Wooster Magazine: Winter 2012

This edition of the Wooster Magazine was published in the Winter of 2012. Students in Professor Mangubi\u27s printmaking class last semester created very large prints with the help of a 12 ton steamroller. The college has a new core message to deliver, America\u27s premier college for mentored undergraduate research. Recent books published by alumni are on page six. The Communication Sciences and Disorders major is featured from page eight to nineteen. The next section highlights alumni and current students/faculty working with sculpture as their art medium of choice. Annie B Irish was Wooster\u27s first female faculty member and PhD recipient, her legacy is recalled from page 29 to 35.https://openworks.wooster.edu/wooalumnimag_2011-present/1023/thumbnail.jp

P4-CoDel: Experiences on Programmable Data Plane Hardware

Fixed buffer sizing in computer networks, especially the Internet, is a compromise between latency and bandwidth. A decision in favor of high bandwidth, implying larger buffers, subordinates the latency as a consequence of constantly filled buffers. This phenomenon is called Bufferbloat. Active Queue Management (AQM) algorithms such as CoDel or PIE, designed for the use on software based hosts, offer a flow agnostic remedy to Bufferbloat by controlling the queue filling and hence the latency through subtle packet drops. In previous work, we have shown that the data plane programming language P4 is powerful enough to implement the CoDel algorithm. While legacy software algorithms can be easily compiled onto almost any processing architecture, this is not generally true for AQM on programmable data plane hardware, i.e., programmable packet processors. In this work, we highlight corresponding challenges, demonstrate how to tackle them, and provide techniques enabling the implementation of such AQM algorithms on different high speed P4-programmable data plane hardware targets. In addition, we provide measurement results created on different P4-programmable data plane targets. The resulting latency measurements reveal the feasibility and the constraints to be considered to perform Active Queue Management within these devices. Finally, we release the source code and instructions to reproduce the results in this paper as open source to the research community

P4-CoDel:Experiences on Programmable Data Plane Hardware

Fixed buffer sizing in computer networks, especially the Internet, is a compromise between latency and bandwidth. A decision in favor of high bandwidth, implying larger buffers, subordinates the latency as a consequence of constantly filled buffers. This phenomenon is called Bufferbloat. Active Queue Management (AQM) algorithms such as CoDel or PIE, designed for the use on software based hosts, offer a flow agnostic remedy to Bufferbloat by controlling the queue filling and hence the latency through subtle packet drops. In previous work, we have shown that the data plane programming language P4 is powerful enough to implement the CoDel algorithm. While legacy software algorithms can be easily compiled onto almost any processing architecture, this is not generally true for AQM on programmable data plane hardware, i.e., programmable packet processors. In this work, we highlight corresponding challenges, demonstrate how to tackle them, and provide techniques enabling the implementation of such AQM algorithms on different high speed P4-programmable data plane hardware targets. In addition, we provide measurement results created on different P4-programmable data plane targets. The resulting latency measurements reveal the feasibility and the constraints to be considered to perform Active Queue Management within these devices. Finally, we release the source code and instructions to reproduce the results in this paper as open source to the research community

Reliable Network Services in Future Internet Service Provider Networks: Reliable and Efficient Control Plane Applications for Virtualized Data Planes in Software-Defined Networking

Driven by highly efficient over-the-top content providers, traffic on the Internet is increasing and puts pressure on Internet service providers (ISPs) to increase their efficiency as well. A promising approach to increase the efficiency of ISP networks is software-defined networking (SDN). SDN achieves this by separating the control from the data plane through a network protocol and thereby enabling increased automation and resource efficiency. However, today’s SDN-based control planes, consisting of control plane applications and an SDN controller to coordinate the data plane access, do not meet the reliability requirements for services in ISPs networks. With SDN, network services consist of multiple control plane applications combined in a single control plane. The control path in data plane elements is responsible for processing SDN protocol messages to configure the packet processing pipeline, termed data path. Today’s SDN controller designs do not virtualize the control path adequately, i.e., the effects of messages from different applications are not sufficiently isolated. Thereby, misbehaving low priority applications can block the control paths for essential high priority applications in ISP networks such as the network fabric. This lack of isolation can lead to control plane applications to fail unexpectedly and prevent the whole control plane from operating reliably. To this end, we introduce a novel, systematic resource-oriented approach to characterize the control paths in SDN data planes as well as a virtualization design for throughput aspects of control paths to increase the reliability among control plane applications. Based on these findings, we analyze the requirements of applications to operate on virtualized data planes. Local bottlenecks that only affect a single data plane element can be mitigated by shifting load to a different element. We apply this approach to our network function chaining design and investigate its effectiveness and provide insights on how the application should decide on the specifics of the mitigation process. Global control path bottlenecks affect a complete area of an ISP network. We analyze the interaction pattern that our novel Adaptive Software-Defined Multicast (ASDM) and Adaptive Bit-Index Software-Defined Multicast (ABSDM) designs require to identify such a bottleneck. Furthermore, we show how a global packet matching memory bottleneck can be mitigated by shifting the applications’ resource usage from matching memory to data rate. We demonstrate the effectiveness of the ASDM application for mitigating control path resource bottlenecks and thereby making it reliable. In this thesis, we close gaps in the virtualization of control paths that affect both SDN controllers and control plane applications. Thereby, we enable reliable SDN controllers and propose designs for reliable control plane applications to deliver SDN-based network services in ISP networks

Reliable Network Services in Future Internet Service Provider Networks: Reliable and Efficient Control Plane Applications for Virtualized Data Planes in Software-Defined Networking

Driven by highly efficient over-the-top content providers, traffic on the Internet is increasing and puts pressure on Internet service providers (ISPs) to increase their efficiency as well. A promising approach to increase the efficiency of ISP networks is software-defined networking (SDN). SDN achieves this by separating the control from the data plane through a network protocol and thereby enabling increased automation and resource efficiency. However, today’s SDN-based control planes, consisting of control plane applications and an SDN controller to coordinate the data plane access, do not meet the reliability requirements for services in ISPs networks. With SDN, network services consist of multiple control plane applications combined in a single control plane. The control path in data plane elements is responsible for processing SDN protocol messages to configure the packet processing pipeline, termed data path. Today’s SDN controller designs do not virtualize the control path adequately, i.e., the effects of messages from different applications are not sufficiently isolated. Thereby, misbehaving low priority applications can block the control paths for essential high priority applications in ISP networks such as the network fabric. This lack of isolation can lead to control plane applications to fail unexpectedly and prevent the whole control plane from operating reliably. To this end, we introduce a novel, systematic resource-oriented approach to characterize the control paths in SDN data planes as well as a virtualization design for throughput aspects of control paths to increase the reliability among control plane applications. Based on these findings, we analyze the requirements of applications to operate on virtualized data planes. Local bottlenecks that only affect a single data plane element can be mitigated by shifting load to a different element. We apply this approach to our network function chaining design and investigate its effectiveness and provide insights on how the application should decide on the specifics of the mitigation process. Global control path bottlenecks affect a complete area of an ISP network. We analyze the interaction pattern that our novel Adaptive Software-Defined Multicast (ASDM) and Adaptive Bit-Index Software-Defined Multicast (ABSDM) designs require to identify such a bottleneck. Furthermore, we show how a global packet matching memory bottleneck can be mitigated by shifting the applications’ resource usage from matching memory to data rate. We demonstrate the effectiveness of the ASDM application for mitigating control path resource bottlenecks and thereby making it reliable. In this thesis, we close gaps in the virtualization of control paths that affect both SDN controllers and control plane applications. Thereby, we enable reliable SDN controllers and propose designs for reliable control plane applications to deliver SDN-based network services in ISP networks

Software-Defined Multicast for Over-the-Top and Overlay-based Live Streaming in ISP Networks

The increasing amount of over-the-top (OTT) live streams and the lack of global network layer multicast support poses challenges for a scalable and efficient streaming over the Internet. Content Delivery Networks (CDNs) help by delivering the streams to the edge of almost every Internet Service Provider (ISP) network of the world but usually also end there. From there on, the streams are to be delivered to the clients using IP unicast, although an IP multicast functionality would be desirable to reduce the load on CDN nodes, transit links, and the ISP infrastructure. IP multicast is usually not available due to missing control and management features of the protocol. Alternatively, Peer-to-Peer (P2P) mechanisms can be applied to extend the overlay multicast functionality of the CDN towards the clients. Unfortunately, P2P only improves the situation for the CDN but makes it more challenging for the ISP as even more unicast flows are generated between clients inside and outside the ISP network. To tackle this problem, a Software-Defined Networking-based cross-layer approach, called Software-Defined Multicast (SDM), is proposed in this paper, enabling ISPs to offer network layer multicast support for OTT and overlay-based live streaming as a service. SDM is specifically tailored towards the needs of P2P-based video stream delivery originating from outside the ISP network and can easily be integrated with existing streaming systems. Prototypical evaluations show significantly improved network layer transmission efficiencies when compared to other overlay streaming mechanisms, down to a level as low as for IP multicast, at linearly bounded costs