In the last few years, the emergence of Programmable Data Planes and the appearance of programming protocol-independent languages such as P4 have offered powerful tools to define new network protocols, as well as to redesign existing network applications and systems. Network telemetry is one of the main areas of interest identified by the P4 Application Working Group. The collection of network-wide, fine-grained network information in real-time is a critical requirement for the design of useful and adequate monitoring tools that can be integrated into complex Operations, Administration & Maintenance applications. Recent research has focused on the definition and implementation of in-band monitoring systems, where specifically dedicated monitoring packets are not required. Even though the In-Band Network Telemetry specification proposed by the P4 Language Consortium is the starting point of many of the in-band monitoring systems, this is not the only alternative. Therefore, in this work, we will describe and compare other P4-based in-band passive telemetry proposals.

OverSim is a new open-source overlay network simulation framework based on the discrete event simulation system OMNeT++. OverSim includes several structured and unstructured P2P (peer-to-peer) protocols. It also includes an underlay model derived from the INET framework of OMNeT++, which includes simulation models of all network layers from the MAC layer onwards. For this and other reasons, this framework overcomes several drawbacks of existing P2P simulators, and it is considered one of the most powerful tools for the research community. This paper contains a very low-level description of the simulation of a particular P2P application using OverSim. It also contains information about how to use it in general P2P simulations.The aim is to provide an introduction to this powerful tool for the workers in the field of P2P networking.