基于MPTCP耦合的自适应带宽估计算法

多路径TCP(MultiPath TCP,MPTCP)协议既能满足用户对数据高速传输的需求又具有较高的稳定性,故提出一种基于MPTCP耦合的自适应带宽估计算法(Adaptive Bandwidth Estimation Algorithm Based on Coupling of MPTCP,ABEC?MPTCP).为...     

一种基于链路传输延迟的MPTCP拥塞控制算法*

由于传统TCP拥塞控制算法直接应用到MPTCP(Multipath Transport Control Protocol)中存在公平性问题,以及不能有效地发挥多路径传输的优势,因而从公平性方面对MPTCP现有拥塞控制算法进行研究.研究发现,现有的MPTCP拥塞控制算法均受到相同的回路时间限制.提出一种基于链路延迟的RTT补偿算法(Compensating for RTT mismatch,C-RTT ).该算法通过设置网络带宽占用比参数以及对MPTCP连接的子流设置侵略因子,从而保证瓶颈链路处MPTCP数据流和TCP数据流公平地共享可用带宽.最后通过NS3仿真实验证明,该算法能够有效地补偿链路中因RTT不等引起的公平性问题,并避免链路之间数据的非周期抖动,且保证了多路径传输的优越性.     

多路径TCP拥塞控制算法研究

首先介绍了多路径传输协议的几种典型的拥塞控制算法,然后对MPTCP协议进行了理论分析,包括MPTCP拥塞控制算法在瓶颈链路TCP公平性、平衡拥塞能力以及flap现象,实验分析表明LINKED INCREASES算法效果最好。最后,指出其存在的问题,并指出了进一步的研究方向。     

PTCP Incast in Data Center Networks

In recent years, dual-homed topologies have appeared in data centers in order to offer higher aggregate bandwidth by using multiple paths simultaneously. Multipath TCP （MPTCP） has been proposed as a replacement for TCP in those topologies as it can efficiently offer improved throughput and better fairness. However, we have found that MPTCP has a problem in terms of incast collapse where the receiver suffers a drastic goodput drop when it simultaneously requests data over multiple servers. In this paper, we investigate why the goodput collapses even if MPTCP is able to actively relieve hot spots. In order to address the problem, we propose an equally-weighted congestion control algorithm for MPTCP, namely EW-MPTCP, without need for centralized control, additional infrastructure and a hardware upgrade. In our scheme, in addition to the coupled congestion control performed on each subflow of an MPTCP connection, we allow each subflow to perform an additional congestion control operation by weighting the congestion window in reverse proportion to the number of servers. The goal is to mitigate incast collapse by allowing multiple MPTCP subflows to compete fairly with a single-TCP flow at the shared bottleneck. The simulation results show that our solution mitigates the incast problem and noticeably improves goodput in data centers.     

基于MPTCP的非对称多链路传输调度方法述评

随着通信及网络技术的发展,移动终端设备往往配备多个网络接口,具有多链路的网络接入能力。为实现多链路传输,互联网工程任务组提出了新型的多路径传输控制协议（Multipath Transmission Control Protocol,MPTCP）。如何合理进行MPTCP数据包调度为用户提供更大带宽、提高数据传输可靠性,并最大化网络资源利用率,成为网络通信领域的重要课题。首先,介绍了MPTCP的基本功能和其在数据调度中面临的主要挑战;然后,针对非对称多链路下的MPTCP传输调度算法,从减少数据包乱序、降低传输延迟、提高链路利用率,以及结合强化学习四个角度分析和比较了近年来的多路径传输相关研究;最后,结合当前研究热点展望了MPTCP的未来发展趋势。     

移动流媒体并行多路传输机制研究

随着我国移动终端的多样化以及人们对网络需求的不断增长,我国移动网络数据的传输数量在近5年增长迅速。然而人们利用移动终端进行网络传输时,通常会受到网络带宽、网络拥塞、网络时延等因素的影响。传统的传输控制协议(Transmission Control Protocol, TCP)与用户数据报协议(User Datagram Protocol, UDP)使用单条路径进行网络传输,已不能很好地满足人们对高速率、实时播放、大吞吐量等网络传输的需求。为了解决这一问题,文章提出一种移动流媒体并行多路传输机制,即多路径传输协议(Multipath Transmission Control Protocol, MPTCP)。该协议可充分发挥多路径传输特性,一方面优化了网络传输的性能,另一方面提高了用户的体验感。     

网络切换对TCP吞吐量和公平性的影响分析

无线移动网络的发展日新月异.TCP协议是目前互联网上使用的最为广泛的端到端可靠传输协议,但其应用在无线网络上的时候,TCP性能下降明显.文中详细分析了TCP移动网络的切换对TCP造成影响的几个重要方面.最后通过在NS2上进行实验揭示了对多个TCP流公平性的影响,即切换后RTT越小的TCP流的吞吐量增长的越快,同时静态链路会夺取无线链路的链路资源.     

MPTCP中一种减缓缓存阻塞的重传策略

MPTCP中子流间的性能差异、受限的缓存区将导致接收端缓存区阻塞,影响MPTCP整体性能.综合考虑子流的延迟、丢包率、拥塞控制窗口和慢启动门限,提出一种新的重传策略RTX-DLCS.仿真证明该策略能有效减缓缓存区阻塞,提高MPTCP吞吐量.     

多路径TCP协议性能分析

现有的网络终端通常配有多个网络接口,被称为"多宿主"主机,拥有多个可用的IP地址。多路径TCP能够同时使用这些接口进行数据传输,提高数据传输的效率和稳定性。通过搭建真实环境测试平台,剖析了多路径TCP的工作机制,并对多路径TCP的性能进行测试分析。     

一种移动TCP协议—ACKP协议

如今网络结构是同时包括有线固定网和无线网络的网络结构。本文针对无线网络对TCP提出的新要求及相应的解决办法进行了阐述,重点介绍了一种新的TCP协议的改进方法,即ACKP(Partial Acknowledge)协议。     

Google QUIC performance over a public SATCOM access

Google Quick UDP Internet Connections (QUIC) accounts for almost 10 % of the Internet traffic, and the protocol is not standardized at the Internet Engineering Task Force (IETF) yet. We distinguish Google QUIC (GQUIC) and IETF QUIC (IQUIC) since there may be differences between the two. Both Google and IETF versions run over UDP and cannot be split the way satellite systems usually do with TCP connections. The need for adapting any‐QUIC parameters needs to be evaluated. Since GQUIC is available, we analyze its behavior over a satellite communication system. In our evaluations, GQUIC quick connection establishment does not compensate an inappropriate congestion control. The resulting page downloading time doubles when using GQUIC as opposed to the performance with optimized split TCP connections. This paper concludes that specific tuning are required when any‐QUIC runs over a high bandwidth delay product (BDP) network.     

网络存储的发展历程及新兴的iSCSI

目前SAN和NAS存储正在迅速发展，DAS的生存空间越来越小。今天超过1／3的存储是网络化的，如果不是因为FC的高成本和复杂性．这个数字还会更大。iSCSI是IETF一种新的标准协议．它将SCSI命令压缩到TCP／IP包．使数据块在IP网络上传播。和FC-SAN相比．高速千兆iSCSI耙SCSI、以太网和TCP／IP结合起来，具有许多优势．如建立在稳定和熟悉的标准上；较低的总拥有成本，安装和维修费用很低；较高程度的可操作性，减少了异构网络和电缆．使用一般的以太网交换机而不是特殊的FC交换机；等等。     

区分服务网络中的TCP友好公平体系

区分服务(Differentiated Services)是IETF为实现IP服务质量(QoS)而定义的一个体系结构。研究表明,在该体系中存在不公平问题,该文将TCP友好(TCP Friendly)的概念引入到DS网络中,并定义了DS网络中的TCP友好的公平性,仿真验证了目前IETF定义的流量调节(TrafficConditioning)以及丢包策略等机制不能很好地实现TCP友好公平性,因而提出了直接拥塞控制机制来实现这一公平性。     

DCCP Congestion Control with Virtual Recovery to Achieve TCP-Fairness

The Datagram Congestion Control Protocol (DCCP) has been standardized by the IETF as an unreliable transport protocol for real-time streaming applications. DCCP features unreliable data delivery and congestion control to achieve timely transmission and to fairly share bandwidth with TCP respectively. However, we found that unfair bandwidth sharing between DCCP and TCP still exists because DCCP does not utilize fast recovery. This paper proposes a novel congestion control for DCCP, called TCP-friendly DCCP (TF-DCCP), which lets DCCP own "virtual recovery" and thus enter congestion avoidance simultaneously with TCP. Simulation results demonstrate that TF-DCCP can provide excellent TCP-fairness.     

TCP移动性应用层支持方案的研究

如何在无线通信系统中提供高效的移动连接,让移动节点能够随时、随地保持业务的连续性是当前研究的热点。IETF提出的SIP协议以其灵活、容易部署等特性较好地解决了移动节点的全局移动性问题。然而,在利用SIP实现移动TCP应用过程中,频繁的切换过程将会导致TCP连接中断的发生,从而使得各种会话过程和预定业务不能正常进行。就此问题提出了一种基于SIP　EYEagent与SIPINFOmethod实现TCP应用移动性的解决方案。     

An Adaptive Delayed Acknowledgment Strategy to Improve TCP Performance in Multi-hop Wireless Networks

In multi-hop wireless networks, transmission control protocol (TCP) suffers from performance deterioration due to poor wireless channel characteristics. Earlier studies have shown that the small TCP acknowledgments consume as much wireless resources as the long TCP data packets. Moreover, generating an acknowledgment (ACK) for each incoming data packet reduces the performance of TCP. The main factor affecting TCP performance in multi-hop wireless networks is the contention and collision between ACK and data packets that share the same path. Thus, lowering the number of ACKs using the delayed acknowledgment option defined in IETF RFC 1122 will improve TCP performance. However, large cumulative ACKs will induce packet loss due to retransmission time-out at the sender side of TCP. Motivated by this understanding, we propose a new TCP receiver with an adaptive delayed ACK strategy to improve TCP performance in multi-hop wireless networks. Extensive simulations have been done to prove and evaluate our strategy over different topologies. The simulation results demonstrate that our strategy can improve TCP performance significantly.     

SCTP安全威胁分析及对策

流控制传输协议(SCTP)用于基于IP的网络上传输PSTN信令。本文在传输机制、多宿主机、多数据流等方面与TCP进行了特征比较,并进一步详细分析了SCTP存在的四种典型的安全威胁,提出了相应的解决方案。     

软交换信令网关中传输协议的探讨

信令网关是软交换系统的重要组成部分,它用于解决现有No.7信令网与IP网之间的无缝融合问题.本文首先介绍了信令网关协议栈的参考模型,以及IETF建议的流控制传输协议的特点,最后总结了SCTP协议优于TCP协议的一些特性.     

Performance Metrics for IEEE 802.21 Media Independent Handover (MIH) Signaling

The IEEE 802.21 Media Independent Handover (MIH) working group is developing a set of mechanisms to facilitate migration of mobile users between access networks that use different link-layer technologies. Among these are mobility managers that create and process signaling messages to facilitate handovers. The MIH signaling architecture being developed in the Internet Engineering Task Force (IETF) allows any transport layer protocol to carry MIH messages. The IETF has considered using the unreliable but lightweight transport available with the User Datagram Protocol (UDP) as well as the reliable stream-oriented transport with congestion control offered by the Transmission Control Protocol (TCP). In this paper we develop mathematical models that result in expressions for the characteristic function of the time required to complete exchanges of an arbitrary number of MIH signaling messages between a mobile node (MN) and a remote mobility manager (MM). Our models also provide expressions for the average amount of overhead associated with MIH message exchanges due to retransmissions either by the MIH signaling entities or by the transport-layer protocol. In addition, we provide simulation results that confirm the results from the mathematical model and illustrate the effect of varying transport parameters such as the TCP maximum retransmission timeout.