Satellite Internet Service
Spead Tweaks

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What is DrTCP and how do I use it?
DrTCP is a small utility that provides a window to the area of your registry that stores adjustable TCP settings. Using this program is a very easy way to adjust settings that can make a huge difference in your download speed.

You can download DrTCP now by clicking
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When you load up DrTCP, go to the field marked "Adapter Settings". If you are tweaking the computer that is directly connected to the satellite modem, in that field, use the small arrow to the right to select "Satellite USB Device". If you are tweaking a network client computer, choose the Network Interface Card (NIC) for that computer.

Don't forget to save your changes and re-boot to have them take effect.

In the actual tweak instructions, we assume you are using DrTCP.

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Important Info for WIN2K SP1 users using DrTCP!!
When you installed the DirecPC, DirecWay, Earthlink or Pegasus software on your computer, it installs a registry key called GlobalMaxTcpWindowSize. If you are using WIN2K you should upgrade to Service Pack 2 to fix a bug in this key that causes DrTcp changes to have no effect on RWIN. If you don't want to upgrade to SP2, then you must delete the key. Note: You do not need to delete this key if you are using Win2K SP2 or above or XP.

Using Regedit you can find the key at: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
Open the Parameters folder and locate the key GlobalMaxTCPWindowSize, right click on it and choose delete.

After the key is deleted you can set your RWIN with DrTCP, reboot, and the RWIN you selected will be used.

Remember, that if you upgrade or re-install your satellite software, you will need to use regedit to delete this key again.
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Optimal Settings for Satellite Return (Two-Way) Systems
Tcp Receive Window (RWIN): 224360
Window Scaling: YES
Time Stamping: NO
Selective Acks: YES
Path MTU Discovery: YES
Black Hole Detection: NO
Max Duplicate Acks: 3
TTL: 64
MTU: 1500

Try these settings first. If you find that your download speeds are at or over 1,500kbs with these settings, then increase the RWIN to 474280, so that you can get the full download speed potential available to you. If your speeds are ALWAYS below 1,500kbs, raising your RWIN any higher than 224360 won't help, and may actually hurt your connection speed.
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Is there something I can do to improve my upload speeds with SRS?
One tweak for upload speed is to turn Path MTU Discovery to YES in DrTCP. Without this switch turned on, Windows treats the Satellite Upstream path as a dial-up path, and changes the MTU for the path to 576, regardless of what you have the MTU set for on the adapter. By turning Path MTU Discovery on, Windows will see that the upstream path minimum MTU is 1460-1500 bytes, and will adjust accordingly. - PD

2. A registry tweak has been found and tested to improve upload speeds on Satellite Return Systems. The only problem is that it only pertains to certain operating systems, with certain processors, with certain amounts of memory. This tweak requires modifying the registry, so please be sure to back up your registry before doing any of these modifications. This tweak has been extensively tested, and has not shown any signs of being problematic with any system. The details for the certain systems that this works on are below, but don't be afraid to try them if you fall out of these parameters. The registry modification can easily be deleted if it doesn't work for you or if you just want rid of it.

The following details have found to have the best impact of this tweak:

Operating system:
Windows XP (Home and Pro)
Windows 2000

Processor:
Pentium 3
Pentium 4
AMD

Minimum memory:
384mb SDRAM
256mb DDRAM
256mb RDRAM

*512mb of any RAM seemed to be the platform where things work the best. Any more than 512mb didn't see any improvements.


There are 2 different values to enter in the registry for the 2 different operating systems:
Windows XP - 18000
Windows 2000 - 17a00
Don't be afraid to try either one though - throughout the testing these values coupled with these operating systems seemed to get the best results.


Here are the instructions for the tweak. Please be sure to back up your registry first!

\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters

Open Run and type in regedit click ok.

click on
HKEY_LOCAL_MACHINE
SYSTEM
CurrentControlSet
Services
AFD

Right Click on AFD and select New, and Key name the new Key Parameters
Click on Parameters.
On the right side you will see (Default) right click in the empty area and select New, DWORD Value.
Name this Dword value DefaultSendWindow
Double click on DefaultSendWindow and enter either 17a00 or 18000 leave it on Hexadecimal.

Click OK, close and then reboot.

If you don't like it, all you have to do is delete the Parameters entry. Remember, always backup your registry.


This tweak has been found to double our upload speeds for Satellite Return Systems.


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Is there anything I can do to improve the performance of the DW proxy server
Try changing your proxy port from 83 to 85. To do this open up control panel and go to internet options.Then click on connection tab. Then click on LAN settings. Then click on advanced. Then change port from 83 to 85. If you have Internet Explorer open you can get to the same place by clicking on tools at top. Then internet options and go from there.
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Reduce your cache for better browsing
This technique has been reported by many users to enhance the "snappiness" of browsing with these high latency connections.

It seems that Satellite Return Systems (SRS) get more of a benefit than Dial Return Systems (DRS) from this tweak, because of the greater latency with SRS.

Try reducing your browser's cache to 1mb size.

In IE, go to Tools -> Internet Options. Under "Temporary Internet Files" press the "settings" button. Under "Temporary Internet Files Folder" change the number in the box to 1. Press OK, then OK again.
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Should I try speed patches I see at other sites?
Using "one size fits all" speed tweak patches is an incredibly bad idea. Here are just a few reason why:

1. These patches were never developed with the high latency and high speed combination of satellite in mind.

2. Because the developers don't know how many TCP adapters are on your system, they play tricks to make sure all adapters get "tweaked". One of the most common tricks is to assume there will be no more than 10 adapters, and therefore to create registry entries for 10 adapters. Since almost no one has 10 TCP adapters on their computer, this creates many excess registry entries causing extra overhead and great confusion if you ever need to figure out what is what in your registry.

3. Many of the patches give you no way to undo the changes you made after they have completely destroyed your connection, or only to undo themselves incompletely. Many people have had to re-format their drives and re-install a clean copy of their o/s to fix the problems created by speed patches.

The bottom line is that by using DrTCP, you control the changes and you can always change things back to if you like.

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I Tweaked with DrTCP but the Tweak Tester doesn't report the changes.
With DirecPC/Direcway systems, including Earthlink and Pegasus express since you have no public IP, the tweak tester gets confused as to what machine to test. The result is you are seeing results from an intermediate machine at the DPC NOC.

Ignore any results you get from the DSLR tweak tester if you are on a DirecPC/Direcway based system. The results you are getting from the tweak tester are not for your computer.
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I'm sharing my connection on a LAN. Do I need to do more?
Yes. In order to get the client computers on a network to have the same performance as the host computer, there is a bit more work to be done. A three-step process. You can skip step one if you are not using Windows 98SE with ICS on the host computer.

1. First if you are using Windows 98SE and ICS, a registry key is created that is killing your speed, even on the host. This key was originally put in to support dial-up internet connections and has been removed from subsequent versions of Windows. You need to delete the key or at least give it a null value. Since you have DrTCP it's easy. Open DrTCP on the host computer. Find the section entitled "ICS Settings". In that section, there is a window marked "Internet MTU". Delete any value in that window. Make it blank. Push "Save", exit, and re-boot.

Now you need to get the client computer(s) up to speed.

2. Load DrTCP on each client. In the "adapter settings" window, choose the Network Interface Card (NIC) for that machine. Make the settings exactly the same as the settings you put on the host machine for "Satellite USB Device". Push Save, exit and re-boot.

3. Your host machine was set up by the DPC software install to use several simultaneous TCP connections. This is done to reduce the effects of latency on browsing, and the result can be quite dramatic. You will want your client(s) to have the same advantage, but for them you will have to make the registry keys manually using regedit. (Start->Run->Regedit)

Basically you need to add two registry keys. Below you will find where in the registry to put the keys and what to name the keys. Navigate to the locations specified in the left pane, then in the right pane, right click and choose to create a "New" Dword value. Name them exactly as shown. Once they are there, double click on each and insert the value 15 (HEX). Once you've done that, exit regedit, re-boot. Your work is done.

WinXP and Win2k: All DWORD Values

HKEY_USERS.DEFAULTSoftwareMicrosoftWindowsCurrentVersionInternet Settings

MaxConnectionsPerServer
MaxConnectionsPer1_0Server

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionInternet Settings

MaxConnectionsPerServer
MaxConnectionsPer1_0Server

WINME / 98 All DWORD Values

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionInternet Settings
MaxConnectionsPer1_0Server
MaxConnectionsPerServer

4. (Submitted by Seagreen) There are a few more settings that need to be added to the client machine's NIC Network properties.

Add the Host's IP address (192.168.0.1) as the Default Gateway and as the preferred DNS server. Add a Hughes DNS server (usually 198.77.116.8) to the DNS servers list as an alternate after the Host machine's IP address. Adding these helps speed up the client machine's Domain Name Resolution and consequently, browsing. It also helps the client machine get email from POP accounts.

Follow the instructions below for your particular OS:

Windows 98:

Start => Settings => Control Panel => click on the Network icon or right-click on the Network Neighborhood icon and choose 'Properties'. Either way gets you into the Network configuration screens.
From the list of installed clients, protocols and services, locate TCP/IP bound to the NIC It will look something like this: TCP/IP -> your network card. The arrow indicates the protocol is bound to that adapter. Highlight that and then click the Properties button. This gets you into the TCP/IP configuration screens. Click the DNS Configuration tab. Put as dot in the 'Enable DNS' radio button.
Then add the DNS servers, starting with the Host machine's IP address (192.168.0.1). Add the Hughes' DNS servers' IP addresses (198.77.116.8) in after that. For domain, enter "direcway.com."
Next click the Gateway tab and enter 192.168.0.1 as an installed gateway. 'OK' your way out, you'll be asked for the Windows 98 CD if the CAB files are not on your HD and you'll be asked to reboot.

Windows ME:

Start => Settings => Control Panel => click on Network icon, or right-click on My Network Places icon on desktop, and choose 'Properties'. Either way gets you into Network Configuration screens. From the list of installed clients, protocols and services, locate TCP/IP bound to the NIC It will look something like this: TCP/IP -> your network card. The arrow indicates the protocol is bound to that adapter. Highlight that and then click the Properties button. This gets you into the TCP/IP configuration screens. Click the DNS Configuration tab. Put a dot in the 'Enable DNS' radio button.
Then add the DNS servers, starting with the Host machine's IP address (192.168.0.1). Add the Hughes' DNS servers' IP addresses (198.77.116.8) in after that. For domain, enter "direcway.com."
Next click the Gateway tab and enter 192.168.0.1 as an installed gateway. 'OK' your way out, you'll be asked for the Windows ME CD if the CAB files are not on your HD and you'll be asked to reboot.

Windows 2000:

Start => Settings => Network and Dialup Connections. Highlight and right-click on your LAN listing (usually called Local Area Connection) and choose 'Properties.' Highlight TCP/IP and click 'Properties.'
On the following screen, enter the host's IP (192.168.0.1) address as the default gateway and as the Preferred DNS server. Add a Hughes DNS server (198.77.116.8) as an alternate.

Windows XP:

Right click on My Network Places icon on the desktop or Start => Settings => Network Connections. Select "properties". Right click on the Local Area Connection icon and chose Properties. Highlight TCP/IP and click the 'Properties' button. If you are not configuring the IP address manually, but obtaining it from the Host machine, you will not be able to enter a default gateway on the initial screen. Add the DNS servers, starting with the Host's IP address (192.168.0.1) followed by a Hughes DNS server (198.77.116.8). Click the 'Advanced' button. On the IP Settings tab, add the host machine's IP address (192.168.0.1) as the default gateway. Click the DNS tab and add direcway.com as the DNS suffix for this connection. 'OK' your way out and close the network properties interface.



Where do the tweak numbers come from?

All of the recommended "optimal settings" were formulated by a combination of theory, long hours of testing, and results reported by DSLR members. The specifics of what the settings mean and why we set them a certain way for satellite connections follow.

By far, the most important setting is the TCP Receive Window or RWIN. The Tcp Receive Window is nothing more than a data buffer. Think of it as a bucket. Your RWIN setting determines how big the bucket is. Data is coming down from the satellite, filling the bucket. Your computer is emptying the bucket as it processes the contents. We can't let the bucket overflow, or we would have to ask the sender to re-send what got spilled on the floor. That's inefficient.

If the bucket gets empty, your computer is doing nothing, just waiting for the stream to start again, also inefficient.

The other problem is there is a lag between the time your computer says "Send more, my bucket is almost empty" or "My bucket is almost full, please stop" and the time the sender gets that message. And another lag between when the sender starts sending again or stops, and the result hits your computer. That's latency.

If the bucket is the perfect size, it is never completely full nor completely empty until there is no more stuff to send. The perfect size bucket allows your computer to send the messages at the right time such that the data stops just before the bucket fills and starts just before the bucket empties. Now you can have too large a bucket, because the sender expects to hear those messages now and then. If it doesn't hear from you, it thinks your bucket isn't getting anything at all so it keeps sending the same stuff, over and over, until it gives up on you and stops sending anything. Very inefficient!

RWIN is determined mathematically. The required variables for the equation are Maximum Potential Speed (MPS) of the line, Maximum Segment Size (MSS) of the packet and Return Trip Time (RTT)(which most people measure with "ping" tests). Depending on the type of connection, a multiplier is usually applied to RTT to account for bad ping days. But generally the simple construction of the equation would be (MPS * Average Worst RTT)/8. The result is then converted to the nearest multiple of MSS.

Selective Acks enables re-transmissions of data to consist only of lost packets, rather than entire receive windows. It is very important to enable selective acks when using large receive windows.

Window Scaling allows for RWIN values above 65535. Since Windows only allocates 2 bytes to represent the RWIN value, a value greater than 65535 cannot be represented. By turning Window Scaling on, a scaling factor is applied to the value found in the two bytes to represent larger numbers.

TTL is Time To Live and determines how many hops a packet is allowed to take before being declared lost. If the value is too small, unnecessary packet loss occurs as packets that just haven't reached their destination are lost. If it's too large, then too much time is spent waiting on packets that are truly lost.

Time Stamping: Time stamping adds timing header information to each packet so that Windows can calculate RTT on the fly and use this information to estimate the best points in the empty/full cycle of the receive window to send AKS. Logic would say that would have to make a Long Fat Pipe (meaning high latency, high speed) connection such as satellite more efficient. The reality is that with DirecPC/DirecWay based systems, while it slightly but measurably increases speed, it also prevents certain web sites from loading correctly and can make some email attachments cause email to hang. So the recommendation is for it to be off for DPC, because a number of us have had problems with it turned on.

Path MTU Discovery: This setting changes your MTU on the fly to match the smallest MTU on your path to the server you are communicating with. Testing has shown that tunring it on can, in some cases significantly improve upload speed on two-way systems. Please note that you may notice little or no difference in upload speed "tests" as the file size used on test sites (about 50KBS) is just too small to measure the speed without being skewed by the high latency of a satellite system. To more accurately measure your results, use an FTP client and do an FTP upload to a server of a 750KB file or larger.

Black Hole Detection: Does absolutely nothing if Path MTU Discovery is disabled, may cause problems even when it is enabled...leave it off

Max Dup Acks: Valid values are 1, 2 or 3. Win2k defaults to 2, 98 and ME default to 3. Probably makes absolutely no difference one way or another which value is chosen. It defines the number of duplicate AKS that are allowed to be sent before Windows invokes Fast Re-Transmission. This would occur in a packet loss situation. Windows gets an out of sequence ACK. It figures some packets must have been lost. It sends an ACK back for the lost packet. When the receiver sees the first ACK for a packet, then either 1, 2 or 3 more for the same packet, depending upon how max dup acks is set, it re-sends the whole segment again figuring that it must be lost...that's fast re-transmission.

source: http://www.highspeedsat.com