Match-action programmable switches enable highperformance custom packet processing without custom hardware. However, these switches are expensive and cannot currently be reasonably shared between multiple tenants since a switch provider cannot guarantee a share of the switch resources such as SRAM or TCAM for each tenant. Each match-action pipeline executes only a single program, and merging P4 source code from multiple tenants into a combined program gives no guarantee that the combined program fits onto the pipeline. We want to overcome this by showing how to divide the resources of an RMT-based matchaction pipeline into slices which can be rented out individually. The resource usage of a program is checked if it matches the slice to enable safe composition with other programs. By giving shared access to most of the PHV, our approach allows for large numbers of programs on a shared pipeline. We implemented our approach for the Tofino programmable switch and successfully limited the resource usage of real P4 programs. Our evaluation shows that slicing often results in the same (and sometimes even higher) number of programs that can be accommodated on a switch, compared to merging P4 programs without resource guarantees. Additionally, our approach significantly reduces the computation time to determine that a composition does not fit onto a switch.

Access to networks for purposes of executing remote services has become a dominant form of communication, while virtualization has enabled the flexible and fast deployment of those services across distributed locations. This seems at odds with the design that drives the network layer of the Internet. Our paper presents an approach to flexibly deploy a network layer solution for optimizing service access within a single domain, while retaining full connectivity to Internet-based services. We discuss design considerations and the resulting design. We analyze expected gains from our solution.

Stations in Cyber-Physical Systems (CPSs) and especially Industrial Internet of Things applications often work towards a common goal, but not all their tasks may be equally important to reach this goal. Hence, stations need to prioritize traffic because network resources are limited. To increase the service quality by utilizing otherwise unused network resources, stations may also opt to use cooperation instead of contention. Many existing standards and academic approaches focus on implementing either cooperation or Quality of Service (QoS) mechanisms. In this paper, we evaluate how to leverage cooperation to improve QoS. Since stations in wireless industrial applications often communicate locally, we focus on the MAC layer. We identify a set of useful cooperation mechanisms that increase the packet delivery ratio, and then extend them by several packet prioritization strategies and evaluate in multiple simulated industrial scenarios. As a result, we provide a set of guidelines for protocol designers to combine different mechanisms depending on the requirements imposed by industrial applications. Moreover, we provide and evaluate an exemplary combination of mechanisms derived from our results aiming at high reliability and low latency.

Increasing network speeds challenge the packet processing performance of networked systems. This can mainly be attributed to processing overhead caused by the split between the kernel-space network stack and user-space applications. To mitigate this overhead, we propose Santa, an application agnostic kernel-level cache of frequent requests. By allowing user-space applications to offload frequent requests to the kernel-space, Santa offers drastic performance improvements and unlocks the speed of kernel-space networking for legacy server software without requiring extensive changes.