Variable Application Requirements Lead to the Selection of Communication Services

1. Variable Application Requirements Lead to the Selection of Communication Services 27th October 2011 RahamatullahKhondoker, Bernd Reuther and Paul Müller

2. Outline • Motivation • Description of Requirements and Offerings • Service Selection • Conclusion

3. Motivation • The number of Internet applications are increasing, each with its specific requirements demands • Future networks could evolve by providing a variety of virtual networks capabilities 4G 3G WLAN 2G Ethernet

4. Motivation • The number of Internet applications are increasing, each with its specific requirements demands Runtime S&C • Future networks could also evolve by providing a variety of protocol stacks capabilities Partial runtime Design-time Conventional TCP/IP UDP/IP SCTP/IP …

5. Motivation • The evolutionofthenetworkcanbeachievedby • decouplingapplicationsfromthenetworks, and • selectingthebestnetworkorprotocolautomaticallybased on theapplicationrequirements Solution: Description ofRequirementsandOfferings Solution: Service Selection

6. Description of Requirements and Offerings

7. Communication Service • A communication service • can be seen as a set of visible effects of the underlying implementation of a protocol, mechanism or (virtual) network • hides implementation mechanisms • Examples of effects • Reliable transmission • Addressing • Security • Routing • Loss Detection • Loss Reduction • Loop Avoidance • Connection Management • etc.

8. Description of Requirements and Offerings • A Service Description Language (SDL)[Ref. 1] consists of • a set of vocabularies (e.g., effect, operator, attribute) • a grammar (e.g., an operator connects an effect to an attribute) • Both application requirements and network offerings can be described by using the construct • The packet loss offering of the TCP/IP protocol stack can be expressed as • An administrator constraint can be expressed as Ref. 1. R. Khondoker, E. M. Veith, and P. Mueller, “A description language for communication services of future network architectures,” Will be Published in the Proceedings of the Network of Future, Paris, France, 2011.

9. Description of Requirements and Offerings • This constructallowstheselectionprocessto • choosebothfine-grained (a protocol) andcoarse-grainedservices (protocolgroups, (virtual) networks) in a homogeneousway • be flexible • select an appropriateservicebymatchingthedescriptionoftheofferedservicewiththerequirement becausethe same elements/componentsareused asnewlydevelopedservicesorapplicationrequirementscanbedescribed asbotharedescribedusingthe same construct

10. Service Selection

11. Service Selection Process • The aimoftheselectionprocessistochoosethebestservicebased on givenapplicationrequirementsandtheoperatingenvironment Fig 1. Service SelectionProcess

12. Service Selection Process • Selectingthebestserviceusing a singleeffectsuch asdelayis trivial • However, communicationserviceshave multiple effectswhicharedepedent on eachother Fig 2. Interdependenciesamongtheeffects

13. Service Selection: Methodology • Service Selection Methodology • Selecting a service by comparing more than one criteria is a multi-criteria decision making problem • For solving such a problem, we need Multiple Criteria Decision Analysis (MCDA) methods • Several algorithms (MAUT, AHP, ELECTRE III, Evamix) exist for doing this • Only AHP allows interdependent criteria [Ref 2] • We used Analytic Hierarchy Process (AHP) • Checking consistency of evaluation measures • Reduces biased behavior in decision making process • AHP must be adapted for automatic service selection Ref. 2. A. de Montis, P. D. Toro, B. Droste-Franke, I. Omann, and S. Stagl, “Assessing the quality of different mcda methods,” 2000.

14. Service Selection: AHP Moderately More ModeratelyLess AbsolutelyLess Absolutely More Equal Fig. Pairwise comparisonscale 9 -3 -7 -1 or 1 3 5 7 -5 -9 Fig. AnalyticHierarchyProcess (AHP)

15. Service Selection: Usage of AHP • AHP in servicedescriptionandselection • Input • A setofeffects • Requirements • Pairwise priorityassignment • Calculateonepriorityforeacheffect • Offers • Pairwise priorityassignment • This requires a mapping mechanism which cannot be done by AHP • Calculateonepriorityforeacheffect • Output • A service with the highest priority value

16. Service Selection • The priorityassigned in requirementsneedstobemappedtotheofferedservices • Pairwise prioritizationofservices per effect • The mapping must begeneric • The mappingshouldbemonotonic • A linear mappingofmeasuredvaluestoprioritizationis not adequate • An approachformappingisproposedtousemonotonicinterpolation/extrapolation Hints 9 Measured value Priority +/- 1 -9 Measuredvalueofoffers Fig. Values in termsofhints

17. Example: AHP in Service Selection Application Requirements Delay Throughput AHP Service1 Delay Throughput Service1 Service2 Offerings

18. Summary and Outlook • Applications use the network differently, therefore they have different network requirements • At the same time, networking capabilities and protocols make advances • We have seen how applications can make use of advancing network capabilities • Describing requirements and offerings • Supports the parallel development of both applications and communication services • supports evolution of the Internet • Service selection process • can use the protocols as soon as they emerge

19. Thanks for your attention • Any questions, comments or concerns?

20. M. RahamatullahKhondoker, M.Sc. Phone: +49 (0)631 205-26 43 Fax: +49 (0)631 205-30 56 Email: khondoker@informatik.uni-kl.de Internet: http://www.icsy.de