Kimiya Mohammadtaheri

Pedro Mizuno, Kimiya Mohammadtaheri, Linfan Qian et al.

Transport protocols continue to evolve to meet the demands of new applications, workloads, and network environments, yet implementing and evolving transport protocols remains difficult and costly. High-performance transport stacks tightly interweave protocol behavior with system-level mechanisms such as packet I/O, memory management, and concurrency control, resulting in large code bases where protocol logic is scattered and hard to modify -- an issue exacerbated by modern heterogeneous execution environments. This paper introduces transport programs, a target-independent abstraction that precisely and centrally captures a transport protocol's reactions to relevant transport events using abstract instructions for key transport operations such as data reassembly, packet generation and scheduling, and timer manipulation, while leaving execution strategy and low-level mechanisms to the target. We show that transport programs can express a diverse set of transport protocols, be efficiently realized on targets built over DPDK and Linux XDP, achieve performance comparable to hand-optimized implementations, and enable protocol changes and portability across targets without modifying underlying infrastructure.

Kimiya Mohammadtaheri, David Gao, Samuel Zhang et al.

The network transport layer is increasingly implemented in the NIC hardware to meet the performance demands of modern workloads, but this has made it difficult to evolve or deploy new transport protocols. Existing approaches either fix protocol logic in the data-path or build protocol-specific assumptions into the architecture that limit the range of protocols that can be supported on a single hardware substrate. We present PITA, a protocol-independent transport architecture that enables full data-path programmability while sustaining line-rate performance. PITA eliminates protocol-specific assumptions by structuring the data-path around a uniform abstraction over events, state, and instructions, and rethinks core components, including scheduling, packet generation, and data reassembly, to operate on this abstraction. We evaluate PITA along key dimensions reflecting the goals of its protocol-agnostic datapath design. Specifically, we show that PITA supports diverse protocol semantics by showing it can implement TCP and \roce on the same data path and preserve their distinct end-to-end behavior. Through targeted microbenchmarks and synthesis on Alveo U250 cards, we show that PITA's redesigned components sustain high performance under demanding conditions, with modest hardware overhead and meeting timing at 250MHz.