'Etuate Cocker (PhD)

Network traffic using the Transmission Control Protocol (TCP) across shared bottleneck satellite channels can suffer significant impairment due to TCP queue oscillation. Coding
of such network traffic across multiple Internet Protocol (IP) packets allows packet loss to be masked from the senders, letting TCP senders sustain higher goodput rates. We argue that the
concept of tunneling coded traffic across a satellite link is a flexible one and does… Show more

Network traffic using the Transmission Control Protocol (TCP) across shared bottleneck satellite channels can suffer significant impairment due to TCP queue oscillation. Coding
of such network traffic across multiple Internet Protocol (IP) packets allows packet loss to be masked from the senders, letting TCP senders sustain higher goodput rates. We argue that the
concept of tunneling coded traffic across a satellite link is a flexible one and does not rely on a one-size-fits-all solution. This paper discusses a number of network topology options for the
deployment of coding, from the perspective of satellite providers,Internet service providers, end users and third-party entities. Show less

The use of Voice over IP (VoIP) applications such as Skype has revolutionised communication, shifting from Plain Old Telephone Service (POTS) transmission of analog voice signals to that of of digitised voice, video and data packets over a single shared transmission channel. However, latency and jitter remain a serious problem for VoIP and other real-time protocols in intercontinental applications. Their impact on VoIP traffic can be estimated by the ITU-T Mean Opinion Score (MOS)… Show more

The use of Voice over IP (VoIP) applications such as Skype has revolutionised communication, shifting from Plain Old Telephone Service (POTS) transmission of analog voice signals to that of of digitised voice, video and data packets over a single shared transmission channel. However, latency and jitter remain a serious problem for VoIP and other real-time protocols in intercontinental applications. Their impact on VoIP traffic can be estimated by the ITU-T Mean Opinion Score (MOS) estimators.

Our research tracks the estimated MOS across a large number of long-distance paths between different endpoint pairs as part of an ongoing longitudinal study, which times packet transmission and arrival in a global network of computers exchanging synthetic VoIP-like traffic. This paper discusses the design of the MOS estimation, the large open access data set it creates, and presents results from the first three years of operation. Show less

Satellite-based Internet links often feature link bandwidths significantly below those of the ground networks on either side. This represents a considerable bottleneck for traffic between those networks. Excess traffic banks up at IP queues at the satellite gateways, which can prevent conventional TCP connections from reaching a transmission rate equilibrium. This well-known effect, known as queue oscillation can leave the satellite link severely underutilised, with a corresponding impact on… Show more

Satellite-based Internet links often feature link bandwidths significantly below those of the ground networks on either side. This represents a considerable bottleneck for traffic between those networks. Excess traffic banks up at IP queues at the satellite gateways, which can prevent conventional TCP connections from reaching a transmission rate equilibrium. This well-known effect, known as queue oscillation can leave the satellite link severely underutilised, with a corresponding impact on the goodput of TCP connections across the link. Key to queue oscillation are sustained packet losses from queue overfow at the satellite gateway that the TCP senders cannot detect quickly due to the long satellite latency. Network-coded TCP (TCP/NC) can hide packet loss from TCP senders in such cases, allowing them to reach equilibrium. Show less

Conventional TCP performance is significantly impaired under long latency and/or constrained bandwidth. While small Pacific Island states on satellite links experience this in the extreme, small populations and remoteness often rule out submarine fibre connections and their communities struggle to reap the benefits of the Internet. Network-coded TCP (TCP/NC) can increase goodput under high latency and packet loss, but has not been used to tunnel conventional TCP and UDP across satellite links… Show more

Conventional TCP performance is significantly impaired under long latency and/or constrained bandwidth. While small Pacific Island states on satellite links experience this in the extreme, small populations and remoteness often rule out submarine fibre connections and their communities struggle to reap the benefits of the Internet. Network-coded TCP (TCP/NC) can increase goodput under high latency and packet loss, but has not been used to tunnel conventional TCP and UDP across satellite links before. We report on a feasibility study aimed at determining expected goodput gain across such TCP/NC tunnels into island targets on geostationary and medium earth orbit satellite links. Show less

Conceptionally, the User Datagram Protocol (UDP) should be well-suited for real-time applications, e.g., for Voice over IP (VoIP). However, many such applications, e.g., Skype, use the Transmission Control Protocol (TCP) either as a primary protocol or as a backup protocol when UDP is blocked, despite TCP’s flow control-related data delays. This paper proposes a technique for the estimation of the application buffer requirements of such TCP-based applications and the amount of data congestion… Show more

Conceptionally, the User Datagram Protocol (UDP) should be well-suited for real-time applications, e.g., for Voice over IP (VoIP). However, many such applications, e.g., Skype, use the Transmission Control Protocol (TCP) either as a primary protocol or as a backup protocol when UDP is blocked, despite TCP’s flow control-related data delays. This paper proposes a technique for the estimation of the application buffer requirements of such TCP-based applications and the amount of data congestion in real-time TCP data streams. We apply this technique to data collected from a global network exchanging synthetic real-time traffic over TCP. Our results show that the buffering requirements vary widely with time and path but can be substantial in many cases. Show less

Real-time Internet applications such as telephony, video conferencing and remote control are increasing in importance. A critical requirement for such applications is the ability to receive data packets in correct order with minimal delay (latency) and loss of data. Most Internet Service Providers (ISP) try to achieve this by adding bandwidth in the form of additional infrastructure (links and routers) and load balancing to meet the continuous Internet traffic growth. In terms of real-time… Show more

Real-time Internet applications such as telephony, video conferencing and remote control are increasing in importance. A critical requirement for such applications is the ability to receive data packets in correct order with minimal delay (latency) and loss of data. Most Internet Service Providers (ISP) try to achieve this by adding bandwidth in the form of additional infrastructure (links and routers) and load balancing to meet the continuous Internet traffic growth. In terms of real-time protocols, such upgrades are not exclusively beneficial, however. They tend to increase the number of routers (and hence router queues) a packet has to pass through, and increase the potential for out-of-order delivery of packets. Our paper presents the baseline results of a longitudinal study which aims to investigate the effects of such infrastructure changes on international realtime traffic. Show less