TRACEROUTE ALGORITHM

Abstract

As we all know Internet is actually network of networks. There are millions of machines which are interacting simultaneously with each other through this single service. Client is never connected to the server directly, due to connections of various networks our request for the particular data from the server reach to us through various networks. Traceroute lets us determine the path that IP datagrams follow from our host to some other destination. It uses the IPv4 TTL field or the IPv6 hop limit field and two ICMP messages. It starts by sending UDP datagram to the destination with a TTL (or hop limit) of 1. This datagram causes the first-hop router to return an ICMP “time exceeded in transit error”. The TTL is then increased by one and another UDP datagram is sent, which locates the next router in the path. When the UDP datagram reaches the final destination, the goal is to have that host return an ICMP “port unreachable” error. This is done by sending the UDP datagram to a random port that is (hopefully) not in use on that host.