Enhanced Data Streaming LLC v. Cisco Systems Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Enhanced Data Streaming LLC (Delaware)
  • Defendant: Cisco Systems, Inc. (Delaware)
  • Plaintiff’s Counsel: Fabricant LLP
• Case Identification: 2:25-cv-01038, E.D. Tex., 01/16/2026
• Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because Defendant Cisco maintains regular and established places of business, including data centers and offices, in Allen and Richardson, Texas, transacts substantial business, and has committed alleged acts of infringement within the district.
• Core Dispute: Plaintiff alleges that Defendant’s Aggregation Service Routers and Catalyst/Nexus Switches infringe five patents related to network data packet distribution, dynamic fragmentation, bandwidth allocation, fault-tolerant MAC address assignment, and equipment protection architectures.
• Technical Context: The technologies at issue relate to managing performance, efficiency, and reliability in high-speed computer networks, which are critical for services like IPTV, enterprise networking, and data centers.
• Key Procedural History: The complaint alleges that the patents' prior owner, Orckit IP LLC, sent a notice letter to Cisco on March 20, 2017, identifying the patents-in-suit and the accused products. This event is cited as the basis for Plaintiff's willful infringement allegations. Additionally, U.S. Patent RE50,398 is a reissue of U.S. Patent 9,185,151, with the complaint alleging the asserted claims are substantially identical.

Case Timeline

Date	Event
2000-07-27	Earliest Priority Date for U.S. Patent No. 6,891,855
2002-08-02	Earliest Priority Date for U.S. Patent No. 7,032,135
2003-05-13	Earliest Priority Date for U.S. Patent No. 7,336,605
2005-05-10	U.S. Patent No. 6,891,855 Issued
2006-04-18	U.S. Patent No. 7,032,135 Issued
2006-09-22	Earliest Priority Date for U.S. Patent No. 7,660,234
2007-10-16	Earliest Priority Date for U.S. Reissue Patent No. RE50,398
2008-02-26	U.S. Patent No. 7,336,605 Issued
2010-02-09	U.S. Patent No. 7,660,234 Issued
2015-11-10	U.S. Patent No. 9,185,151 (Original of RE50,398) Issued
2017-03-20	Prior patent owner allegedly sent notice letter to Cisco
2025-04-22	U.S. Reissue Patent No. RE50,398 Issued
2026-01-16	First Amended Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Reissue Patent No. RE50,398 - *"Device, Method and System for Media Packet Distribution"*

The Invention Explained

• Problem Addressed: In Internet Protocol Television (IPTV) systems, the delay experienced by a user when changing channels, known as "zap-time," can be significant and negatively impact user experience (Compl. ¶ 34). This delay is often caused by the need to wait for the next complete reference frame (I-frame) in the video stream before decoding can begin.
• The Patented Solution: The invention describes a system that generates an "appliance specific media stream" from a primary multicast broadcast. In response to a channel change request, this generator can convert the multicast stream to a unicast stream for the specific requesting device and retransmit it with a calculated delay. This delay is determined based on timing parameters to reduce the perceived zap-time for the user, for example by providing a specially prepared stream that starts with an I-frame more quickly ('398 Patent, Abstract; col. 16:6-18).
• Technical Importance: The technology aims to make the IPTV channel-surfing experience more comparable to traditional broadcast television by minimizing the latency inherent in packet-based video distribution.

Key Claims at a Glance

• The complaint asserts at least Claim 1 of the ’398 Patent (Compl. ¶ 30).
• Independent Claim 1 elements include:
  • A device for retransmitting a received media stream broadcast.
  • A communication module to receive a request for a given IP media stream from a media presentation appliance.
  • A stream generator to convert a single appliance specific version of the requested media stream from multicast to unicast in response to the request.
  • The stream generator retransmits with a delay the converted unicast version.
  • A delay time for the delayed version is determined to reduce zap-time.
  • Content in the unicast version is substantially identical to content in the multicast version.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 6,891,855 - *"Dynamic Packet Fragmentation"*

The Invention Explained

• Problem Addressed: On communication channels with variable data rates, such as Digital Subscriber Lines (DSL), transmitting large, low-priority data packets (like email) can introduce significant delay and jitter for small, time-sensitive packets (like voice-over-IP) that must wait for the large packet to finish transmitting ('855 Patent, col. 1:16-46). Statically fragmenting all packets into small sizes to mitigate this is inefficient on high-speed connections due to overhead.
• The Patented Solution: The invention proposes a method and apparatus that dynamically adjusts the maximum allowed size of data fragments based on the current transmission rate of the channel. When the channel rate is low, packets are broken into smaller fragments to prevent delaying high-priority traffic. When the rate is high, the fragment size limit increases, which a reduces the percentage of overhead and improves overall transmission efficiency ('855 Patent, Abstract; col. 2:32-45).
• Technical Importance: This approach provides an adaptive solution that balances low latency for priority services with high efficiency for bulk data transfer across networks with fluctuating bandwidth.

Key Claims at a Glance

• The complaint asserts at least Claim 1 of the ’855 Patent (Compl. ¶ 49).
• Independent Claim 1 elements include:
  • A method for transmitting data over a channel having a variable transmission rate.
  • Determining the rate of transmission of the data over the channel.
  • Receiving a datagram for transmission at the determined rate.
  • Dividing the datagram into fragments of a size no greater than a size limit that is set for the datagram responsive to the determined rate of transmission.
  • Transmitting the fragments over the channel.
  • The size limit is set such that the time to transmit each fragment is no greater than a predetermined maximum time, which corresponds to a maximum delay for high-priority services.
• The complaint does not explicitly reserve the right to assert dependent claims.

U.S. Patent No. 7,336,605 - *"Bandwidth Allocation for Link Aggregation"*

• Patent Identification: 7,336,605, "Bandwidth Allocation for Link Aggregation," issued February 26, 2008.
• Technology Synopsis: This patent describes a method for allocating bandwidth across multiple parallel physical links that form a single logical link. The system allocates bandwidth with a "predefined safety margin" based on measured load fluctuations to ensure that the guaranteed bandwidth of the connection is maintained even with non-uniform traffic distribution among the links ('605 Patent, Abstract).
• Asserted Claims: At least Claim 1 (Compl. ¶ 69).
• Accused Features: The complaint alleges that Cisco's ASR 1000 Series Routers, which implement features like per-tunnel QoS for DMVPN and adaptive QoS, infringe by allocating bandwidth with a safety margin to account for traffic fluctuations across aggregated links (Compl. ¶ 70, 72-73).

U.S. Patent No. 7,660,234 - *"Fault-Tolerant Medium Access Control (MAC) Address Assignment in Network Elements"*

• Patent Identification: 7,660,234, "Fault-Tolerant Medium Access Control (MAC) Address Assignment in Network Elements," issued February 9, 2010.
• Technology Synopsis: The patent discloses a system for fault-tolerant MAC address assignment in a network element with a backplane, tributary modules, and a common function module (CFM). The CFM assigns MAC addresses from a memory on the backplane; if it cannot access the backplane memory, it uses a secondary set of MAC addresses stored in its own local memory to ensure continuous operation ('234 Patent, Abstract).
• Asserted Claims: At least Claim 10 (Compl. ¶ 87, 94).
• Accused Features: The complaint accuses Cisco Catalyst 9500 Series Switches, alleging their StackWise Virtual technology performs the claimed method. It alleges the active switch assigns MAC addresses from backplane memory (EEPROM) when available, and from a secondary source (virtual MAC addresses) upon failover or when the backplane memory is inaccessible (Compl. ¶ 88-90).

U.S. Patent No. 7,032,135 - *"Equipment Protection Using a Partial Star Architecture"*

• Patent Identification: 7,032,135, "Equipment Protection Using a Partial Star Architecture," issued April 18, 2006.
• Technology Synopsis: This patent describes a fault protection architecture for communication equipment using a "partial star" topology. A central interface card is linked to multiple spoke interface cards via a protection bus. On at least one spoke, two spoke cards are connected together, allowing for both 1:N (one-to-many) and 1:1 (one-to-one) protection configurations using the same physical backplane traces ('135 Patent, Abstract).
• Asserted Claims: At least Claim 11 (Compl. ¶ 108).
• Accused Features: The complaint alleges that Cisco Nexus 7000 Series Switches, when arranged in a spine-and-leaf architecture, implement the claimed partial star configuration. It is alleged that the use of peer-keepalive links and virtual port channel (vPC) for failure detection and traffic rerouting constitutes the claimed method of fault protection (Compl. ¶ 107-110).

III. The Accused Instrumentality

Product Identification

• The complaint names two categories of accused products: "Accused Cisco Routers" and "Accused Cisco Switches" (Compl. ¶ 22). The infringement allegations for the '398, '855, and '605 patents focus on the Cisco ASR 1000 Series Aggregation Services Routers (Compl. ¶ 30, 49, 69). The allegations for the '234 and '135 patents focus on the Cisco Catalyst 9500 Series Switches and the Cisco Nexus 7000 Series Switches, respectively (Compl. ¶ 87, 105).

Functionality and Market Context

• The Accused Routers (e.g., ASR 1000 Series) are described as advanced network devices for aggregating various services like data, voice, and video (Compl. ¶ 30). The complaint highlights features such as Multicast VPN (MVPN), Multicast Service Reflection, Precision Time Protocol (PTP), and Multilink PPP (MLP) (Compl. ¶ 31, 33, 34, 50). These features are alleged to enable efficient retransmission of IP media streams and dynamic management of data transmission over variable-rate channels. The complaint includes a diagram from Cisco documentation illustrating the use of an ASR 1000 router as a "quadruple-play edge router" (Compl. p. 10).
• The Accused Switches (e.g., Catalyst 9500, Nexus 7000) are enterprise-grade core and aggregation switching platforms (Compl. ¶ 87). The complaint points to functionalities like StackWise Virtual MAC address management for fault tolerance in the Catalyst 9500 (Compl. ¶ 89) and the FabricPath spine-and-leaf architecture with virtual port channel (vPC) for high availability in the Nexus 7000 (Compl. ¶ 106-108). A network topology diagram from a Cisco white paper is referenced to show the accused spine-and-leaf architecture (Compl. p. 53, Fig. 4).

IV. Analysis of Infringement Allegations

RE50,398 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a device for retransmitting a received IP media stream broadcast...	The Cisco ASR 1000 Series Router is a device designed to connect various services, including retransmitting IPTV and streaming video, voice, and data.	¶30-31	col. 16:6-9
a communication module adapted to receive from a media presentation appliance a request for a given IP media stream	The ASR 1000 router has communication ports (e.g., Gigabit Ethernet) for receiving requests from media presentation appliances.	¶32	col. 15:47-51
a stream generator adapted to convert, in response to the request..., one single appliance specific version of the requested media stream from multicast to unicast...	The ASR 1000 router's "Multicast Service Reflection" feature is alleged to convert a media stream from multicast to unicast in response to a request. The complaint provides a diagram from Cisco documentation illustrating "Multicast-to-Unicast Destination Translation" (Compl. p. 13, Fig. 2).	¶33	col. 16:9-15
and to retransmit with a delay the converted unicast, appliance specific, version of the requested media stream...	The router retransmits the requested media stream with a delay.	¶33	col. 16:12-18
wherein a delay time for the delayed version... is determined to reduce zap-time... at least partly based on a timing parameter of the request...	The router's implementation of IEEE 1588v2 Precision Time Protocol ("PTP") is alleged to be a packet-based message exchange protocol used for synchronizing clocks and determining a delay time to reduce zap-time.	¶34	col. 16:15-18
wherein content in the unicast appliance specific version... is substantially identical to content in the multicast appliance specific version...	The "Multicast Service Reflection" feature is alleged to retransmit substantially identical content from a multicast stream into a unicast stream.	¶35	col. 15:38-41

Identified Points of Contention

• Scope Questions: A central question may be whether the general-purpose "Multicast Service Reflection" feature, which translates network addresses, constitutes the claimed "stream generator" that creates a "single appliance specific version" of a stream.
• Technical Questions: The analysis may focus on whether Cisco's implementation of the IEEE 1588v2 PTP standard, a general-purpose clock synchronization protocol, is in fact used to determine a delay time specifically "to reduce zap-time," as required by the claim, or if its function is unrelated to channel change latency.

6,891,855 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method for transmitting data over a channel having a variable transmission rate...	The ASR 1000 Series Routers are designed to handle data transmission over channels with variable rates, such as aggregated low-speed links or DSL-based networks.	¶50-51	col. 3:1-6
determining the rate of transmission of the data over the channel...	In DSL-based networks, the ASR 1000 router is alleged to dynamically adjust bandwidth using media-rate information received from a DSLAM, which is embedded in PPPoE tags.	¶52	col. 4:60-62
receiving a datagram for transmission over the channel at the determined rate of transmission...	The ASR 1000 router's MLPoE feature supports receiving datagrams for transmission by employing Link Fragmentation and Interleaving ("LFI").	¶53	col. 4:63-65
dividing the datagram into fragments of a size no greater than a size limit that is set for the datagram responsive to the determined rate of transmission...	The multilink fragmentation process in the ASR 1000 router allegedly breaks large packets into smaller fragments, with the fragment size dynamically calculated using parameters influenced by the link's bandwidth and a fragment delay value.	¶54	col. 4:65-col. 5:2
wherein the size limit is set such that a length of time required to transmit each of the fragments is no greater than a predetermined maximum time...	The LFI and MLP features allegedly set a size limit for each fragment to ensure timely transmission without delaying priority packets like voice or video, with the maximum time corresponding to the delay applicable to high-priority services. The complaint includes a diagram showing large datagrams being fragmented while IP voice packets are not (Compl. p. 26, Fig. 1).	¶56-57	col. 3:8-13

Identified Points of Contention

• Scope Questions: The term "responsive to the determined rate of transmission" may be a key point of dispute. The question will be whether the accused routers automatically and dynamically adjust the fragment size limit based on real-time channel conditions, as the patent suggests, or if the size is primarily determined by static, user-defined configurations.
• Technical Questions: Evidence will be needed to show that the accused routers perform the specific calculation for fragment size based on the transmission rate as described in the patent, rather than using a different or more generalized Quality of Service (QoS) mechanism for prioritizing traffic.

V. Key Claim Terms for Construction

'398 Patent, Claim 1

• The Term: "delay time... is determined to reduce zap-time"
• Context and Importance: This term links a technical feature (determining a delay time) to a specific purpose (reducing zap-time). Infringement may depend on whether the accused PTP functionality is proven to be used for this specific purpose. Practitioners may focus on this term because Cisco may argue that PTP is a standard clock synchronization tool with no inherent connection to reducing channel change latency.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification may discuss delay and timing in the general context of improving stream delivery, which could support a broader reading not strictly limited to zap-time.
  • Evidence for a Narrower Interpretation: The specification explicitly links the determination of the delay to reducing zap-time, stating the delay is "determined to reduce zap-time associated with presenting the requested media stream" ('398 Patent, col. 16:15-18). This language suggests a purpose-driven limitation.

'855 Patent, Claim 1

• The Term: "a size limit that is set... responsive to the determined rate of transmission"
• Context and Importance: This term is the core of the claimed invention, defining the dynamic nature of the fragmentation. The case may turn on whether the accused products' fragmentation size is truly "responsive to" the transmission rate in an automated way. Practitioners may focus on this term because many networking devices use static fragmentation sizes or QoS policies that are configured by an administrator, which might not be considered "responsive" in the manner claimed.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The specification's general discussion of fragmentation in variable-rate environments could be argued to cover any system where an administrator could manually change the fragment size in response to known rate changes.
  • Evidence for a Narrower Interpretation: The specification provides a specific formula for calculating a temporary fragment length: Temp_Frag_Length=Int{ (Max_Wait×Rate)/8}-Overhead, where "Rate" is the "actual, instantaneous rate of channel 25" ('855 Patent, col. 5:11-20). This provides strong support for a narrow construction requiring an automatic, calculated response to the measured transmission rate.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement for all patents-in-suit. The allegations are based on Defendant Cisco providing customers and end-users with products along with publicly available instructions—such as user manuals, configuration guides, product literature, and website information—that allegedly instruct them on how to operate the Accused Products in a manner that directly infringes the asserted claims (Compl. ¶ 41, 61, 78, 97, 115).
• Willful Infringement: The complaint alleges willful infringement based on pre-suit knowledge. The primary basis is a notice letter allegedly sent by the prior patent owner to Cisco on March 20, 2017, which identified the patents and accused products (Compl. ¶ 24). The complaint further alleges that Cisco adopted a policy of not reviewing the patents of others, which it characterizes as willful blindness (Compl. ¶ 40, 60, 77, 96, 114).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of functional purpose: do Cisco's general-purpose networking features, such as Multicast Service Reflection and the PTP timing protocol, perform the specific, purpose-driven functions required by the '398 patent claims, namely creating an "appliance specific version" of a stream with a delay calculated "to reduce zap-time"?
• A key evidentiary question will be one of operational dynamics: for the '855 patent, does the accused routers' multilink fragmentation process automatically and dynamically adjust the fragment size limit in direct response to the measured transmission rate of the channel, or is this limit a static parameter set by a network administrator?
• A central legal question regarding damages will be Cisco's state of mind: given the allegation of a 2017 notice letter, the dispute will likely involve a fact-intensive inquiry into whether Cisco's continued sale of the accused products after that date constituted objective recklessness sufficient to support a finding of willful infringement.