However, inherent problems are the reason for the inefficient working of the applications in the cloud environment [3]. For example, the traffic monitoring and health monitoring application in the smart cities cannot afford the delay in communication from the origin of data to the cloud data center, and then again, at the end-point application. Therefore, the fog computing concept has emerged recently. It reduces the network traffic and processing time of data by bringing end-user closer to the cloud services at the edge of the network [4]. Cisco [5] has given the FC's primary definition as \"Fog Computing is a paradigm that extends Cloud computing and services to the edge of the network.\" The Fog Node (FN) helps in the execution of IoT application, which is one of the basic fundamental entities in FC. Generally, the FC acts as an intermediate layer between cloud infrastructure and end devices/end users. IoT applications need low latency, geo-distribution, awareness, and mobility support. The proposed BFAN architecture is aimed at improving the mentioned param by processing most of the data near to the end-users or end-devices. The security is enhanced with the Blockchain technology. Blockchain is a chain of blocks that grows with each transaction and is linked through cryptography. The block is a combination of transaction data, timestamp, and previous blocks' cryptographic hash. It is a new buzzword that is capable of attracting many developers and researchers. Blockchain helps to provide true redundancy and full decentralization. The smart contract resource allocation algorithm helps to provide the on-demand resources and, bills are generated after the usage. The key is managed by the user and fragment stores in the encrypted format. There is no third party involved in controlling and accessing data. Therefore, there is no way to recover the lost private keys. The monitoring of resource utilization helps in comparing the value of performance metrics in service level agreement (SLA) with real-time values. This helps to provide the quality of service (QoS) to the end-user. The storage cost of Amazon S3 is $25 per TB/month, where Blockchain's cost is approximately $2 per TB/month [6]. Thus, the blockchain has the potential to reduce the storage cost by up to 80%. The FNs can be chosen as the nearest medium for processing and storage, which can reduce the delay of data transfer at a remote location as well as save energy. The proposed BFAN framework attempts to answer various issues such as:  
* Security: The security in the smart-cities concerned with cyber-security and physical security. In this article, the protection of data from attacks, computing infrastructure, and network are performed using Blockchain technology. * Caching: Low-latency is one of the vital aspects of smart-city. To achieve this, caching is used to store more frequent data at different locations in a network. Caching also helps to reduce network congestion by avoiding the flow of repeated data on the network. Fog computing with caching enables a variety of applications in smart cities. * Scalability: This enables elastic services in Fog computing in order to provide the Quality of Service (QoS). Dew computing concepts is applied in the proposed BFAN architecture to provide a fast and scalable cloud-like environment near to the IoE devices. * Sustainability: The energy-efficient frameworks is the current requirement for smart cities using renewable energy sources. The sustainability aim is to reduce carbon footprints. Nowadays, brown sources produce more than 80% of the energy used in data-centers [7; 8]. Therefore, we consider sustainability as a major concern in the article. The proposed BFAN framework helps to reduce the carbon footprint, increase the profit and hardware reliability. * Context-awareness: An ability to obtains the node locations and information of the environment is called context-awareness.