A Survey on Multipath Transport Protocols
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paper_title: A Concurrent Multipath TCP and Its Markov Model

paper_content:

Concurrent Multipath Transport (CMT) has been of increasing interest recently for aggregating bandwidth, balancing load, and increasing reliability. In this paper we propose a concurrent multipath Transport Control Protocol (cmpTCP), which is an extension of TCP New Reno and Steam Control Transmission Protocol (SCTP). The proposed cmpTCP has been implemented by altering and extending library-based open-source for SCTP. The proposed cmpTCP manages transport control parameters of all paths simultaneously; a scheduler concurrently dispatches packets over all the paths from a common transmission queue. However, one virtual retransmission queue is maintained for each path, and the receiver sends acknowledgment for a packet on the same path on which the packet is received. A Markov model for estimation of expected window size of each path has been proposed. Next, the proposed model has been utilized to derive an expression for computing average data transmission rate when the proposed cmpTCP is used. To validate performance of the proposed model, two host computers were connected through two independent network emulators. Each network emulator runs on a separate computer, and the network parameters are adjusted independently. We used our cmpTCP for transferring files from one host to the other. Comparison of experimental results with model predicted results shows excellent agreement.
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paper_title: Improved data distribution for multipath TCP communication

paper_content:

Multi-homed environments are increasingly common, especially for mobile users. To efficiently utilize multiple access lines for single file transfer, multipath TCP communication methods have been proposed. A multipath TCP enables simultaneous distributed data transfer between two end-points on multiple TCP connections. However, these methods cannot fully utilize the available bandwidth of multiple paths because they do not properly consider the end-to-end delay of packet transmission, so out-of-order data arrival at a receiver causes a bottleneck in data sort operations. This problem is more severe in environments where the quality of each path is different or unstable, such as in wireless environments. To solve this problem, we propose a multipath TCP communication method that includes a data distribution method to enable in-order delivery at a receiver. We call this arrival-time matching load-balancing (ATLB). ATLB continuously calculates the delay of each path, including the TCP queuing delay at a sender and the network delay, and then sends a data segment through the TCP connection with the lowest end-to-end delay. Simulation results show that ATLB improves end-to-end throughput, especially in heterogeneous environments where the quality of paths differs. For example, ATLB enabled twice the throughput with the conventional multipath TCP. We also report performance evaluation results from our ATLB test bed system in a wireless network environment. Our ATLB test bed system was able to fully utilize the aggregate available bandwidth of unstable multiple wireless links.
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paper_title: An Introduction to the Stream Control Transmission Protocol (SCTP)

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This document provides a high level introduction to the capabilities supported by the Stream Control Transmission Protocol (SCTP). It is intended as a guide for potential users of SCTP as a general purpose transport protocol.
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paper_title: The resource pooling principle

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Since the ARPAnet, network designers have built localized mechanisms for statistical multiplexing, load balancing, and failure resilience, often without understanding the broader implications. These mechanisms are all types of resource pooling whichmeans making a collection of resources behave like a single pooled resource. We believe that the natural evolution of the Internet is that it should achieve resource pooling by harnessing the responsiveness of multipath-capable end systems. We argue that this approach will solve the problems and limitations of the current piecemeal approaches.
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paper_title: A Transport Layer Approach for Improving End-to-End Performance and Robustness Using Redundant Paths

paper_content:

Recent work on Internet measurement and overlay networks has shown that redundant paths are common between pairs of hosts and that one can often achieve better end-to-end performance by adaptively choosing an alternate path [8, 28]. In this paper, we propose an end-to-end transport layer protocol, mTCP, which can aggregate the available bandwidth of those redundant paths in parallel. By striping one flow's packets across multiple paths, mTCP can not only obtain higher end-to-end throughput but also become more robust under path failures. When some paths fail, mTCP can continue sending packets on other living paths and the recovery process normally takes only a few seconds. Because mTCP could obtain an unfair share of bandwidth under shared congestion, we integrate a shared congestion detection mechanism into our system. It allows us to dynamically detect and suppress paths with shared congestion so as to alleviate the aggressiveness problem. mTCP can also passively monitor the performance of several paths in parallel and discover better paths than the path provided by the underlying routing infrastructure. We also propose a heuristic to find disjoint paths between pairs of nodes using traceroute. We have implemented our system on top of overlay networks and evaluated it in both Planet-Lab and Emulab.
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paper_title: The End-to-End Performance Effects of Parallel TCP Sockets on a Lossy Wide-Area Network

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This paper examines the effects of using parallel TCP flows to improve end-to-end network performance for distributed data intensive applications. A series of transmission experiments were conducted over a wide-area network to assess how parallel flows improve throughput, and to understand the number of flows necessary to improve throughput while avoiding congestion. An empirical throughput expression for parallel flows based on experimental data is presented, and guidelines for the use of parallel flows are discussed.
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paper_title: An Evaluation of Multi-Path Transmission Control Protocol (M/TCP) with Robust Acknowledgement Schemes

paper_content:

We propose a new end-to-end transport protocol called Multi-path Transmission Control Protocol (M/TCP) and its two robust acknowledgement (ACK) schemes. Our protocol is designed as an alternative TCP option to improve reliability and performance of the Internet. The M/TCP sender simultaneously transmits data via multiple controlled paths to the receiver. Our protocol requires no modification in IP layer. Two M/TCP endpoints establish multiple paths between them by subscribing to multiple ISPs. The two robust ACK schemes proposed in this paper aim at improving M/TCP performance over the Internet with high packet loss in ACK channels. Performances between our protocol and TCP Reno are compared in terms of throughput and fairness by using ns2 simulator. Simulation results indicate that M/TCP achieves higher throughput than TCP Reno in situation of random drop and burst traffic with small buffer size. When there is network congestion on reverse path, M/TCP with the proposed robust ACK schemes performs better than M/TCP with the conventional immediate ACK scheme.
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paper_title: Improved data distribution for multipath TCP communication

paper_content:

Multi-homed environments are increasingly common, especially for mobile users. To efficiently utilize multiple access lines for single file transfer, multipath TCP communication methods have been proposed. A multipath TCP enables simultaneous distributed data transfer between two end-points on multiple TCP connections. However, these methods cannot fully utilize the available bandwidth of multiple paths because they do not properly consider the end-to-end delay of packet transmission, so out-of-order data arrival at a receiver causes a bottleneck in data sort operations. This problem is more severe in environments where the quality of each path is different or unstable, such as in wireless environments. To solve this problem, we propose a multipath TCP communication method that includes a data distribution method to enable in-order delivery at a receiver. We call this arrival-time matching load-balancing (ATLB). ATLB continuously calculates the delay of each path, including the TCP queuing delay at a sender and the network delay, and then sends a data segment through the TCP connection with the lowest end-to-end delay. Simulation results show that ATLB improves end-to-end throughput, especially in heterogeneous environments where the quality of paths differs. For example, ATLB enabled twice the throughput with the conventional multipath TCP. We also report performance evaluation results from our ATLB test bed system in a wireless network environment. Our ATLB test bed system was able to fully utilize the aggregate available bandwidth of unstable multiple wireless links.
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paper_title: Performance Evaluation of Multiple TCP connections in iSCSI

paper_content:

Storage area networks (SANs) based on fibre channel have been used extensively in the last decade while iSCSI is fast becoming a serious contender due to its reduced costs and unified infrastructure. This work examines the performance of iSCSI with multiple TCP connections. Multiple TCP connections are often used to realize higher bandwidth but there may be no fairness in how bandwidth is distributed. We propose a mechanism to share congestion information across multiple flows in "Fair-TCP" for improved performance. Our results show that Fair-TCP significantly improves the performance for I/O intensive workloads.
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paper_title: Increasing performances of TCP data transfers through multiple parallel connections

paper_content:

Although Transmission Control Protocol (TCP) is a widely deployed and successful protocol, it shows some limitations in present-day environments. In particular, it is unable to exploit multiple (physical or logical) paths between two hosts. This paper presents PATTHEL, a session-layer solution designed for parallelizing stream data transfers. Parallelization is achieved by striping the data flow among multiple TCP channels. This solution does not require invasive changes to the networking stack and can be implemented entirely in user space. Moreover, it is flexible enough to suit several scenarios — e.g. it can be used to split a data transfer among multiple relays within a peer-to-peer overlay network.
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paper_title: Transport level mechanisms for bandwidth aggregation on mobile hosts

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Present mobile computing does not support the simultaneous use of multiple heterogeneous network interfaces for a single transport layer connection. We describe a solution for channel aggregation at the transport layer, which provides increased bandwidth to mobile nodes. We present R-MTP (reliable multiplexing transport protocol), a rate-based reliable transport protocol capable of multiplexing data from a single application data stream across multiple network interfaces. Due to the lossy nature of wireless links in mobile environments, R-MTP tracks packet interarrival time for discrimination between congestion-based and transmission-based losses as well as better bandwidth estimation. The challenges to such a reliable protocol lie in the coordination of packets across streams with varying channel characteristics. Our experimental results validate R-MTP's bandwidth estimation and loss characterization techniques. Successful bandwidth aggregation is demonstrated in ideal and lossy environments.
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paper_title: Coupled Multipath-Aware Congestion Control

paper_content:

Often endpoints are connected by multiple paths, but communications ::: are usually restricted to a single path per socket. Resource usage ::: within the network would be more efficient were it possible for these ::: multiple paths to be used concurrently. The use of multiple paths ::: simultaneously, specifically within a Multipath TCP protocol, ::: necessitates the development of new congestion control algorithms. If ::: existing algorithms such as TCP New Reno were run independently on ::: each path, the multipath flow would take more than its fair share if ::: there was a common bottleneck. Further, it is desirable that a source ::: with multiple paths available will transfer more traffic using the ::: least congested of the paths, hence achieving resource pooling. This ::: would increase the overall utilization of the network and also its ::: robustness to failure. This document presents a congestion control ::: algorithm which couples the congestion control algorithms running on ::: different subflows by linking their increase functions, and ::: dynamically controls the overall aggresiveness of the multipath flow. ::: The result is a practical algorithm that is fair to TCP at bottlenecks ::: while moving traffic away from congested links.
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Title: A Survey on Multipath Transport Protocols
Section 1: INTRODUCTION
Description 1: This section introduces the context in which multipath transport protocols are utilized, highlighting the prevalence of multiple network interfaces in mobile devices and the benefits of multipath connections.

Section 2: MULTIPATH TRANSPORT PROTOCOLS
Description 2: This section presents various transport protocols that support multipath, identifying key protocols like ATLB, Fair-TCP, PATTHEL, R-MTP, and cTCP, and explaining their mechanisms.

Section 3: MULTIPATH TCP
Description 3: This section describes the IETF's Multipath TCP (MPTCP), detailing its goals, main mechanisms for connection management, and how it uses new TCP options for multipath capabilities.

Section 4: Traffic control in MPTCP
Description 4: This section elaborates on MPTCP's redefined traffic control mechanisms, including congestion control, flow control, acknowledgement management, loss packets recovery, failure management, data distribution over paths, managing out-of-sequence data arrival, and path management.

Section 5: CONCLUSION
Description 5: This section summarizes the findings of the paper, outlining the benefits and potential improvements of implementing multipath transport protocols.