A tool that can check the path followed by one data packet as it travels through a network such as the Internet.
To comprehend what traceroute and the Traceroute software program are used for, readers need to understand that information sent or received on the Internet comes in tiny pieces and not in the original piece in its entirety. For example, when requestors visit a Website, they want to retrieve a Web page. The server of that Website receives the request for the Web page and sends the Web page to the requestor. However, the requestor does not receive the whole Web page all at one time. Instead, it is divided into little pieces called packets. These packets reach the requestor by traveling through the Internet, passing through several computers along their way. Each packet is like a letter in that it has a sender and a receiver.
Computers linked to the Internet use a packet-switching technique to transmit packets from one computer to another. The packet is essentially handled as a “hot potato,” meaning that the “sending” computer (such as the server of the Website the requestor is visiting) sends it to the closest router, a communication device that connects two or more network segments. This router receives the packet and looks at the recipient address. If the recipient address is correct, the packet stops moving on and is delivered locally to the computer with the correct destination address. If the recipient address is not correct, the packet is sent on to the next nearest router, and if the recipient address is still not correct, the packet is sent on to the next nearest router. The cycle continues until the packet reaches the recipient with the correct recipient address. It may so happen that the Web page will pass through routers in several countries before reaching the requestor and the correct recipient address.
Also, if some routers along the path are not functional, the Web page must select another path, and if any routers or network segments are heavily loaded, there will be a delay before replying.
For these reasons, the Traceroute software program was developed, a tool that can check the path followed by one packet. System administrators can use the software to not only discover the path taken but also to see the amount of time it took for the packet to reach the correct address recipient.
Every IP packet has a field named TTL (TimeToLive) containing a value ranging from 0 to 255. Every router receiving the packet looks at that value and subtracts 1 from it. This procedure continues until the content of the TTL field reaches 0 or 1. When the TTL field reaches 0, the router destroys it. Such a mechanism is necessity or else a packet would travel on forever because it was unable to find the correct recipient.
Silvestri, M. Traceroute. [Online, 2000.] Wowarea Website. http://www .wowarea.com/english/researches/wg4_traceroute.htm.