## 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 c_{min} denote the minimum edge capacity, let d_{max} denote the maximum demand, and let b_{max} denote the maximum benefit of a request. Let Δ_{max} denote an upper bound on the number of processing stages a request undergoes. If c_{min}/(Δ_{max} ・ d_{max}) = Ω((logm)/ε^{2}), then with probability at least 1 – 1/m − exp(−Ω(ε^{2} ・ opt^{∗}/(b_{max} ・ d_{max}))), the algorithm computes a (1 − ε)-approximate solution.

Original language | English |
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Title of host publication | Structural Information and Communication Complexity - 23rd International Colloquium, SIROCCO 2016, Revised Selected Papers |

Editors | Jukka Suomela |

Publisher | Springer Verlag |

Pages | 374-390 |

Number of pages | 17 |

ISBN (Print) | 9783319483139 |

DOIs | |

State | Published - 2016 |

Event | 23rd International Colloquium on Structural Information and Communication Complexity, SIROCCO 2016 - Helsinki, Finland Duration: 19 Jul 2016 → 21 Jul 2016 |

### Publication series

Name | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
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Volume | 9988 LNCS |

ISSN (Print) | 0302-9743 |

ISSN (Electronic) | 1611-3349 |

### Conference

Conference | 23rd International Colloquium on Structural Information and Communication Complexity, SIROCCO 2016 |
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Country/Territory | Finland |

City | Helsinki |

Period | 19/07/16 → 21/07/16 |