how-to block ads
|
| | | | FAQ Revisions | Editors: KeysCapt  , jazzman916 , FAQFixer , FROSTY
Last modified on 2008-08-25 21:31:19
| |
|
|
5.0 Connection and Tweaking·I'm not getting the advertised DSL speeds. What's wrong? What can I do?
·How do I tweak my connection settings for the best results?
·How can I tweak my FastAccess Lite (768Kbps/128Kbps) connection?
·How can I tweak my FastAccess Ultra (1.5Mbps/256Kbps) connection?
·How can I tweak my FastAccess Xtreme 3.0 (3Mbps/384Kbps) connection?
·How can I tweak my FastAccess Xtreme 6.0 (6Mbps/512Kbps) connection?
·Should I use the BellSouth Speed Optimization Tool?
·Detailed MTU & RWIN procedures and information
·How do I find my optimum MTU setting?
·How do I change the MTU or RWIN using the DrTCP tool?
·How do I change my RWIN (Receive Window) using DrTCP?
·What information should I use for the BBR Tweaks Test when using FastAccess?
·What is meant by 'FastPath' and 'Interleaving'? What is a 'Noise Profile'?
·How can I tell if my line is 'Fastpath' or 'Interleave'?
·I have used PPPoA for a long time but now it won't connect. What's wrong?
·What are PPPoA, PPPoE, and Bridged Connections?
·Can I switch from PPPoA to PPPoE and back?
·Can switching between PPPoA and PPPoE lock the gateway router?
·Can I get a 'bridged' connection from BellSouth?
·Does BellSouth block ports?
·Static IP address and Dynamic IP address?
·What is 'ping time'?
·What is latency?
·Can I do anything to reduce my ping time?
·Can I reduce or eliminate packet loss?
·Why do some speedtest results appear greater than the cap?
·Should I adjust the MTU on my NIC or my router?
·Does BellSouth have IP release times? Does BellSouth use DHCP?
·What is doubling NATing?
·What happens if my RWIN (Receive Window) is too small or too big?
·What is MaxSyn Profile?
·Can I disable the auto-tuning RWIN function for Windows Vista?
| | | Typically, poor or fluctuating speeds usually fall into one of 5 categories:
Section 1 - Software/Configuration Issues
Section 2 - Account provisioning is incorrect
Section 3 - Physical problems
Section 4 - Provisioning rates versus speed test websites
Section 5 - Many speed tests are not reliable
Important Recommendation: It is suggested that you use the Official BellSouth FastAccess Speed Test Website for your speed tests. It stays on BellSouth's network and eliminates some variables associated with other speed test sites.
Section 1 - Software/Configuration Issues
Computers, modems, and routers must be configured and functioning correctly.
1. Make sure your computer(s) are tweaked correctly.
-FastAccess Lite (768/128) Tweak
-FastAccess Ultra (1472/256) Tweak
-FastAccess Xtreme (3000/384) Tweak
-FastAccess Xtreme (6000/512) Tweak
2. Make sure your PC is free of spyware, adware, viruses, or any applications that may be running in the background and using upload/download bandwidth. Even a small amount of upload traffic can drastically effect your download speeds.
3. If you are using a third party router (wired or wireless) in conjunction with your modem remove it and connect directly to one PC and recheck your speeds. If your speeds increase and the router is suspect, make sure you have the newest firmware installed.
4. Make sure your NIC and modem (or router) are negotiating a full-duplex (10Mb or more) connection. 10Mb half-duplex connections may create situations where you can not get full download speeds in the higher tier services. Check your modem event logs for connection information.
Section 2 - Account provisioning is incorrect
If you have just upgraded to a higher service tier your order may not be completed or there may be an issue with the order. To check your order status click here. Additionally, your modem may not be configured with the correct username or you may have been provisioned on the wrong service tier. If you are seeing speeds that are consistent with another speed tier (such as 768/128), verify that the proper username/password is configured on the modem. If the username is correct, contact BellSouth and have them verify your service provisioning.
Section 3 - Physical Problems
1. Make sure the DSL filters are installed properly, present on all devices, and functioning properly. This is probably the #1 reason for many speed related issues. The BellSouth supplied filters have two outputs, one for phones/faxes/etc and the for DSL. It is very important that all phones/faxes/etc have a filter installed. Filters can also go bad for various reasons so just because a filter is installed properly does not mean it is still functioning properly. To eliminate the filters as a cause of problem remove all filters and POTS devices from every jack in the home. Replace the filters and POTS devices one at a time and test the modem for any speed or stat changes. If your speeds drop off dramatically then replace that filter. Home alarm systems also interfere with DSL. To troubleshoot, simply disconnect any line going to the alarm control module (even if you do not currently subscribe to the service) and check your speed and modem stats. If the alarm is causing issues you can install a special filter designed for alarms systems or call the alarm company for advice.
2. Pull your modem stats and event logs and save/print them while connected in your normal configuration before you make any changes or troubleshoot. Reference the guidelines within the modem stats FAQ to determine if your modem stats are good or not. If your stats and logs look good then you probably do not a physical problem and should look elsewhere. Best advice #1: After you have saved the previous logs, clear them and let the modem create new entries specifically for your testing. If your stats are poor you will have to do further troubleshooting by pulling your modem stats from the NID. Best advice #2: Run the test from the NID for as long as possible. You may have an intermittent issue that doesn't show up if you only check for a minute or two. If you are experiencing troubles at a specific time try and test at that time (if possible). Make sure you recheck the modem logs.
3. If your stats are much better at the NID, you have an issue within the house. Double check that the DSL filters are correctly installed and functioning. Bypass any surge protectors because some are incompatible with DSL and even if they are compatible, they may have gone bad. Completely disconnect or install a filter on any alarm system (even if you do not have active service). Eliminate any possible sources of EMI (Electromagnetic Interference) near the modem or the phone line. A simple hand held AM radio can also be used to track down noisy electrical problems. Tune the radio to a lower frequency so you hear only static. Pass the radio near the suspected device and if you hear a major change in the amount of static that device may be causing the problems. Check for loose connections and damaged wire if possible. You can eliminate the need to disconnect alarm systems and individual filters completely by installing a homerun. Customers who live in apartments can also install a homerun by using a specialized splitter.
4. If your modems stats are poor at the NID then it could be a local line issue or a bad modem. A call to BellSouth is in order. If they conclude the modem is bad they may replace it if it's still under warranty. If they conclude it is a local line issue they will troubleshoot further. BellSouth may or may not have the ability to fix your line issue. It may be easily fixed by a simple call or a local tech, but it may be a distance problem that is uncorrectable.
Section 4 - Provisioning rates versus Speed Tests
Your slow speeds may just be the way your line is provisioned and the speed test you use. Advertised DSL speeds are sometimes your "connection rate" or "data rate" not "download speed". Due to overhead and signaling it is not possible to download end-user data at actual advertised speeds. Depending on the type of service and whether you are served from a remote DSLAM or not you will have a minimum of roughly 12.5% overhead.
9.4% 5 byte overhead within 53 byte ATM cell
0.5% 8 byte PPPoE overhead
1.3% 20 byte IP overhead
1.3% 20 byte TCP overhead
12.5% Total Signal Overhead (minimum)
So a DSL customer with advertised speeds of 1472/256 will have a real world end user data speeds of roughly 1250/220 at best.
Section 5 - Many speed tests are not reliable
Most speed test websites have limited bandwidth or overall capacity that may erroneously provide poor speed results. It is suggested that you use the Official BellSouth FastAccess Speed Test Website for your speed tests. If you have good speeds from the BellSouth website but slow speeds from other sites you should not worry about it because the problem is their website...not your connection.
Andy Houtz DSL
 feedback form
 feedback form
by Andy Houtz edited by FAQFixer
last modified: 2008-06-30 16:14:49 | | | Properly setting your RWIN and MTU can make a dramatic difference in overall speeds. Since the recommendations can be specific based on your service provisioning click on the proper link below for your situation. Learn more about RWIN and MTU.
-FastAccess Lite (768/128) Tweak
-FastAccess Ultra (1472/256) Tweak
-FastAccess Xtreme (3000/384) Tweak
-FastAccess Xtreme (6000/512) Tweak
Important Note: Do not use the BellSouth "Optimizer" software. It does not set the optimum MTU or RWIN and should be completely avoided. Click here for more information.
Andy Houtz DSL
feedback form
feedback form
by FAQFixer
last modified: 2008-02-29 10:05:32 | | | FastAccess Lite customers should use the Quick Tweak Method shown below.
Important Notes:
1. Do not use the BellSouth "Optimizer" software. It does not set the optimum MTU or RWIN and should be completely avoided. Click here for more information.
2. Never run an MTU larger than 1492 bytes when utilizing PPPoE connectivity; which is the standard for FastAccess. Click here for more information.
3. You should not use an RWIN above 65535 for FastAccess. Click here for more information.
4. Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
 Quick Tweak Method
Download DrTCP here and set your MTU to 1492 and your RWIN to 52272 on your network adaptor(s). These settings are optimal for almost all Lite customers. Instructions for using DrTCP are available here. Remember to restart your PC after you have saved the changes.
Detailed Tweak Method
People with nothing but free time on their hands can use the more Detailed Tweak Method which requires multiple tests and multiple changes to the settings in order to hit your connection's "sweet spot". Usually, your detailed tweak results will probably be the same or very close to the numbers in the Quick Tweak Method. Click here for detailed instructions.
Additional Information
•Some Linksys router models/firmware have an "Auto" MTU capability that does not function correctly. You must enable the manual MTU function and adjust the size to 1492 (or less).
•There may be more than one network adapter showing in the pull down menu for your PC. Additionally, if you have multiple computers on the network, the NICs should use the the same MTU/RWIN settings.
•Learn more about RWIN and MTU.
Andy Houtz DSL
feedback form
feedback form
by jazzman916 edited by FAQFixer
last modified: 2008-08-13 15:44:34 | | | FastAccess Ultra customers should use the Quick Tweak Method shown below.
Important Notes:
1. Do not use the BellSouth "Optimizer" software. It does not set the optimum MTU or RWIN and should be completely avoided. Click here for more information.
2. Never run an MTU larger than 1492 bytes when utilizing PPPoE connectivity; which is the standard for FastAccess. Click here for more information.
3. You should not use an RWIN above 65535 for FastAccess. Click here for more information.
4. Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Quick Tweak Method
Download DrTCP here and set your MTU to 1492 and your RWIN to 52272 on your network adaptor(s). These settings are optimal for almost all Ultra customers. Instructions for using DrTCP are available here. Remember to restart your PC after you have saved the changes.
Detailed Tweak Method
People with nothing but free time on their hands can use the more Detailed Tweak Method which requires multiple tests and multiple changes to their settings in order to hit your connection's "sweet spot". Usually, your detailed tweak results will probably be the same or very close to the numbers in the Quick Tweak Method. Click here. for detailed instructions.
Additional Information
•There may be more than one network adapter showing in the pull down menu for your PC. Additionally, if you have multiple computers on the network, the NICs should use the the same MTU/RWIN settings.
•Some Linksys router models/firmware have an "Auto" MTU capability that does not function correctly. You must enable the manual MTU function and adjust the size to 1492 (or less).
•Learn more about RWIN and MTU.
Andy Houtz DSL
feedback form
feedback form
by jazzman916 edited by FAQFixer
last modified: 2008-08-13 15:44:07 | | | FastAccess Extreme 3.0 customers should use the Quick Tweak Method shown below.
Important Notes:
1. Do not use the BellSouth "Optimizer" software. It does not set the optimum MTU or RWIN and should be completely avoided. Click here for more information.
2. Never run an MTU larger than 1492 bytes when utilizing PPPoE connectivity; which is the standard for FastAccess. Click here for more information.
3. You should not use an RWIN above 65535 for FastAccess. Click here for more information.
4. Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Quick Tweak Method
Download DrTCP here and set your MTU to 1492 and your RWIN to 63888 on your network adaptor(s). These settings are optimal for almost all Extreme 3.0 customers. Instructions for using DrTCP are available here. Remember to restart your PC after you have saved the changes.
Detailed Tweak Method
People with nothing but free time on their hands can use the more Detailed Tweak Method which requires multiple tests and multiple changes to their settings in order to hit your connection's "sweet spot". Usually, your detailed tweak results will probably be the same or very close to the numbers in the Quick Tweak Method. Click here. for detailed instructions.
Additional Information
•Some Linksys router model/firmware have an "Auto" MTU capability that does not function correctly. You must enable the manual MTU function and adjust the size to 1492 (or less).
•There may be more than one network adapter showing in the pull down menu for your PC. Additionally, if you have multiple computers on the network, the NICs should use the the same MTU/RWIN settings.
•Learn more about RWIN and MTU.
Andy Houtz DSL
feedback form
feedback form
by jazzman916 edited by FAQFixer
last modified: 2008-08-13 15:45:05 | | | FastAccess Extreme 6.0 customers should use the Quick Tweak Method shown below.
Important Notes:
1. Do not use the BellSouth "Optimizer" software. It does not set the optimum MTU or RWIN and should be completely avoided. Click here for more information.
2. Never run an MTU larger than 1492 bytes when utilizing PPPoE connectivity; which is the standard for FastAccess. Click here for more information.
3. You should not use an RWIN above 65535 for FastAccess. Click here for more information.
4. Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Quick Tweak Method
Download DrTCP here and set your MTU to 1492 and your RWIN to 63888 on your network adaptor(s). These settings are optimal for almost all Extreme 6.0 customers. Instructions for using DrTCP are available here. Remember to restart your PC after you have saved the changes.
Detailed Tweak Method
People with nothing but free time on their hands can use the more Detailed Tweak Method which requires multiple tests and multiple changes to their settings in order to hit your connection's "sweet spot". Usually, your detailed tweak results will probably be the same or very close to the numbers in the Quick Tweak Method. Click here. for detailed instructions.
Additional Information
•Some Linksys router model/firmware have an "Auto" MTU capability that does not function correctly. You must enable the manual MTU function and adjust the size to 1492 (or less).
•There may be more than one network adapter showing in the pull down menu for your PC. Additionally, if you have multiple computers on the network, the NICs should use the the same MTU/RWIN settings.
•Learn more about RWIN and MTU.
Andy Houtz DSL
feedback form
feedback form
by FAQFixer
last modified: 2008-08-13 15:45:31 | | | Absolutely not! The MTU and RWIN recommendations are not correct nor the most efficient. There are multiple reasons (see additional rant) why you should not use the tool, but the three main reasons are:
1. It sets the MTU size to 1400, which is way too low and actually creates additional traffic and processing. Learn more about MTU.
2. The recommended RWIN usually is not an even multiple of the MSS (MTU minus 40 bytes) so it also creates additional traffic and processing. Learn more about RWIN.
3. In some cases it recommends an RWIN that is too large.
You should use the specific tweak FAQ associated with your level of service:
FastAccess Lite Tweak FAQ (MTU: 1492 RWIN: 52272)
FastAccess Ultra Tweak FAQ (MTU: 1492 RWIN: 52272)
Extreme 3.0 Tweak FAQ (MTU: 1492 RWIN: 63888)
FastAccess 6.0 Tweak FAQ (MTU: 1492 RWIN: 63888)
Additional Rant:
1)The 1400 byte MTU size was originally selected more than 5 years ago to compensate for an issue with specific network traffic that didn't handle fragmentation/reassembly well. That network issue is no longer exists and hasn't been a problem for years. Additionally, changes made in the CPE helped alleviate certain fragmenting problems. 1400 bytes was also selected because some older applications, such as VPNs, did not automatically lower the MTU and would not work correctly.
2) Using an MTU of 1400 with BellSouth's current network and backbone creates additional packets and traffic. It sends and receives packets that are much smaller than optimum so more packets (and time) are required to send the same amount of data. With the additional packet comes additional overhead. So by recommending 1400 BellSouth has not solved any problems, but created more traffic on their network.
3) The Optimizer also may incorrectly recommend an RWIN that is too high or not an even multiple of the MSS. Routinely the Optimizer selects 65535 for Extreme, not because it is the proper setting, but simply because it is the largest RWIN you can have without enabling windows scaling (which creates it's own problems). RWIN should always be an even multiple of the MSS (MTU minus 40 bytes). As recommended by BellSouth an acknowledgement must be sent to the sender right in the middle of receiving a packet. That packet is dumped and has to be resent after the sender gets the acknowledgement from the receiver. So, if they continue to recommend an MTU of 1400 they should at least make the RWIN 65280.
1360 X 48 = 65280.
4) They should universally be recommending an MTU of 1492 and a RWIN of 63888 (at least for Extreme 3.0 and 6.0). The 1 in 10,000 customer that needs an MTU lower than 1492 should not be the yardstick for recommendations that create additional traffic for every customer.
It's embarrassing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Andy Houtz DSL
feedback form
feedback form
by FAQFixer
last modified: 2008-02-29 10:08:57 | | | The most important thing you can do to your PC to maximize broadband performance is to optimize your MTU and RWIN values. Before you make any changes run a baseline speed test to a reliable test site and record your results...then get tweaking!
MTU (Maximum Transfer Unit)
MTU is the maximum packet size (in bytes) that can be transported reliably across any particular network; IP Ethernet in this case. The maximum size of an IP Ethernet packet is 1500, but overhead like IP, TCP, and PPPoE must also be taken into account. The wrong MTU will actually prevent you from accessing some web sites or FTP sites. It may even cause you to not authenticate properly on mail servers or secure web sites. There are too many variables to be able to estimate what your optimum MTU should be, but there is an test that can determine your correct MTU. Although this simple test is accurate for testing end points, many users may find that a lower MTU may be better for their particular circumstances.
Important Notes:
•Due to additional complications, VPNs require a different MTU. Please refer to the VPN MTU FAQ.
•If you have a network with multiple PCs every computer should be set up with the same MTU. Additionally, some PCs may use several Network Adapters or a VPN client adapter on one PC so you must verify you are changing the Network Adapter associated with your broadband service or VPN client.
• The built in PPPoE client for Windows XP uses an MTU that is set to 1480. The MTU For more information please reference this XP MTU article. This only applies if you are running the built in XP PPPoE client!
• Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Although the Broadband Reports Tweak Test offers very good general information, it may give erroneous or misleading MTU recommendations and its information should not to used. Since it simply looks at whether you use PPPoA or PPPoE, it can not give accurate, individualized MTU analysis. To guarantee the proper MTU customers should use the following procedure:
Go to the MTU Ping Test and record your results.
You can download DrTCP here (see example below) or find a similar registry editing application to easily change and adjust your MTU. Remember, you must change the MTU on the correct network adapter (if you have more than one) and you must reboot your machine in order for the settings to take place.
RWIN (Receive Window)
The TCP Receive Window can be thought of as the main data gate keeper to your computer. It sets the limits on the amount of data (in bytes) that can be received and buffered before it must send an acknowledgement to the sender. If the number is too low you will tie up bandwidth with frequent and unnecessary acknowledgements. Too high of an RWIN will create a slowdown if any packets need to be retransmitted. Helpful hint: When you increase your bandwidth you can also increase your RWIN.
There are mathematical calculations that can be used to obtain your optimum RWIN, but they are complicated and rely on variables that can easily change. I suggest using real-life testing with some guidelines from the Tweak Test:
Run the Tweaks Test using the correct FastAccess Tweak Settings and record the RWIN recommendations. FYI:
Record the "MSS Requested" number (usually 1452 or 1460 due to default settings) shown in the left column of the results. Note: All RWIN values should be an even multiple of your MSS.
Use the following recommendations as a basic starting point for RWIN settings based on your service.
FastAccess Extreme 3.0 and 6.0 = 63888
FastAccess Ultra = 52272
FastAccess Lite = 52272
Change your RWIN to the value recommended above using DrTCP or similar registry editing application. Remember to change the RWIN on the correct network adapter (if you have more than one) and reboot your machine.
Retest your download speeds and record any changes.
Retest again using a higher RWIN value until you find your optimum speeds. When trying different RWIN values make sure you use EVEN multiples of your MSS.
For example: A standard FastAccess DSL connection could use:
1452 MSS
x 34 Even Multiple
49368 RWIN
The next higher even multiple is 24 so the RWIN value would be:
1452 MSS
x 36 Even Multiple
52272 RWIN
Changing the MTU and RWIN values
You can download DrTCP here or any similar registry editing application to change your MTU and RWIN. An example of changing the MTU using DrTCP is shown below.
Note: There may be more than one network adapter showing in the pull down menu for your PC. You must make sure you change the MTU and RWIN on the correct network adapter associated with your broadband connection or VPN client. You must also reboot your computer in order for the new settings to take place. Additionally, if you have a network with more than one PC, all computers should be tweaked.
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2008-07-10 09:05:12 | | | Important Recommendation: This FAQ is for pointy headed people with no life that are just dying to get their command prompt fix and do some interesting (albeit completely boring) tests. I strongly recommend you download DrTCP, set your MTU on your NIC(s) to 1492 as shown here, and do something better with your time. That said, if you wish to continue please proceed.
Summary
One of the easy and most accurate ways to test for optimum MTU is to do a simple DOS Ping test. You will simply send out ping requests and progressively lower your packet size until the packet no longer needs to be fragmented. Although this simple test is accurate for testing end points, users may find that a lower MTU may be better for their particular circumstances. Important Note: MTU must be 1492 (or lower) when using PPPoE connectivity. More detailed information about the effects of MTU can be found here.
Important Notes:
•Due to additional complications, VPNs require a different type of MTU test. Please refer to the VPN MTU Test.
•If you have a network with multiple PCs every computer should be set up with the same MTU. Additionally, some PCs may use several Network Adapters or a VPN client adapter on one PC so you must verify you are changing the Network Adapter associated with your broadband service or VPN client.
• The built in PPPoE client for Windows XP uses an MTU that is set to 1480. For more information please reference this XP MTU article. This only applies if you are running the built in XP PPPoE client!
Finding the Correct MTU
To find the correct MTU for your configuration you must run a simple DOS Ping test. You will simply send out ping requests and progressively lower your packet size until the packet no longer needs to be fragmented. Please reference the following steps:
The command for this ping test is ping www.dslreports.com -f -l xxxx.
•You can use any well known, pingable domain like ping www.google.com -f -l xxxx in place of www.dslreports.com for the test.
•There is a single space between each command.
•"-l" is a lower case letter L, not the number one.
•The last four numbers are the test packet size.
Step 1
Open a DOS prompt screen by clicking on Start>Programs>MSDOS-PROMPT. You can also use the Run Command by clicking on Start>Run then type in "command" for Windows 95/98/ME or "cmd" for Windows 2000/XP.
Step 2
At the DOS Prompt type in ping www.dslreports.com -f -l 1472 and hit Enter. Notice that the packet needs to be fragmented. (Figure 1)
Step 3
Drop the test packet size down (10 or 12 bytes) and test again. Notice that the packet still needs to be fragmented. (Figure 2)
Step 4
Drop the test packet size down more and test again until your reach a packet size that does not fragment. (Figure 3)
Step 5
Once you have a test packet that is not fragmented increase your packet size in small increments and retest until you find the largest possible packet that doesn't fragment.
Step 6
Take the maximum packet size from the ping test and add 28. You add 28 bytes because 20 bytes are reserved for the IP header and 8 bytes must be allocated for the ICMP Echo Request header. Remember: You must add 28 to your results from the ping test!
An example:
1440 Max packet size from Ping Test
+ 28 IP and ICMP headers
1468 Your optimum MTU Setting
Step 7
You can download DrTCP here or find a similar registry editing application that will allow you to easily change your MTU. An example of changing the MTU using DrTCP is shown below. (Figure 4)
Additional Important Information
Very Important Note: There may be more than one network adapter showing in the pull down menu for your PC. You must make sure you change the MTU on the correct network adapter associated with your broadband connection or VPN client. You must also reboot your computer in order for the new settings to take place. Additionally, if you have a network with more than one computer, all NICs and router(s) should have the the same MTU setting. Please reference the links below to learn how to change the MTU on some popular routers:
•MTU change on a Linksys Router
•Some Linksys router model/firmware have an "Auto" MTU capability that does not function correctly. You must enable the manual MTU function and adjust the size to 1492 (or less).
•MTU change on a D-Link Router
Andy Houtz
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2008-08-13 15:46:54 | | | Important Note: Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Step 1
Download DrTCP here and open the application.
Step 2
Enter the desired MTU in the appropriate field. Very Important Note: Due to additional overhead you must use an MTU of 1492 or less when utilizing PPPoE connectivity (which is the default standard for BellSouth connectivity). Some applications may require an even lower MTU to work properly. Additional information about finding your optimum MTU can be found here.
Pictures by Andy Houtz
Step 3
Enter the desired RWIN in the appropriate field and click on Save. RWIN should always be an even multiple of your MSS. MSS is always your MTU size minus 40 bytes. Additional information on proper RWIN sizing can be found here. An example of proper RWIN size is shown below as well as recommended settings based on your service:
1452 MSS
x 26 Even Multiple
37752 RWIN
Recommended RWIN initial settings (assuming an MTU of 1492):
FastAcces Extreme 6.0 (6000/512) = 63888
FastAcces Extreme 3.0 (3000/384) = 63888
FastAccess Ultra (1500/256) = 37752
FastAccess Lite (256/128)= 26136
Step 4
There may be more than one network adapter showing in the pull down menu for your PC. Additionally, if you have a network with more than one computer, all NICs, adpaters, and router(s) must have the the same MTU setting. Use the Adapter Settings pulldown and select any other network adapter (if available) and enter the proper values as needed. Repeat Steps 2 and 3 for all adapters until they have the correct information.
Step 5
Restart your computer!!! The changes will not take effect until you do so!
Additional information:
Please reference the links below to learn how to change the MTU on some popular routers:
•MTU change on a Linksys Router
•MTU change on a D-Link Router
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2007-08-23 13:06:49 | | | Important Information
Windows Vista has an auto-tuning function that automatically adjusts your settings, so tweaking is not possible. You can disable auto-tuning for troubleshooting connectivity issues. Click here to find out how.
Step 1
Download DrTCP here and open the application.
Step 2
Select the network adapter associated with your broadband connection. Important Note: There may be more than one network adapter showing in the pull down menu for your PC.
Pictures by Andy Houtz
Step 3
Enter the suggested RWIN in the appropriate field and click Save. Select any other network adapters (if any) and enter the proper RWIN as needed. Remember, RWIN should always be an even multiple of your MSS. MSS is always your MTU size minus 40 bytes. An example of proper RWIN size is shown below:
1452 MSS
x 26 Even Multiple
37752 RWIN
Recommended RWIN initial settings (assumming an MTU of 1492):
FastAcces Extreme (6000/512) = 63888
FastAcces Extreme (3000/384) = 63888
FastAccess Ultra (1500/256) = 52272
FastAccess Lite (768/128)= 52272
Step 4
Restart your computer! The changes will not take effect until you do so!
Important Additional Note: If you are also using DrTCP to adjust your MTU never run an MTU larger than 1492 when utilizing PPPoE connectivity; which is the standard for FastAccess. Click here for more information.
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2007-08-23 13:07:40 | | | The picture below details tweak settings for common modems and network equipment for FastAccess (including PCData/IFITL) customers. If the Tweak Test suggest changing your PC's RWIN or MTU, please refer to the MTU/RWIN FAQ.
Picture by Andy Houtz
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2006-12-27 22:35:33 | | | When a customer is put on a "Noise Profile" usually their DSL line is changed from FastPath to Interleaved.
Interleaving is an error correction protocol that is implemented for your line at the DSLAM. With Interleaving enabled, the DSLAM can correct errors in the data stream it receives before passing that data to your gateway router. It is usually implemented on noisy or marginal lines and can greatly increase sync stability and effectively eliminate "first hop" packet loss. The largest drawback to Interleaving is that it will increase your ping time, specifically to your first hop gateway router.
If Interleaving is not enabled on your line, it is configured as FastPath. FastPath allows the DSLAM to pass the data received from you to the first hop router without performing any error correction. As a result, marginal lines could experience an increase in packet loss and decrease in sync stability (i.e. frequent sync loss). However, FastPath has lower ping times, especially to the first hop router.
The BellSouth DSG (Digital Services Group) is responsible for manually adding or removing customers from a Noise Profile. Interleaving can also be provisioned automatically without human intervention when line quality drops below certain perimeters.
Friendly Advice/Time Saver: Even though you may (after a large amount of effort) be able to call the Helpdesk and get switched to Fastpath, there's usually a reason you are interleaved, so you may or may not be able to connect without it. Typically, the system will automatically switch back to interleaved after a short time anyway.
Check here to see if your line is Fastpath or Interleave.
Andy Houtz
feedback form
feedback form
by leevis edited by FAQFixer
last modified: 2007-06-22 14:25:57 | | | Your DSL modem may provide information to indicate if your line is FastPath or Interleaved.
BellSouth Supplied Westell 2100/2200/6100
Users must access the Modem Interface, enter Expert Mode and click on Statistics ->ADSL for the information as shown here.
Alcatel SpeedTouch Home
Users must access the STH Expert Mode and check Operational Data information as shown here.
Cayman 3220-H
Users should use the Cayman Quick Start Guide for instructions on how to log in using Telnet or the console port. Once logged in, click on the DSL link and check the Data information as shown here.
Cisco 837
Access the router CLI and enter sh dsl int atm 0. Fast Path or Interleave information will be displayed below the corresponding protocol as shown here.
If your modem software does not provide the information, you will need to contact BellSouth FastAccess Customer Support and have them contact the BellSouth DSG. For more information about interleaving and fastpath click here.
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2006-12-27 22:35:17 | | | BellSouth is making major changes to the DSLAM/Edge router network for DSL. The new PPP termination devices use PPPoE exclusively. The updates and changes are ongoing and most customers are notified beforehand so it does not cause a disruption in service. You may be shipped a new modem based on the type of modem BellSouth initially provided.
Most customers are in one of two situations:
1. If you have an older modem that only does PPPoA (such as the Alcatel Stingray) you will need a completely new modem. If you did not receive a replacement modem contact BellSouth for a compatible modem/router.
2. If you have a modem that does both PPPoA/oE you will need to make sure it is configured to utilize PPPoE.
Important Note: PPPoE has additional overhead and you should adjust your MTU settings on your NIC(s) to 1492 or less. Click here for more information.
Andy Houtz
feedback form
feedback form
by FAQFixer
last modified: 2007-02-12 10:57:25 | | | There are currently three types of FastAccess connection. The original Bridged/DHCP service is no longer being offered. So for new installs this leaves two: PPPoA or PPPoE.
PPPoA (PPP over ATM):
ADSL access via Point-to-Point Protocol (aka Dial-Up Networking). The "FastAccess ADSL" icon is located in the Dial-Up Networking folder. The user authenticates with userid and password, then connects. This is similar to dialup except no actual dialing takes place. Only available with the PCI or USB modems (or various unsupported alternative modems and routers).
PPPoE (PPP over Ethernet):
Another dial-up type connection method. PPPoE client software is from NTS (or various unsupported alternatives). The icon is typically located in a NTS EnterNet 300 folder. (As of EnterNet 1.34, integration with DUN is also possible.) Username, password and then connect as with PPPoA. Note that an additional layer of software is involved here.
Bridged/DHCP (RFC 1483):
Uses a standard DHCP network client which is native to every OS. DHCP should automatically negotiate an IP 'lease' on bootup. No special icons in any folders, no dialup type operations, no username and/or password required to connect, and no specialized software is required. This was the original type of service, but has been phased out in favor of PPPoE/A as of late spring/early summer 2000. This most closely resembles true 'always on'.
PPPoE/A Connectivity
All new installations are now PPP. This can be either PPPoE (PPP over Ethernet) or PPPoA (PPP over ATM), two similar yet different protocols. Both use a mechanism similar to a dialup style connection: username and password are required. The server passes a (dynamic) IP address, netmask and other networking details back to the client once authentication has been successful.
The main difference is that with PPPoA, most of the work is done at the hardware level. So a modem that supports PPPoA is required. The Efficient 3060 and 4060 modems both support PPPoA (the Alcatel 1000/STH does not). The appropriate driver then needs to be loaded. The default connection method is via Windows DUN. A separate client ala NTS EnterNet is not required. DSL runs over ATM from the DSLAM to the modem no matter what modem we use. So this would seem to be the 'cleanest' solution for PPP customers.
PPPoE works via the 1483 Bridged driver, and requires client software to manage the session. This means that PPPoE is the only choice for Alcatel 1000/STH modem owners, and also IFITL customers. In fact, PPPoE will work with any of the four modems being offered. The officially supported PPPoE client is NTS's EnterNet, though there are various alternatives. All of which are unsupported, by the way.
PPPoE, by requiring client software, also means there is more overhead due to the additional ethernet layer. And consequently more system resources are used to maintain the connection. This may not be significant depending on your hardware and horsepower.
IFITL users do not need to worry about the modem drivers, since they don't use a modem at all. But still they need the PPPoE client (NTS) software in order to connect.
One of the drawbacks of the current PPP implementations is occasional disconnects. Apparently, the protocols are sensitive to any hiccup in the connection. One consequence here is that your IP address will change each time the connection is re-established. This is not just a BellSouth problem, but seems to be an industry wide issue with PPPoX implementations.
So why PPP? Aren't we trying to get away from dialup type connections?
Well, the answer from any ISP on this is that PPP simplifies a number of things on their end. They can essentially use their same infrastructure as their already well established, and much larger, dialup base. Simpler, means easier, means less costly. In any case, it is here to stay.
Bridged/DHCP Connectivity
DHCP/Bridged service was the original FastAccess ADSL service. This is no longer being offered, as all new installs are now PPPoX.
DHCP (Dynamic Host Configuration Protocol) is a time-tested networking protocol for assigning IP addresses. It allows clients on a TCP/IP network to request and be assigned IP addresses dynamically from a centrally located server, and also to discover other necessary information about the network to which they are connected.
The DHCP server has a fixed pool of IPs, and assigns these when it receives a valid request. In our case, we are assigned 'sticky' IPs. Although these are dynamic (ie, not static), they tend to remain the same for long periods of time -- many months in some cases. The IP is 'leased' from the server's pool of available addresses, and eventually this lease must be renewed, or it will 'expire'.
The client's OS automatically requests a renewal after a predetermined period of time, and the server usually automatically complies. BellSouth.net is using a twelve hour lease. The server also provides other information to the client, such as nameservers, gateway, netmask, and broadcast address. All these are necessary in order to function on any TCP/IP network. The server also sets the maximum, allowed lease period. All this is handled fairly transparently and quietly by most operating systems. The initial request is broadcast during boot and special drivers are required.
The DHCP servers typically have names such as:
sun00sdf.sdf.bellsouth.net
This one happens to also double as the local FastAccess primary nameserver. There would also seem to be a secondary, backup server: 'sun01sdf.sdf.BellSouth.net'. Some cities may still be using names such as ns.rdu.BellSouth.net. These seem to also do double duty as nameserver and DHCP server.
How do they know who we are? There has to be method of authenticating the user as a valid customer.
We are recognized by the 'MAC' addresses of our network adaptor. This is a unique hardware address (looks something like: 00 50 04 A8 77 11) that is recorded in a BellSouth database. The 'adaptor' may either be the Network Card as is the case of the Alcatel external, ethernet modems, or in the case of the Efficient Networks USB and PCI modems, the modem itself.
If you buy your own modem, or router, this will likely have its own, unique MAC address. Which means that anytime the network device is changed, BellSouth will need to know about it, or you won't be able to connect. This can be done by calling the FastAccess HelpDesk so they can register your new MAC address.
Note:
A recent round of upgrades included a conversion from Cisco to Redback 'termination' routers. And implemented a Redback feature known as 'Secure ARP'. Secure ARP has eliminated the ARP and IP broadcasts that used to be all too common. Nice improvement. It has also taken away the ability to assign ourselves static IPs when the DHCP server was down.
Footnotes:
· PPPoE/A are fairly recent protocols. While it is increasingly popular with large ISPs like BellSouth, these are considered less reliable than former DHCP/Bridged set up by many. Occasional disconnects are the biggest complaint. This seems to be the nature of the beast.
· All the Efficient Networks modems supplied by BellSouth have built in diagnostics. Apparently true of the 3Com PCI as well. The Alcatel 1000/SpeedTouch ethernet modems have none unfortunately, and probably is one reason BSIS is reluctant to use these. (Alcatel USB???)
· If you are on Bridged/DHCP service, and you change your Network Card that is connected to the modem, you will have to re-register the new MAC address with tech support, or you won't be able to connect. They can walk you through this. Also true if you are using a PCI or USB modem and change to a different modem. PPPoX does NOT require MAC address registration. It is not used.
· For an alternative OS (Linux, *BSD, OS/2, BeOS, Solaris), your only real hope is the ethernet Alcatel. This connects via ethernet to a NIC, and will work with any OS. Another option is to buy your own modem or router outright. Just make sure it is compatible with BellSouth's DMT (Alcatel compatible) based DSL service. There are other possibilities, notably CAP based service that will not work! Be aware that while there are a number of modems, routers, etc that work just fine with BellSouth, the only ones actually supported are those as provided by BSIS.
· BellSouth does supply the Cayman 3220H router for Business ADSL. By all accounts, this is a good quality combo modem/router. Cost from BellSouth is about $300 (?). Works with PPPoA and Bridged mode, and is NAT ready.
· FastAccess ADSL is 'full rate' ADSL. BellSouth is not offering G.Lite at this time. Also, it is 'non-interleaved' or 'Fast' DMT. This is good for ping times.
One way to simplify the modem/driver/client mess, is to purchase a router. There are any number of models available. Some come with an integrated modem, and all handle the common protocols (DHCP, PPPoX). This takes all the burden off of your computer, since the router 'does it all'. Unfortunately, BSIS does not officially support any routers at this time. (The exception being the Cayman 3220 that is supported under the business plan.)
feedback form
feedback form
by tomsprat edited by Andy Houtz
last modified: 2004-02-26 16:50:00 | | | In most service areas you can freely switch between PPPoA and PPPoE. It is important to note that it may take the BellSouth gateway routers several minutes to properly detect the switch. Also note that in very rare instances, the routers may become "stuck" in PPPoE mode. In this case, it would be necessary to contact BellSouth Technical Support to switch back to PPPoA.
feedback form
feedback form
by leevis edited by KeysCapt
last modified: 2004-01-31 10:49:14 | | | Switching the protocol from PPPoA to PPPoE or vice versa should have no effect on your BellSouth gateway router. In the past, it was not uncommon for the gateway router to become "stuck" in PPPOE mode. When that would happen, it was necessary for BellSouth to physically "reset" the router before it would recognize a switch to PPPoA. This problem was addressed in an update to the gateway router's firmware. Although the update apparently did not completely eliminate the problem, it is now extremely rare.
feedback form
feedback form
by leevis edited by KeysCapt
last modified: 2004-01-31 10:50:30 | | | BellSouth no longer offers a bridged connection option to new customers. This service was originally offered by BellSouth but was replaced by PPPoA/PPPoE.
feedback form
feedback form
by leevis edited by KeysCapt
last modified: 2004-01-31 10:50:56 | | | In order to reduce email spam and open relays, BellSouth filters Port 25 (SMTP - Mail) for almost all residential accounts. If you are unable to send or experience sporadic email sending and use an email domain other than "bellsouth.net" you may be blocked. If you have a secondary (non BellSouth) email check the BellSouth Port 25 FAQ for more info. Currently, BellSouth only filters Port 25. If you have ports blocked (other than 25) check the configuration settings on your equipment or software (modem, router, firewall, or PC applications, etc).
Andy Houtz DSL
feedback form
feedback form
by Andy Houtz edited by FAQFixer
last modified: 2006-12-27 22:34:27 | | | There are two ways an ISP can allocate or assign an IP address to you for use on the internet; static and dynamic.
Static IP Address
A static IP address is assigned to your computer by your ISP and is permanent. Each time you connect to the internet, the same address is used. This address is never used by any other computer or device.
Dynamic IP Address
It would be simple if every computer that connects to the Internet could have its own static IP address, but when the Internet was first conceived, the architects didn't foresee the need for an unlimited number of IP addresses. Consequently, there are not enough IP addresses to go around. To get around that problem, many Internet service providers economize on the IP addresses they possess by temporarily assigning an IP address to each computer from a pool of IP addresses. The temporary IP address is called a dynamic IP address. As a result, the IP address may be different each time the computer connects to the Internet.
|
|
