1,740 research outputs found
Lying Your Way to Better Traffic Engineering
To optimize the flow of traffic in IP networks, operators do traffic
engineering (TE), i.e., tune routing-protocol parameters in response to traffic
demands. TE in IP networks typically involves configuring static link weights
and splitting traffic between the resulting shortest-paths via the
Equal-Cost-MultiPath (ECMP) mechanism. Unfortunately, ECMP is a notoriously
cumbersome and indirect means for optimizing traffic flow, often leading to
poor network performance. Also, obtaining accurate knowledge of traffic demands
as the input to TE is elusive, and traffic conditions can be highly variable,
further complicating TE. We leverage recently proposed schemes for increasing
ECMP's expressiveness via carefully disseminated bogus information ("lies") to
design COYOTE, a readily deployable TE scheme for robust and efficient network
utilization. COYOTE leverages new algorithmic ideas to configure (static)
traffic splitting ratios that are optimized with respect to all (even
adversarially chosen) traffic scenarios within the operator's "uncertainty
bounds". Our experimental analyses show that COYOTE significantly outperforms
today's prevalent TE schemes in a manner that is robust to traffic uncertainty
and variation. We discuss experiments with a prototype implementation of
COYOTE
Measuring and Understanding Throughput of Network Topologies
High throughput is of particular interest in data center and HPC networks.
Although myriad network topologies have been proposed, a broad head-to-head
comparison across topologies and across traffic patterns is absent, and the
right way to compare worst-case throughput performance is a subtle problem.
In this paper, we develop a framework to benchmark the throughput of network
topologies, using a two-pronged approach. First, we study performance on a
variety of synthetic and experimentally-measured traffic matrices (TMs).
Second, we show how to measure worst-case throughput by generating a
near-worst-case TM for any given topology. We apply the framework to study the
performance of these TMs in a wide range of network topologies, revealing
insights into the performance of topologies with scaling, robustness of
performance across TMs, and the effect of scattered workload placement. Our
evaluation code is freely available
Improving Oblivious Reconfigurable Networks with High Probability
Oblivious Reconfigurable Networks (ORNs) use rapidly reconfiguring switches
to create a dynamic time-varying topology. Prior theoretical work on ORNs has
focused on the tradeoff between maximum latency and guaranteed throughput. This
work shows that by relaxing the notion of guaranteed throughput to an
achievable rate with high probability, one can achieve a significant
improvement in the latency/throughput tradeoff. For a fixed maximum latency, we
show that almost twice the maximum possible guaranteed throughput rate can be
achieved with high probability. Alternatively for a fixed throughput value,
relaxing to achievement with high probability decreases the maximum latency to
almost the square root of the latency required to guarantee the throughput
rate.
We first give a lower bound on the best maximum latency possible given an
achieved throughput rate with high probability. This is done using an LP
duality style argument. We then give a family of ORN designs which achieves
these tradeoffs. The connection schedule is based on the Vandermonde Basis
Scheme of Amir, Wilson, Shrivastav, Weatherspoon, Kleinberg, and Agarwal,
although the period and routing scheme differ significantly. We prove
achievable throughput with high probability by interpreting the amount of flow
on each edge as a sum of negatively associated variables, and applying a
Chernoff bound. This gives us a design with maximum latency that is tight with
our lower bound (up to a log factor) for almost all constant throughput values.Comment: 19 pages, 1 figur
- …