110,187 research outputs found
MULTIMEDIA STREAMING PLATFORM BANDWITH CONTROLL CONGESTION DETECTION AND BANDWIDTH ADAPTATION
We propose a platform for distributed multimedia systems. The proposed platform is implemented using the Netscape Portable Runtime (NSPR) and the Cross-Platform Component Object Model (XPCOM). This ensures system portability, flexibility and performance. The platform is equipped with a congestion detection algorithm and a bandwidth control mechanism thus controlling the transfer rates between the communication parties. Using this kind of bandwidth management this platform allows real-time streaming across multiple networks.real-time multimedia platform; XPCOM components; congestion detection; bandwidth control
Congestion Control for Network-Aware Telehaptic Communication
Telehaptic applications involve delay-sensitive multimedia communication
between remote locations with distinct Quality of Service (QoS) requirements
for different media components. These QoS constraints pose a variety of
challenges, especially when the communication occurs over a shared network,
with unknown and time-varying cross-traffic. In this work, we propose a
transport layer congestion control protocol for telehaptic applications
operating over shared networks, termed as dynamic packetization module (DPM).
DPM is a lossless, network-aware protocol which tunes the telehaptic
packetization rate based on the level of congestion in the network. To monitor
the network congestion, we devise a novel network feedback module, which
communicates the end-to-end delays encountered by the telehaptic packets to the
respective transmitters with negligible overhead. Via extensive simulations, we
show that DPM meets the QoS requirements of telehaptic applications over a wide
range of network cross-traffic conditions. We also report qualitative results
of a real-time telepottery experiment with several human subjects, which reveal
that DPM preserves the quality of telehaptic activity even under heavily
congested network scenarios. Finally, we compare the performance of DPM with
several previously proposed telehaptic communication protocols and demonstrate
that DPM outperforms these protocols.Comment: 25 pages, 19 figure
Impact of RoCE Congestion Control Policies on Distributed Training of DNNs
RDMA over Converged Ethernet (RoCE) has gained significant attraction for
datacenter networks due to its compatibility with conventional Ethernet-based
fabric. However, the RDMA protocol is efficient only on (nearly) lossless
networks, emphasizing the vital role of congestion control on RoCE networks.
Unfortunately, the native RoCE congestion control scheme, based on Priority
Flow Control (PFC), suffers from many drawbacks such as unfairness,
head-of-line-blocking, and deadlock. Therefore, in recent years many schemes
have been proposed to provide additional congestion control for RoCE networks
to minimize PFC drawbacks. However, these schemes are proposed for general
datacenter environments. In contrast to the general datacenters that are built
using commodity hardware and run general-purpose workloads, high-performance
distributed training platforms deploy high-end accelerators and network
components and exclusively run training workloads using collectives
(All-Reduce, All-To-All) communication libraries for communication.
Furthermore, these platforms usually have a private network, separating their
communication traffic from the rest of the datacenter traffic. Scalable
topology-aware collective algorithms are inherently designed to avoid incast
patterns and balance traffic optimally. These distinct features necessitate
revisiting previously proposed congestion control schemes for general-purpose
datacenter environments. In this paper, we thoroughly analyze some of the SOTA
RoCE congestion control schemes vs. PFC when running on distributed training
platforms. Our results indicate that previously proposed RoCE congestion
control schemes have little impact on the end-to-end performance of training
workloads, motivating the necessity of designing an optimized, yet
low-overhead, congestion control scheme based on the characteristics of
distributed training platforms and workloads
IP-Level Satellite Link Emulation with KauNet
Distributed applications and transport protocols communicating over a satellite link may react very strongly to conditions specific to that kind of link. Providing a evaluation framework to allow tests of real implementations of such software in that context is quite a challenging task. In this paper we demonstrate how the use of the general-purpose KauNet IP-level emulator combined with satellite-specific packet loss patterns can help by reproducing losses and delays experienced on a satellite link with a simple Ethernet LAN setup. Such a platform is an essential tool for developers performing continuous testing as they provide new features for e.g. video codecs or transport-level software like DCCP and its congestion control components
Performance analysis of WMNs by WMN-GA simulation system for different WMN architectures and TCP congestion-avoidance algorithms considering uniform distribution
(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, we evaluate the performance of two Wireless Mesh Networks (WMNs) architectures considering throughput, delay, jitter and fairness index metrics. For simulations, we used ns-3, Distributed Coordination Function (DCF) and Optimized Link State Routing (OLSR). We compare the performance for Transmission Control Protocol (TCP) Tahoe, Reno and NewReno for uniform distribution of mesh clients by sending multiple Constant Bit Rate (CBR) flows in the network. The simulation results show that for both WMN architectures, the PDR values of TCP congestion-avoidance algorithms are almost the same. For Hybrid WMN architecture, the throughput of TCP Reno is better than other algorithms. However, for I/B WMN, the throughput of TCP Tahoe is higher than other algorithms. The delay and jitter of TCP NewReno are a little bit lower compared with other algorithms. The I/B WMN architecture, the fairness index of TCP congestion-avoidance algorithms is almost the same.Peer ReviewedPostprint (author's final draft
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