| 1. |
- Bjurefors, Fredrik, et al.
(author)
-
A Testbed for Evaluating Delay Tolerant Network Protocol Implementations
- 2008
-
In: Proceedings 5th Swedish National Computer Networking Workshop.
-
Conference paper (peer-reviewed)abstract
- We present our delay tolerant network testbed and methodology, for testing opportunistic networking protocols and applications, without having to modify the software. To support multiple operating systems running on a single physical computer, virtual machines are at the core of the testbed. Scripted communication opportunities are used to model connectivity in the network. A set of benchmark connectivity models are available to perform evaluations with predictable protocol behavior; dynamic topologies from real-world traces are also supported. Using this environment, we evaluate the testbed with a delay tolerant application and compare the outcome to that of a real-world experiment. Finally, we discuss our results and the limitations of the testbed.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Nordström, Erik, et al.
(author)
-
A Cross-Environment Study of Routing Protocols for Wireless Multi-hop Networks
- 2007
-
Reports (other academic/artistic)abstract
- We study ad hoc routing protocol mechanisms that impact the performance during and after periods of connectivity change. Our evaluation procedure is facilitated by using a structured and tool-supported approach, combining real world experiments with simulation and emulation. This method enables us to find performance-critical time regions in our traces. Our analysis shows that performance is largely determined by how accurately a protocol senses connectivity in these regions. Inaccurate sensing can seriously affect the performance of the protocol, even after the critical regions. We identify three significant problems with sensing that we call Self-interference, TCP backlashing and Link cache poisoning. We discuss their effect on the design of sensing mechanisms in routing protocols and suggest how the protocols can be made more robust.
|
|
| 6. |
- Nordström, Erik, et al.
(author)
-
Comparing Simulation, Emulation, and Real-World Experimental Results in Mobile Ad hoc Networks
- 2006
-
In: 6th Scandinavian Workshop on Wireless Ad-hoc Networks (ADHOC'06).
-
Conference paper (peer-reviewed)abstract
- We compare the major MANET protocols, AODV, DSR and OLSR, using a set of the same scenarios recreated in simulation, emulation and real world. The purpose of this is twofold: 1. To explore the utility of simulation and emulation in direct relation to the real world in the area of mobile ad hoc networks. We explore potential discrepancies in the results that could either improve the confidence in previous research or to indicate the need for deeper exploration. To our knowledge, no previous work has done this in the consistent manner that we have. Our work may also function as a validation to previous findings in simulation and emulation. 2. To compare, side-by-side, the performance of the major MANET routing protocols to better understand the trade-offs in the design choices of the different protocols and how they can complement each other to improve MANET routing. The MANET research area has reached a level of maturity, both in terms of protocol specifications and implementations, where we believe this type of comparison is necessary to further the development and standardization of MANET technology. In this paper we will concentrate on the first aspect of exploring potential discrepancies in the results. Significant differences have been identified in delay variation, packet loss, and interaction with transport layer protocols.
|
|
| 7. |
- Nordström, Erik, et al.
(author)
-
Evaluating Wireless Multi-hop Networks Using a Combination of Simulation, Emulation, and Real World Experiments
- 2007
-
In: Proceedings of the 1st international workshop on System evaluation for mobile platforms (MobiEval'07). - New York : ACM Association for Computing Machinery. - 9781595937629 ; , s. 29-34
-
Conference paper (peer-reviewed)abstract
- Mobile ad hoc networks suffer from complex interactions between protocols on different levels. To identify and explain anomalies found in real world experiments we propose to combine real world testing with simulation and emulation. By inspecting the differences in the results obtained using the three evaluation methods we can efficiently identify when anomalies occur and get a hint about where to further investigate. Our approach has proved to be valuable in an extensive comparison of the routing protocols AODV, DSR, and OLSR. The study resulted in two gigabytes of log data that required an efficient and structured method to isolate important time regions for further manual analysis. We discuss our approach and present some key findings.
|
|
| 8. |
|
|
| 9. |
- Saksena, Mayank, et al.
(author)
-
Graph Grammar Modeling and Verification of Ad Hoc Routing Protocols
- 2007
-
Reports (other academic/artistic)abstract
- We present a technique for modeling and automatic verification of network protocols, based on graph transformation. It is suitable for protocols with a potentially unbounded number of nodes, in which the structure and topology of the network is a central aspect, such as routing protocols for ad hoc networks. Safety properties are specified as a set of undesirable global configurations. We verify that there is no undesirable configuration which is reachable from an initial configuration, by means of symbolic backward reachability analysis. In general, the reachability problem is undecidable. We implement the technique in a graph grammar analysis tool, and automatically verify several interesting non-trivial examples. Notably, we prove loop freedom for the DYMO ad hoc routing protocol. DYMO is currently on the IETF standards track, to potentially become an Internet standard.
|
|
| 10. |
|
|
