Traceroute is the service computer program intended for definition of routes of data in networks TCP/IP. Traceroute it is based on report ICMP. ICMP (Internet Control Message Protocol - the report of operating messages) - the network report for transfer of commands and error messages, carries out diagnostic functions and informs on mistakes or failures in networks on the basis of report IP. For example the known utility ping uses ICMP for finding-out of availability of the removed unit.

The program traceroute carries out sending data to the specified unit of a network, thus displaying data on all intermediate routers through which there have passed data on a way to target unit. In case of problems on delivery up to any unit the program traceroute allows to define data, on which site of a network there were malfunctions. Traceroute enters into delivery of the majority of modern network operational systems. In systems Microsoft Windows this program carries the name tracert.

Definition of intermediate routers - traceroute sends a series of packages of data to target unit, thus each time increasing on 1 value of field TTL (time of a life). It is a field usually specifies a maximum quantity of routers which can be passed by a package. The first package sends with TTL, equal 1 and consequently the first router returns back message ICMP, specifying on impossibility of delivery of data. Traceroute fixes the address of a router, and also time between sending of a package and reception of the answer (these data are deduced on the monitor a computer). Then traceroute repeats sending a package, but already with TTL, equal 2, that allows the first router to pass a package further.

Process repeats until at certain value TTL the package will not reach target unit. At reception of the answer from this unit process of trace is considered completed.

Using the utility traceroute it is possible to learn a route which will pass a package of the information between two any points. It gives the information on transits of the traffic both possible places and the reasons of its delay. For example, at inaccessibility of your site in the Internet it is possible to learn where exactly communication (packages are lost) interrupts. It enables to draw a conclusion on fault in this problem of yours the Internet service of the provider or a hosting service of the provider.

If you the Internet service the provider using the given utility at emergencies in your network it is possible to find out easily what equipment has failed or what liaison channel. It will allow you to send a repair brigade to strictly certain place, instead of to send it on the communication line to search for breakage or the given up equipment.

Using the utility traceroute some times on different routes - it is possible to define structure of the computer network of your city or region. The information on the intermediate units which are passed by a test package of data, allows to judge the scheme of connections various the Internet service of providers in your region or even the country.

The further development of the utility traceroute became the service developed on its basis - looking glass. This service possesses more ample opportunities, than the considered utility. Its use allows to see all external connections (highway) of this or that provider having entered only number of its independent system (AS). Thus, there is opened an information about peering (BGP) connections of any provider.

Looking glass service is on any professional internet service provider site. As it is possible to find set of independent services of this type in the Internet. Frequently they are added by some useful utilities, we shall not stop on which.