Georg Post

Passive online RTT estimation for flow-aware routers using one-way traffic

With the introduction of new generation high speed routers, and with the help of “flow-aware” traffic management, it becomes possible to improve the Quality of Service for users as well as the network efficiency for ISPs. An example of the “flow-aware” traffic management is the Alcatel-Lucent “Semantic Networking” framework where short-lived flows are processed with high priority and long-lived flows are controlled on a per flow basis. In order to control efficiently the flows, it is useful to know an estimate of the Round Trip Time (RTT). In the present work, we provide an online RTT estimation algorithm which is passive and needs one-way traffic only. The one-way traffic requirement is essential for the application of the algorithm for “flow-aware” traffic management inside the network. To the best of our knowledge, there was no online one-way traffic RTT estimators. Tests on a controlled testbed and on the Internet demonstrate high accuracy of the proposed estimator.

Networks for high-bandwith services combining photonic circuit cross-connects with packet switches

We describe the dimensioning and benchmarking of packet transport networks with aggregated link capacities up to the Tbit/s range, using a circuit-switching (cross-connect) infrastructure below packet-switching nodes. The different network solutions to be evaluated are designed to carry large numbers of high-definition video and other data streams, with upper bounds on packet latency and packet loss rate for all flows. Trends of evolution are analyzed, based on a performance and cost comparison of several node architectures with different associated transport technologies (packet and circuit layers). Simulations of packet-switch nodes under pseudo-self-similar traffic, extraction of analytical models for latency and loss, end-to-end best path selection, and constrained optimization of crossconnect and packet-switch resources are combined to derive the dimensioning of all the network elements. As a result of this study, photonic cross-connects associated with carrier-grade Ethernet switches appear as the most efficient architectures, thanks to cost savings for transit traffic. Single-layer solutions involving for example only packet-switch routers turn out to be more expensive.

From Packets to XLFrames: Sand and Rocks for Transfer of Mice and Elephants

Looking into the future, this paper presents the effects of having packets of large sizes, called XLFrames (XLFs), in a network. The analysis is motivated by the fact that the Internet is soon to witness stupendous amounts of traffic that have to be processed and switched at amplifying line rates; and this brings forth multiple challenges in the form of energy efficiency, network performance and end-host performance. Increasing the size of packets in the Internet has far-reaching incentives that otherwise appear hard to achieve. We foresee an Internet that multiplexes both packets (sand) and XLFs (rocks). As a first step, we analyse the effects of introducing XLFs in a network, and find the following: (i) the amount of packet-header processing is greatly reduced, (ii) while the fair multiplexing of XLFs with standard packets can be achieved using a careful queue management in routers.

Analysis of the Effects of XLFrames in a Network

The phenomenal increase in network capacity to hundreds and thousands of Gbits/s in the core as well as Gbits/s at the access, is soon to witness stupendous amounts of packets that have to be processed and switched at amplifying line rates. Looking into the future, we address the need for the integration of packets of larger size, called XLFrames (XLFs), into the future Internet framework. This paper analyses the effects of introducing XLFs in a network that has both packets and XLFs. We evaluate the gains in terms of processing power and throughput. As we observe that XLFs have an impact on loss rate and fairness, we study how, with minimal efforts at routers while keeping the existing protocols (TCP/UDP, IP), XLFs may integrate in the current scenario.