OSI Model

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In the beginning the development of networks was chaotic. Each vendor had its own proprietary solution.The bad part was that one vendor’s solution was not compatible with another vendor’s solution.. This is where the idea for the OSI-model was born, having a layered approach to networks our hardware vendors would design hardware for the network, and others could develop software for the application layer. Using an open model which everyone agrees on means we can build networks that are compatible with each other. Read the rest of this entry »

The Traceroute Application

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The “traceroute” program contains a client interface to ICMP. Like the “ping” program, it may be used by a user to verify an end-to-end Internet Path is operational, but also provides information on each of the Intermediate Systems (i.e. IP routers) to be found along the IP Path from the sender to the receiver. Traceroute uses ICMP echo messages. These are addressed to the target IP address. The sender manipulates the TTL (hop count) value at the IP layer to force each hop in turn to return an error message.