Many Internet users, for which secure connections from providers are used, may experience discomfort associated with the inability to open some Internet resources. The solution to the problem is sometimes solved radically - the router or provider changes, but there is a high probability of correcting the situation on your own by setting up only one parameter called MTU in the router. What it is, how to find and configure it correctly are the issues that are discussed in this article.
Clarification
To increase the speed of the Internet through communication channels , packet data is used. After all, it makes no sense to send and receive information for each bit, downloading the channel. Therefore, a technology was created that allows you to collect the data stream in a special package, which is transmitted over distances. Upon receipt of the package, the destination computer simply unpacks it and receives the source data. In the process of using such a system, limitations were identified that led to a loss of speed with increasing packet size. Due to this, they introduced the corresponding standard - the maximum transmission package for equipment (Maximum Transmission Unit), and MTU for short, in the router. What is it, of course, it remains to identify the reasons why this standard does not work correctly.
Paranoia or safety
Naturally, any standard provides for the solution of problems in emergency situations. For MTU, a special fragmentation was developed, which allowed at a low level to resize the packet at the request of the destination computer on the network. The request itself was fulfilled at the TCP transport layer using the ICMP protocol, the task of which is to transmit service messages. Data link layer protocols when it is impossible to receive a packet send a message about the impossibility of this. The sender reduces the size of the package and sends again. However, this does not always work. Indeed, very often lazy administrators manage Internet resources, who, instead of fine-tuning the security system, go the easy way, disabling, in their opinion, unnecessary protocols. Naturally, ICMP is one of them. But there is no message - there is no problem, the end user, for some reason, does not use the paid service in full.
Great ping score
And in order to forever leave the doubts that technical support of any provider puts into the user's mind, you need to know an important fact - the ping command is not an indicator. Since its primary task is to check the availability of the resource, but not the quality of the communication channel. You can verify this yourself by running ping ya.ru on the command line. The response from the destination server will indicate that a packet of 32 bytes has been received. And if you send a packet set by the standard of 1500 bytes? The command will look like this: ping ya.ru –f –l 1500. Where l is the size of the packet, and f is the fragmentation ban. Problems can appear, starting from the impossibility of acceptance, ending with losses on the channel. Taking into account that all information received from the Internet is transmitted in large packets, trusting the ping command to check the channel is impractical. In this case, the packet size is nothing but the MTU value, editing which can improve the Internet.
Provider Features
First of all, you need to understand what Maximum Transmission Unit parameter is set for the provider. If the Internet service is provided by supplying a twisted-pair cable, without any network settings, there will be no problems. But in cases of using secure PPPoE channels or virtual private VPNs, you need to be prepared that you can’t do without setting up a router and a computer. There are a lot of options for determining the correct package size, as well as solutions to the problem, and attention will be paid to several, most effective methods. Naturally, you can try to find out the MTU parameter from the provider in the telephone mode and register it on the router, but this is too simple and, most likely, impossible due to the low competence of the operator.
Maybe the problem is different
It is possible that the inaccessibility of some web pages does not occur due to incorrect MTU settings in the router, that this fix will not solve the problem. You need to know exactly in which direction to move. To do this, the user needs to go into the settings of his router and lower the default MTU to 1400 bytes. After saving and rebooting, try to go to the desired resource again. If the problem persists, return the settings to their original position and start looking for a solution in the other direction. However, according to many users, resizing the maximum package downwards gives a positive result and all resources, including online games, are available. True, another problem arises - the speed of opening pages and downloading files decreases. It is required to open the parameters of the router and fine-tune the MTU.
From words to deeds
In order to go to the settings, you need to enter the address of the router in the address bar of any browser and, having entered the authorization window, enter the login and password. Naturally, if the administrator made the settings on the part of the provider, it was his responsibility to fix problems with the Internet. But other users know the password that is actually set and the login to the access point. In any case, without authorization, the problem cannot be fixed, because the parameters of the router will not be available.
In the end, there are no hopeless situations. You can find out the network settings from the provider, reset the router and factory settings and make the connection yourself. The media has enough instructions for setting up the necessary hardware, not to mention branded travel guides from the manufacturer, which can be found on the seller’s official websites.
How to find MTU in the router
The D-Link router is considered to be the most popular in Russia, so all the fine-tuning examples will be described on the basis of its functionality, which are not very different from other routers. Once in the main menu of the device settings, you need to look at the WAN item in the "Network" section. This item is responsible for building a communication channel between the router and the provider's equipment; its presence is mandatory in any network device. Once in the right menu, the user can detect several connections that have the status of "connected". Preference should be given to one that has the flag "default gateway". Set the cursor to the selected connection. By clicking the “change” button (or “add” - each version has its own name), the user will be taken to the fine-tuning menu. Find the desired item labeled MTU. Change the parameter by clicking on the pencil image in the selected field. Set the desired size. Save settings and reboot the router.
Correct router settings always bear fruit
Setting MTU in the router, as practice shows, is the key for many channels built on virtual private networks. However, few people know that fine-tuning the quality of the connection depends on two more points, which are always next to the MTU field. Correct setting of all parameters always solves problems in networks that have physical wear. D-Link router, Zuxel, Cisco, Linksys and some other devices automatically fill in important parameters. In such cases, without a special desire to change the parameter is not worth it.
- Keep Alive. The created virtual network is constantly supported by the router, from the moment it is turned on until the power is turned off.
- LCP interval. The parameter is specified in seconds and sets the frequency of requests from the router to the equipment of the provider to verify the channel’s performance.
- LCP dips. A parameter that allows disconnecting from the equipment of the provider in order to establish a new, better communication channel in case of failure to return several packets sent earlier.
Private Network Standards
If there is no desire to conduct experiments on your own, determining the desired MTU size, you can use the technical data prescribed in the standards.
- PPPoE connection. Attaches its own data to each transmitted packet to ensure security, which is usually called a header. This header takes 8 bytes from each packet, leaving the channel able to transmit 1492 bytes. The ADSL operation is built on this technology, so changing the MTU is necessary to configure modems.
- Private VPN and PPP networks. Here, the MTU is more dependent on the hardware of the server to which you are connecting. Indeed, in addition to the provider, the connection can be used to connect to the workplace at the enterprise using a remote connection. The parameter of 1400 bytes is considered optimal, but fine tuning is not prohibited.
Help Software
It is possible to determine the necessary MTU size without experimenting with a router using software. For example, the TCP Optimizer program performs independent calculations on the communication channel and gives the result to the user with a full description of the problem. It is quite convenient, but resource-intensive. After all, the program needs to be found, downloaded, installed and figured out its performance. Having figured it out, any user will find that the application uses the banal ping of some resource on the Internet. It turns out that you can determine the MTU from the command line? Simply, you just need to reduce the packet size by one until the server response is positive - ping ya.ru –f –l 1499.
Many software products for setting up networks offer fine-tuning by editing the system registry by writing special keys for network equipment. Such functionality was in demand in systems of the last century, however, modern operating systems can adapt themselves to the created communication channel, and sometimes, to work efficiently, after fine-tuning the router, it is necessary to restart the computer.
Finally
Having received information about the MTU in the router, what it is and how to fine-tune the equipment, you can proceed to direct actions aimed at improving the operability of the communication channel. However, before you begin, you need to know that not all routers allow you to change their characteristics. For example, the company ZTE, known for its 3G modems, considered that the MTU setup violates some internal safety rules. Accordingly, changing the necessary parameters manually will fail. Experts recommend installing equipment purchased from the provider, or at least coordinate the choice with the Internet provider before buying.