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Effectiveness of Segment Routing Technology in Reducing the Bandwidth and Cloud Resources Provisioning Times in Network Function Virtualization Architectures^{ †}

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## Abstract

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## 1. Introduction

- the proposal of a scalable and ETSI compliant orchestration architecture in Multi-Provider NFV environments;
- the definition of a SRv6-based data plane for the SFC routing applicable for the proposed scalable orchestration;
- the proposal of an ad hoc algorithm for the proposed orchestration architecture and the investigation of its computational complexity;
- the comparison in terms of computational complexity of the proposed solution with respect to the one of a traditional orchestration.

## 2. Related Work

## 3. Proposal of a Scalable and ETSI Compliant NFV Orchestration Architecture

- the NFVO needs to acquire a lot of information and the graph representing the entire network topology and the available cloud and bandwidth resources can become very complex;
- the SFC Routing and Cloud and Bandwidth resource Allocation (SRCBA) algorithm does not scale with the increase in both the number of servers and switches of the NFVI-PoP networks;
- the solution is not applicable in the case of multi-provider NFV environments in which the providers of each NFVI-PoP may need to hire the organization of their own NFVI-PoP network and not make it visible to the owner of the NFVO.

## 4. Segment Routing Based SFC Routing

## 5. Cloud and Bandwidth Resource Allocation Problem

#### 5.1. NFVI-PoP, Network and Traffic Model

- ${\overline{v}}_{i}\in {\overline{V}}_{A}$ and ${\overline{w}}_{i}\in {\overline{V}}_{A}$ denote the originating and terminating access nodes the SFC;
- ${M}_{i}$ is the number of service functions to be executed for the SFC according to a given order; we assume that the SFs belong to a set of F types;
- $\overrightarrow{{s}_{i}}$ is a 1’s or 0’s matrix of size ${M}_{i}\times F$; the component ${s}_{i}(j,k)$ assumes the value 1 if the j-th SF to be executed is a k-th type SF;
- ${b}_{i}$ is the bandwidth offered by the i-th SFC.

#### 5.2. SFC Routing and Cloud and Bandwidth Resource Allocation (SRCBA) Algorithm

## 6. Numerical Results

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 3.**A segment routing based data/control plane for the scalable NFV orchestration architecture.

**Figure 4.**Application example of the SFC Routing and Cloud and Bandwidth resource Allocation (SRCBA) algorithm to the case of a cloud infrastructure composed by three Network Function Virtualization Infrastructure-Point of Presence (NFVI-PoP), that is NFVI-PoP-1, NFVI-PoP-2 and NFVI-PoP-3 equipped with two, two and one servers, respectively; one FW VNFI and one IDS VNFI are already activated in the NFVI-PoP-1 and NFVI-PoP-3, respectively. The SRCBA algorithm has to accommodate a Service Function Chain (SFC) composed of one Firewall (FW) and one Intrusion Detection System (IDS).

**Figure 5.**Construction of the multi-stage graph for the Scalable Orchestration solution of the SRCBA algorithm. The cases x = 3$ (

**a**) and x = 8$ (

**b**) for the bandwidth interconnection cost between NFVI-PoP-1 and NFVI-PoP-3 of Figure 4 are reported.

**Figure 7.**Construction of the multi-stage graph for the SO solution of the SRCBA algorithm. The cases x = 3$ (

**a**) and x = 8$ (

**b**) for the bandwidth interconnection cost between NFVI-PoP-1 and NFVI-PoP-3 of Figure 4 are reported.

**Figure 9.**NSFNET (USA) network composed of 16 switches and 25 links. The four cases with a number ${N}_{NFVI}$ of NFVI-PoPs equal to 4 (

**a**), 7 (

**b**), 10 (

**c**) and 14 (

**d**) are considered.

**Figure 10.**Composition of the Service Function Chain; four types are considered: the first one composed of a Firewall (FW) (

**a**), the second one composed of an FW and an Intrusion Detection System (IDS) (

**b**); the third one composed of an FW, an IDS and a Network Address Translator (NAT) (

**c**); and the fourth one composed of an FW, an IDS, a NAT and a Proxy (

**d**).

**Figure 11.**SRCBA execution time versus the number of SFC requests for the TO and SO solutions and when the Deutsche Telekom network is considered. The TO solution is investigated when the number ${N}_{s}$ of servers in each NFVI-PoP equals 4.

**Figure 12.**SRCBA execution time versus the number of SFC requests for the TO and SO solutions and when the Deutsche Telekom network is considered. The TO solution is investigated when the number ${N}_{s}$ of servers in each NFVI-PoP is equal to 2, 4 and 6.

**Figure 13.**SRCBA execution time versus the number of SFC requests for the TO and SO solutions. The number ${N}_{NVFI}$ of NFVIs is varied from 4 to 14 and the NFVI-PoPs are located as shown in Figure 9. The TO solution is investigated when the number ${N}_{s}$ of servers in each NFVI-PoP is equal to 4.

**Figure 14.**Total cost versus the number of SFC requests for the TO and SO solutions. The number ${N}_{NVFI}$ of NFVIs is varied from 4 to 14 and the NFVIs are located as shown in Figure 9. The TO solution is investigated when the number ${N}_{s}$ of servers in each NFVI-PoP is equal to 4.

**Table 1.**Maximum processing capacity and allocated number of cores for the software modules implementing FW, IDS, NAT and Proxy.

Maximum Processing Capacity (${\mathit{C}}^{\mathit{pr},\mathit{max}}$) | Number of Cores Allocated (${\mathit{n}}^{\mathit{c}}$) | |
---|---|---|

FW | 0.9 Gbps | 4 |

IDS | 0.6 Gbps | 8 |

NAT | 0.9 Gbps | 2 |

Proxy | 0.9 Gbps | 4 |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Eramo, V.; Lavacca, F.G.; Catena, T.; Polverini, M.; Cianfrani, A. Effectiveness of Segment Routing Technology in Reducing the Bandwidth and Cloud Resources Provisioning Times in Network Function Virtualization Architectures. *Future Internet* **2019**, *11*, 71.
https://doi.org/10.3390/fi11030071

**AMA Style**

Eramo V, Lavacca FG, Catena T, Polverini M, Cianfrani A. Effectiveness of Segment Routing Technology in Reducing the Bandwidth and Cloud Resources Provisioning Times in Network Function Virtualization Architectures. *Future Internet*. 2019; 11(3):71.
https://doi.org/10.3390/fi11030071

**Chicago/Turabian Style**

Eramo, Vincenzo, Francesco G. Lavacca, Tiziana Catena, Marco Polverini, and Antonio Cianfrani. 2019. "Effectiveness of Segment Routing Technology in Reducing the Bandwidth and Cloud Resources Provisioning Times in Network Function Virtualization Architectures" *Future Internet* 11, no. 3: 71.
https://doi.org/10.3390/fi11030071