DCT
6:21-cv-00261
Sable Networks Inc v. Cloudflare Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Sable Networks, Inc. (California) and Sable IP, LLC (Delaware)
- Defendant: Cloudflare, Inc. (Delaware)
- Plaintiff’s Counsel: Capshaw Derieux LLP; Robins Kaplan LLP; Berger & Hipskind LLP
- Case Identification: 6:21-cv-00261, W.D. Tex., 01/20/2023
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendant maintains a regular and established place of business in Austin, Texas, where it employs personnel and conducts business operations related to the Accused Products.
- Core Dispute: Plaintiff alleges that Defendant’s network services and server infrastructure, including its content delivery network and security products, infringe three patents related to managing network data traffic through micro-flow analysis, quality of service prioritization, and load balancing.
- Technical Context: The patents address foundational challenges in managing internet traffic, specifically how to ensure quality of service (QoS) for delay-sensitive applications like voice and video by breaking large data streams into manageable "micro-flows" for more granular routing and control.
- Key Procedural History: The complaint notes that Defendant Cloudflare previously petitioned for inter partes review (IPR) of the ’431 and ’919 patents, but the Patent Trial and Appeal Board (PTAB) denied institution, finding Cloudflare had not shown a reasonable likelihood of prevailing. The complaint also indicates Plaintiff anticipates moving to dismiss its infringement claim regarding the ’593 patent, which is notable as public records show the asserted claim of that patent has been disclaimed.
Case Timeline
| Date | Event |
|---|---|
| 2000-04-19 | Priority Date for ’431 and ’919 Patents |
| 2004-12-22 | Priority Date for ’593 Patent |
| 2005-10-11 | ’431 Patent Issued |
| 2006-03-14 | ’919 Patent Issued |
| 2012-08-14 | ’593 Patent Issued |
| 2021-03-15 | Initial Complaint Filed |
| 2021-05-24 | Cloudflare's Answer to Initial Complaint Filed |
| 2021-06-23 | Sable's Preliminary Infringement Contentions Served |
| 2023-01-13 | Sable's Final Infringement Contentions Served |
| 2023-01-20 | First Amended Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,954,431 - Micro-Flow Management, issued October 11, 2005
The Invention Explained
- Problem Addressed: Conventional internet routing protocols at the time struggled to provide guaranteed Quality of Service (QoS) because they aggregated many small data streams into large, inflexible "composite flows." This made it difficult to manage network congestion and prioritize delay-sensitive traffic like voice or video, which could be disrupted by the behavior of other, less critical data streams within the same composite flow (U.S. 6,954,431 B2, col. 1:12-2:65).
- The Patented Solution: The invention proposes managing traffic at a more granular "micro-flow" level, where a micro-flow is a uniquely identifiable set of packets from a single transmission (e.g., one video stream). The first packet of each micro-flow carries a set of quantified QoS descriptors (e.g., guaranteed rate, maximum delay variation). Switches along the network path store this "per-flow state information" and use it to route and police each micro-flow individually, ensuring its specific QoS requirements are met without being impacted by other flows ('431 Patent, Abstract; col. 5:40-65).
- Technical Importance: This state-based approach to traffic management provided a mechanism to offer quantifiable service guarantees over IP networks, a critical step for enabling reliable real-time applications that were becoming increasingly prevalent (Compl. ¶¶ 4, 28).
Key Claims at a Glance
- The complaint asserts at least independent claim 19, which depends on independent claim 10. The elements of independent claim 10 are:
- a means for determining a capacity of a buffer containing a microflow based on a characteristic;
- a means for assigning an acceptable threshold value for the capacity of the buffer over a predetermined period of time;
- a means for delegating a portion of available bandwidth in the network to the microflow; and
- a means for using the buffer for damping jitter associated with the microflow ('431 Patent, col. 18:49-64).
U.S. Patent No. 7,012,919 - Micro-Flow Label Switching, issued March 14, 2006
The Invention Explained
- Problem Addressed: In traditional Label Switched Path (LSP) networks (like MPLS), large aggregate flows are routed along a single path. If that path fails or becomes congested, the entire large flow must be rerouted, which requires significant spare bandwidth on alternate paths and can result in slow and inefficient fault recovery (U.S. 7,012,919 B1, col. 3:1-41).
- The Patented Solution: The invention provides for more intelligent load balancing by selecting a specific LSP for each individual micro-flow from a set of available paths. The selection is based on the micro-flow's specific QoS type and the current utilization of the available LSPs. This allows network traffic to be distributed more granularly and dynamically across the network infrastructure ('919 Patent, Abstract; col. 4:1-12).
- Technical Importance: By applying load balancing at the micro-flow level rather than the aggregate flow level, the invention enabled more efficient use of network resources and faster, more flexible recovery from network failures (Compl. ¶41).
Key Claims at a Glance
- The complaint asserts at least independent claim 25. The essential elements are:
- separating the first aggregate flow into a plurality of individual micro-flows at the ingress line card, each individual micro-flow comprising a data flow;
- routing the micro-flows to an egress line card, the egress line card being selected based on a quality of service of each individual micro-flow;
- assembling the plurality of individual micro-flows into a second aggregate flow having a quality of service capable of supporting the quality of service of the plurality of micro-flows, the assembling being performed at the egress line card; and
- transmitting the second aggregate flow over the network connection ('919 Patent, col. 23:1-14).
Multi-Patent Capsule
- Patent Identification: U.S. Patent No. 8,243,593, Mechanism for Identifying and Penalizing Misbehaving Flows in a Network, issued August 14, 2012.
- Technology Synopsis: The patent describes a method for identifying and controlling undesirable network traffic, which may be disguised to evade detection by conventional means (Compl. ¶55). The invention monitors the "behavioral statistics" of a data flow (e.g., data rate, duration) to determine if it is exhibiting undesirable behavior and, if so, enforces a penalty such as an increased probability of dropping its packets (Compl. ¶¶ 56-57, 61).
- Asserted Claims: At least claim 5 (Compl. ¶125).
- Accused Features: Cloudflare's DDoS Protection service, including its Gatebot functionality, eXpress Data Path (XDP) / extended Berkeley Packet Filter (eBPF) packet processing, and flowtrackd functionality (Compl. ¶114).
III. The Accused Instrumentality
Product Identification
- The accused instrumentalities are primarily Cloudflare's server infrastructure ("Gen 6 Edge Servers" through "Gen 11 Edge Servers") and the various network services they provide, including Cloudflare Magic Transit, Argo Smart Routing, WARP, Magic Firewall, Traffic Manager, Stream, and DDoS Protection (Compl. ¶¶ 65, 90, 114).
Functionality and Market Context
- The complaint alleges that these products and services constitute a global network that manages and secures vast amounts of internet traffic for Cloudflare's customers (Compl. ¶¶ 21-23). The allegedly infringing functionality involves the systems and methods Cloudflare uses to process, route, and prioritize data packets ("micro-flows") within its network. For example, the complaint alleges the products determine buffer capacity for micro-flows, delegate bandwidth, and limit jitter ('431 Patent allegations) (Compl. ¶¶ 68, 70, 73). It further alleges the products separate aggregate flows into individual micro-flows and route them based on quality of service ('919 Patent allegations) (Compl. ¶¶ 94-95). A product table for Plaintiff's S-Series Service Controllers illustrates technical specifications related to "Flow QoS" and various flow rates (MR, GR, AR, CR) that are central to the patented technology (Compl. p. 7).
IV. Analysis of Infringement Allegations
U.S. Patent No. 6,954,431 Infringement Allegations
| Claim Element (from Independent Claim 10) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a means for determining a capacity of a buffer containing a microflow based on a characteristic; | The Accused Products allegedly "determine the capacity of a buffer containing a micro-flow based on a characteristic." | ¶68 | col. 10:45-54 |
| a means for assigning an acceptable threshold value for the capacity of the buffer over a predetermined period of time; | The Accused Products allegedly "assign an acceptable threshold value for the capacity of the buffer" and "enable the setting of thresholds for a buffer." | ¶¶69, 71 | col. 10:45-54 |
| a means for delegating a portion of available bandwidth in the network to the microflow; | The Accused Products allegedly "delegate a portion of available bandwidth in the network to the micro-flow." | ¶70 | col. 10:19-34 |
| a means for using the buffer for damping jitter associated with the microflow. | The Accused Products allegedly "use the buffer for damping jitter associated with the micro-flow" and "use buffers to limit jitter which is delay variance." | ¶¶72, 73 | col. 10:41-44 |
Identified Points of Contention
- Scope Questions: A central dispute may arise from the use of "means-plus-function" language in claim 10. The scope of each claim element is limited to the corresponding structures disclosed in the patent specification and their equivalents. This raises the question of whether Cloudflare’s accused software-based functionalities (e.g., XDP/eBPF) are structurally equivalent to the specific hardware-based structures (e.g., linecards, policing schedulers) described in the ’431 patent’s 2000-era disclosure.
- Technical Questions: What evidence does the complaint provide that Cloudflare's systems perform the specific function of "damping jitter" using a buffer as required by the claim, versus other methods of managing latency and network performance?
U.S. Patent No. 7,012,919 Infringement Allegations
| Claim Element (from Independent Claim 25) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| separating the first aggregate flow into a plurality of individual micro-flows at the ingress line card... | The Accused Products allegedly "separate the first aggregate flow into a plurality of individual micro-flows at the ingress line card." | ¶94 | col. 4:1-12 |
| routing the micro-flows to an egress line card, the egress line card being selected based on a quality of service of each individual micro-flow; | The Accused Products allegedly "route the micro-flows to an egress line card, the egress line card being selected based on a quality of service of each individual micro-flow." | ¶95 | col. 4:1-12 |
| assembling the plurality of individual micro-flows into a second aggregate flow... | The Accused Products allegedly "assemble the plurality of individual micro-flows into a second aggregate flow." | ¶96 | col. 4:1-12 |
| transmitting the second aggregate flow over the network connection. | The Accused Products allegedly "transmit the second aggregate flow over a network connection." | ¶97 | col. 4:1-12 |
Identified Points of Contention
- Scope Questions: Can the term "ingress line card" as used in the patent, which describes a specific piece of hardware in a network switch, be construed to read on a software-based data plane operating on a general-purpose server, as is common in modern cloud infrastructure?
- Technical Questions: What evidence does the complaint provide that Cloudflare's "Argo Smart Routing" or other accused routing services perform the specific function of selecting an "egress line card" (or its equivalent) based on the "quality of service of each individual micro-flow," as opposed to other routing metrics like latency, congestion, or cost?
V. Key Claim Terms for Construction
For the ’431 Patent:
- The Term: "microflow"
- Context and Importance: This term is foundational to the patent, as the invention is premised on managing network traffic at the "micro-flow" level. Its definition will be critical for determining whether the data streams managed by Cloudflare's systems meet the claimed definition.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification defines a micro-flow broadly as "a uniquely identifiable set of data signals that typically have the same open system interconnection model network layer and transport layer characteristics" ('431 Patent, col. 5:44-49). This language could support a construction covering any identifiable stream of packets sharing common header information.
- Evidence for a Narrower Interpretation: The detailed description provides specific examples of micro-flows in the context of TCP and UDP traffic and their associated QoS descriptors ('431 Patent, col. 9:9-24). A defendant may argue that the term should be limited by these specific embodiments.
For the ’919 Patent:
- The Term: "quality of service"
- Context and Importance: The selection of an egress path in asserted claim 25 is explicitly "based on a quality of service of each individual micro-flow." The definition of this term will determine what type of routing decisions fall within the claim's scope.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term is used generally in the background to refer to metrics like delay, jitter, and loss ('919 Patent, col. 7:1-13). This could support a construction encompassing any performance metric.
- Evidence for a Narrower Interpretation: The specification provides a detailed breakdown of specific QoS "service types," including Available Rate (AR), Maximum Rate (MR), and Guaranteed Rate (GR), each with its own set of quantitative descriptors ('919 Patent, col. 7:45-48). A party could argue the term should be construed to require one of these specific, defined types of QoS.
VI. Other Allegations
Indirect Infringement
- The complaint does not plead separate counts for indirect infringement.
Willful Infringement
- The complaint alleges willful infringement for all three patents. The allegations are based on Cloudflare's knowledge of the patents since at least the filing of the initial complaint on March 15, 2021 (Compl. ¶¶ 80, 104). The complaint further supports willfulness by alleging that Cloudflare continued to expand its infringing activities after receiving Sable's infringement contentions and, significantly, after its IPR petitions against the ’431 and ’919 patents were denied institution by the PTAB (Compl. ¶¶ 82-83, 106-107).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of structural equivalence for the '431 patent: can the "means for" limitations, which are defined by specific hardware structures in the patent's specification (e.g., linecards, ASICs, schedulers), be proven to read on the allegedly corresponding functions performed by Cloudflare's modern, software-defined networking architecture running on general-purpose servers?
- A key evidentiary question will be one of functional operation for the '919 patent: what technical evidence will show that Cloudflare’s routing systems select paths for individual data streams based on the specific "quality of service" parameters taught in the patent, as opposed to other common network performance metrics such as latency or packet loss?
- The dispute over willfulness may be significant, centering on whether Cloudflare's decision to continue its accused activities after the PTAB declined to institute inter partes review of two of the asserted patents constituted objective recklessness.