Using a PPPoE Broadband Router : Settings and Tweaks
I drafted this, based on my own experience (and other detail I’ve collected and found in the past) because of the many questions and issues posted here, involving a properly setup PPPoE Broadband Router for use in the MyWireless (MW) network.
Presumption is made that users are aware that the basic configuration of their routers will require the activation of two settings “Dynamic PPPoE”, & “Always on” mode.
This given, the main issue should be to focus on your Tcp Receive Window (RWIN), and MTU (Maximum Transmission Unit) settings as these are the important things that will affect your speed. (Most published recommendations are based on much higher broadband speeds, as used in the USA… and are simply not (in my opinion) effective on our high latency MW network).
I have done these tweaks myself, using dr.TCP. To my knowledge, this software is basically nothing more than an interface into the Windows registry.
TTL - A default of 128 is recommended.
Remember that TTL is not a speed setting, but rather related to hop count.
DHCP - If your PC tends to freeze regularly, your computer may well be looking for a DHCP server that is problematic or faulty. Also problems can occur with the DHCP services that can initiate every few minutes to look for a DHCP server. Best bet is to disable the DHCP server setup (in-built in your router) and then manually configure your ip address and setup etc., remembering that your PC must now point to the router to become the default gateway.
RWIN – Here is a simplified but effective approach. Measure your average ping times to the Sentech or IS web site adding 60% to cover the inevitable slower wireless communications etc. Multiply that by your MW package speed (i.e. 128, 256 etc) and then divide that value by 8. Now you have your raw RWIN value.
i.e on a MW 256K package with a 300ms average latency (x 60%).
480 x 256kbps = 122880 divided by 8 = 15360 RWIN.
Users who leave their RWIN at default (this is way too high) will get an inefficient solution when trying to use PPPoE on the MW network.
MTU - The best way to test for an optimum MTU setting is to do a simple DOS Ping test. Simply send ping requests and progressively lower the packet size until the packet fragmented error goes away!
Note: MW Users may well find that a lower MTU may be better for their particular circumstances.
Here is what you do:
ping -f -l 1472 www.sentech.co.za (That is lower case F and L)
Then continue testing, reducing the 1472 in unit’s of 10 until you no longer get any fragmented error messages. Then start increasing by 1 until you reach a figure without fragmented errors. In my case, with a D-Link DI-604 router I found it to be 1422.
Now… add to this a figure 28 (IP/ICMP header of 28 bytes) and this is your Max MTU. I.e. in my case 1422+28=1450
Ensure that the Router and ALL your PC’s now have the same MTU (i.e. 1450) setting.
When using PPPoE, your maximum MTU setting should never be greater than 1492.
If you get your MTU wrong, uploading, or browsing, may not just be sluggish… it may well freeze, or not work at all!
I drafted this, based on my own experience (and other detail I’ve collected and found in the past) because of the many questions and issues posted here, involving a properly setup PPPoE Broadband Router for use in the MyWireless (MW) network.
Presumption is made that users are aware that the basic configuration of their routers will require the activation of two settings “Dynamic PPPoE”, & “Always on” mode.
This given, the main issue should be to focus on your Tcp Receive Window (RWIN), and MTU (Maximum Transmission Unit) settings as these are the important things that will affect your speed. (Most published recommendations are based on much higher broadband speeds, as used in the USA… and are simply not (in my opinion) effective on our high latency MW network).
I have done these tweaks myself, using dr.TCP. To my knowledge, this software is basically nothing more than an interface into the Windows registry.
TTL - A default of 128 is recommended.
Remember that TTL is not a speed setting, but rather related to hop count.
DHCP - If your PC tends to freeze regularly, your computer may well be looking for a DHCP server that is problematic or faulty. Also problems can occur with the DHCP services that can initiate every few minutes to look for a DHCP server. Best bet is to disable the DHCP server setup (in-built in your router) and then manually configure your ip address and setup etc., remembering that your PC must now point to the router to become the default gateway.
RWIN – Here is a simplified but effective approach. Measure your average ping times to the Sentech or IS web site adding 60% to cover the inevitable slower wireless communications etc. Multiply that by your MW package speed (i.e. 128, 256 etc) and then divide that value by 8. Now you have your raw RWIN value.
i.e on a MW 256K package with a 300ms average latency (x 60%).
480 x 256kbps = 122880 divided by 8 = 15360 RWIN.
Users who leave their RWIN at default (this is way too high) will get an inefficient solution when trying to use PPPoE on the MW network.
MTU - The best way to test for an optimum MTU setting is to do a simple DOS Ping test. Simply send ping requests and progressively lower the packet size until the packet fragmented error goes away!
Note: MW Users may well find that a lower MTU may be better for their particular circumstances.
Here is what you do:
ping -f -l 1472 www.sentech.co.za (That is lower case F and L)
Then continue testing, reducing the 1472 in unit’s of 10 until you no longer get any fragmented error messages. Then start increasing by 1 until you reach a figure without fragmented errors. In my case, with a D-Link DI-604 router I found it to be 1422.
Now… add to this a figure 28 (IP/ICMP header of 28 bytes) and this is your Max MTU. I.e. in my case 1422+28=1450
Ensure that the Router and ALL your PC’s now have the same MTU (i.e. 1450) setting.
When using PPPoE, your maximum MTU setting should never be greater than 1492.
If you get your MTU wrong, uploading, or browsing, may not just be sluggish… it may well freeze, or not work at all!
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