Improving Oblivious Reconfigurable Networks with High Probability

Oblivious Reconfigurable Networks (ORNs) use rapidly reconfiguring switches to create a dynamic time-varying topology. Prior theoretical work on ORNs has focused on the tradeoff between maximum latency and guaranteed throughput. This work shows that by relaxing the notion of guaranteed throughput to an achievable rate with high probability, one can achieve a significant improvement in the latency/throughput tradeoff. For a fixed maximum latency, we show that almost twice the maximum possible guaranteed throughput rate can be achieved with high probability. Alternatively for a fixed throughput value, relaxing to achievement with high probability decreases the maximum latency to almost the square root of the latency required to guarantee the throughput rate. We first give a lower bound on the best maximum latency possible given an achieved throughput rate with high probability. This is done using an LP duality style argument. We then give a family of ORN designs which achieves these tradeoffs. The connection schedule is based on the Vandermonde Basis Scheme of Amir, Wilson, Shrivastav, Weatherspoon, Kleinberg, and Agarwal, although the period and routing scheme differ significantly. We prove achievable throughput with high probability by interpreting the amount of flow on each edge as a sum of negatively associated variables, and applying a Chernoff bound. This gives us a design with maximum latency that is tight with our lower bound (up to a log factor) for almost all constant throughput values.Comment: 19 pages, 1 figur

Exploiting the Synergy Between Gossiping and Structured Overlays

In this position paper we argue for exploiting the synergy between gossip-based algorithms and structured overlay networks (SON). These two strands of research have both aimed at building fault-tolerant, dynamic, self-managing, and large-scale distributed systems. Despite the common goals, the two areas have, however, been relatively isolated. We focus on three problem domains where there is an untapped potential of using gossiping combined with SONs. We argue for applying gossip-based membership for ring-based SONs---such as Chord and Bamboo---to make them handle partition mergers and loopy networks. We argue that small world SONs---such as Accordion and Mercury---are specifically well-suited for gossip-based membership management. The benefits would be better graph-theoretic properties. Finally, we argue that gossip-based algorithms could use the overlay constructed by SONs. For example, many unreliable broadcast algorithms for SONs could be augmented with anti-entropy protocols. Similarly, gossip-based aggregation could be used in SONs for network size estimation and load-balancing purposes

Partitioned Paxos via the Network Data Plane

Consensus protocols are the foundation for building fault-tolerant, distributed systems, and services. They are also widely acknowledged as performance bottlenecks. Several recent systems have proposed accelerating these protocols using the network data plane. But, while network-accelerated consensus shows great promise, current systems suffer from an important limitation: they assume that the network hardware also accelerates the application itself. Consequently, they provide a specialized replicated service, rather than providing a general-purpose high-performance consensus that fits any off-the-shelf application. To address this problem, this paper proposes Partitioned Paxos, a novel approach to network-accelerated consensus. The key insight behind Partitioned Paxos is to separate the two aspects of Paxos, agreement, and execution, and optimize them separately. First, Partitioned Paxos uses the network forwarding plane to accelerate agreement. Then, it uses state partitioning and parallelization to accelerate execution at the replicas. Our experiments show that using this combination of data plane acceleration and parallelization, Partitioned Paxos is able to provide at least x3 latency improvement and x11 throughput improvement for a replicated instance of a RocksDB key-value store

A Brief Overview of the NEBULA Future Internet Architecture

NEBULA is a proposal for a Future Internet Architecture. It is based on the assumptions that: (1) cloud computing will comprise an increasing fraction of the application workload offered to an Internet, and (2) that access to cloud computing resources will demand new architectural features from a network. Features that we have identified include dependability, security, flexibility and extensibility, the entirety of which constitute resilience.NEBULA provides resilient networking services using ultrareliable routers, an extensible control plane and use of multiple paths upon which arbitrary policies may be enforced. We report on a prototype system, Zodiac, that incorporates these latter two features