The Transmission Control Protocol.

Today many end hosts are equipped with multiple interfaces. These interfaces can be utilized simultaneously by multipath protocols to pool resources of the links in an efficient way while also providing resilience to eventual link failures. However how to schedule the data segments over multiple links is a challenging problem, and highly influences the performance of multipath protocols.In this paper, we focus on different schedulers for Multipath TCP. We first design and implement a generic modular scheduler framework that enables testing of different schedulers for Multipath TCP. We then use this framework to do an in-depth analysis of different schedulers by running emulated and real-world experiments on a testbed. We consider bulk data transfer as well as application limited traffic and identify metrics to quantify the scheduler's performance. Our results shed light on how scheduling decisions can help to improve multipath transfer.

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Experimental evaluation of multipath TCP schedulers

Mobile devices equipped with multiple network interfaces can increase their throughput by making use of parallel transmissions over multiple paths and bandwidth aggregation, enabled by the stream control transport protocol (SCTP) However, the different bandwidth and delay of the multiple paths will determine data to be received out of order and in the absence of related mechanisms to correct this, serious application-level performance degradations will occur This paper proposes a novel quality-aware adaptive concurrent multipath transfer solution (CMT-QA) that utilizes SCTP for FTP-like data transmission and real-time video delivery in wireless heterogeneous networks CMT-QA monitors and analyses regularly each path's data handling capability and makes data delivery adaptation decisions to select the qualified paths for concurrent data transfer CMT-QA includes a series of mechanisms to distribute data chunks over multiple paths intelligently and control the data traffic rate of each path independently CMT-QA's goal is to mitigate the out-of-order data reception by reducing the reordering delay and unnecessary fast retransmissions CMT-QA can effectively differentiate between different types of packet loss to avoid unreasonable congestion window adjustments for retransmissions Simulations show how CMT-QA outperforms existing solutions in terms of performance and quality of service

CMT-QA: Quality-Aware Adaptive Concurrent Multipath Data Transfer in Heterogeneous Wireless Networks

The stream control transmission protocol (STCP) is being standardized by the IEFT as a reliable transport protocol to transport SS7signaling messages over IP networks. Due to its attractive features such as multistreaming and multihoming, SCTP has received much attention from the network community, in terms of both research and development. This article introduces the main features of SCTP, and discusses the state of the art in SCTP research and development activities. We also provide a survey of the available products that use SCTP. Finally with a view to stimulating further research in this area, the challenges faced by the SCTP research community are identified.

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SCTP: state of the art in research, products, and technical challenges

For the past 20 years (1980-2000), applications and end users of the TCP/IP suite have employed one of two protocols: the transmission control protocol or the user datagram protocol. Yet some applications already require greater functionality than what either TCP or UDP has to offer, and future applications might require even more. To extend transport layer functionality, the Internet Engineering Task Force approved the stream control transmission protocol (SCTP) as a proposed standard in October 2000. SUP was spawned from an effort started in the IETF Signaling Transport (Sigtrans) working group to develop a specialized transport protocol for call control signaling in voice-overt (VoIP) networks. Recognizing that other applications could use some of the new protocol's capabilities, the IETF now embraces SCTP as a general-purpose transport layer protocol, joining TCP and UDP above the IP layer. Like TCP, STCP offers a point-to-point, connection-oriented, reliable delivery transport service for applications communicating over an IP network.

SCTP: new transport protocol for TCP/IP

The Stream Control Transmission Protocol (SCTP) is a general-purpose transport layer protocol providing a service similar to TCP - plus a set of advanced features to utilize the enhanced capabilities of modern IP networks and to support increased application requirements. Nowadays, there are SCTP implementations for all major operating systems. While SCTP was standardized as an RFC several years ago, there is still significant ongoing work within the IETF to discuss and standardize further features in the form of protocol extensions. In this article, we first introduce the SCTP base protocol and already standardized extensions. After that, we focus on the ongoing SCTP standardization progress in the IETF and give an overview of activities and challenges in the areas of security and concurrent multipath transport.

Stream control transmission protocol: Past, current, and future standardization activities

With the deployment of more and more resilience-critical Internet applications, there is a rising demand for multi-homed network sites. This leads to the desire for simultaneously utilising all available access paths to improve application data throughput. This is commonly known as Concurrent Multipath Transfer (CMT); approaches for several Transport Layer protocols have been proposed. Combined with Resource Pooling~(RP), CMT can also fairly coexist with concurrent non-CMT flows. Current approaches focus on symmetric paths (i.e. similar bandwidth, delay and error rate). However, asymmetric paths are much more likely -- particularly for realistic Internet setups -- and efficient CMT usage on such paths is therefore crucial. In this paper, we first show the challenges of plain as well as RP-aware CMT data transport over asymmetric paths. After that, we introduce mechanisms for efficient transport over such paths. Finally, we analyse the performance of our approaches by using simulations.

https://www.wiwi.uni-due.de/fileadmin/fileupload/I-TDR/SCTP/Paper/Globecom2010.pdf

On the Use of Concurrent Multipath Transfer over Asymmetric Paths

The steadily growing deployment of resilience-critical Internet services is leading to an increasing number of Multi-Homed network sites. Asymmetric Digital Subscriber Lines (ADSL) are an inexpensive way to add a secondary Internet access connection. With the development of Multi-Path Transport Layer protocols - like Multipath TCP (MPTCP) and the Stream Control Transmission Protocol (SCTP) furnished by a Concurrent Multipath Transfer (CMT-SCTP) extension - there is also a strong interest in utilising all access connections simultaneously to improve the data throughput of the applications. However, combining network paths over ADSL with paths over other access technologies like fibre optic links implies highly dissimilar paths with significantly different bandwidths, delays and queuing behaviours. Efficient Multi-Path transport over such dissimilar paths is a challenging task for the new Transport Layer protocols under development. In this paper, we show the difficulties of Multi-Path transport in a real-world dissimilar path setup which consists of a high-speed fibre optic link and an ADSL connection. After that, we present an optimised buffer handling technique which solves the transport efficiency issues in this setup. Our optimisation is first analysed by simulations. Finally, we also show the usefulness of our approach by experimental evaluation in a real Multi-Homed Internet setup.

https://www.wiwi.uni-due.de/fileadmin/fileupload/I-TDR/SCTP/Paper/PAMS2011.pdf

Evaluation of Concurrent Multipath Transfer over Dissimilar Paths

Today, a steadily growing number of devices contains multiple network interfaces. For example, nearly all smartphones are equipped with at least W-LAN as well as 3G/4G interfaces. In consequence, there is a rising demand for so-called multi-path transfer, which utilizes all of these interfaces simultaneously in order to maximize the payload throughput of applications. Currently, this so-called multi-path transfer is very actively discussed by the IETF, in form of the Multi-Path TCP (MPTCP) extension for TCP as well as the Concurrent Multi-path Transfer extension for SCTP (CMT-SCTP). Their larger-scale deployment in the Internet is expected for the near future. A key issue that prevents the standardization of these approaches is the fairness to concurrent TCP flows. A multi-path transfer should behave “TCP-friendly”, i.e. cause no harm to the performance of the very widely deployed TCP-based applications. In this paper, we first extend the notion of “fairness” from single-path transport to multi-path transport. Furthermore, we introduce the relevant congestion control approaches in the IETF context for single-path as well as multi-path transfer. We simulatively analyze these approaches in a couple of interesting network configuration scenarios, in order to show their behavior with special regard to the fairness definitions. Particularly, we also point out items of further discussion which are the result of the current approaches.123

https://www.wiwi.uni-due.de/fileadmin/fileupload/I-TDR/SCTP/Paper/ICC2012.pdf

On the fairness of transport protocols in a multi-path environment

The new general purpose transport protocol SCTP (Stream Control Transmission Protocol) has been developed for transport of signaling data, such as Signaling System No. 7 MTP level 2 or 3 user primitives, over IP networks. Since this application has especially high requirements towards the underlying transport protocol concerning reliability and fast recognition and recovery from failures, SCTP-based transmission must provide a high degree of network level fault tolerance. In our contribution we look at a typical link failure scenario in a multi-homed setup, and investigate two options for fast recovery from such an event, namely seamless SCTP switch-over, and a user level switch-over as has been suggested for the MTP Level 2 peer adaptation layer. Moreover, we will analyze necessary parameter settings for fast recovery from the failure situation. 1

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Erwin P. Rathgeb

Papers

Stream control transmission protocol: Past, current, and future standardization activities

On the Use of Concurrent Multipath Transfer over Asymmetric Paths

Evaluation of Concurrent Multipath Transfer over Dissimilar Paths

On the fairness of transport protocols in a multi-path environment

On the Use of SCTP in Failover-Scenarios