Hitesh Ballani

A High-Radix, Low-Latency Optical Switch for Data Centers

By: 
Dan Alistarh, Hitesh Ballani, Paolo Costa, Adam Funnell, Joshua Benjamin, Philip Watts, Benn Thomsen
Appears in: 
CCR August 2015

We demonstrate an optical switch design that can scale up to a thousand ports with high per-port bandwidth (25 Gbps+) and low switching latency (40 ns). Our design uses a broadcast and select architecture, based on a passive star coupler and fast tunable transceivers. In addition we employ time division multiplexing to achieve very low switching latency. Our demo shows the feasibility of the switch data plane using a small testbed, comprising two transmitters and a receiver, connected through a star coupler.

Silo: Predictable Message Latency in the Cloud

By: 
Keon Jang, Justine Sherry, Hitesh Ballani, Toby Moncaster
Appears in: 
CCR August 2015

Many cloud applications can benefit from guaranteed latency for their network messages, however providing such predictability is hard, especially in multi-tenant datacenters. We identify three key requirements for such predictability: guaranteed network bandwidth, guaranteed packet delay and guaranteed burst allowance. We present Silo, a system that offers these guarantees in multi-tenant datacenters. Silo leverages the tight coupling between bandwidth and delay: controlling tenant bandwidth leads to deterministic bounds on network queuing delay.

Enabling End-Host Network Functions

By: 
Hitesh Ballani, Paolo Costa, Christos Gkantsidis, Matthew P. Grosvenor, Thomas Karagiannis, Lazaros Koromilas, Greg O'Shea
Appears in: 
CCR August 2015

Many network functions executed in modern datacenters, e.g., load balancing, application-level QoS, and congestion control, exhibit three common properties at the data plane: they need to access and modify state, to perform computations, and to access application semantics -- this is critical since many network functions are best expressed in terms of application-level messages. In this paper, we argue that the end hosts are a natural enforcement point for these functions and we present Eden, an architecture for implementing network functions at end hosts with minimal network support.

R2C2: A Network Stack for Rack-scale Computers

By: 
Paolo Costa, Hitesh Ballani, Kaveh Razavi, Ian Kash
Appears in: 
CCR August 2015

Rack-scale computers, comprising a large number of microservers connected by a direct-connect topology, are expected to replace servers as the building block in data centers. We focus on the problem of routing and congestion control across the rack's network, and find that high path diversity in rack topologies, in combination with workload diversity across it, means that traditional solutions are inadequate. We introduce R2C2, a network stack for rack-scale computers that provides flexible and efficient routing and congestion control.

Decentralized task-aware scheduling for data center networks

By: 
Fahad R. Dogar, Thomas Karagiannis, Hitesh Ballani, Antony Rowstron
Appears in: 
CCR August 2014

Many data center applications perform rich and complex tasks (e.g., executing a search query or generating a user’s news-feed). From a network perspective, these tasks typically comprise multiple flows, which traverse different parts of the network at potentially different times. Most network resource allocation schemes, however, treat all these flows in isolation – rather than as part of a task – and therefore only optimize flow-level metrics.

A Study of Prefix Hijacking and Interception in the Internet

By: 
Hitesh Ballani, Paul Francis, and Xinyang Zhang
Appears in: 
CCR October 2007

There have been many incidents of prefix hijacking in the Internet. The hijacking AS can blackhole the hijacked traffic. Alternatively, it can transparently intercept the hijacked traffic by forwarding it onto the owner. This paper presents a study of such prefix hijacking and interception with the following contributions: (1). We present a methodology for prefix interception, (2). We estimate the fraction of traffic to any prefix that can be hijacked and intercepted in the Internet today, (3).

CONMan: A Step Towards Network Manageability

By: 
Hitesh Ballani and Paul Francis
Appears in: 
CCR October 2007

Networks are hard to manage and in spite of all the so called holistic management packages, things are getting worse. We argue that the difficulty of network management can partly be attributed to a fundamental flaw in the existing architecture: protocols expose all their internal details and hence, the complexity of the ever-evolving data plane encumbers the management plane.

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