There has been many inquiries on optimizing the Malaysian Broadband Services ( Streamyx ) but there is none available in the web, so we are setting up one in hope that users in Malaysia may benefit from it.
Q: Max MTU: How do I find mine? (#695)
A: The MTU setting controls the maximum ethernet packet size your PC will send (you did know the internet works in packets, didn't you?). Why a limit? because although larger packets can be constructed and sent, Your ISP and Internet backbone routers and equipment will chop up (fragment) any larger than their limit, then these parts are re-assembled by the target equipment before reading. This fragmentation, and re-assembly is not optimal.
MTU and Windows and Defaults
Unless otherwise set, windows defaults MTU to 1500, or a lower value of 576 for external networks. 1500 is ok unless you are running PPPoE, or want to use IPSec (Secure VPNs), or both, (it is then too big). 576 is not efficient for the broadband/internet, (it is too small).
Finding the largest MTU, by EXPERIMENT
If your MTU is too low already, (maybe 576), the following method will not be able to detect whether you can switch to an optimal size..... So first follow "CHANGING MTU for PPPoE" to reset MTU to 1500, reboot, then come back to this!
The best value for MTU is that value just before your packets get fragmented. How do you find out that? By using Ping at an MSDOS command prompt.
Go to Start/ Programs/ MSDOS-PROMPT, and type....
ping -f -l 1472 www.streamyx.com.my -t ( Use streamyx to ping for Malaysian Broadband )
(That is a dash-ell not a dash-one. Also note the spaces in-between the sections) Press Enter. Then reduce 1472 by 10 until you no longer get the "packet needs to be fragmented" error message. Then increase by 1 until you are 1 less from getting "packet need to be fragmented" message again.
Add 28 more to this (since you specified ping packet size, not including IP/ICMP header of 28 bytes) And this is your MaxMTU.
Note:If you can ping through with the number at 1472, you are done! Stop right there. Add 28 and your MaxMTU is 1500.
For PPPoE, your MaxMTU should be no more than 1492, to allow space for the 8 byte PPPoE "wrapper", but again, experiment to find the optimal value.. For PPPoE, the stakes are high: if you get MTU wrong, you may not just be sub-optimal, things like UPLOADING, or web pages, may stall, or not work at all!
*USE DRTCP,TweakMASTER to change your MTU.
TCP Receive Window: This is where you set RWIN (RcvWindow). RWIN is the single most important tweak. Raising Rwin from default (8760 for Win95/98/98SE/NT and 17520 for WinME/2K/XP), can greatly improve download speeds. Why? Here is my kindergarten analogy: Default RWIN for broadband, is like having a tiny straw in a thick milk shake, only so much can get through the straw (line), so fast. By putting a larger straw (higher RWIN) in that same thick shake, you allow more shake (data) to come through faster, to a point that is. After which, there is no more improvement, and shake (data) can start spilling all over (packet loss). So the key is, to find an RWIN that fits your line just right. This is blank before changing from default. ( MTU-40 x 16 works best on Malaysian Broadband )
The formula for finding your "ideal" RWIN, is to take your latency (average ping time in ms x 1.5), multiply that by your advertised (download) speed, and divide that by 8.
Q: Max MTU: How do I find mine? (#695)
A: The MTU setting controls the maximum ethernet packet size your PC will send (you did know the internet works in packets, didn't you?). Why a limit? because although larger packets can be constructed and sent, Your ISP and Internet backbone routers and equipment will chop up (fragment) any larger than their limit, then these parts are re-assembled by the target equipment before reading. This fragmentation, and re-assembly is not optimal.
MTU and Windows and Defaults
Unless otherwise set, windows defaults MTU to 1500, or a lower value of 576 for external networks. 1500 is ok unless you are running PPPoE, or want to use IPSec (Secure VPNs), or both, (it is then too big). 576 is not efficient for the broadband/internet, (it is too small).
Finding the largest MTU, by EXPERIMENT
If your MTU is too low already, (maybe 576), the following method will not be able to detect whether you can switch to an optimal size..... So first follow "CHANGING MTU for PPPoE" to reset MTU to 1500, reboot, then come back to this!
The best value for MTU is that value just before your packets get fragmented. How do you find out that? By using Ping at an MSDOS command prompt.
Go to Start/ Programs/ MSDOS-PROMPT, and type....
ping -f -l 1472 www.streamyx.com.my -t ( Use streamyx to ping for Malaysian Broadband )
(That is a dash-ell not a dash-one. Also note the spaces in-between the sections) Press Enter. Then reduce 1472 by 10 until you no longer get the "packet needs to be fragmented" error message. Then increase by 1 until you are 1 less from getting "packet need to be fragmented" message again.
Add 28 more to this (since you specified ping packet size, not including IP/ICMP header of 28 bytes) And this is your MaxMTU.
Note:If you can ping through with the number at 1472, you are done! Stop right there. Add 28 and your MaxMTU is 1500.
For PPPoE, your MaxMTU should be no more than 1492, to allow space for the 8 byte PPPoE "wrapper", but again, experiment to find the optimal value.. For PPPoE, the stakes are high: if you get MTU wrong, you may not just be sub-optimal, things like UPLOADING, or web pages, may stall, or not work at all!
*USE DRTCP,TweakMASTER to change your MTU.
TCP Receive Window: This is where you set RWIN (RcvWindow). RWIN is the single most important tweak. Raising Rwin from default (8760 for Win95/98/98SE/NT and 17520 for WinME/2K/XP), can greatly improve download speeds. Why? Here is my kindergarten analogy: Default RWIN for broadband, is like having a tiny straw in a thick milk shake, only so much can get through the straw (line), so fast. By putting a larger straw (higher RWIN) in that same thick shake, you allow more shake (data) to come through faster, to a point that is. After which, there is no more improvement, and shake (data) can start spilling all over (packet loss). So the key is, to find an RWIN that fits your line just right. This is blank before changing from default. ( MTU-40 x 16 works best on Malaysian Broadband )
The formula for finding your "ideal" RWIN, is to take your latency (average ping time in ms x 1.5), multiply that by your advertised (download) speed, and divide that by 8.
Note: If setting RWIN below 8192, try using even multiples of MSS.
Windows Scaling: 65535 is the highest RWIN you can use without Windows Scaling being turned on. So simply put, Scaling is needed to enter any number higher than 65535. However, you must also have the updated vtcp.386 patch (WinME/2K/XP does not need a patch). Relax though, most users do not need to go higher than 65535. Windows Scaling "Defaults" to off (same as No).
Time Stamping: The need for this seems to be in question, at least with RWIN under 65535. If you have a line where latency varies a lot, or a "long fat pipe" (for example, pure satellite connection), then Time stamping should be beneficial, so experiment with it. Time Stamping "Defaults" to off (same as No).
Selective Acks: This improves throughput (speed) on lines that tend to lose packets, by re-transmitting only packets that were lost, if any. "Defaults" to on (same as Yes) in Win98/98SE/ME/2K/XP and is N/A in Win95/NT.
Path MTU Discovery: This automatically sets your MTU (maximum transmission unit) to what type of line you have (dial-up (576), broadband 1492-1500). This is the size of packets that you can receive. The highest MTU that one can have is 1500. For users with PPPoE connection software, 1492 and lower. Without PPPoE, it should default to 1500. "Defaults" to on (same as Yes) in Win98/98SE/ME/2K/XP/NT, and is N/A in Win95.
Black Hole Detection: This discovers routers on the WEB that cause MTU Discovery to work sub-optimally. "Defaults" to off (same as No) in Win95/98/98SE/ME/2K/XP.
Max. Duplicate ACKs: This allows for faster re-transmission of packets (information), when packet loss is encountered. "Defaults" to blank, where blank stands for 3 in Win98/98SE/ME, 2 in WinNT/2K/XP, and is N/A in Win95.
TTL: Time To Live is the amount of hops (servers) that a transmission of packets will take before all packets are lost. If you were receiving packets from 20 hops away, and TTL was set to 19 or less, all packets would be lost before they reach you. Streamyx has an average of 8% packet loss. "Defaults" to blank, where blank stands for 32 in Win95, 128 in Win98/98SE/ME/2K/XP.
Adapter settings: This is where you set your MTU. Use the drop-down menu to find your NIC (Ethernet card). If you do not know which adapter you should set, please ask. Do not set them all the same. (Note: If your MTU is 1500 by default, it will be blank in DRTCP. Also: Only physical NIC's supported for XP, no dial-up adapters.
Note: DRTCP defaults to showing the dial-up adapter. This has nothing to do with the other settings. It does not matter which adapter is visible when setting anything except MTU. Also: Upon reboot the dialup adapter will be showing, regardless of which adapters MTU was set.
ICS Settings: Internet MTU is set when Internet Connection Sharing (a Microsoft program) is enabled and being used on your PC. This is where 2 or more PCs share the same Internet connection, though only one can “surf?at a time. ICS MTU should match that of the PC. This is grayed out if ICS is not being used (not ready for Win2K/XP).
Also: By right clicking on the logo and choosing "About", you will find information about the version of Windows you use.
Great, so what should you set all of these to? ( Malaysian streamyx RWIN seems to work best at MTU-40 x 16 )Most users can leave all of them at Default except for RWIN (surprise!), as this has been determined to be best, most of the time, thus being "Default". After making any changes, click Save, then Exit, then reboot (restart) your PC. Use the Tab button on your keyboard to move about DRTCP. If you do not reboot, the settings will not "take".
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