Abstract
We study the allocation problem of a compound request for a service chain in a software defined network that supports network function virtualization. Given a network that contains servers with limited processing power and of links with limited bandwidth, a service chain is a sequence of virtual network functions (VNFs) that service a certain flow request in the network. The allocation of a service chain consists of routing and VNF placement, namely each VNF from the sequence is placed in a server along a path. It is feasible if each server can handle the VNFs that are assigned to it, and if each link on the path can carry the flow that is assigned to it. A request for service is composed of a source and a destination in the network, an upper bound on the total latency, and a specification in the form of a directed acyclic graph (DAG) of VNFs that provides all service chains that are considered valid for this request. In addition, each pair of server and VNF is associated with a cost for placing the VNF in the server. Given a request, the goal is to find a valid service chain of minimum total cost that respects the latency constraint or to identify that such a service chain does not exist. We show that even the feasibility problem is NP-hard in general graphs. Hence we focus on DAGs. We show that the problem is still NP-hard in DAGs even for a very simple network, and even if the VNF specification consists of only one option (i.e., the virtual DAG is a path). On the other hand, we present an FPTAS for the case where the network is a DAG. In addition, based on our FPTAS, we provide algorithms for instances in which the service chain passes through a bounded number of vertices whose degree is larger than two.
| Original language | English |
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| Title of host publication | Algorithmic Aspects of Cloud Computing - 3rd International Workshop, ALGOCLOUD 2017, Revised Selected Papers |
| Editors | Alex Delis, George Pallis, Dan Alistarh |
| Publisher | Springer Verlag |
| Pages | 27-40 |
| Number of pages | 14 |
| ISBN (Print) | 9783319748740 |
| DOIs | |
| State | Published - 2018 |
| Event | 3rd International Workshop on Algorithmic Aspects of Cloud Computing, ALGOCLOUD 2017 - Vienna, Austria Duration: 5 Sep 2017 → 5 Sep 2017 |
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 | 10739 LNCS |
| ISSN (Print) | 0302-9743 |
| ISSN (Electronic) | 1611-3349 |
Conference
| Conference | 3rd International Workshop on Algorithmic Aspects of Cloud Computing, ALGOCLOUD 2017 |
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| Country/Territory | Austria |
| City | Vienna |
| Period | 5/09/17 → 5/09/17 |
Bibliographical note
Publisher Copyright:© Springer International Publishing AG 2018.
Funding
Research supported in part by Network Programming (Neptune) Consortium, Israel. D. Rawitz—Partially supported by the Israel Science Foundation (grant no. 497/14).
| Funders | Funder number |
|---|---|
| Israel Science Foundation | 497/14 |