Performance Enhancing Proxy Research Articles

PEPesc: A TCP Performance Enhancing Proxy for Non-Terrestrial Networks

Non-terrestrial networks (NTNs) using flying objects such as satellites play key roles in the next-generation wireless system (6 G). The NTN links with long propagation delay and random packet losses pose a great challenge to the performance of Transport Control Protocol (TCP), which many Internet applications rely on. Performance enhancing proxy (PEP) is an easy-to-deploy approach for improving TCP's performance. In this paper, we design and implement a novel PEP called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PEPesc</i> which has two distinctive features. First, it features <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">retransmission-free</i> loss recovery, using an adaptive packet-level forward erasure correction method called streaming coding (SC). Second, as packet losses are recovered by SC, the congestion control problem is simplified to rate control and local acknowledgement between entities based on bandwidth estimation. Based on a queueing theoretic analysis of the design, we carefully devise a protocol and implement PEPesc as an open-source application. Extensive evaluations show that PEPesc can achieve much higher <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">and</i> smoother goodput than the canonical TCP variants and than other existing open-source PEPs in applications including <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iperf</i> and HTTP-based adaptive streaming, and achieves similar performance in web browsing. Finally, we also present a deployment case over a real-world geostationary satellite link.

Evaluation of TCP Congestion Control Algorithms with traffic control policies in a PEP-based geosynchronous satellite scenario

Much work has been done in recent years comparing TCP variants in many scenarios, including the satellite one. Some of these studies were carried out with the ns-2 and ns-3 simulators, which may give a good idea of the behavior of these TCP variants, although the results cannot be considered completely realistic. Some of the latest studies use virtualization to derive a variety of measures to test the suitability of Congestion Control Algorithms in a more realistic way. Such studies also take into account new variants of TCP, such as Google’s BBR. However, few of these works have evaluated the behavior of these variants in a scenario based on Performance Enhancing Proxies. Furthermore, no emphasis has been placed on those variants of TCP that try to maximize throughput and minimize delay, which is crucial in many services with low latency requirements. Our paper aims to fill this gap, offering a comparative assessment of the performance of these three TCP flavors: BBR, YeAH and CUBIC. We have created four different approaches to mix these TCP flavors with two traffic control techniques, including Active Queue Management (AQM) policies. To perform the testings, we have developed a TCP-Splitting satellite Emulation Framework (TSEF), a platform that allows us to evaluate the performance of TCP flavors on the forward channel of a geosynchronous satellite scenario based on Performance Enhancing Proxies (PEPs). According to our results, we can conclude that the application of AQM policies and ECN marks on aggressive TCP flavors like CUBIC is mandatory to maximize throughput and minimize delay.

Priority switching scheduler

SummaryWe define a novel core network router scheduling architecture called priority switching scheduler (PSS), to carry and isolate time constrained and elastic traffic flows from best‐effort traffic. To date, one possible solution has been to implement a core DiffServ network with standard fair queuing and scheduling mechanisms as proposed in the well‐known “A Differentiated Services Code Point (DSCP) for Capacity‐Admitted Traffic” from RFC5865. This architecture is one of the most selected solutions by internet service provider for access networks (e.g., customer‐premises equipment) and deployed within several performance‐enhancing proxies (PEPs) over satellite communications (SATCOM) architectures. In this study, we argue that the proposed standard implementation does not allow to efficiently quantify the reserved capacity for the AF class. By using a novel credit‐based shaper mechanism called burst limiting shaper (BLS) to manage the AF class, we show that PSS can provide the same isolation for the time constrained EF class while better quantifying the part allocated to the AF class. PSS operates both when the output link capacity is fixed (e.g., wire links and terrestrial networks) or might vary due to system impairments or weather condition (e.g., wireless or satellite links). We demonstrate the capability of PSS through an emulated SATCOM scenario with variable capacity and show the AF output rate is less dependent on the EF traffic, which improves the quantification of the reserved capacity of AF, without impacting EF traffic.

Reducing the acknowledgement frequency in IETF QUIC

SummarySatellite networks usually use in‐network methods (such as Performance Enhancing Proxies for TCP) to adapt the transport to the characteristics of the forward and return paths. QUIC is a transport protocol that prevents the use of in–network methods. This paper explores the use of the recently–standardised IETF QUIC protocol with a focus on the implications on performance when using different acknowledgement policies to reduce the number of packets and volume of bytes sent on the return path. Our analysis evaluates a set of ACK policies for three IETF QUIC implementations, examining performance over cellular, terrestrial and satellite networks. It shows that QUIC performance can be maintained even when sending fewer acknowledgements, and recommends a new QUIC acknowledgement policy that adapts QUIC's ACK Delay value based on the path RTT to ensure timely feedback. The resulting policy is shown to reduce the volume/rate of traffic sent on the return path and associated processing costs in endpoints, without sacrificing throughput.

A Virtual PEP for Web Optimization over a Satellite-Terrestrial Backhaul

The availability of network softwarization and virtualization technology in the field of telecommunications has opened the door to a radical review of the applications, protocols, and deployment models. In this evolving framework, old assumptions and constraints specific to satellite communications must be carefully re-assessed. To this aim, we revisit the role of the performance enhancing proxy (PEP), replaced by a chain of custom virtual network functions properly enabled to optimize common web traffic performance over a backhaul dynamically enabled with a supplementary satellite link. The resulting virtual PEP (vPEP) is compliant with the breakthrough virtualization and slicing paradigms and can fruitfully exploit the advanced features of the most recent IETF technologies such as QUIC and MPTCP.

Multi-classification approaches for classifying mobile app traffic

The growing usage of smartphones in everyday life is deeply (and rapidly) changing the nature of traffic traversing home and enterprise networks, and the Internet. Different tools and middleboxes, such as performance enhancement proxies, network monitors and policy enforcement devices, base their functions on the knowledge of the applications generating the traffic. This requirement is tightly coupled to an accurate traffic classification, being exacerbated by the (daily) expanding set of apps and the moving-target nature of mobile traffic. On the top of that, the increasing adoption of encrypted protocols (such as TLS) makes classification even more challenging, defeating established approaches (e.g., Deep Packet Inspection).To this end, in this paper we aim to improve the performance of classification of mobile apps traffic by proposing a multi-classification (viz. fusion) approach, intelligently-combining outputs from state-of-the-art classifiers proposed for mobile and encrypted traffic classification. Under this framework, four classes of different combiners (differing in whether they accept soft or hard classifiers' outputs, the training requirements, and the learning philosophy) are taken into account and compared. The present approach enjoys modularity, as any classifier may be readily plugged-in/out to improve performance further. Finally, based on a dataset of (true) users' activity collected by a mobile solutions provider, our results demonstrate that classification performance can be improved according to all considered metrics, up to +9.5% (recall score) with respect to the best state-of-the-art classifier. The proposed system is also capitalized to validate a novel pre-processing of traffic traces, here developed, and assess performance sensitivity to traffic object (temporal) segmentation, before actual classification.

A Novel Flow Regulation Protocol to Optimize the End-to-End Performance and Fairness Over LEO Satellite Network

The major challenge in the utilization of satellite network for the Internet access is its differing nature with wired network. To increase the performance of TCP-based applications over satellite network, performance enhancement proxies (PEP) had been incorporated. However, the existing PEP solutions have violated the end-to-end semantics of Internet applications. To solve this problem and to meet the future needs of the communication network, next-generation transport architecture (Iyengar and Ford in flow splitting with fate sharing in a next-generation transport services architecture, 2009; in A next-generation transport services architecture, 2009. http://tools.ietf.org/html/draft-iyengar-ford-tng-00) has been proposed. In this architecture, flow regulation functions (flow regulation layer) are factored out from end-to-end best delivery (endpoint layer). As a contribution to this research direction, we propose a novel flow regulation protocol to control the flows in terms of congestion, error and fairness over the Low Earth Orbit satellite environment. Simulation results reveal that the proposed protocol can provide optimized end-to-end performance (high throughput, high goodput and high information efficiency) without violating end-to-end semantics, and it also meets the network-level objective of fairness among the flows.

위성 통신에서 Cross-layer 기반 PEP 성능 평가

위성 통신은 넓은 지역에 통신 서비스를 제공하는 광역 네트워크이다. 하지만, 위성 통신은 대역폭이 제한되고 매우 긴 전파 지연 시간과 높은 BER(Bit Error Rate)로 인해 위성 통신을 고려하지 않은 TCP의 성능이 저하 된다. 본 논문에서는 위성 통신에서의 TCP 성능을 향상시키기 위해 DVB-RCS(Digital Video Broadcasting-Return Channel via Satellite) 네트워크 환경을 고려한 cross-layer 기반 PEP(Performance Enhancing Proxy) 기술을 제안한다. 제안하는 프로토콜은 TCP와 링크 계층 간 위성 자원 할당 정보를 정보 교환을 통해 최적의 TCP CWND(Congestion Window)를 설정한다. 제안한 프로토콜의 성능 평가를 위해 리눅스 기반의 PEP 테스트 베드를 구현하였다. 성능 평가 결과 다양한 BER에서 제안한 프로토콜은 위성 자원 할당 정보를 이용하여 최적의 TCP CWND 크기를 설정하기 때문에 단일 및 다중 세션 환경에서 기존 TCP 보다 제안한 프로토콜이 더 좋은 성능을 보여준다는 것을 확인할 수 있었다. Satellite communication is a wide area network (WAN) which provides communication service worldwide. However, the performance of TCP can be seriously degraded in the satellite networks due to limited bandwidth, long round-trip time (RTT) and high bit error rate (BER) over satellite links. In order to improve the performance of TCP, this paper proposes cross-layer Performance Enhancing Proxy (PEP) in digital video broadcasting-return channel via satellite (DVB-RCS) networks. The proposed protocol sets TCP Congestion Window (CWND) size by using satellite resource allocation information exchanged between TCP and the link-layer. we implement PEP testbed based on Linux to evaluate the performance of the proposed protocol. The simulation results show that the proposed protocol performs better than standard TCP both in single and multiple sessions in variant BER, because the proposed protocol sets TCP CWND size by using satellite resource allocation.

Transfer time analysis of file transfer framework with AL-FEC in SOTM networks

In this paper, we propose a fully reliable file-transfer framework with application layer forward error correction (AL-FEC) in satellite communications on the move (SOTM) systems. In particular, the proposed framework uses a two-way acknowledgement (ACK) exchange mechanism. The proposed framework is implemented into a performance-enhancing proxy to minimize the system change. Furthermore, we analyze the file-transfer time of the proposed framework by Markov chain. The analysis results show that the proposed framework outperforms TCP in terms of the file-transfer time and the goodput. Furthermore, in the transfer of a large-sized file, the overhead of the proposed AL-FEC mechanism is small in terms of the resource efficiency.

위성 통신 시스템에서 TCP연결 분할 기반 PEP의 성능 평가

A satellite communication system is one of viable solutions for Internet applications running in wide areas. However, the performance of TCP can be seriously degraded in the satellite networks due to long round-trip time (RTT) and high bit error rate (BER) over satellite links. Therefore, a performance enhancing proxy(PEP) based TCP splitting connection scheme is used in the satellite link to improve the TCP performance. In this paper, we implement PEP testbed and conduct experiment to evaluate the performance of TCP splitting connection by comparing with high-speed TCP solutions in various environments. In our experimental environment, we consider multiple connections, high packet loss, and limited bandwidth. The experiment results show that PEP improves the TCP throughput than high-speed TCP variants in various environments. However, there is no improvement of the TCP throughput with the limited bandwidth because there is packet loss caused by both the congestion and the channel error.

An end‐to‐end alternative to TCP PEPs: Initial Spreading, a TCP fast start‐up mechanism

SummaryWhile Transmission Control Protocol (TCP) Performance Enhancing Proxy (PEP) solutions have long been undisputed to solve the inherent satellite problems, the improvement of the regular end‐to‐end TCP congestion avoidance algorithms and the recent emphasis on the PEPs drawbacks have opened the question of the PEPs sustainability.Nevertheless, with a vast majority of Internet connections shorter than ten segments, TCP PEPs continue to be required to counter the poor efficiency of the end‐to‐end TCP start‐up mechanisms. To reduce the PEPs dependency, designing a new fast start‐up TCP mechanism is therefore a major concern. But, while enlarging the Initial Window (IW) up to ten segments is, without any doubt, the fastest solution to deal with a short‐lived connection in an uncongested network, numerous researchers are concerned about the impact of the large initial burst on an already congested network.Based on traffic observations and real experiments, Initial Spreading has been designed to remove those concerns whatever the load and type of networks. It offers performance similar to a large IW in uncongested network and outperforms existing end‐to‐end solutions in congested networks. In this paper, we show that Initial Spreading, taking care of the satellite specificities, is an efficient end‐to‐end alternative to the TCP PEPs. Copyright © 2015 John Wiley &amp; Sons, Ltd.

TETRA Backhauling via Satellite: Improving Call Setup Times and Saving Bandwidth

In disaster management scenarios with seriously damaged, not existing, or saturated communication infrastructures satellite communications can be an ideal means to provide connectivity with unaffected remote terrestrial trunked radio (TETRA) core networks. However, the propagation delay imposed by the satellite link affects the signalling protocols. This paper discusses the suitability of using a satellite link for TETRA backhauling, introducing two different architectures. In order to cope with the signal delay of the satellite link, the paper proposes and analyzes a suitable solution based on the use of a performance enhancing proxy (PEP). Additionally, robust header compression (ROHC) is discussed as suitable technology to transmit TETRA voice via IP-based satellite networks.

위성 통신에서 신뢰성 향상을 위한 랜덤 선형 네트워크 코딩 기술

본 논문에서는 위성 통신에서 신뢰성 향상을 위한 랜덤 선형 네트워크 코딩 적용 기술을 제안한다. 제안하는 프로토콜에서는 PEP (Performance Enhancement Proxy)에서 네트워크 코딩된 여분의 패킷을 전송하여 만약 데이터 패킷이 무선 채널 에러에 의해 손실되었다 할지라도 복구 할 수 있다. 또한 본 논문에서는 제안한 프로토콜을 위성 통신에 적용했을 때의 TCP 처리율 수학적 모델을 제시하고 제안한 프로토콜의 성능을 평가했다. 성능 평가 결과, 제안하는 프로토콜은 발신 측 PEP에서 여분의 네트워크 코딩된 패킷을 전송하고 수신 측 PEP에서 여분의 네트워크 코딩된 패킷을 이용하여 손실된 패킷을 복구하기 때문에 패킷 손실률을 감소시켜 기존 TCP보다 처리율 측면에서 우수한 성능을 나타냈다. In this paper, we propose a method for applying random linear network coding in satellite communication to improve reliability. In the proposed protocol, network-coded redundancy (NC-R) packets are transmitted in the PEP (Performance Enhancement Proxy). Therefore, if data packets is lost by wireless channel error, they can be recovered by NC-R packets. We also develop the TCP performance model of the proposed protocol and evaluate the performance of the proposed protocol. In the simulation results, It is shown that the proposed protocol can improve the TCP throughput as compared with that of the conventional TCP because the NC-R packets is sent by the sender-side PEP and the receiver-side PEP use these packets to recover the lost packets, resulting in reducing the packet loss in TCP.

Deploying Internet Protocol Security in satellite networks using Transmission Control Protocol Performance Enhancing Proxies

SUMMARYApplications that use the reliable Transmission Control Protocol (TCP) have a significant degradation over satellite links. This degradation is mainly a consequence of the congestion control algorithm used by standard TCP, which is not suitable for overcoming the impairments of satellite networks. To alleviate this problem, two TCP Performance Enhancing Proxies (PEPs) can be deployed at the edges of the satellite segment. Then these PEPs can use different mechanisms such as snooping, spoofing and splitting to achieve a better TCP performance. In general, these mechanisms require the manipulation of the Internet Protocol (IP) and TCP headers that generates a problem when deploying the standard IP security (IPsec) protocol. The security services that IPsec offers (encryption and/or authentication) are based on the cryptographic protection of IP datagrams, including the corresponding IP and TCP headers. As a consequence, these cryptographic protections of IPsec conflict with the mechanisms that PEPs use to enhance the TCP performance in the satellite link. In this article, we detail the reasons that cause this conflict, and we propose three different approaches to deploy IPsec in a scenario with TCP PEPs. Our proposals provide different trade‐offs between security and TCP performance in some typical scenarios that use satellite networks. Copyright © 2012 John Wiley &amp; Sons, Ltd.

An IP-ERN architecture to enable hybrid E2E/ERN protocol and application to satellite networking

We propose an architecture based on a hybrid E2E-ERN approach allowing ERN protocols to be inter-operable with current IP-based networks. Without introducing complex operations, the resulting E2E-ERN protocol provides inter and intra protocol fairness and benefits from all ERN advantages when possible. We detail the principle of this novel architecture, called IP-ERN, and show that this architecture is highly adaptive to the network dynamics and is compliant with every TCP feature, IPv4, IPv6 as well as IP-in-IP tunneling solutions. As a possible use case, we test this architecture as a potential candidate to replace Performance Enhancing Proxies (PEPs) commonly-used over satellite IP-based networks. Compared to splitting PEP, the IP-ERN architecture does not break the E2E connectivity, still achieves high satellite link utilization and fairness without needs of extra fault tolerant mechanisms.

A novel network architecture for train-to-wayside communication with quality of service over heterogeneous wireless networks

In the railway industry, there are nowadays different actors who would like to send or receive data from the wayside to an onboard device or vice versa. These actors are e.g., the Train Operation Company, the Train Constructing Company, a Content Provider, etc. This requires a communication module on each train and at the wayside. These modules interact with each other over heterogeneous wireless links. This system is referred to as the Train-to-Wayside Communication System (TWCS). While there are already a lot of deployments using a TWCS, the implementation of quality of service, performance enhancing proxies (PEP) and the network mobility functions have not yet been fully integrated in TWCS systems. Therefore, we propose a novel and modular IPv6-enabled TWCS architecture in this article. It jointly tackles these functions and considers their mutual dependencies and relationships. DiffServ is used to differentiate between service classes and priorities. Virtual local area networks are used to differentiate between different service level agreements. In the PEP, we propose to use a distributed TCP accelerator to optimize bandwidth usage. Concerning network mobility, we propose to use the SCTP protocol (with Dynamic Address Reconfiguration and PR-SCTP extensions) to create a tunnel per wireless link, in order to support the reliable transmission of data between the accelerators. We have analyzed different design choices, pinpointed the main implementation challenges and identified candidate solutions for the different modules in the TWCS system. As such, we present an elaborated framework that can be used for prototyping a fully featured TWCS.

E2E KEEP: End to End Key Exchange and Encryption Protocol for Accelerated Satellite Networks

Accelerating methods are used to enhance TCP performance over satellite links by employing Performance Enhancement Proxies (PEPs). However, providing a secure connection through the PEPs seems to be impossible. In this paper an appropriate method is proposed in order to provide an accelerated secure E2E connection. We show an efficient secure three-party protocol, based on public key infrastructure (PKI), which provides security against spiteful adversaries. Our construction is based on applying asymmetric cryptography techniques to the original IKE protocol. Security protocols use cryptography to set up private communication channels on an insecure network. Many protocols contain flaws, and because security goals are seldom specified in detail, we cannot be certain what constitute a flaw. Proofing security properties is essential for the development of secure protocol. We give a logic analysis of the proposed protocol with the BAN-logic and discuss the security of the protocol. The result indicates that the protocol is correct and satisfies the security requirements of Internet key exchange. Based on the results of this preliminary analysis, we have implemented a prototype of our security protocol and evaluated its performance and checked safety properties of security protocol, and the results show that the protocol is robust and safe against major security threats.

Throughput Improvement for TCP with a Performance Enhancing Proxy Using a UDP-Like Packet Sending Policy

Throughput Improvement for TCP with a Performance Enhancing Proxy Using a UDP-Like Packet Sending Policy

Delay- and Disruption-Tolerant Networking (DTN): An Alternative Solution for Future Satellite Networking Applications

Satellite communications are characterized by long delays, packet losses, and sometimes intermittent connectivity and link disruptions. The TCP/IP stack is ineffective against these impairments and even dedicated solutions, such as performance enhancing proxies (PEPs), can hardly tackle the most challenging environments, and create compatibility issues with current security protocols. An alternative solution arises from the delay- and disruption-tolerant networking (DTN) architecture, which specifies an overlay protocol, called bundle protocol (BP), on top of either transport protocols (TCP, UDP, etc.), or of lower layer protocols (Bluetooth, Ethernet, etc.). The DTN architecture provides long-term information storage on intermediate nodes, suitable for coping with disrupted links, long delays, and intermittent connectivity. By dividing the end-to-end path into multiple DTN hops, in a way that actually extends the TCP-splitting concept exploited in most PEPs, DTN allows the use of specialized protocols on the satellite (or space) links. This paper discusses the prospects for use of DTN in future satellite networks. We present a broad DTN overview, to make the reader familiar with the characteristics that differentiate DTN from ordinary TCP/IP networking, compare the DTN and PEP architectures and stacks, as a preliminary step for the subsequent DTN performance assessment carried out in practical LEO/GEO satellite scenarios. DTN security is studied next, examining the advantages over present satellite architectures, the threats faced in satellite scenarios, and also open issues. Finally, the relation between DTN and quality of service (QoS) is investigated, by focusing on QoS architectures and QoS tools and by discussing the state of the art of DTN research activity in modeling, routing, and congestion control.

TCP accelerator for DVB-RCS SATCOM dynamic bandwidth environment with HAIPE

A high assurance IP encryption (HAIPE) compliant protocol accelerator is proposed for military networks consisting of red (or classified) networks and black (or unclassified) networks. The boundary between red and black sides is assumed to be protected via a HAIPE device. However, the IP layer encryption introduces challenges for bandwidth on demand satellite communication. The problems experienced by transmission control protocol (TCP) over satellites are well understood: While standard modems (on the black side) employ TCP performance enhancing proxy (PEP) which has been shown to work well, the HAIPE encryption of TCP headers renders the onboard modem's PEP ineffective. This is attributed to the fact that under the bandwidth-on-demand environment, PEP must use traditional TCP mechanisms such as slow start to probe for the available bandwidth of the link (which eliminates the usefulness of the PEP). Most implementations recommend disabling the PEP when a HAIPE device is used. In this paper, we propose a novel solution, namely broadband HAIPE-embeddable satellite communications terminal (BH-eST), which utilizes dynamic network performance enhancement algorithms for high latency bandwidth-on-demand satellite links protected by HAIPE. By moving the PEP into the red network and exploiting the explicit congestion notification bypass mechanism allowed by the latest HAIPE standard, we have been able to regain PEP's desired network enhancement that was lost due to HAIPE encryption (even though the idea of deploying PEP at the modem side is not new). Our BHeST solution employs direct video broadcast-return channel service (DVB-RCS), an open standard as a means of providing bandwidth-on-demand satellite links. Another issue we address is the estimation of current satellite bandwidth allocated to a remote terminal which is not available in DVB-RCS. Simulation results show that the improvement of our solution over FIX PEP is significant and could reach up to 100%. The improvement over the original TCP is even more (up to 500% for certain configurations).