DEFT: Distributed, Elastic, and Fault-tolerant State Management of Network Functions

Network function virtualization is the key to developing elastically scalable and fault-tolerant network functions (e.g. load balancer, firewall etc.). By integrating NFV and SDN technologies, it is feasible to dynamically reroute traffic to new network function (NF) instances in the event of an NF failure or overload scenario. The fact that the majority of network functions are stateful makes the task more challenging. State migration and state replication are common approaches in achieving elasticity and fault tolerance. The majority of the studies in the literature either emphasize fault tolerance or elastic scalability while designing a state management system for network functions. In this paper, we have designed a complete state management system, called DEFT, that meets both elasticity and fault-tolerance goals. Our system also supports strong consistency on global state updates. While existing designs rely on a central controller or remote central storage to achieve strong consistency on state updates, DEFT utilizes distributed consensus mechanism to achieve the same. We have done a proof of concept implementation of DEFT and extensively tested DEFT under several model conditions to evaluate its scalability and performance. Our experimental results show that DEFT is scalable and maintains a considerably high throughput throughout. It incurs minimal performance overhead while achieving strong consistency on state updates

Role of Various Classes in the Revolt Of 1857

Culturally the Indians were always “one”. The Titular Mughal Emperor was there to serve as a thread of unity among the Indians. The British showed disrespect to the Emperor which offended the Indians in General and the Muslims in special. India possesses its own economic system mainly based on agriculture and small industry. The foreign rulers were sending Indian raw-materials to Britain for feeding their new born industries and thus were exploiting Indian resources. The “Doctrine of Lapse” or “Escheat” policy destroyed the Indian Industries. Indian Artisans, craftsman etc. became jobless and the burden of farmland increased. Poverty grabbed seriously the people. The Indian soldiers were paid low-salaries (starting from Rs. 7 to the end of Rs. 9). Indian soldiers were ill-treated in Army by the English causing rise of discrimination in their mind. The number of Indians in Army was far larger than the British sepoys (ratio 6:1). Most of the Indian soldiers were belong to Brahmin and Thakurs of East-India. A general discontent existed among all the Indian soldiers. Such dis-satisfaction were intensified by the Lord Canning introduction of “General Service Act” which required by the sepoys to march anywhere of British Empire. It is obvious that Indian sepoys had natural love and respect their motherland and faith of their own religion. The introduction of Enfield rifle with the cartridges greased with the fat of cow and pig, obnoxious to both the Hindus and Muslims set the spark that enkindled the embers of discontent of the Indian sepoy stored in them for a long time