Military Communications and Information Technology: A Trusted ...
Military Communications and Information Technology: A Trusted ... Military Communications and Information Technology: A Trusted ...
262 Military Communications and Information Technology... In a manner similar to how the number of parent nodes may be controlled through the p max parameter, the number of children may be controlled by a parameter c max . This allows for more control over the structure of the tree and has two advantages. • A node is less prone to be overloaded by multicast forwards. The more outgoing edges a forwarder has the more messages are to be sent. In environments without native multicast support every inbound message causes the same number of transmissions as there are children of this forwarder. • Subscription storms are avoided. As a consequence of a parent node failure, all former child nodes try to resubscribe to other nodes in a short time frame, resulting in a subscription burst. This is undesirable in terms of network utilization. The c max value was set to unlimited, 25 and 10. In Fig. 7 the effects on the path length are shown. The effects on the success ratio in Fig. 6 are a direct consequence of the increased path length. The impact of a c max = 25 can be seen as a compromise between the disadvantage of reduced resilience against churn and the advantage of improved balance of the dissemination structure. A value of c max = 10 shows a more grave impact on the performance of the system. When c max is too low, it becomes more likely that nodes are unable to subscribe because all parent candidates have already reached their maximum child count. The c max value should be chosen according to the expected churn, the network transfer rates and the number of subscribers. Table II. KadScribe parameters KadScribe p max 1, 2, 3 c max ∞, 25, 10 parentTimeout 45 s childTimeout 45 s 4 3.5 3 path length 2.5 2 1.5 1 0.5 0 inf 25 10 c max Figure 7. Effect of c max on the path length
Chapter 3: Information Technology for Interoperability and Decision... 263 V. Summary and conclusion The presented peer-to-peer publish/subscribe mechanism is an approach to combine the advantages of application based multicast – scalability and usability – with the challenging nature of disadvantaged networks. The result is a scalable and robust publish/subscribe system capable of working in disadvantaged networks. For the future it is envisioned to integrate the publish/subscribe mechanism into a system which provides access control, group management and a unified messaging interface. Such a system could be a service-oriented architecture framework. Also the publish/subscribe mechanism of KadScribe will be improved. The research on KadScribe will focus on a further reduction of the required transmission bandwidth and increased robustness. Dynamically determined timeouts could be used in the future to adapt to changing network conditions. Opportunistic listening and multicasting are techniques which may be useful to further reduce the required transmission bandwidth and it can speed up bootstrapping. The collection of packets and sending them in a burst is a promising approach to react to the constraints of data radios. REFERENCES [1] S.A. Baset and H.G. Schulzrinne, An analysis of the skype peer-to-peer internet telephony protocol. INFOCOM 2006. 25th IEEE International Conference on Computer Communications. Proceedings, 25:1-11, 2006. [2] I. Baumgart, B. Heep, and S. Krause, OverSim: A Flexible Overlay Network Simulation Framework. In Proceedings of 10th IEEE Global Internet Symposium (GI ’07) in conjunction with IEEE INFOCOM 2007, Anchorage, AK, USA, pp. 79-84, May 2007. [3] T. Berners-Lee, Originator of the web and director of the world wide web consortium talks about where we’ve come, and about the challenges and opportunities ahead. IBM developerWorks Interviews, July 2006. [4] M. Castro, P. Druschel, A.-M. Kermarrec, A. Nandi, A. Rowstron, and A. Singh, Splitstream: High-bandwidth content distribution in a cooperative environment. In IPTPS’03, February 2003. [5] M. Castro, P. Druschel, A.-M. Kermarrec, A. Nandi, and A. Rowstron, Scribe: A large-scale and decentralized application-level multicast infrastructure. IEEE Journal on Selected Areas in Communication (JSAC), 20(8):1489-1499, October 2002. [6] S. Cheshire and M. Krochmal, Multicast dns. RFC draft-cheshire-dnsextmulticastdns-15, IETF, Dec 2011. [7] P. Druschel, A. Haeberlen, and J. Hoye et al., Freepastry. Technical report, Rice University, 2009. accessed on 2011-02-13. [8] T. Ginzler, A robust and scalable publish/subscribe mechanism for peer-to-peer networks. PhD thesis, Military University of Technology, Warsaw, Poland, 2011.
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Chapter 3: <strong>Information</strong> <strong>Technology</strong> for Interoperability <strong>and</strong> Decision...<br />
263<br />
V. Summary <strong>and</strong> conclusion<br />
The presented peer-to-peer publish/subscribe mechanism is an approach to<br />
combine the advantages of application based multicast – scalability <strong>and</strong> usability –<br />
with the challenging nature of disadvantaged networks. The result is a scalable <strong>and</strong><br />
robust publish/subscribe system capable of working in disadvantaged networks.<br />
For the future it is envisioned to integrate the publish/subscribe mechanism into<br />
a system which provides access control, group management <strong>and</strong> a unified messaging<br />
interface. Such a system could be a service-oriented architecture framework. Also<br />
the publish/subscribe mechanism of KadScribe will be improved. The research<br />
on KadScribe will focus on a further reduction of the required transmission<br />
b<strong>and</strong>width <strong>and</strong> increased robustness. Dynamically determined timeouts could<br />
be used in the future to adapt to changing network conditions. Opportunistic<br />
listening <strong>and</strong> multicasting are techniques which may be useful to further reduce<br />
the required transmission b<strong>and</strong>width <strong>and</strong> it can speed up bootstrapping. The collection<br />
of packets <strong>and</strong> sending them in a burst is a promising approach to react<br />
to the constraints of data radios.<br />
REFERENCES<br />
[1] S.A. Baset <strong>and</strong> H.G. Schulzrinne, An analysis of the skype peer-to-peer internet<br />
telephony protocol. INFOCOM 2006. 25th IEEE International Conference on Computer<br />
<strong>Communications</strong>. Proceedings, 25:1-11, 2006.<br />
[2] I. Baumgart, B. Heep, <strong>and</strong> S. Krause, OverSim: A Flexible Overlay Network<br />
Simulation Framework. In Proceedings of 10th IEEE Global Internet Symposium (GI ’07)<br />
in conjunction with IEEE INFOCOM 2007, Anchorage, AK, USA, pp. 79-84, May 2007.<br />
[3] T. Berners-Lee, Originator of the web <strong>and</strong> director of the world wide web consortium<br />
talks about where we’ve come, <strong>and</strong> about the challenges <strong>and</strong> opportunities ahead. IBM<br />
developerWorks Interviews, July 2006.<br />
[4] M. Castro, P. Druschel, A.-M. Kermarrec, A. N<strong>and</strong>i, A. Rowstron, <strong>and</strong> A. Singh,<br />
Splitstream: High-b<strong>and</strong>width content distribution in a cooperative environment.<br />
In IPTPS’03, February 2003.<br />
[5] M. Castro, P. Druschel, A.-M. Kermarrec, A. N<strong>and</strong>i, <strong>and</strong> A. Rowstron, Scribe:<br />
A large-scale <strong>and</strong> decentralized application-level multicast infrastructure. IEEE Journal<br />
on Selected Areas in Communication (JSAC), 20(8):1489-1499, October 2002.<br />
[6] S. Cheshire <strong>and</strong> M. Krochmal, Multicast dns. RFC draft-cheshire-dnsextmulticastdns-15,<br />
IETF, Dec 2011.<br />
[7] P. Druschel, A. Haeberlen, <strong>and</strong> J. Hoye et al., Freepastry. Technical report, Rice<br />
University, 2009. accessed on 2011-02-13.<br />
[8] T. Ginzler, A robust <strong>and</strong> scalable publish/subscribe mechanism for peer-to-peer networks.<br />
PhD thesis, <strong>Military</strong> University of <strong>Technology</strong>, Warsaw, Pol<strong>and</strong>, 2011.