Abstract
Data center networks offer multiple parallel paths between a source-destination pair. But, due to the use of TCAM based single logical step `path-search and selection' mechanism in the switches, most of the existing packet forwarding systems can utilize only a single-best path. It prevents them from utilizing the benefit of multiple paths for achieving application-specific QoS objectives. In this work, we propose P4KP, a programmable switch-based novel scheme for utilizing the top-k best paths toward a destination in a QoS-aware manner. P4KP complements TCAM's path-selection capability using SRAM; decouples path-searching from path-selection and facilitates the path-selection using an SRAM-based data structure. Its SRAM-based data structure reduces costly TCAM usage and enables the efficient update of the top-k best paths in the data plane. P4KP also provides a bitmask-based API to express the QoS-based policy for selecting one-of-the-top-k best paths. We implemented P4KP using P4 language to demonstrate that it is realizable in currently available programmable switches while maintaining line-rate throughput. Our preliminary evaluation shows that P4KP significantly reduces the stateful memory consumption in programmable switches and achieves improved performance.
Highlights
Data center networks (DCN) typically contain multiple paths between a source-destination pair to carry traffic from various applications with diverse QoS objectives
Supporting application-specific QoS objectives is one of the most crucial design goals in futuristic data center networks. Driven by this goal and the opportunities provided by the PISA switches, we propose P4KP: a QoS-aware scheme for managing top-k best paths and QoS policy-aware selection of one-of-the-top-k paths using P4 supported programmable switches
The path will not be in the P4KP data structure during this period, and no packet can be forwarded through the path. To reduce the duration of transient configuration, control messages for insertion and deletion can be concatenated into the same control packet
Summary
Data center networks (DCN) typically contain multiple paths between a source-destination pair to carry traffic from various applications with diverse QoS objectives. As a result, supporting QoS aware path selection algorithm using TCAM suffers from scalability problems Considering these facts, most of the existing PISA switchbased works use a QoS aware single-best-path [13] or ECMP [14] like QoS unaware multipath capable policy-based packet forwarding schemes. TCAMs are the main instrument for path search and selection in PISA switches Their multi-stage pipeline-based architecture [6] provides scope for complementing the capabilities of TCAMs. traditional switches were designed for a fixed set of protocols with no or little support for utilizing multipath to achieve application-specific QoS objectives. Supporting application-specific QoS objectives is one of the most crucial design goals in futuristic data center networks Driven by this goal and the opportunities provided by the PISA switches, we propose P4KP: a QoS-aware scheme for managing top-k best paths and QoS policy-aware selection of one-of-the-top-k paths using P4 supported programmable switches.
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