Alex C. Snoeren

Inside the Social Network's (Datacenter) Network

By: 
Arjun Roy, Hongyi Zeng, Jasmeet Bagga, George Porter, Alex C. Snoeren
Appears in: 
CCR August 2015

Large cloud service providers have invested in increasingly larger datacenters to house the computing infrastructure required to support their services. Accordingly, researchers and industry practitioners alike have focused a great deal of effort designing network fabrics to efficiently interconnect and manage the traffic within these datacenters in performant yet efficient fashions. Unfortunately, datacenter operators are generally reticent to share the actual requirements of their applications, making it challenging to evaluate the practicality of any particular design.

California Fault Lines: Understanding the Causes and Impact of Network Failures

By: 
Daniel Turner, Kirill Levchenko, Alex C. Snoeren, and Stefan Savage
Appears in: 
CCR October 2010

Of the major factors affecting end-to-end service availability, network component failure is perhaps the least well understood. How often do failures occur, how long do they last, what are their causes, and how do they impact customers? Traditionally, answering questions such as these has required dedicated (and often expensive) instrumentation broadly deployed across a network.

Every Microsecond Counts: Tracking Fine-Grain Latencies with a Lossy Difference Aggregator

By: 
Ramana Rao Kompella, Kirill Levchenko, Alex C. Snoeren, and George Varghese
Appears in: 
CCR October 2009

Many network applications have stringent end-to-end latency requirements, including VoIP and interactive video conferencing, automated trading, and high-performance computing—where even microsecond variations may be intolerable. The resulting fine-grain measurement demands cannot be met effectively by existing technologies, such as SNMP, NetFlow, or active probing. We propose instrumenting routers with a hash-based primitive that we call a Lossy Difference Aggregator (LDA) to measure latencies down to tens of microseconds and losses as infrequent as one in a million.

Cloud Control with Distributed Rate Limiting

By: 
Barath Raghavan, Kashi Vishwanath, Sriram Ramabhadran, Kenneth Yocum, and Alex C. Snoeren
Appears in: 
CCR October 2007

Today’s cloud-based services integrate globally distributed resources into seamless computing platforms. Provisioning and accounting for the resource usage of these Internet-scale applications presents a challenging technical problem. This paper presents the design and implementation of distributed rate limiters, which work together to enforce a global rate limit across traffic aggregates at multiple sites, enabling the coordinated policing of a cloud-based service’s network traffic.

Automating Cross-Layer Diagnosis of Enterprise Wireless Networks

By: 
Yu-Chung Cheng, Mikhail Afanasyev, Patrick Verkaik, Péter Benkö, Jennifer Chiang, Alex C. Snoeren, Stefan Savage, and Geoffrey M. Voelker
Appears in: 
CCR October 2007

Modern enterprise networks are of sufficient complexity that even simple faults can be difficult to diagnose — let alone transient outages or service degradations. Nowhere is this problem more apparent than in the 802.11-based wireless access networks now ubiquitous in the enterprise. In addition to the myriad complexities of the wired network, wireless networks face the additional challenges of shared spectrum, user mobility and authentication management.

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