An approximation algorithm for path computation and function placement in SDNs

Guy Even, Matthias Rost, Stefan Schmid

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

We consider the task of embedding multiple service requests in Software-Defined Networks (SDNs), i.e. computing (combined) mappings of network functions on physical nodes and finding routes to connect the mapped network functions. A single service request may either be fully embedded or be rejected. The objective is to maximize the sum of benefits of the served requests, while the solution must abide node and edge capacities. We follow the framework suggested by Even et al. [5] for the specification of the network functions and routing of requests via processing-androuting graphs (PR-graphs): a request is represented as a directed acyclic graph with the nodes representing network functions. Additionally, a unique source and a unique sink node are given for each request, such that any source-sink path represents a feasible chain of network functions to realize the service. This allows for example to choose between different realizations of the same network function. Requests are attributed with a global demand (e.g. specified in terms of bandwidth) and a benefit. Our main result is a randomized approximation algorithm for path computation and function placement with the following guarantee. Let m denote the number of links in the substrate network, ε denote a parameter such that 0 < ε < 1, and opt denote the maximum benefit that can be attained by a fractional solution (one in which requests may be partly served and flow may be split along multiple paths). Let cmin denote the minimum edge capacity, let dmax denote the maximum demand, and let bmax denote the maximum benefit of a request. Let Δmax denote an upper bound on the number of processing stages a request undergoes. If cmin/(Δmax ・ dmax) = Ω((logm)/ε2), then with probability at least 1 – 1/m − exp(−Ω(ε2 ・ opt/(bmax ・ dmax))), the algorithm computes a (1 − ε)-approximate solution.

Original languageEnglish
Title of host publicationStructural Information and Communication Complexity - 23rd International Colloquium, SIROCCO 2016, Revised Selected Papers
EditorsJukka Suomela
PublisherSpringer Verlag
Pages374-390
Number of pages17
ISBN (Print)9783319483139
DOIs
StatePublished - 2016
Event23rd International Colloquium on Structural Information and Communication Complexity, SIROCCO 2016 - Helsinki, Finland
Duration: 19 Jul 201621 Jul 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume9988 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference23rd International Colloquium on Structural Information and Communication Complexity, SIROCCO 2016
Country/TerritoryFinland
CityHelsinki
Period19/07/1621/07/16

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