  The network layer is central to the networking scientific area. It is around
the network layer that all the data communications develop, and one of its main
tasks is to allow the identification of each single interface/machine between
the potentially many interfaces in a network. This seminar addresses some of
the issues that are usually presented to young Computer Science Engineering
students in the course of several classes, but also presents some topics that
are not address in networking courses. It is mostly focused on using Internet
Protocol addresses in Local Area Networks, also considering issues that belong
to the Wide Area Networks, such as data aggregation. This document summarizes
the content of a seminar, therefore it comprehends both teaching and
researching subject. The seminar starts with a history of the evolution of the
communication protocols from the early days of networks up until IPv6. It
describes a new approach to define the addresses of network interfaces using
Variable Length Subnet Masks, as usually this is a not an easy task for
Computer Science Engineering undergraduate students. This summary also
describes some of the limitations of the data communication in todays'
networks, proposing some solutions, where possible, including a novel mean of
connectionless data transmission by using IPv6 addresses, by extension of
previously published research. The way the seminar is organized provides a
history to the past of the Internet Protocol, a view of some of its well-known
current limitations, and a glimpse into a possible future regarding an improved
connectionless layer 3 data transfer protocol.
