Discontinuous Galerkin Method with Parallel Dynamic Adaptation and Discrete Adjoint for Tsunami Simulations

Several tsunami events occurred during the past decade, and the models used for their simulation have been constantly improved. We present different numerical tools likely to improve the simulation of tsunamis, in order to obtain a fast and accurate tsunami forecast in a short amount of time. Based on a high-order discontinuous Galerkin discretization, hp-refinement is introduced, as well as parallel dynamic load balancing. Adjoint-based data assimilation is used to reconstruct the initial condition automatically from buoy measurements. The use of those numerical tools is illustrated with the simulation of the March 2011 Japanese tsunami. For this example, the model is able to reconstruct the tsunami source and accurately forecast its far-field propagation in a computational time 20 times faster than the physical propagation time. Included in a more realistic model, the presented numerical tools are most likely to improve real-time tsunami forecasts

Mille-Feuille: Putting ISP traffic under the scalpel

For Internet Service Provider (ISP) operators, getting an accurate picture of how their network behaves is challenging. Given the traffic volumes that their networks carry and the impossibility to control end-hosts, ISP operators are typically forced to randomly sample traffic, and rely on aggregated statistics. This provides coarse-grained visibility, at a time resolution that is far from ideal (seconds or minutes). In this paper, we present Mille-Feuille, a novel monitoring architecture that provides fine-grained visibility over ISP traffic. Mille-Feuille schedules activation and deactivation of traffic-mirroring rules, that are then provisioned network-wide from a central location, within milliseconds. By doing so, Mille-Feuille combines the scalability of sampling with the visibility and controllability of traffic mirroring. As a result, it supports a set of monitoring primitives, ranging from checking key performance indicators (e.g., one-way delay) for single destinations to estimating traffic matrices in sub-seconds. Our preliminary measurements on existing routers confirm that Mille-Feuille is viable in practice

TCPLS: Closely Integrating TCP and TLS

TCP and TLS are among the most essential protocols in today's Internet. TCP ensures reliable delivery of data while TLS secures the data transfer. Following the layered model, TLS was designed to be as independent as possible from the underlying transport protocol.This paper revisits this assumption and demonstrates the various benefits that a closer integration between TCP and TLS brings. We implement a first TCPLS prototype that demonstrates the feasibility of this integration. We show its usefulness on different use cases such as the benefit of bandwidth aggregation during a connection migration, and discuss several open research directions

xBGP: When you can’t wait for the IETF and vendors

Thanks to the standardization of routing protocols such as BGP, OSPF or IS-IS, Internet Service Providers (ISP) and enterprise networks can deploy routers from various vendors. This prevents them from vendor-lockin problems. Unfortunately, this also slows innovation since any new feature must be standardized and implemented by all vendors before being deployed. We propose a paradigm shift that enables network operators to program the routing protocols used in their networks. We demonstrate the feasibility of this approach with xBGP. xBGP is a vendor neutral API that exposes the key data structures and functions of any BGP implementation. Each xBGP compliant implementation includes an eBPF virtual machine that executes the operator supplied programs. We extend FRRouting and BIRD to support this new paradigm and demonstrate the flexibility of xBGP with four different use cases. Finally, we discuss how xBGP could affect future research on future routing protocols

Data Center Networking with multipath TCP

Recently new data center topologies have been proposed that offer higher aggregate bandwidth and location independence by creating multiple paths in the core of the network. To effectively use this bandwidth requires ensuring different flows take different paths, which poses a challenge. Plainly put, there is a mismatch between single-path transport and the multitude of available network paths. We propose a natural evolution of data center transport from TCP to multipath TCP. We show that multipath TCP can effectively and seamlessly use available bandwidth, providing improved throughput and better fairness in these new topologies when compared to single path TCP and randomized flow-level load balancing. We also show that multipath TCP outperforms laggy centralized flow scheduling without needing centralized control or additional infrastructure