Implementation of (O-)CGR in The ONE

Routing in Delay-/Disruption-Tolerant Networking (DTN) requires specific solutions as link impairments prevent the use of ordinary Internet algorithms, based on a timely dissemination of network topology information. Among DTN routing algorithms there is a dichotomy between opportunistic and deterministic (scheduled) solutions. The former are numerous and apply to terrestrial environments; CGR is the most widely supported algorithm designed for scheduled connectivity, and it is usually applied to space networks. However, in an attempt to provide a unified approach, an opportunistic variant of CGR, Opportunistic CGR (OCGR) has been recently proposed by some of the authors. Performance evaluations are normally carried out for opportunistic solutions by means of simulators, such as The ONE considered in this paper. CGR by contrast is more often studied by means of small testbeds. As the simulation approach could be complementary for CGR, and essential for OCGR, the authors have recently ported both of them into The ONE, by developing and releasing as free software a specific additional package. The aim of this paper is to show the rationale of this choice and discuss the many challenges that needed to be tackled to achieve this primary goal.