WIN7 XP Setting the MTU to increase download speed

There may be very few Reyou that have noticed the impact of the "MTU" value of the "native, network" on their own network performance. For faster download speeds, the MTU value is set incorrectly, as if running in high heels.

What is the MTU?

"Mtu= Maximum Transmission Unit unit: bytes"

The various network operations that we do when we use the Internet are implemented through a "packet" transfer. The MTU specifies the maximum size of the packets that can be transmitted in the network, and in our usual Ethernet, the MTU is 1500 bytes. Packets that exceed this size will split the extra pieces and transfer them separately.

Why does MTU affect network performance?

Let's take a look at this, in Windows, the default MTU value is also 1500 bytes, but "different access methods, network operators in different regions, different routers" have different MTU settings.

For example: ADSL access MTU is 1492 bytes, assuming a need to transmit 3000 bytes of data b, if the entire transmission process of the MTU is 1500, then 2 packets can be transmitted. But then the ADSL access Mode MTU is 1492 bytes, the packet because of this MTU difference is split into 3 additional (for the sake of understanding, the "packet header" is not taken into account for the time being)

Obviously this increases the number of packets that need to be transferred, and the process of unpacking the package is a waste of time. If you use a consistent MTU from the local to the network, you can avoid additional unpacking.

How much does it affect download speed?

Take Evans home line quality of telecommunications 4M bandwidth for example, the operating system MTU value to 1492, and then the router's MTU value from 1460 to 1492, the download speed from the original 435kb/s to 450kb/s, improved 15kb/s. The detection results of the telecom bandwidth detection tool also increased from 4.09M to 4.19M.

How do I set the MTU properly?

Faster download speed, for the users of thunder, obviously very meaningful. But the MTU setting cannot be a value universal, so we pay attention to set the MTU reasonably.

So what's the reason for the MTU value?

Let's start by looking at what's unreasonable:

1, the local MTU value is greater than the network MTU value, the local transport of packets too large causes the network to be split after the transfer, not only to generate additional packets, and consumption of "unpacking, package" time.

2, the local MTU value is less than the network MTU value, the local transmission of the packet can be transmitted directly, but did not fully utilize the network to give the packet transmission size of the upper limit, the transmission capacity is not fully played.

So we know that the so-called reasonable setting of the MTU value, is to let the local MTU value and the network's MTU value consistent, can not only fully play the transmission performance, and do not let the packet split.

The next most important thing is to find out how much the MTU is reasonable for your network environment.

Here's how:

1, press Win+r key combination, bring up the "Run" menu, enter "cmd" and then return

2. Enter "Ping-l 1472-f www.baidu.com" in the "Command Prompt" window that appears and then enter

Meaning:

Ping: initiates a probe request;

-L (lowercase in L): limits the size of the probe packet;

1472: Packet size is 1472 bytes;

-F: Disable router splitting of packets

Www.baidu.com: Set Baidu as the detection target

(You asked me why I didn't use Google as my goal?) Considering that Google has been a wall from time to time, forget it. ）

3. There are 2 kinds of situations:

(1), if you receive a reply, then your network allows the maximum MTU value is 1500 bytes, the same as the system defaults, only need to set the router's MTU value also to 1500;

(2), if there is a need to split the packet but set DF. Or Packer needs to being fragmented but DF set, that means the packet size exceeds the network-qualified MTU size. The probe packet size needs to be reduced again. (To cut, I changed the probe package to 1473)

4, press "Up ARROW" to restore the command just entered, and then 5 for the span to reduce the packet size of 1467 bytes, again enter the probe.

5. There are also two possible ways to do this:

(1), if there is a return, indicating that the packet is less than the MTU limit, the packet size +3 is again probed, if not returned after +3, the packet size is reduced by 1 to detect.

(2), if there is no return, continue to reduce the packet size by 5, until there is a return after the operation in 5 (1).

6. Until you find the packet-1, with a return, it means that you have detected the exact packet size allowed by the MTU. (e.g. reduced from 1465 to 1464 with return, then the allowable packet size is 1464)

7, but the above value can not be set to the operating system or router MTU, you find the packet size needs to add 28 bytes of "Packet Header" is the full packet size.

(For example: The detected packet size is 1464, then add 28 bytes, the final mtu=1492 bytes)

8. Finally, you only need to set the MTU value in the router and operating system to the result you obtained.

Router Setup method See router manual! It is recommended to modify the operating system MTU using software such as Windows Optimizer, Super Bunny Magic Settings, and Master Lu.

The following are the more complex methods:

(1), XP operating system Setup method:

1, press WIN+R combination key, bring up the "Run" menu, enter regedit, and then enter;

2, choose "Hkey_local_machine>system>currentcontrolset>services>tcpip>parameters>interface";

3, in the interface may have many items, you need to observe the key value, there will be an item with your network card IP consistent, select the item;

4. Then right-click on the key, select "Edit > New >dword value", and name it "MTU" on the right;

5, right click on the MTU, select "Modify", in the pop-up window select "Decimal", fill in your reasonable MTU value can be reached.

(2), Vista, Win7 operating system Setup method:

1, enter the system disk: \windows\system32\ find Cmd.exe, right button "Run as Administrator";

2. In the "Command Prompt" window that appears, enter "netsh interface ipv4 show subinterfaces" and enter to view the current MTU value

3, then enter "netsh interface ipv4 set subinterface" to modify the connection name "mtu= you come to a reasonable value store=persistent" and enter can be

For example: "netsh interface ipv4 set subinterface" Local Area Connection "mtu=1492 store=persistent"

WIN7 XP Setting the MTU to increase download speed