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Full PON Virtulisation Supporting Multi-Tenancy Beyond 5G



In this paper, we introduce a virtualization technique to enable fully customizable resource sharing for Passive Optical Networks. We provide a summary of the concept, economic challenges and implementation.
Full PON Virtulisation Supporting
Multi-Tenancy Beyond 5G
Nima Afraz, Frank Slyne and Marco Ruffini
CONNECT Center, Trinity College Dublin, Ireland
{nafraz, fslyne, marco.ruffini}
Abstract: In this paper, we introduce a virtualization technique to enable fully customiz-
able resource sharing for Passive Optical Networks. We provide a summary of the concept,
economic challenges and implementation. © 2019 The Author(s)
OCIS codes: 060.4250 Networks; 060.4256 Networks, network optimization.
1. Introduction
The current scene on the broadband/mobile operators’ market is an oligopoly, where novelty is limited by the
market development policies of a hand-full of operators. The cost of entering this market is unaffordably high for
smaller service providers who could bring considerable revenue to the access market by introducing new services.
Sharing the last mile of access networks, which is the most CAPEX demanding part, can dramatically reduce the
required initial investment and facilitate market entrance for new operators. However, the current sharing methods,
especially in fixed access networks, operate at too a high-level (e.g., virtual unbundled local access (VULA)) where
they are not capable of providing enough control over the service provided to the customers [1]. Other proposals
exists for a low-level access, which typically translate in assigning a dedicated wavelength to a second operator.
However, besides being inefficient, they are currently hindered by the fact that multi-wavelength PON (e.g., NG-
PON2) has not been deployed anywhere due to its high cost. Therefore, we propose a new sharing technique for
Passive Optical Networks (PONs) which meets the above-mentioned methods in the halfway by providing frame-
level scheduling control for the operators while being more affordable and easier to attract new entrants [2]. In the
next section, we will elaborate on the importance of providing scheduling control for the operators. Then we will
slightly touch on the economic market challenges in multi-tenant fixed access sharing environments and finally
share some details about the test-bed implementation of the proposed sharing method.
2. The Sharing Model
Due to their worldwide deployment and efficiency of resource usage, PON networks are considered a strong
candidate for providing networks’ services to 5G networks and beyond [3]. However, the capability of the current
PON networks to support new services with stringent and diverse requirements such as latency has been a center
of focus for a large and growing body of literature.
Merging Engine
… …
Fig. 1. Multi-Tenant PON Layout with vDBA
Final BwMap
InP (Auctioneer)
Excess Demand
Fig. 2. Multi-Tenant PON Sharing Market
However in the upstream, conventional PON scheduling schemes, called Dynamic Bandwidth Allocation
(DBA), are incapable of supporting low latency as it operates extensive and time-consuming signaling between
the OLT and the ONUs. Our proposed virtualisation of the DBA (vDBA), recently standardised in the BroadBand
Forum (BBF) TR-402 and depicted in Figure 1, allows different Virtual Network Operators (VNOs) to implement
their flavour of the DBA, providing them with the required flexibility to control the upstream scheduling, paving
the way for adoption of PONs as primary transport network solution for new bandwidth-intensive services (5G,
Virtual reality etc.). In [4] we have addressed the possibility of providing the required control to the VNOs by ded-
icating virtual and programmable instances of the DBA algorithms. Therefore, each VNO will operate a portion
of the network and their bandwidth allocation decision (referred to as bandwidth map (BwMap)) is aggregated
by the merging engine in the final BwMap is issued. The technical details of this work are further discussed in
subsection 3.
One issue that arises once the scheduling is passed to VNOs is that without proper incentives, VNOs have little
motivation in sharing any unused capacity with other VNOs, making the overall PON inefficient. Indeed, once
VNOs can fully control their slice scheduling their best strategy is to always pretend they need all the contracted
capacity, which might otherwise be re-directed to a competing VNO. To address this challenge, we have pro-
posed [5] monetization of the excess PON slices where using an auction mechanism the VNOs can trade their
excess capacity in return for monetary compensation (depicted in Figure 2). Through rigorous theoretical proofs
and market simulations in [6] we validate that the proposed market will incentivize the VNOs to trade their excess
resources in a setting where any attempt to manipulate the market will lead to worst or the same outcome. Nonethe-
less, the previous work assumes an open access architecture where a fully trusted central authority (Infrastructure
Provider (InP)) is in charge of operating the market (bookkeeping, conducting the auction, settlements, etc.). This
assumption may not be valid considering the new network ownership models. Hence, the natural progression of
this work is to study distributed means of consensus (e.g., Blockchain-based Smart Contracts) which do not rely
on a central entity.
3. Implementation
Our vDBA concept was demonstrated in [7] on test bed incorporating a physical PON, a set of emulated ONUs, a
traffic generator and a multi-access edge computing node. The physical PON was implemented on Xilinx VC709
FPGA boards, operating at symmetric 10Gb/s line rate.
Fig. 3. vDBA edge Compute stack
The PON hardware and software virtualisation architecture is shown in Fig. 3. The Multi-access Edge Com-
puting (MEC) node hosted the Merging Engine (ME) and the vDBA functions for the Virtual Network Operators
(VNOs), implemented as Virtual Network Functions. The Merging Engine is the element that blends together all
virtual bandwidth maps from the different VNOs so as to generate one physical bandwidth Map allocation) and
the SDN control plane. Due to the real-time critical nature of receiving and transmitting status report messages
from the ONUs (called DBRUs) and Bandwidth Map data, our latest implementation [8], [9] made advanced use
of the Data Plane Development Kit (DPDK) toolkit to optimize the packet transfer through the physical host to
and from the Virtual Network Functions.
1. M. Ruffini, Multidimensional convergence in future 5g networks, JLT, 35 (3), Feb. 2017.
2. A. Elrasad et al., Virtual dynamic bandwidth allocation enabling true PON multi-tenancy, OFC 2017, paper
3. J. S. Wey et al., Passive optical networks for 5g transport: Technology and standards, JLT, July 2018.
4. A. Elrasad et al., Frame level sharing for DBA virtualization in multi-tenant PONs, ONDM 2017.
5. N. Afraz et al., DBA capacity auctions to enhance resource sharing across virtual network operators inmulti-
tenant PONs. OFC 2018, paper Th1B.3.6.
6. , A sharing platform for multi-tenant pons, JLT, 36 (23) Dec 2018.
7. F. Slyne et al., Demonstration of real time VNF implementation of OLT with virtual DBA for sliceable
multi-tenant PONs, OFC 2018, papaer Tu3D.4.
8. F. Slyne et al., Experimental demonstration of DPDK optimised VNF implementation of virtual DBA in a
multi-tenant PON ECOC 2018.
9. M. Ruffini et al., Moving the network to the cloud: The cloud central office revolution and its implications
for the optical layer. JLT 37 (7), April 2019.
With the rapid development of new broadband services such as high-definition video (HDV), teleconferencing, and virtual reality(VR)/augmented reality(AR), there has been explosive growth in network traffic, and the quality-of-service requirements for such network services are more becoming more and more diverse; making it challenging with higher requirements. Passive optical network (PON) has turned out to be an important part of current and future communication network systems because of its low cost, low energy consumption, simple structure, easy expansion, and easy maintenance. However, the current traditional time-division multiplexing passive optical network (TDM-PON) can no longer be used to meet the explosive growth in the bandwidth demands of users, to deal with dynamic resource allocation to high-speed users, multi-granularity, and efficient carrying of multi-services of next-generation passive optical network (NG-PON). The development in the bandwidth access methods for NG-PON networks has become a research hotspot at home and abroad. Based on an in-depth study of resource allocation strategies for next-generation passive optical networks(NG-PONs), this thesis analyzes and classifies state-of-the-art mechanisms for implementing the dynamic and fair resource allocation strategies in NG-PON; focus on game theory bandwidth allocation scheme to solve the excess bandwidth distribution in XGs-PON; focuses on the QoS mapping scheme to solve the integration problem of PON and 5G network; focuses on the load adaptive dynamic bandwidth aggregation algorithm to solve the dynamic virtual bandwidth aggregation problem in Multi-Tenant PON; and focuses on the passive optical network structure of The Multi-OLT Metro access network. Solves the problem of collaboration between optical line terminals (OLTs) and optical network units (ONUs). The main research work and innovation points of the thesis are as follows: (1) For each ONU’s bandwidth requirement, a shared pool of resources is accessible at the OLT in PON. Towards this end, benchmark bandwidth distribution schemes try to allocate each ONU’s required bandwidth based on its service agreements, without considering excess or unused bandwidth significantly. Toward this objective, a novel approach of dynamic bandwidth scheme, called Bayesian auction game theory (BAGT-DBA) for XGs-PON, is presented. The BAGT-DBA applies the game theory concept for bandwidth distribution based on ONUs’ service agreements while also considering excess or unused bandwidth in XGs-PON, which results in improving the system's latency and revenue for the XGs-PON vendors. The simulation results show that the proposed BAGT-DBA results in throughput that is 4%, 39%, and 51% higher than IBU, ORR, and PAS, and lower upstream delays than the other schemes. BAGT DBA also improves the bandwidth utilization by up to 38% to 50% compared to IBU, ORR, and PAS schemes and exhibits the minimum frame loss ratio. (2) The integration of the XGPON network with the 5G WLAN network is a suitable solution for next-generation high-speed access internet service. Toward this objective, it is an important to integrate the different network standard properly according to different QoS requirement. Therefore, a new QoS mapping scheme, called the highest cost first(HCF), is recommended for integration of XG-PON and 5G Wi-Fi standards known as IEEE 802.11ac. With the help of proposed QoS mapping, the delay-sensitive application experiences a significant reduction in upstream delays. Compared to earlier work the HCF and IACG DBA combination results in the reduction of up to 54.8% and 53.4% mean US delays. This happens because of 50% to 65% better bandwidth assignment by the IACG DBA process due to efficient mapping by the HCF algorithm. (3) In order to solve the problem of a dynamic virtual bandwidth aggregation in multi-tenant passive optical network; a load adaptive merging algorithm (LAMA) is presented for merging engines of multi-tenant passive optical network. LAMA aggregates various individual virtual bandwidth maps (VBWmaps) into a single physical bandwidth map (PhyBWmap) according to the adaptive loads/shares of each Tenant, which results in improving the performance of the merging engine in multi-tenant PON architecture. As a comparative analysis, the LAMA algorithm utilizes about 96% and 74% available bandwidth under self-similar and Poisson traffic scenarios at the higher load, respectively. The results also show that the proposed scheme offers more throughput with lower upstream delays in the multi-tenant PON environment. (4) Multi-OLT scenarios waste some available bandwidth due to the lack of appropriate collaboration between different OLTs and ONUs. For this purpose, the concept of network coding is applied, and an efficient virtual multi-OLT PON (VM-PON) network architecture is suggested. Utilizing the XOR network coding method and an extra wavelength, two heavily loaded ONUs migrate/switch from one OLT to another OLT without loss of their bandwidth demand, simultaneously. Dynamically regrouping of ONUs improves the network performance and reduce latency, in the VM-PON. The comparative simulation results demonstrate that the proposed VM-PON work achieved 37% throughput greater than traditional TDM-PON with a lower frame loss ratio and lower upstream delay and jitter. KEYWORDS: PON, DBA, Game theory, virtual bandwidth aggregation, VM-PON
Full-text available
Wavelength division multiplexing\time division multiplexing passive optical network (WDM/TDM-PON) is the attractive candidate for PON bandwidth sharing among multiple service providers, featuring massive bandwidth and longer reach. This infrastructure reduces the overall cost of the Fiber-to-the-premises (FTTP) services and offers relatively lower tariffs for the end customers. The dynamic bandwidth and wavelength allocation (DBWA) process in such PON networks ensure the fair sharing of the available bandwidth resources among the virtual network operators (vNOs). The earlier reported DBWA schemes with multiple vNOs have not efficiently utilized the unused and residual upstream bandwidth. This study presents a novel load adaptive merging algorithm (LAMA) for converting various individual virtual bandwidth maps(vBWmaps) into a single physical bandwidth map (phyBWMap). The LAMA scheme modifies the existing strict priority scheme called the Priority-Based Merging Algorithm (PBMA) scheme and improves the performance of the merging engine by allocating the phyBWMap in a load adaptive manner to the vNOs in the multi-tenant PON architecture. The proposed algorithm is compared with PBMA in terms of throughput efficiency, upstream delay, and capacity utilization under self-similar and Poison traffic scenarios. The results show that the proposed scheme offers higher bandwidth utilization resulting in increased throughput with lower upstream delays in the multi-tenant PON environment.
Full-text available
This paper presents the concept of virtual dynamic bandwidth allocation (DBA), a method we propose to virtualize upstream capacity scheduling in passive optical networks (PONs), which provides multiple independent virtual network operators with the ability to precisely schedule their upstream traffic allocation. After a brief introduction on the evolution of access network sharing, we present our virtual DBA architecture, detailing its main components. We then provide a summary of the work done in this area from both theoretical and practical implementation perspectives. In this paper, we propose a novel stateless algorithm for merging multiple independent virtual bandwidth maps based on priority classes and analyze its performance in terms of efficiency of capacity allocation and latency. Through our results, we discuss the existence of a trade-off between traffic load and grant size distribution versus efficiency and latency. We find that, different from a residential single-tenant application, when PONs are used for low-latency and multi-tenant applications, the system has better overall performance if grants are allocated in small size. In addition, our analysis shows that for high-priority, strict latency services, our proposed merging algorithm presents delay performance that is independent of the traffic distribution considered.
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We propose an economic-robust auction mechanism for multi-tenant PON's capacity sharing that operates within the DBA process. We demonstrate that our mechanism improves PON utilization by providing economic sharing incentives across VNOs and infrastructure providers.
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We propose a virtual-DBA architecture enabling true PON multi-tenancy, giving Virtual Network Operators full control over capacity assignment algorithms. We achieve virtualization enabling efficient capacity sharing without increasing scheduling delay compared to traditional (non-virtualized) PONs.
Software Defined Networking (SDN) and Network Function Virtualisation (NFV) have recently changed the way we operate networks. By decoupling control and data plane operations and virtualising their components, they have opened up new frontiers towards reducing network ownership costs and improving usability and efficiency. Recently, their applicability has moved towards public telecommunications networks, with concepts such as the Cloud Central Office (cloud-CO) that have pioneered its use in access and metro networks: an idea that has quickly attracted the interest of network operators. By merging mobile, residential and enterprise services into a common framework, built around commoditised data centre types of architectures, future embodiments of this Central Office (CO) virtualisation concept could achieve significant capital and operational cost savings, while providing customised network experience to high-capacity and low-latency future applications. This tutorial provides an overview of the various frameworks and architectures outlining current network disaggregation trends that are leading to the virtualisation/cloudification of central offices. It also provides insight on the virtualisation of the access-metro network, showcasing new software functionalities like the virtual Dynamic Bandwidth Allocation (DBA) mechanisms for Passive Optical Networks (PONs). In addition, we explore how it can bring together different network technologies to enable convergence of mobile and optical access networks and pave the way for the integration of disaggregated Reconfigurable Add Drop Multiplexer (ROADM) networks. Finally, this paper discusses some of the open challenges towards the realisation of networks capable of delivering guaranteed performance, while sharing resources across multiple operators and services.
  • M Ruffini
M. Ruffini, Multidimensional convergence in future 5g networks, JLT, 35 (3), Feb. 2017.
  • J S Wey
J. S. Wey et al., Passive optical networks for 5g transport: Technology and standards, JLT, July 2018.
A sharing platform for multi-tenant pons
, A sharing platform for multi-tenant pons, JLT, 36 (23) Dec 2018.
Demonstration of real time VNF implementation of OLT with virtual DBA for sliceable multi-tenant PONs
  • F Slyne
F. Slyne et al., Demonstration of real time VNF implementation of OLT with virtual DBA for sliceable multi-tenant PONs, OFC 2018, papaer Tu3D.4.