[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-86417-en":3,"doc-seo-86417-105":30,"detail-sidebar-cat-0-en-105":91},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":20,"is_deleted":4,"is_public":21,"is_downloadable":21,"audit_status":21,"page_count":22,"language":23,"language_code":24,"site_id":25,"html_lang":24,"table_of_contents":26,"faqs":27,"seo_title":13,"seo_description":14,"update_tm":28,"read_time":29},86417,4398048949847,"Eliana","https://ap-avatar.wpscdn.com/avatar/400002536579ef2da7f?_k=1778318612642679267",8,"Research & Report","Single-Connection Mixed-Criticality Transport with CATS Bounded Guarantees","Mixed-criticality systems—satellite terminals, industrial telemetry-and-control, embedded and tactical links, and other constrained environments—often multiplex a small latency-critical message class with bulk traffic over a single commodity transport connection. A FIFO stream can starve the critical class under load, while parallel connections add five-tuples and may be unavailable or lose single-flow fairness. CATS (Conductordriven Asymmetric Transport Scheme) prioritizes sender-side TCP traffic with conductor-driven classes, just-in-time sequence numbers, and a credit-based shaper, yielding deterministic non-starvation, single-flow fairness, and provably bounded per-class delay. Structural limits explain why in-band single-connection priority cannot be tail-latency universal, motivating a QUIC escape with isolated streams and end-host guarantees. An ns-3 evaluation and QUIC proof-of-concept support all claims.","Single-Connection Mixed-Criticality Transport with CATS: Bounded Guarantees, Three Structural Limits,  \nand a QUIC Escape  \nSyed Muhammad Aqdas Rizvi   \nIndependent Researcher  \nAlumnus, Lahore University of Management Sciences (LUMS)  \nKarachi, Pakistan  \n[s.muhammadaqdasrizvi@gmail.com | 25100166@lums.edu.pk](s.muhammadaqdasrizvi@gmail.com | 25100166@lums.edu.pk)  \narXiv :2606 . 16924v2 [ cs .NI] 13 Jul 2026  \nAbstract—Mixed-criticality applications, such as satellite terminals, industrial telemetry-and-control, embedded systems, tactical, and other constrained mixed-criticality links, often multiplex a small, latency-critical message class and bulk traffic over a single commodity transport connection. A single FIFO connection can starve the critical class under load. The obvious alternative, opening parallel connections, costs an additional five-tuple (often blocked by carrier-grade NAT, port budgets, and operator policy) and is not always available; when the critical class is light, two connections can also be bandwidth-fair only in aggregate rather than single-flow fair. We present CATS (Conductordriven Asymmetric Transport Scheme), a sender-side, receivertransparent transport-layer priority scheme over commodity TCP: a Conductor assigns each message a priority class and just-intime sequence numbers, governed by a credit-based shaper. CATS provides the one combination its alternatives cannot: deterministic non-starvation together with single-flow fairness, plus a provable bounded per-class delay.  \nWe then show that, crucially, CATS-over-TCP is not a taillatency mechanism, and why. Three structural barriers bound single-connection in-band priority at three layers: the in-order sequence space (head-of-line blocking), the shared congestion window (cross-class coupling), and the per-flow granularity of network QoS (in-band priority is invisible to it). The same barriers explain why fair-queuing and even the modern lowlatency standard L4S cannot help a single connection, and why two parallel connections reduce the latency tail at the cost of an additional flow. We give CATS-over-QUIC as the principled escape: independent streams with per-stream isolation under aggregatecoupled congestion control self-isolate at the endpoint, attaining the guarantees on one fair flow. An ns-3 evaluation across loss, contention, and handover regimes, and a QUIC proof-of-concept, support every claim, including the negative ones.  \nIndex Terms—transport priority, mixed-criticality, QUIC, satellite networking, congestion control, fair queuing  \nI. INTRODUCTION  \nMany systems carry two very different kinds of traffic over a single transport connection: a small, latency-critical class (control commands, coordination messages, model-routing decisions) interleaved with bulk transfers such as logs, model weights, sensor dumps, or media. This pattern is the norm in settings where a second connection is costly or unavailable: satellite and non-terrestrial terminals behind carrier-grade NAT, embedded and industrial endpoints with tight socket and port budgets, and existing single-socket applications that cannot be  \nre-architected. In these settings the critical class and the bulk class are not separable into independent network flows; they share one byte stream, one congestion controller, and one path.  \nA single first-in-first-out connection serves this mix badly. Under load the critical class queues behind the bulk backlog and starves: in our experiments a FIFO connection delivers0 of 300 critical messages within the measurement window under sustained contention, because the head of the send buffer is perpetually bulk data. The obvious remedy is to give the critical class its own parallel connection. This works, but at a cost that is easy to overlook: N parallel connections require N separate five-tuples, which are blocked by carrier-grade NAT, tight socket and port budgets, single-socket application constraints, and operator policy, and may be unavail","cbCaiqQMnpQ2UXBa","https://ap.wps.com/l/cbCaiqQMnpQ2UXBa","pdf",409299,4,1,10,"English","en",105,"# Abstract\n# Introduction\n## Mixed-criticality traffic over a single connection\n## Limitations of FIFO and parallel connections\n## The CATS approach and guarantees\n## Limits of CATS-over-TCP","[{\"question\":\"What problem does the paper target in mixed-criticality transport over a single connection?\",\"answer\":\"It targets starvation of a small latency-critical message class when the connection carries both critical and bulk traffic, as a FIFO stream can queue critical messages behind bulk backlog under contention.\"},{\"question\":\"How does CATS achieve deterministic non-starvation and single-flow fairness?\",\"answer\":\"CATS is sender-side and receiver-transparent: a Conductor assigns priority classes and just-in-time sequence numbers, while a credit-based shaper controls how classes share the connection, enabling deterministic progress for the critical class and unconditionally single-flow fairness on one connection.\"},{\"question\":\"Why is CATS-over-TCP not a tail-latency mechanism?\",\"answer\":\"The paper argues the limitation is structural across three layers: in-order sequence space causing head-of-line blocking, shared congestion window coupling across classes, and network QoS granularity that makes in-band priority effectively 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problem does the paper target in mixed-criticality transport over a single connection?","Question",{"text":75,"@type":76},"It targets starvation of a small latency-critical message class when the connection carries both critical and bulk traffic, as a FIFO stream can queue critical messages behind bulk backlog under contention.","Answer",{"name":78,"@type":73,"acceptedAnswer":79},"How does CATS achieve deterministic non-starvation and single-flow fairness?",{"text":80,"@type":76},"CATS is sender-side and receiver-transparent: a Conductor assigns priority classes and just-in-time sequence numbers, while a credit-based shaper controls how classes share the connection, enabling deterministic progress for the critical class and unconditionally single-flow fairness on one connection.",{"name":82,"@type":73,"acceptedAnswer":83},"Why is CATS-over-TCP not a tail-latency mechanism?",{"text":84,"@type":76},"The paper argues the limitation is structural across three layers: in-order sequence space causing head-of-line blocking, shared congestion window coupling across classes, and network QoS granularity that makes in-band priority effectively invisible.","https://schema.org",{"og:url":52,"og:type":87,"og:title":13,"og:site_name":58,"og:description":14},"article",{"robots":89,"canonical":52},"index,follow",{"doc_id":7,"site_id":25},{"code":4,"msg":5,"data":92},[93,97,101,105,110,115,120,123,128,131,134],{"id":21,"doc_module":4,"doc_module_name":46,"category_name":94,"show_sort_weight":95,"slug":96},"Story & 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