Abstract

Synchronized time is critical to distributed systems and network applications in a datacenter network. Unfortunately, many clock synchronization protocols in datacenter networks such as NTP and PTP are fundamentally limited by the characteristics of packet switching networks. In particular, network jitter, packet buffering and scheduling in switches, and network stack overheads add non-deterministic variances to the round trip time, which must be accurately measured to synchronize clocks precisely. In the first part of the talk, I will present the Datacenter Time Protocol (DTP), a clock synchronization protocol that does not use packets at all, but is able to achieve nanosecond precision. In essence, DTP uses the physical layer of network devices (servers and switches) to implement a decentralized clock synchronization protocol. By doing so, DTP eliminates most non-deterministic elements in clock synchronization protocols and achieves a bounded precision.

In the second part of the talk, I will discuss some of my ongoing work which leverages tight synchronization amongst the nodes in a rack to build an efficient networking stack for rack-scale architectures. Finally I will briefly discuss some of my future work where I plan to combine synchronization with programmability (via P4) to address some of the core challenges in the current datacenter networks.

Bio: Vishal Shrivastav is a second year graduate student at Cornell University, advised by Prof. Hakim Weatherspoon. His research interests span building high performance networking systems for datacenter and rack-scale domains. Before coming to Cornell, Vishal did his undergraduate studies at Indian Institute of Technology (IIT), Kharagpur.