This paper extends BlockSim by introducing energy-consumption and carbon-footprint metrics that are tightly integrated with its event-driven execution model, enabling sustainability-aware evaluation alongside conventional performance metrics. The proposed extension instruments core simulation events to estimate computational and communication energy at both node and network levels, then converts electricity demand to CO 2 emissions using an emission-factor formulation that can be configured to represent different grid carbon intensities. Using the extended simulator, controlled experiments are conducted on representative PoW and PoS consensus scenarios under varying miner populations and workloads. The framework reports aggregate energy and CO 2 , as well as normalized indicators per block and per transaction, supporting reproducible “what-if” analysis without external post-processing and enabling direct comparison of protocol configurations as networks scale. The framework additionally distinguishes economically driven Proof-of-Work (PoW) energy consumption, in which the expected mining reward and cryptocurrency price are explicit inputs, from validator-count-driven Proof-of-Stake (PoS) energy consumption; it varies the carbon emission factor across grid scenarios; and it is positioned as a scenario-based evaluation tool for preliminary what-if analysis rather than a precise real-world energy estimator.
Layer 2 scaling solutions—including payment-channel-based Lightning Networksand rollup-based off-chain execution environments—are commonly understood aslinear scaling projects for blockchain transaction throughput. This paper proposesan alternative structural interpretation: the emergence of Layer 2 is not a continuous increase in system capacity, but a percolation phase transition that occurswhen the density of off-chain channels or cross-rollup connections crosses a critical threshold. During this phase transition, the system shifts from a fragmentedlocally connected state to a globally routable giant connected state. The paperanalyzes the Lightning Network and the rollup ecosystem as comparative cases.Empirical studies of the Lightning Network show that its scale-free topology forcescritical hub nodes to bear a disproportionate connection load, thereby binding thenetwork’s global connectivity to the survival of a few high-centrality nodes. Therollup ecosystem faces the structural predicament of liquidity fragmentation, and itsevolution toward cross-rollup interoperability likewise exhibits a phase-transitionlogic from quantitative change to qualitative change in network effects. Based onthe above analysis, this paper distills three design principles for Layer 2 scalability:facilitating the institutionalization of cross-domain connections, avoiding overlyhomogenized cognitive convergence, and implementing differentiated verificationrouting among tasks with different security requirements.
This preprint is available in two versions: French (main_fr.pdf / main_fr.tex) and English (main_en.pdf / main_en.tex). The English abstract follows. For over one hundred and fifty years, all railway signalling architectures have rested on a single assumption: safety authority resides in the ground infrastructure. The network authorises; the train obeys. We question its necessity. The physical safety condition is a local property of the train and its environment, verifiable without external authorisation. We propose an architecture — AEGIS (Autonomous Embedded Ground-Independent Signalling) — in which neither primary safety nor installation coordination depends on a centralised ground authority: the ground provides certified data, the train reasons, and installation coordination is handled by a topologically partitioned distributed ledger. We examine the architectural properties arising from this inversion, the emergent properties of the resulting system, and the open questions this new paradigm generates.
Lyudmila Kovalchuk, Mariia Rodinko, Roman Oliynykov, Volodymyr Artemchuk
This paper studies the probability of a double-spend attack in an Ouroboros-like Proof-of-Stake (PoS) setting when confirmation decisions must be made for a finite number of blocks. Existing security analyses of Ouroboros-family protocols are mainly asymptotic and therefore do not directly provide the attack probability for a fixed confirmation depth. We consider an analytically tractable model that allows empty slots and multiple slot leaders, and assumes fixed stake distribution within an epoch, one-block growth of the public longest chain in any slot containing at least one honest leader, and next-slot block visibility. These assumptions hold when the time slot length is much greater than the network delay, and are applicable to practical deployment scenarios such as Cardano. Under these assumptions, for the first time, an exact closed-form solution for the success probability of a double-spend attack considering a realistic model with multiple leaders and empty time slots. Numerical examples illustrate how the required confirmation depth depends on the adversarial stake ratio and the active slot coefficient. The results apply to the stated analytical model and do not yet cover delayed fork resolution or the full protocol-level fork-choice and finality mechanisms of Ouroboros Praos.
O presente artigo investiga como o tamanho do bloco afeta a propagação em redes blockchain, recorrendo à modelagem estocástica para quantificar os trade-offs entre throughput, segurança e descentralização. Estudos teóricos e empíricos indicam que blocos maiores elevam o tempo médio de propagação e a variância desse tempo, aumentando a probabilidade de forks e de blocos órfãos em mecanismos de consenso baseados em Prova de Trabalho (PoW) e variantes de Nakamoto. Modelos analíticos e de simulação demonstram que a relação entre o intervalo médio de geração de blocos e o atraso médio de propagação pode ser tratada por meio de sistemas de filas ou de processos de Poisson, nos quais a taxa de forks cresce quando o produto “taxa de blocos × atraso de propagação” se aproxima de um limiar crítico associado a um regime congestionado. Resultados de trabalhos de otimização de tamanho de bloco em PoW sugerem a existência de um tamanho “ótimo” que maximiza a eficiência econômica da rede – isto é, transações por segundo ponderadas pelo risco de órfãos –, e que esse ótimo depende fortemente da largura de banda média da rede e do grau de heterogeneidade entre nós. Evidências empíricas da rede Bitcoin mostram ainda que melhorias de protocolo, tais como Compact Blocks e redes de relay dedicadas, reduzem significativamente o impacto negativo de blocos maiores sobre a propagação, conquanto não eliminem o viés estrutural em favor de nós com melhor conectividade. Conclui-se que a modelagem estocástica do impacto do tamanho de bloco é fundamental para parametrizar blockchains de modo a manter a rede em regime funcional, minimizando taxa de forks e força centralizadora, ao mesmo tempo em que se atende à demanda por maior capacidade transacional na Web3.Blockchain
Payment channel networks enable scalable off-chain payments, but their practical deployment remains constrained by a persistent tension among routing efficiency, liquidity visibility, transaction privacy, and settlement security. Existing multipath routing mechanisms can improve payment success under fragmented liquidity, yet they often expose sensitive balance information, leak structural features of payment routes, and enlarge the attack surface for probing, channel exhaustion, and selective forwarding. This paper presents a novel framework, Adaptive Multipath Proofs (AMPs), for privacy protection and security in payment channel networks. The core idea is to bind multipath routing decisions with lightweight zero-knowledge verifiability, allowing intermediate nodes to validate path feasibility, fragment consistency, and settlement constraints without learning exact channel balances, the complete payment amount, or the global route structure. AMP integrates three mechanisms: a hidden-liquidity feasibility proof that supports privacy-preserving route selection, an adaptive payment-splitting strategy that dynamically determines fragment allocation according to network congestion and balance uncertainty, and a proof-coupled settlement guard that enforces atomicity and timeout consistency across all payment fragments. Together, these mechanisms reduce information leakage while preserving robust payment execution under dynamic network conditions. Experimental evaluation on real Lightning Network topologies and synthetic stress scenarios demonstrates that AMP significantly lowers balance disclosure and endpoint inference risk, improves payment completion under skewed liquidity distributions, and introduces only moderate computational and communication overhead. The results indicate that adaptive proof-carrying multipath routing offers a practical and effective direction for building secure, privacy-preserving, and high-success payment channel networks.
O presente artigo investiga a otimização do throughput em redes blockchain baseadas em mecanismos de consenso Proof-of-Stake (PoS) a partir de um estudo comparativo de latência entre diferentes arquiteturas, parâmetros de configuração e arranjos de infraestrutura de rede. Partindo do desafio clássico da engenharia de sistemas distribuídos de conciliar escalabilidade, segurança e descentralização – conhecido popularmente como trilema do blockchain –, analisa-se como decisões de projeto, dentre as quais se incluem o desenho do protocolo de consenso, a duração dos intervalos (slots), o tamanho dos blocos, o número de validadores ativos e a topologia da rede P2P, afetam simultaneamente o volume de transações processadas por unidade de tempo e o tempo de confirmação percebido pelos usuários finais. A metodologia adotada combina revisão sistemática da literatura sobre modelos de desempenho em sistemas distribuídos e blockchains PoS, comparação de estudos empíricos que mensuram throughput e latência em plataformas públicas de referência – particularmente Ethereum pós-Merge, Solana e Polkadot – e análise conceitual dos trade-offs identificados. Os resultados obtidos sugerem que técnicas de otimização orientadas a parâmetros, tais como ajuste fino de tempos de slot e políticas de propagação acelerada de blocos, combinadas a inovações em camada de consenso – dentre as quais se destacam mecanismos híbridos com Proof of History e execução paralela de transações –, podem reduzir significativamente a latência de confirmação sem necessariamente comprometer a segurança criptográfica ou a robustez da rede. Entretanto, emergem limites estruturais associados à variabilidade de condições de rede em escala global, à heterogeneidade de capacidade computacional entre nós validadores e às exigências clássicas de tolerância a falhas bizantinas, os quais impõem fronteiras práticas ao ganho de throughput em ambientes permissionless. Conclui-se que uma abordagem sistêmica, que integre ajuste criterioso de parâmetros, desenho criterioso da infraestrutura de nós e mecanismos de monitoramento e benchmarking contínuos, é fundamental para o amadurecimento da infraestrutura Web3 e para o suporte a aplicações com requisitos estritos de qualidade de serviço, entre as quais se incluem protocolos de finanças descentralizadas, mercados de capitais tokenizados e aplicações sensíveis ao tempo.
Proof-of-Stake (PoS) networks rely on economic staking guarantees to align validator behavior with network security. However, a growing class of architectures permits validators to reuse, rehypothecate, or synthetically represent the same stake across multiple validation contexts. This paper defines <i>Double-Staking Validator Drift</i> as a structural vulnerability in which a validator’s effective economic exposure diverges from its apparent security contribution. We demonstrate how this drift undermines slashing guarantees, enables risk amplification, and creates false decentralization signals across PoS Layer-1 and restaking ecosystems. Existing mitigations—including slashing, social governance, and restaking policies—are shown to be insufficient due to enforcement blind spots and cross-domain opacity. We propose a logic-layer enforcement model that introduces validator-level stake exclusivity, temporal binding, and deterministic enforcement across consensus domains. This approach restores economic integrity to PoS security models and closes a critical gap in current network designs.
Blockchain networks have revolutionized decentralized applications but remain vulnerable to evolving security threats due to their reliance on static consensus mechanisms that cannot adapt to changing threat landscapes. This paper addresses this critical security gap by proposing Autonomous Defense-Adaptive Consensus Optimisation for Blockchain Networks (ADACON), an original framework for the dynamic adjustment of consensus mechanisms based on Bayesian threat detection. The research investigates how real-time adaptation between multiple consensus protocols can enhance blockchain resilience while maintaining performance. The approach integrates a Bayesian Threat Detector, Consensus Adapter, and Network State monitor in a modular architecture that continuously assesses network conditions and switches between five consensus mechanisms (PoW, PoS, PBFT, PoA, DPoS) as threats emerge. The framework was evaluated through comprehensive simulations involving 1,000 nodes, testing response to six distinct attack vectors, including Sybil, DoS, Byzantine, Eclipse, Majority, and Routing attacks. Results demonstrate that ADACON effectively identifies and responds to varied attacks with a latency of 29.7 ms and throughput of 833 TPS). Statistical validation across five independent simulation runs (seeds 5-9) confirmed framework reliability with consistent performance metrics (CV < 7.1% for latency, 5.4% for throughput). Delegated Proof of Stake emerged as the most frequently selected mechanism (23.2%) due to its balanced performance across multiple security dimensions. Significantly, the system exhibited greater adaptability and attack coverage than existing hybrid approaches. The previous high switching frequency was reduced by using hysteresis, i.e., by providing dwell time and an improved threshold that avoids unnecessary switching. The study concludes that dynamic consensus adaptation offers substantial security advantages for blockchain networks, particularly in high-security environments like financial systems and critical infrastructure. However, further research must focus on optimizing switching frequency and developing secure transition protocols to maximize effectiveness. ADACON represents an incremental extension tested toward more resilient blockchain systems that can autonomously respond to emerging threats while balancing security, performance, and resource utilization.
G.B. Bhavana, R. S. Anand, J. Ramprabhakar, Josep M. Guerrero · 6 authors
Integration of renewable-energy (RE) sources of energy into local microgrids, decentralised energy markets using blockchain based peer-to-peer (P2P) energy trading is gaining more traction due to its ability to enable transparent, autonomous, and secure transactions among distributed energy resources (DERs). Due to the large variety in microgrid topologies and their respective operational constraints, a key challenge to obtaining the most effective trading framework is the choice of blockchain consensus protocol that suits a given microgrid type. Choice of consensus mechanism solely affects the reliability and security of a network. This paper presents a quantitative comprehensive evaluation of various blockchain consensus mechanisms such as Proof-of-Work (PoW), Proof-of-Stake (PoS), Delegated Proof-of-Stake (DPoS), Proof-of-Elapsed-Time (PoET), Practical Byzantine Fault Tolerance (PBFT), Raft, and Tendermint to determine their suitability for P2P energy trading in microgrids. Various metrics such as fault tolerance, energy efficiency, latency, throughput and consensus time were evaluated for multiple consensus mechanisms through simulations. This paper also studies node-scaling impact on the protocols and presents a final decision framework to match the suitable protocol with various microgrid topologies.
Jorge Soria, Jorge Moya Velasco, Carlos Estévez-Mendoza
Decentralized Physical Infrastructure Networks (DePIN) represent an emerging organizational form for operating physical infrastructure through blockchain-based coordination. DePIN through decentralized protocols and token-based payment mechanisms incentivize independent agents to deploy, maintain, and monetize real-world infrastructure, such as wireless networks, storage units, or sensors. This article presents a first formal economic analysis of DePIN architectures, modelling investment decisions under network effects in a blockchain-native Decentralized Autonomous Organization (DAO), with protocol-defined reward schemes. It establishes the equilibrium conditions that support decentralized provision, where token prices internalize participation, service reliability, and network coverage. Furthermore, it identifies a minimum viable coverage threshold determined by costs and network effects. Through a multi-agent machine learning simulation, we confirm that decentralized provision improves efficiency compared to centralized models. The results support the economic viability of DePIN and provide design guidelines for future decentralized infrastructure protocols. Finally, we propose an DAO incentive mechanism to implement First Best provision in Decentralized Physical Infrastructure Networks.
Ethereum’s transaction pool (mempool) dynamics and fee market efficiency critically affect transaction inclusion, validator workload, and overall network performance. This research empirically analyzes gas price variations, mempool clearance rates, and block finalization times in Ethereum’s proof-of-stake ecosystem using real-time data from Geth and Prysm nodes. We observe that high-fee transactions are consistently prioritized, while low-fee transactions face delays or exclusion—despite EIP-1559’s intended improvements. Mempool congestion remains a key factor in validator efficiency and proposal latency. We provide empirical evidence of persistent fee-based disparities and show that extremely high fees do not always guarantee faster confirmation, revealing inefficiencies in the current fee market. To address these issues, we propose congestion-aware fee adjustments, reserved block slots for low-fee transactions, and improved handling of out-of-gas vulnerabilities. By mitigating prioritization bias and execution inefficiencies, our findings support more equitable transaction inclusion, enhance validator performance, and promote scalability. This work contributes to Ethereum’s long-term decentralization by reducing dependence on high transaction fees for network participation.
Michael D. Norman, Simon Brown, Mallesh M. Pai, Laurence Smith
This paper presents a novel staking coopetition design aimed at incentivizing decentralization and continuous growth of economic security within a proof-of-stake system. Staking rewards follow a nonlinear mapping relative to stake size. This affords the highest effective yields to smaller operators, fueling network growth and giving users an incentive to delegate their stake to smaller operators. This prevents the preferential accrual and centralization of stake seen in popular blockchains such as Ethereum, where popular liquid staking protocols control large fractions of the total stake thereby having outsized potential impacts on the economic security of the protocol. The proposed system addresses key challenges such as Sybil attacks and offers a comprehensive framework for future research and implementation. We introduce innovative mechanisms and gamification elements, to enhance user engagement and provide transparency in emissions.
ABSTRACT The emergence of wireless technology brought about enhanced communication across various devices, resulting in the demand for efficient and reliable wireless networks, like wireless mesh networks (WMNs) and mobile Ad‐hoc Networks (MANETs). MANETs are known for their decentralized nature, rapid deployment, infrastructure‐less operation, adaptability, and ease of use in several applications and outdoor events. Despite their flexibility, they often face challenges relating to security vulnerabilities, together with blackhole and grayhole attacks, and trade‐offs in terms of performance relating to reliability and integrity. This paper proposes an improved, innovative routing protocol for Ad‐hoc On‐Demand Distance Vector (AODV) by infusion of blockchain's proof of stake (PoS) consensus mechanism named PoSAODV, whose objective is to enhance security, energy‐efficiency, and adaptability while reducing packet loss rate, routing overheads, and increasing throughput. Smart contract‐based validator selection was utilized to ensure fairness and reduce blackhole and grayhole attacks. The result obtained through simulation demonstrates that PoSAODV outperforms the original AODV by reduced latency of 0.79 ms , average throughput of 45 Mbps , and packet delivery ratio of 80%–100% in both unsafe and safe environments. This makes PoSAODV suitable for resource‐constrained ad‐hoc networks with dynamic topologies.
Ethereum has adopted a rollup-centric roadmap to scale by making rollups (layer 2 scaling solutions) the primary method for handling transactions. The first significant step towards this goal was EIP-4844, which introduced blob transactions that are designed to meet the data availability needs of layer 2 protocols. This work constitutes the first rigorous and comprehensive empirical analysis of transaction- and mempool-level data since the institution of blobs on Ethereum on March 13, 2024. We perform a longitudinal study of the early days of the blob fee market analyzing the landscape and the behaviors of its participants. We identify and measure the inefficiencies arising out of suboptimal block packing, showing that at times it has resulted in up to 70% relative fee loss. We hone in and give further insight into two (congested) peak demand periods for blobs. Finally, we document a market design issue relating to subset bidding due to the inflexibility of the transaction structure on packing data as blobs and suggest possible ways to fix it. The latter market structure issue also applies more generally for any discrete objects included within transactions.
Decentralized physical infrastructure networks (DePINs) are an emerging vertical within "Web3" replacing the traditional method that physical infrastructures are constructed. Yet, the boundaries between DePIN and traditional method of building crowd-sourced infrastructures such as citizen science initiatives or other Web3 verticals are not always so clear cut. In this work, we systematically analyze the differences between DePIN and other Web2 and Web3 verticals. For this, the study proposes a novel decision tree for classifying systems as DePIN. This tree is informed by prior studies and differentiates DePIN from related concepts using criteria such as the presence of a three-sided market, token-based incentives for supply, and the requirement for physical asset placement in those systems. The paper demonstrates the application of the decision tree to various blockchain systems, including Helium and Bitcoin, showcasing its practical utility in differentiating DePIN systems. This research offers significant contributions towards establishing a more objective and systematic approach to identifying and categorizing DePIN systems. It lays the groundwork for creating a comprehensive and unbiased database of DePIN systems, which will inform future research and development within this emerging sector.
Ethereum’s rollup-centric roadmap assumes that adoption of layer-2 (L2) rollups will relieve congestion on the layer-1 (L1) mainnet, but there is little causal evidence on how large that relief is across major protocol changes. We construct a daily panel for Ethereum from August 2021 to December 2024 and estimate the total effect of L2 adoption on L1 congestion using a regime-aware interrupted time-series design that spans the London, Merge, and Dencun upgrades and adjusts for macro demand. In the pre-Dencun regime, a 10 percentage point increase in L2 adoption reduces median L1 base fees by about 11%—roughly 4–5 Gwei per 21k-gas transfer—and yields similar declines in a harmonized congestion index, with only modest changes in block utilization. Combining these elasticities with a Merge-era counterfactual path for L2 adoption, we estimate that observed adoption avoided about $80–$90 million in base and priority fees over 137 days, or roughly $0.6–$0.7 million per day. These effects are precise while L2 adoption is still ramping up but become statistically local once adoption exceeds 85% after Dencun, implying that congestion relief is economically meaningful yet regime-specific. Our findings support continued investment in L2 infrastructure alongside L1 mechanism design and illustrate how to benchmark congestion relief in other multi-layer digital platforms.
This paper presents a multi-contract blockchain framework for inter-provider agreements in 6G networks, emphasizing performance analysis under a realistic Proof-of-Stake (PoS) setting on Ethereum's Sepolia testnet. We begin by quantifying Ethereum Virtual Machine (EVM)-based gas usage for critical operations such as provider registration, service addition, and SLA penalty enforcement, observing that cold writes and deep data structures can each inflate gas consumption by up to 20\%. We then examine block-level dynamics when multiple transactions execute concurrently, revealing that moderate concurrency (e.g., 30--50 simultaneous transactions) can fill blocks to 80--90\% of their gas limit and nearly double finalization times from around 15~seconds to over 30~seconds. Finally, we synthesize these insights into a practical design guide, demonstrating that flattening nested mappings, consolidating storage writes, and selectively timing high-impact transactions can markedly reduce costs and latency spikes. Collectively, our findings underscore the importance of EVM-specific optimizations and transaction scheduling for large-scale decentralized applications in 6G telecom scenarios. The implementation is available online.
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Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Innovative Microfluidic and Catalytic Techniques Innovation
En el ecosistema de las aplicaciones descentralizadas (DApps), la dependencia de un único nodo de blockchain para realizar todas las transacciones presenta varios desafíos críticos, entre ellos la falta de redundancia y la potencial inestabilidad en caso de fallos en dicho nodo. Este problema subraya la necesidad de un sistema que permita la configuración y monitoreo de múltiples nodos, asegurando una alta disponibilidad y un equilibrio de carga eficiente. El presente Trabajo de Final de Grado, titulado "HIGH AVAILABILITY ETHEREUM-LIKE NODE PROXY", aborda esta problemática proponiendo una solución basada en una aplicación desarrollada en Python para monitorear y equilibrar el tráfico entre varios nodos Ethereum JSON-RPC.
Rudolf Kovacs, Sorin Buzura, Bogdan Iancu, Vasile Dădârlat · 6 authors
The network function virtualization (NFV) feature lies at the core of modern networking, and it allows on-demand real-time integration of new network functions, which is a great benefit for large-scale infrastructure networks. In contrast to the functional benefits, NFV introduces software complexity and computational overhead through additional abstraction layers. The current article addresses the function validation problem in large-scale infrastructure networks of Internet Service Providers (ISPs) and proposes the utilization of blockchain as a validation technology, as opposed to implementing a custom validation solution. The current work showcases a practical architecture implementation to address the service validation in service provider large-scale networks. The POX-based solution to control software-defined networks (SDN) for NFV is extended to offer additional blockchain capabilities. Thus, a blockchain node is integrated and executed in the POX SDN controller. Transaction experiments are performed between two endpoints located in remote locations on the Internet, and the detailed results are presented to validate the utilization of the blockchain technology used on SDNs’ control plane.
Pol Alemany, Ricard Vilalta, Raül Muñoz, Ramon Casellas · 5 authors
Data center (DC) interconnection allows us to have optical transmissions between DCs directly connected to optical networks, avoiding the use of a packet-based infrastructure. Thanks to the use of next-generation pluggable coherent optics, it is possible to create connectivity services (CSs) across multiple optical transport domains. In this multi-domain CS scenario, cloud operators and transport operators have to work together in the most dynamic way possible. To do so, they need a common place (i.e., a market) where the transport operators may expose their available optical resources and the cloud operators request (e.g., rent) them to be used in order to create end-to-end (E2E) CSs between DCs. Having multiple transport operators exposing their resource information in a common place requires a set of common rules (i.e., how much of the topology to show) to create E2E CSs requested between cloud operators. This paper makes use of the blockchain technology to present a blockchain-based extension for the software-defined network (SDN) architecture to allow each optical transport operator domain to become a peer in a blockchain network. In there, each peer follows the same rules and shares the same exact level of topology information by using a specific abstraction model to map the optical domain resources. This paper uses a set of three different abstraction models to validate their behavior on a blockchain system when managing multiple domain resources and the deployment of CSs across these domains. To do so, an experimental comparison on how the different abstraction models affect the performance of the blockchain system is presented.
Shifeng Ding, Gangxiang Shen, Kevin X. Pan, Sanjay K. Bose · 6 authors
In communication networks, network virtualization can usually provide better capacity utilization and quality of service (QoS) than what can be achieved otherwise. Under this operation, once the capacity of a virtual optical network (VON) is allocated, it will be static for a certain period, for example, a service contract period. However, in reality, the actual traffic demand of a VON always fluctuates, which would lead to a mismatch between the capacity assigned and the actual traffic demand carried. This mismatch would further cause degradation of provisioned network services and inefficiency in assigned network capacity. To overcome this issue, we propose a new scheme, called spectrum trading (ST), to trade spectrum resources between VONs in the context of an elastic optical network (EON). The key idea is to allow different VONs to trade their spectrum resources according to their actual capacity requirement at different time instants. A VON with unused spectra can trade away its unused spectra to other VONs that are short of spectrum resources at that time. in exchange, it is rewarded with some credit for its contribution to the ST community, which it can then use later to obtain extra capacity, if needed. The trust-worthiness of the trading records between the VONs is ensured in a distributed fashion through a blockchain- assisted ledger that is updated whenever a new trade occurs. A software-defined control plane is also developed to enable spectrum trading with the support of the blockchain-assisted ledger. The performance of the ST scheme is evaluated and compared with the scenario without such trading. Results show that the proposed ST scheme is efficient in improving the QoS of each VON and significantly improves overall network capacity utilization.