# PrismParser: A Framework for Implementing Efficient P4-Programmable Packet Parsers on FPGA
## 3 Proposed P4-Programmable Parser
### Software Overview
#### 3.1.2 P4 Compiled JSON File
Despite the design's support for a 15 Gbps data rate due to its 64-bit bus size and clock frequency limitations, it faces constraints such as limited bus width, required advanced fabrication for higher clock frequencies, latency from multiplexers and control logic, and sequential processing bottlenecks. To improve and support higher throughputs like 40 or 100 Gbps, the design could benefit from increasing bus width, implementing deeper pipeline stages, optimizing multiplexers, and utilizing parallel processing units. ### Limitations and Evolution of the Base Block

Two primary solutions can be considered to enhance our parser's throughput: increasing its operating frequency or expanding the bus size. Alternatively, combining both approaches may also be employed to achieve optimal performance. However, the base design of our packet parser faces inherent challenges that constrain its operational efficiency. The primary issue is achieving higher frequencies, which is impossible with the base design because of its long critical path and single-cycle architecture. The secondary issue lies in its limited throughput capabilities, primarily due to its support for only small bus sizes. Enhancing the parser through larger bus sizes involves maintaining the base design while scaling up the number of multiplexer inputs. While preserving the core architecture, this approach increases resource consumption and a longer critical path. Additionally, it necessitates more complex memory content generation and requires unrolling the Prism Controller to manage the expanded data flow effectively. This limitation impacts the parser's ability to handle high-volume network traffic effectively, necessitating enhancements to accommodate larger data loads. To mitigate these issues, a range of improvements are proposed to augment throughput, focusing on either refining the operational frequency or expanding the bus size capabilities:

* **Enhancement via Higher Frequency**: Increasing the operating frequency to enhance the packet parser's performance is inherently limited due to the current design's optimization boundaries. Achieving higher frequency involves extensive optimization of the control logic and minimization of the latency of multiplexers and other critical components. Given that the current frequency represents the highest possible frequency without compromising system functionality, further enhancements in performance must be sought through other means. Specifically, increasing the bus size offers a viable alternative to achieve higher throughput. This approach involves scaling up the number of multiplexer inputs and expanding the overall architecture to handle larger data loads effectively. * **Enhancement via Larger Bus Sizes**: Two different approaches can enhance the parser through larger bus sizes. The first involves increasing the bus size, which results in larger multiplexers in the Protocol

Figure 4: Protocol Navigator: Protocol Investigator with its Match Detector sub-block and Bitmap Generator. Investigator block. This makes the logic more complex, worsens the critical path, and requires the software-generated configuration and control data to consider the entire path, necessitating fundamental changes in the software script. The second approach replicates the base block with modifications to enable parallel logic, extracting all headers in the input header chunk. ### Overlay Optimization

To address the limitations of the base parser block and enhance throughput and scalability, the initial step was to double the bus size rather than the frequency, presenting fewer constraints and greater feasibility. Building on this foundation, the design was further expanded into an extendable block that can be replicated to support larger bus sizes and frequencies. This section explains the breakdown of the problem and the development of an adjustable design, controllable through generics, to optimize performance. Doubling the throughput can be achieved by increasing either the frequency or the bus size.