to be dropped. Connections to HTTP port 80 are working.

Other good traceroute alternatives include:

[Jump to Contents]

How to share cable modem or DSL on multiple computers

Windows 98 Second Edition and Windows 2000 include Internet Connection Sharing (ICS), which provides basic functionality for sharing a single Internet connection on a small peer-to-peer network. The drawback is that such sharing only works when the sharing computer is up and running, which can be inconvenient. Information on using ICS can be found in:

A third-party alternative that gets high marks for compatibility (e.g., with PPPoE) and ease of use is All Aboard! from InterNetShare.com.

For Apple Macintosh, IPNetRouter from Sustainable Softworks provides similar sharing functionality.

Other alternatives for sharing include:

For basic cabled networking hardware, good vendor choices include:

For information on networking without having to run network cables, see:

[Jump to Contents]

Low-cost server for your small network

In addition to typical server tasks (e.g., file storage, printing), a dedicated network server can also be used for sharing a cable modem or DSL service (e.g., network address translation, proxy) and to provide security (e.g., firewall, filtering), with the advantage that such sharing does not depend on any other computer. (See "How to run multiple computers on cable modem or DSL" and "Security on cable modem or DSL") It can also make it possible to have a more complete Internet presence by providing such services as DNS (domain name service for a custom domain), email, HTTP (World Wide Web pages), FTP, and VPN (virtual private networking, providing secure access to your local network from anywhere on the Internet -- see "VPN/PPTP over cable modem or DSL"). 

Option 1: Windows NT

Microsoft will sell you Small Business Server 4.5 Guided Tour Evaluation Kit for only US$20. It is fully functional with no time limitation, although there is no support and a limit of 6 client access licenses (client machines on your network, not IIS connections). The package includes:

Exchange Server is not a terribly good Internet email server, so you may want to consider replacing it with something like Software.com InterMail Post.Office. (The free download includes support for up to 10 email accounts.)

Option 2: Linux

Linux provides a wealth of standard Internet tools, and is available by download and on CD at little or no cost (e.g., CheapBytes). Although peer support is available on the Internet, setting up and administering Linux can be difficult for those without UNIX experience. Complete Linux distributions include:

Option 3: Solaris

Solaris from Sun Microsystems is the operating system that largely powers the Internet, excelling in both power and reliability. Sun now offers two ways to get Solaris at low cost (for media and shipping):

Setting up and administering Solaris can be difficult for those without UNIX experience.

[Jump to Contents]

How to use cable/DSL and dialup at the same time

Suppose you need to use Windows 95/98 Dial-Up Networking (DUN) to connect to your employer's network. The usual problem is that you lose the use of your cable modem or DSL connection during the DUN connection. The reason that happens is that DUN automatically gets higher routing priority than your cable modem or DSL connection because Windows 95/98 can only have one default route. In other words, your cable modem or DSL connection is still alive, but Windows 95/98 won't use it.

The solution to this problem is a two-step process:

1.  Prevent DUN from getting higher routing priority.

  1. Set up a DUN Connection ("connectoid") for this particular purpose.
  2. Right-click on this DUN connectoid and select Properties.
  3. Click on the Server Types tab.
  4. Un-check any unnecessary network protocols (e.g., NetBEUI, IPX/SPX).
  5. Un-check Log on to network unless it's actually needed (e.g., for your employer's network).
  6. Click on TCP/IP Settings.
  7. Un-check Use default gateway on remote network. (This is the critical item.)
  8. Click OK to close all the dialog boxes.

Now when you connect with this particular DUN connectoid, your cable modem or DSL connection will still work, but the DUN connection won't. To get the DUN connection working, proceed with the second step below after you have connected.

2.  Add manual route(s) for your DUN connection.

  1. Connect with the DUN connectoid created in the first step above.
  2. Run the command "WINIPCFG".
  3. Select "PPP Adapter" in the drop-down list.
  4. Note the IP Address. (Assume it's 206.170.4.214 for illustration purposes.)
  5. Close WINIPCFG.
  6. Suppose the IP address you want to reach through the DUN connection is 207.200.75.200 (netscape.com). To manually add that route through your PPP Adapter (206.170.4.214 in our example), run the command:

    Syntax:

    ROUTE  ADD   destination     gateway

    Example:

    ROUTE  ADD  207.200.75.200  206.170.4.214
  7. Now traffic to the destination you just added (207.200.75.200 in this example) will go out through DUN, and traffic to the rest of the Internet will still go out through your cable modem or DSL connection.
  8. You can add multiple manual routes. You can also use trailing 0 values with a corresponding MASK as destination wildcards; e.g.,
    Destination Mask Means all destinations starting with Example
    207.200.75.0 255.255.255.0 207.200.75. ROUTE ADD 207.200.75.0 MASK 255.255.255.0 206.170.4.214
    207.200.0.0 255.255.0.0 207.200. ROUTE ADD 207.200.0.0 MASK 255.255.0.0 206.170.4.214
  9. When you disconnect DUN your manual routes will be lost, and the IP address of your PPP Adapter will probably change from connection to connection, so this step must be repeated after each connection. 

[Jump to Contents]

How to "bond" multiple cable/DSL and/or dial-up connections

Using multiple cable modem, DSL, and/or dial-up modem connections together for increased speed normally requires either special bonding support from the Internet Service Provider (ISP) or an expensive, sophisticated load-balancing router. An affordable alternative is:

Note: This author has no connection to MidCore Software and has not tested MidPoint Internet Gateway.

[Jump to Contents]

How to share files with NetBIOS over cable modem or DSL

Windows (95/98/NT/2000) includes the capability of sharing files and printers over a network connection by means of NetBIOS (Microsoft Networking). With "NetBIOS over TCP/IP" such sharing can take place over the Internet. Scope ID should be used to enhance NetBIOS security -- see "Increasing NetBIOS Security with Scope ID". Note that NetBIOS provides authentication, but not encryption; for greater security, use VPN/PPTP. (See "VPN/PPTP over cable modem or DSL")

Caveat: Some Internet Service Provider (ISP) filter (block) ports used for NetBIOS because of hysteria over NetBIOS (see "File and Printer Sharing (NetBIOS) Fact and Fiction") and/or genuine concern for subscribers that might inadvertently expose themselves to NetBIOS security risks (see "Security on cable modem or DSL"). In such cases it will not be possible to use NetBIOS over the Internet unless you can persuade the ISP to remove the filter (block) on your particular cable modem or DSL connection.

For more information on using NetBIOS sharing over the Internet, see:

[Jump to Contents]

VPN/PPTP over cable modem or DSL

VPN (Virtual Private Networking) is a means of creating secure connections over the Internet between two computers and/or local area networks (LAN's). Microsoft includes a form of VPN called PPTP (Point-to-Point Tunneling Protocol) in Windows NT/2000, as well as PPTP clients for/in Windows 95/98. See:

[Jump to Contents]

What is PPPoE?

PPPoE stands for Point-to-Point Protocol over Ethernet, a newer alternative to traditional bridging and routing for high-speed Internet connections. Although not an Internet standard, PPPoE is described in the Informational RFC 2516.

Some providers are touting PPPoE ("dynamic IP") as safer than bridge/routed service, but this is a dangerous misconception -- PPPoE is not significantly safer.

PPPoE currently requires either:

Important Notes:

DHCP (long hangs)
If you are running PPPoE software on Windows, and your computer seems to "hang" at startup and/or at times while you are accessing the Internet, the cause may be DHCP timeout. The fix is to set a private IP address (e.g., 192.168.0.1, with a Subnet Mask of 255.255.255.0) Under Windows 95/98, go to Control Panel - Network - TCP/IP pointing to something other than Dial-Up Adapter -  Properties - IP Address.
Internet Explorer "No Connection" Problem
If Internet Explorer keeps reporting that there is "No Connection" but recovers with "Try Again" try installing Service Pack 1.
MTU (access problems)
Certain PPPoE implementations do not work well with an MTU setting of 1500 (the Microsoft Windows default). The work-around is to manually set MTU to a lower value in the range of 1400-1492. This problem is reportedly fixed in Enternet 1.31 for Windows and 5.09b for Macintosh.
Staying Connected
To keep Windows NT/2000 connected after logging off, see Q158909 " How to Keep RAS Connections Active After Logging Off".

For vendor/provider perspectives on PPPoE, see:

For subscriber perspectives on PPPoE (particularly problems resulting from premature deployment), see:

[Jump to Contents]

What is PPPoA?

PPPoA stands for Point-to-Point Protocol over ATM (more precisely ATM Adaptation Layer 5, or AAL5), another newer alternative to traditional bridging and routing for high-speed Internet connections. Unlike PPPoE, PPPoA is an Internet standard as described in RFC 2364.

Some providers are touting PPPoA ("dynamic IP") as safer than bridge/routed service, but this is a dangerous misconception -- PPPoA is not significantly safer.

PPPoA requires hardware with PPPoA support: Linux/BSD support for PPPoA:

See also:

[Jump to Contents]

How to send a fax over cable modem or DSL

Unlike most dial-up modems, a cable or DSL modem is not capable of connecting to fax machines, so cannot send or receive faxes directly. However, it is possible to send and receive faxes over the Internet by using an Internet fax service. For information on such services, some of which are free, see:

[Jump to Contents]

Surge/lightning suppression for cable/DSL

Power surges, particularly those caused by nearby lightning strikes, can damage your cable or DSL modem, or even your computer. A surge/lightning suppresser can provide protection, but unfortunately many of the devices sold in retail stores, particularly the less expensive ones, are not terribly effective. Another problem is that they typically aren't designed for the higher speeds of cable modems and DSL. If you care about such protection, you may want to consider a higher quality "industrial grade" unit specifically designed for high-speed data; good sources of such products include: Good sources of power line only commercial grade surge suppressors include:
Power line surge suppressor standards
At a minimum, make sure that any point of use surge suppressor is UL 1449 Second Edition listed/recognized at a suppressed voltage rating (SVR) of 330 volts. For endurance, the surge suppressor should also be Classified in Accordance with ANSI/IEEE C62.41-1991, Recommended Practices. UL 1449 listed products are not necessarily classified for endurance.
Telecommunications network suppressor standards
At a minimum, make sure that any point of use surge suppressor is UL 497A listed/recognized.

[Jump to Contents]

Which is better, cable or DSL?

It all depends on the particular providers and the particular geographic area. There is no hard and fast rule.

[Jump to Contents]

Third-party email service

What do you do if your ISP has poor email service, or if you anticipate someday switching to a different ISP? Consider a third-party email service, some of which are free. Many people do not realize that they don't have to use services provided by the ISP. Third-party email services are accessible by a web browser (web-based) and/or an email program (POP3) -- be sure to find out what you will be getting. Third-party email services include:

[Jump to Contents]

Third-party news (Usenet) service

What do you do if your ISP has poor news service? Consider a third-party news service. Many people do not realize that they don't have to use services provided by the ISP. Third-party news services are accessible by a web browser (web-based) and/or a news program (NNTP) -- be sure to find out what you will be getting. Commercial third-party news services include:

See also

Public (free) news services

Open public news servers tend to be few and far between, and to disappear without warning, because they can easily be overwhelmed by freeloaders, and abused by spammers. Here are some ways to find one:

[Jump to Contents]

How to buy (rather than rent) a cable modem

Cable modems fall into two categories: proprietary and DOCSIS standard. Buying a proprietary cable modem is probably unwise (due to obsolescence and lack of compatibility) and difficult (since such products are not normally sold at retail). A consumer market for DOCSIS standard modems is expected to develop, but you should only purchase a DOCSIS cable modem if your cable supplier supports the DOCSIS standard. For more information see:

[Jump to Contents]

DSL over DLC (Digital Loop Carrier)

Did your provider tell you that you didn't quality for DSL service because your phone line is served by DLC (aka SLC, Pair Gain, multiplexor)? For a discussion of issues and resolutions related to DSL over DLC, see "Extending Asymmetric Digital Subscriber Line (ADSL) Services to Remote Digital Loop Carrier (DLC) Locations Tutorial" (Web ProForum).

[Jump to Contents]

How to fix phone problems caused by ADSL

One of the advantages of ADSL service is that it can provide both voice and data over the same telephone line by means of "micro-filters" (with G.lite) or a "splitter" (with full rate ADSL) that separate voice (as well as dialup modem and fax) signals from ADSL data signals; e.g.,
ADSL diagram
However, enough ADSL signal can "leak" past some splitters to adversely affect some voice telephones. (The splitter normally used by Pacific Bell is a notable offender. See note below.) The common symptoms are: ADSL suppliers have a bad habit of blaming the problem on your telephone, rather than the splitter. You can insist on a proper splitter, but that can be a frustrating, time consuming hassle. Fortunately, you may well be able to fix the problem yourself with an inexpensive filter that you install next to (or otherwise upstream of) the affected phone(s). Excelsus Technologies (800-457-0967 or 760-753-9108) is a good source of this kind of filter, which it calls the "Z-BLOCKER". In the USA, use the "Z-200 W / USA WALL-PHONE" if you have a wall phone; otherwise use the "Z-200 SM / USA & EUROPE", preferably located as far from the phone as possible.
ADSL diagram with filter
Notes:

[Jump to Contents]

DSL problems caused by your own lighting 

Some DSL modems (e.g., Alcatel 1000) are overly sensitive to RFI ( radio frequency interference). Lighting dimmer switches and/or halogen lights are a common source of such interference. The result can be a degradation of DSL performance or even a complete loss of DSL sync, even when the source of the interference is not in close proximity to the DSL modem (because the interference can be not only radiated, but also conducted through building wiring). Interference is even possible when such switches and/or lights appear to be off, since some still generate interference even when turned off.

If you experience DSL problems, particularly when those problems seem to be worse at certain times of the day, you can check for this possible cause by completely disconnecting all lighting dimmer switches and halogen lights. Putting the DSL modem on a power line RFI filter (included in many surge suppressors -- see "Surge/lightning suppression for cable/DSL") may or may not solve the problem.

If you do determine that a lighting dimmer switch is causing interference, you may be able to solve the problem by replacing it with a switch that generates less interference (i.e., a switch with better RFI filtering). Cheap switches may have little or no RFI filtering; better switches that normally have good RFI filtering may be defective. Switches with good filtering are made by a number of manufacturers, including:

For more information on dimmer switch RFI, see the Lutron FAQ (frequently asked question), "What is radio frequency interference (RFI)?"

See "Other sources of DSL interference" for similar problems caused by switching power "bricks" (external AC power adapters).

For general technical information on tracking down sources of RFI, see "Track and Solve Electrical Interference" by the ARRL (American Radio Relay League, Inc.).

[Jump to Contents]

Other sources of DSL interference 

AM radio stations
According to Nortel Networks, ADSL speeds can be cut by up to 40% by AM radio station interference, a problem that may affect up to 15% of ADSL subscribers. See "AM radio creates ADSL static".
Bridge taps
A "bridge tap" is an unconnected cable that is spliced into your telephone line, usually the remains of a connection to a different telephone subscriber. Bridge taps can cause a variety of problems. Locating and removing them can be difficult and expensive.
DAML
Digital Added Main Line (DAML) telephone line-multiplexors (used to provide more than one phone line over a single cable pair) directly interfere with ADSL and other types of modems. The symptoms with an Alcatel 1000 include ADSL drop/reconnect cycles when the analog line goes offhook, and when automated nightly C.O. line testing occurs.
Disturbers
A "disturber" is another high-speed data service (e.g., ISDN, T-1, DSL) in the same cable bundle as your DSL service. Although DSL is designed to tolerate a certain amount of disturbance, too much disturbance can cause problems, particularly when combined with other sources of interference. Common symptoms of interference from a disturber are DSL problems that occur only at certain times of the day.
MTU
The Maintenance Test Unit (MTU) is a device installed at your location, used to remotely test your phone line. Unfortunately, it can seriously interfere with data communications. Any MTU should be removed.
Power "bricks"
Old style power "bricks" (external AC power adapters) based on transformer technology are usually fine, but some poor new style power "bricks" based on switching technology generate RFI interference much like poor dimmer switches (see "DSL problems caused by your own lighting"). These new style power bricks tend to be noticeably lighter than the old style. Replacing such a switching-type power brick with a transformer-type power brick (available at electronics suppliers; e.g., Radio Shack) should solve the problem. Be sure to get the proper current capacity as well as the proper output voltage.

Unfortunately, there is not much that a DSL subscriber can do about many of these sources of interference (except as noted) other than asking the DSL provider to try to correct any problems.

[Jump to Contents]

Alcatel sync-nosurf (green light lockup) problem

The Alcatel 1000 ADSL modem has a nasty habit of locking up even though the sync light is still green. (This author has received reports of this same problem with the Alcatel Speed Touch Home, but has not had the opportunity to check it.)

When this happens, normal Internet connectivity is lost. Often the only way to recover is to manually remove power from the modem; wait several seconds; and then restore power, whereupon the modem reinitializes, resyncs and resumes normal operation.

For a more permanent fix, the following information provided by Lawrence Baldwin (Bellsouth ADSL Tier-3 Support):

The sync-nosurf (aka "lockup" with green sync light) symptom is a known bug in Alcatel 1000 modem hardware revision (rev) E. Basically the modem's forwarding tables get corrupted and it stops forwarding all unicast traffic. (It will continue to forward broadcast traffic, but that's not of much use.)

You can tell the hardware rev of the Alcatel 1000 modem by checking the serial number on the bottom of the modem:

Serial Number contains Hardware Revision
AA AA E
AB AA G

This problem is caused when the ISP has spanning tree turned on in its backbone routers. You can verify this with a protocol analyzer. (A spanning tree explorer packet is broadcast every 2 seconds, if enabled.)

Rev E modems ship from the factory flashed with Feature Group 1 software (about 18 months old). On the Alcatel DSLAM, the active software will show up as HH3GAA.224. This problem is resolved in Feature Group 4 software (HH3GAA.240).

In cases where the software on the Alcatel DSLAM has been updated to Feature Group 4 (and forced to download to the customer's Alcatel 1000), customers no longer report this symptom.

Bottom-line: If you have a rev E modem, ask for your DSLAM port to be reconfigured to give you the new Feature Group 4 (FG4) software.

Another possible aspect of this problem is ARP (Address Resolution Protocol). It has been reported (but not verified by this author) that the Alcatel ADSL modem will substitute its own MAC address for that of the "gateway" when the DSL link is down. Since ARP entries are cached, this could result in packets not reaching the gateway for some time after the DSL link has recovered (i.e., until the bogus entry for the gateway expires from the cache). If you have a Windows machine networked directly to an Alcatel modem (i.e., not through a router), you can check your ARP cache with the "ARP -a" command, and you can delete specific entries (e.g., your gateway) from the cache with the "ARP -d" command. (Restarting your computer or your router is a clumsy but sure way to flush the entire ARP cache.)

[Jump to Contents]

Alternatives to the Alcatel 1000 for ADSL

One of the biggest ADSL problems was the Alcatel 1000 (now thankfully discontinued) that was used in certain early deployments. It has several known issues, including excessive sensitivity to RFI (e.g., lamp dimmers, halogen lights) and the infamous green-light-but-won't-pass-data problem. It also has limited functionality. Since you will probably be purchasing (rather than renting) your DSL modem, you might want to consider equipment with better reliability and/or more capabilities. (Note that you might have problems getting support from your ADSL provider if you use equipment not supplied by the provider.)

In general, you should be able to use any device that is compliant with (ANSI T1.413) DMT issue 2, particularly if compatibility with Alcatel is claimed:

Important notes:
1 May be compatible with Alcatel, but no specific mention of Alcatel compatibility.
2 Sold only through service providers, not directly to end users.
3 According to Cisco, the 677 is not compatible.
4 According to a report, the Remote 810 is not compatible.

[Jump to Contents]

What is IFITL? FTTC? FTTH?

IFITL stands for "integrated fiber in the loop," another name for "fiber in the loop" (FITL) or "fiber to the curb" (FTTC). This use of optical fiber can extend the reach and/or increase the speed of DSL by shortening the length of the final copper wire run to the home. When fiber reaches all the way to the home, the term becomes "fiber to the home" (FTTH), which can provide very high-speed service without DSL (which works only over copper wire), typically using ATM. For more information, see:

[Jump to Contents]

Other DSL Resources

[Jump to Contents]

TCP/IP Resources

[Jump to Contents]

 
This page has been accessed  COUNTER  times since September 26, 1999.

Button [The Navas Group home page]

Trademarks belong to their owners.