Moderate Source Routing for DTN Space Networks

Opportunities and limits of moderate source routing in delay‐/disruption‐tolerant networking space networks

“…The contact plan used in tests is shown in Table 1. It differs from that used in Caini et al, 19 in three significant aspects: first, an additional contact between GS2 and the space asset has been inserted (#4), to make more complex tests possible; second, the first two contacts between GSs and landers (#1 and #2) no longer overlap, to improve the reading of plots; last, contacts to/from orbiters (#6 and #7) are no longer continuous, but start at +25 s, which helps to simplify analysis. We have also adopted a different contact numbering criterion, to focus attention on the most significant contacts, the first four, now happening in temporal order.…”

“…Although the idea of source routing is simple, its implementation is not. Preliminary versions 19 were implemented by modifying the existing ION code, but later MSR was included in Unibo‐CGR. Although the code has evolved, the MSR algorithm is almost the same; therefore, here, we will limit the treatment to a brief summary, referring the interested reader to the cited paper for more details.…”

“…In the second phase, the saved route must be validated. Two preliminary steps are performed: (a) the residual route must be extracted; (b) then it must be converted into the SABR format, possible only if all contacts of the residual route are present in the contact plan (this step, route conversion, is actually quite elaborate; see Caini et al 19 ). Eventually, the route is validated by calling the same routine used in SABR Phase II.…”

“…The test environment used in this paper is similar to that used in Caini et al, 19 but with different contacts. It was explicitly designed to be particularly challenging for CGR, but also to be as simple as possible to facilitate accurate analysis of results.…”

“…This paper aims to investigate the advantages and limits of source routing when applied to CGR. It focuses on the “moderate source routing” (MSR) implementation of the source routing principle, recently presented by some of the authors in literature 19 . Following the approach originally suggested by another co‐author in literature, 20 MSR captures the time‐variant route calculated by CGR in a special “extension block” within a bundle.…”