Performance issues in asymmetric TCP service provision using broadband satellite

Fairhurst, Gorry; Samaraweera, N.; Sooriyabandara, Mahesh; Harun, Harlina; Hodson, Karen; Donadio, R.

doi:10.1049/ip-com:20010130

Cited by 14 publications

(13 citation statements)

References 11 publications

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“…This results in an intense burst of data packets in the other direction, in response to the burst of compressed ACKs arriving at the server. This phenomenon has been investigated in detail for bidirectional traffic, and recent analytical work [LMS97] has predicted ACK Compression may also result from bi-directional transmission with asymmetry, and was observed in practical asymmetric satellite subnetworks [FSS01]. In the case of extreme asymmetry (k>>1), the inter-ACK spacing can increase due to queuing (section 3.1), resulting in ACK dilation.…”

Section: Bidirectional Trafficmentioning

confidence: 99%

“…For data transfer in the forward direction this results respectively in loss of data packets and ACK packets. Loss of ACKs is less significant than loss of data packets, because it generally results in stretch ACKs [CR98,FSS01].…”

Section: Loss In Asymmetric Network Pathsmentioning

confidence: 99%

“…The reader is referred to [BPK99,Bal98,Pad98,FSS01,Sam99] for more details and experimental results.…”

Section: How Does Asymmetry Degrade Tcp Performance?mentioning

confidence: 99%

“…This may subsequently be used by an expander at the remote end of the tunnel. Further timing information may also be added to control the pacing of the regenerated ACKs [FSS01]. The temporal spacing of the filtered ACKs may also be encoded.…”

Section: Ack Reconstructionmentioning

confidence: 99%

“…These may be either deterministic or random (similar to a random-drop gateway, but should take into consideration the semantics of the items in the queue). Algorithms have also been suggested to ensure a minimum ACK rate to guarantee the TCP sender window is updated [Sam99,FSS01], and to limit the number of data packets (TCP segments) acknowledged by a Stretch ACK. Per-flow state needs to be maintained only for connections with at least one packet in the queue (similar to FRED [LM97]).…”

Section: Type 1: Reverse Link Bandwidth Managementmentioning

confidence: 99%

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TCP Performance Implications of Network Path Asymmetry

Balakrishnan¹,

Padmanabhan²,

Fairhurst³

et al. 2002

Self Cite

100

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This document describes TCP performance problems that arise because of asymmetric effects. These problems arise in several access networks, including bandwidth-asymmetric networks and packet radio subnetworks, for different underlying reasons. However, the end result on TCP performance is the same in both cases: performance often degrades significantly because of imperfection and variability in the ACK feedback from the receiver to the sender.The document details several mitigations to these effects, which have either been proposed or evaluated in the literature, or are currently deployed in networks. These solutions use a combination of local link-layer techniques, subnetwork, and end-to-end mechanisms, consisting of: (i) techniques to manage the channel used for the upstream bottleneck link carrying the ACKs, typically using header compression or reducing the frequency of TCP ACKs, (ii) techniques to handle this reduced ACK frequency to retain the TCP sender's acknowledgment-triggered self-clocking and (iii) techniques to schedule the data and ACK packets in the reverse direction to improve performance in the presence of two-way traffic. Each technique is described, together with known issues, and recommendations for use. A summary of the recommendations is provided at the end of the document. , and several packet radio networks. These networks are increasingly being deployed as high-speed Internet access networks, and it is therefore highly desirable to achieve good TCP performance. However, the asymmetry of the network paths often makes this challenging. Examples of some networks that exhibit asymmetry are provided in the Appendix.Asymmetry may manifest itself as a difference in transmit and receive capacity, an imbalance in the packet loss rate, or differences between the transmit and receive paths [RFC3077]. For example, when capacity is asymmetric, such that there is reduced capacity on reverse path used by TCP ACKs, slow or infrequent ACK feedback degrades TCP performance in the forward direction. Similarly, asymmetry in the underlying Medium Access Control (MAC) and Physical (PHY) protocols could make it expensive to transmit TCP ACKs (disproportionately to their size), even when capacity is symmetric. Asymmetry due to Differences in Transmit and Receive CapacityNetwork paths may be asymmetric because the upstream and downstream links operate at different rates and/or are implemented using different technologies. In networks employing centralized multiple access control, asymmetry may be a fundamental consequence of the hub-and-spokes architecture of the network (i.e., a single base node communicating with multiple downstream nodes). The central node often incurs less transmission overhead and does not incur latency in scheduling its own downstream transmissions. In contrast, upstream transmission is subject to additional overhead and latency (e.g., due to guard times between transmission bursts, and contention intervals). This can produce significant network path asymmetry.Upstream capacity ma...

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Section: Bidirectional Trafficmentioning

confidence: 99%

Section: Loss In Asymmetric Network Pathsmentioning

confidence: 99%

“…The reader is referred to [BPK99,Bal98,Pad98,FSS01,Sam99] for more details and experimental results.…”

Section: How Does Asymmetry Degrade Tcp Performance?mentioning

confidence: 99%

Section: Ack Reconstructionmentioning

confidence: 99%

Section: Type 1: Reverse Link Bandwidth Managementmentioning

confidence: 99%

See 3 more Smart Citations

TCP Performance Implications of Network Path Asymmetry

Balakrishnan¹,

Padmanabhan²,

Fairhurst³

et al. 2002

Self Cite

100

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Dynamics of TCP over BoD satellite networks

Sooriyabandara

Fairhurst

2003

Satell Commun Network

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SUMMARYBandwidth-on-Demand (BoD) mechanisms are used by most next generation satellite systems to efficiently share a limited radio spectrum among a large number of users. BoD design needs to consider a range of engineering issues: the anticipated number of users, interactions with other subsystems, and the contradictory design goals of optimising system utilization and delay/capacity offered to the network traffic. A BoD system may provide a range of quality of service classes to support different user classes and allow optimisation of allocation efficiency. Each class may have different delay and delay variation characteristics. The performance achieved by a TCP flow using such a BoD satellite network is highly dependent on the delay and the variation of the delay experienced by TCP. This paper describes the BoD mechanisms, and their expected impact on TCP behaviour. This discussion is supplemented by simulation results using an implementation of TCP combined with a model of some simple satellite BoD access schemes to characterize the performance and efficiency of BoD algorithms.

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Fair and efficient Transmission Control Protocol access in the IEEE 802.11 infrastructure basic service set

Keceli

Inan

Ayanoğlu

2013

Wireless Communications

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When the stations in an IEEE 802.11 infrastructure basic service set employ Transmission Control Protocol (TCP), this exacerbates per-flow unfair access problem. We propose a novel analytical model to approximately calculate the maximum per-flow TCP congestion window limit that prevents packet losses at the access point buffer and therefore provides fair TCP access both in the downlink and uplink. The proposed analysis is unique in considering the effects of varying number of uplink and downlink TCP flows, differing round trip times among TCP connections and the use of delayed TCP acknowledgment (ACK) mechanism. Motivated by the findings of this theoretical analysis and simulations, we design a link layer access control block to be employed only at the access point in order to resolve the unfair access problem. The proposed link layer access control block uses congestion control and ACK filtering approach by prioritizing the access of TCP data packets of downlink flows over TCP ACK packets of uplink flows. Via simulations, we show that the proposed algorithm can provide both short-term and long-term fair accesses while improving channel utilization and access delay.

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Performance issues in asymmetric TCP service provision using broadband satellite

Cited by 14 publications

References 11 publications

TCP Performance Implications of Network Path Asymmetry

TCP Performance Implications of Network Path Asymmetry

Dynamics of TCP over BoD satellite networks

Fair and efficient Transmission Control Protocol access in the IEEE 802.11 infrastructure basic service set

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