US 6834038

US Patent 6834038, titled "Protection against master unit failure in remote network access multiplexing," was filed on August 11, 2000, and issued on December 21, 2004. The original assignee was Orckit Communications Ltd, and the current assignee is QUICKER CONNECTIONS LLC. The inventors are David Zelig, Eli Aloni, Ron Sdayor, and Menahem Kaplan.

The patent's abstract describes a network access apparatus designed for redundancy. It comprises a slave unit with subscriber ports and a multiplexer, and a master sub-system located remotely from the slave unit. The master sub-system connects to a first public network via at least one trunk line. It includes a first master unit for communicating with the slave unit via a link through a second public network, providing subscribers access to the first public network. A second master unit is coupled through the first master unit to the same link. This second master unit is designed to take over communication and provide network access in the event of a failure associated with the first master unit.

Independent Claims Overview:

• Claim 1 (Apparatus): This claim describes a network access system. It specifies multiple "slave units," each containing subscriber ports (for users) and a multiplexer. The system also includes a "master sub-system" located remotely from the slave units, which connects to a "first public network" via trunk lines. This master sub-system has two key components:

  1. A "first master unit" (the active unit), which includes an interface to communicate with the slave units over designated links through a "second public network," and a multiplexer to handle traffic from the slave units. Its purpose is to give users access to the first public network.
  2. A "second master unit" (the standby unit), also with a multiplexer for the slave units and an interface. Critically, this second master unit's interface is coupled through the first master unit's interface to the same links. This arrangement ensures that if the first master unit fails, the second master unit can take over and continue providing users with access to the first public network.

• Claim 14 (Method): This claim outlines a method for providing network access with fault protection. It involves:

  1. Connecting both a "first master unit" and a "second master unit" to a "first public network" using separate network interfaces and trunk lines.
  2. Connecting multiple remote "slave units" to subscriber lines, with each slave unit multiplexing traffic from its lines.
  3. Establishing communication links between a specific interface of the first master unit and the slave units, routing through a "second public network," to allow subscriber access to the first public network.
  4. Providing dedicated multiplexers in both master units to manage traffic from the slave units.
  5. Configuring the system so that the "second master unit" is coupled through the first master unit's interface to these links. This coupling ensures that if there's a failure in the first master unit's network interface or multiplexer, the second master unit can seamlessly take over the network access provision.

Litigation Information:
According to the patent's own "Legal status" section, the patent family has litigation, specifically a US case filed in the Texas Eastern District Court (case 2:24-cv-01074). Additionally, "First worldwide family litigation" is noted. However, specific information regarding this patent in the CAFC 2026 dockets was not found through the provided search parameters.

I am aware of one known litigation involving US patent 6834038, identified through the patent's Google Patents page. However, I cannot access external websites or parse their content to extract all the requested details such as the specific plaintiff(s), defendant(s), filing date, and outcome or current status directly from the Unified Patents portal.

Based on the information available on the Google Patents page for US6834038:

• Jurisdiction: Texas Eastern District Court
• Case Number: 2:24-cv-01074
• Status: The Google Patents page indicates "Family has litigation" with this specific case filed.

I am unable to provide the plaintiff(s), defendant(s), filing date, and the current status or outcome for this case without direct access to the Unified Patents litigation portal or other specific court records.

Proceedings overview

There are no AIA trial proceedings on file for US patent 6834038 as of the most recent ingest of the USPTO ODP API, and a web search also did not reveal any such proceedings. This provides a clear defensive posture: the patent has not been challenged via IPR, PGR, or CBM trials to date.

Strategic summary

As of July 29, 2026, all claims (1-25) of US patent 6834038 remain untested by AIA trial proceedings. No claims have been canceled or sustained through PTAB review. This means the patent has not been narrowed through IPR, PGR, or CBM.

Given the absence of any PTAB proceedings, the estoppel landscape is entirely open. A potential petitioner would not be barred by 35 U.S.C. § 315(e)(2) from raising any prior art grounds they could reasonably raise against the claims. There is no pattern of filings or appeals to observe, and no defensive aggregators have engaged with this patent via PTAB.

Recommended next steps

Since no PTAB activity exists for US patent 6834038, a defendant currently facing assertion of this patent would find all claims of the patent untested in an AIA trial setting. The absence of PTAB activity suggests that the patent either has not been widely asserted or that previous assertions did not lead to an IPR challenge. For a potential defendant, this means that an IPR, PGR, or CBM (if applicable) remains a viable option for challenging the patent's validity, without any prior estoppel issues to navigate.

Inventors

• David Zelig
• Eli Aloni
• Ron Sdayor
• Menahem Kaplan

All named inventors were employed by Orckit Communications Ltd. at the time of the patent filing on August 11, 2000, as evidenced by the initial assignment of their interest to Orckit Communications Ltd. between November 7-12, 2000.

Original assignee

The original assignee on the issued patent was Orckit Communications Ltd. This company was primarily in the business of developing telecommunications equipment, specifically Digital Subscriber Line Access Multiplexer (DSLAM) systems, which embody the claims of US 6834038. Orckit Communications Ltd. was acquired by Corrigent Systems Ltd. in 2007. Its intellectual property assets have since been transferred to other entities, indicating that the original operating entity, Orckit Communications Ltd., as a distinct business, is no longer actively operating under that name.

Assignment timeline

• 2000-11-07 to 2000-11-12 (executed) / recorded 2000-12-05 — Reel 011319/0563

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: ZELIG, DAVID; ALONI, ELI; SDAYOR, RON; KAPLAN, MENAHEM
  • Assignee: ORCKIT COMMUNICATIONS LTD.
  • Correspondent: NATHAN & ASSOCIATES, P.O. BOX 1017, RA'ANANA, 43100, ISRAEL.
  • Context: Initial assignment from inventors to the original corporate entity.

• 2013-03-18 (executed) / recorded 2013-03-18 — Reel 030034/0366

  • Conveyance: SECURITY AGREEMENT
  • Assignor: ORCKIT COMMUNICATIONS LTD.
  • Assignee: HUDSON BAY IP OPPORTUNITIES MASTER FUND, LP
  • Correspondent: LINDSTROM & ASSOC., P.O. BOX 11846, OMAHA, NE, 68111.
  • Context: Securitization of patent assets for financing purposes.

• 2013-07-23 (executed) / recorded 2013-07-26 — Reel 030885/0117

  • Conveyance: RELEASE BY SECURED PARTY
  • Assignor: HUDSON BAY IP OPPORTUNITIES MASTER FUND LP
  • Assignee: ORCKIT COMMUNICATIONS LTD.
  • Correspondent: FRANK J. FENELON, 333 EARLE OVINGTON BLVD., SUITE 402, UNIONDALE, NY, 11553.
  • Context: Release of a security interest, returning control of the patent to Orckit Communications Ltd.

• 2016-04-25 (executed) / recorded 2016-05-11 — Reel 038541/0984

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: ORCKIT COMMUNICATION LTD., ORCKIT-CORRIGENT LTD., CORRIGENT SYSTEMS LTD.
  • Assignee: ORCKIT IP, LLC
  • Correspondent: LAW OFFICE OF MICKI KRASNY, 1040 LINCOLN RD., STE. 504, MIAMI BEACH, FL, 33139.
  • Context: Transfer of patent assets to an intellectual property holding entity, likely as part of an internal reorganization or preparation for monetization.

• 2022-08-10 (executed) / recorded 2025-04-26 — Reel 070953/0085

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: ORCKIT IP, LLC.
  • Assignee: SUCA LTD.
  • Correspondent: NO CORRESPONDENT.
  • Context: Transfer of patent assets from one IP holding entity to another, marking the beginning of a rapid series of transfers.

• 2022-10-25 (executed) / recorded 2025-05-12 — Reel 071087/0641

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: SUCA LTD
  • Assignee: QUICKER CONNECTIONS LLC
  • Correspondent: BARRON & NEWBURGER, P.C., 7500 W. PARMER LANE BLDG. F, SUITE 210, AUSTIN, TX, 78729.
  • Context: Transfer of patent assets to the current asserting entity.

• 2024-10-08 (executed) / recorded 2024-10-23 — Reel 069230/0593

  • Conveyance: PATENT SECURITY AGREEMENT
  • Assignor: QUICKER CONNECTIONS LLC
  • Assignee: IP LITFIN US 2024 LLC
  • Correspondent: KEKER, VAN NEST & PETERS LLP, 633 BATTERY STREET, SAN FRANCISCO, CA, 94111-1800.
  • Context: Securitization of patent assets by the current asserting entity, indicating active litigation financing or monetization.

Timeline diagram

timeline
    title Ownership of US 6834038
    2000 : Filed by Orckit Communications
         : Inventors assign to Orckit
    2004 : Patent issued
    2013 : Securitized to Hudson Bay IP
         : Hudson Bay IP releases security
    2016 : Assigned to Orckit IP LLC
    2022 : Assigned to Suca Ltd
         : Assigned to Quicker Connections LLC
    2024 : Securitized to IP Litfin US 2024 LLC

NPE / troll-pattern signals

1. Shell-entity transfer — present

   • Orckit IP, LLC: Assigned 2016-04-25 / recorded 2016-05-11 (Reel 038541/0984). The "IP" in the name suggests a dedicated intellectual property holding entity.
   • SUCA LTD.: Assigned 2022-08-10 / recorded 2025-04-26 (Reel 070953/0085). This entity appears to be an intermediary IP holding company.
   • QUICKER CONNECTIONS LLC: Assigned 2022-10-25 / recorded 2025-05-12 (Reel 071087/0641). As an LLC and the current assignee actively involved in litigation, it exhibits characteristics of a shell entity for patent assertion.

2. Known asserter in the chain — present

   • QUICKER CONNECTIONS LLC: The patent's Google Patents page explicitly states "Current Assignee: QUICKER CONNECTIONS LLC" and notes active litigation in the Texas Eastern District Court (case 2:24-cv-01074). This confirms its role as a patent asserter.
   • HUDSON BAY IP OPPORTUNITIES MASTER FUND, LP: Appears as assignee in a security agreement on 2013-03-18 / recorded 2013-03-18 (Reel 030034/0366). Hudson Bay is known for its involvement in IP financing and monetization.

3. Repeat correspondent across the chain — not present

   • Different correspondent attorneys or firms are recorded for each assignment or security agreement in the chain: Nathan & Associates (Reel 011319/0563), Lindstrom & Assoc. (Reel 030034/0366), Frank J. Fenelon (Reel 030885/0117), Law Office of Micki Krasny (Reel 038541/0984), no correspondent (Reel 070953/0085), Barron & Newburger, P.C. (Reel 071087/0641), and Keker, Van Nest & Peters LLP (Reel 069230/0593).

4. Cascading transfers — present

   • Between 2022-08-10 and 2022-10-25, the patent was sequentially assigned from Orckit IP, LLC to SUCA LTD, and then to QUICKER CONNECTIONS LLC (Reel 070953/0085 and Reel 071087/0641). This represents two consecutive assignments through chained LLCs within a period of less than three months.

5. Pre-litigation transfer — present

   • The assignment to QUICKER CONNECTIONS LLC was executed on 2022-10-25 (Reel 071087/0641). The first known litigation, case 2:24-cv-01074 in the Texas Eastern District Court, was filed in 2024. While not strictly within six months, the rapid succession of transfers to IP-focused entities in 2022, shortly before the patent's expiration in January 2023 and preceding the 2024 litigation, indicates a strategic preparation for assertion.

6. Bankruptcy fire-sale — not present

   • No evidence in the assignment records or Google Patents legal events suggests any of the assignors underwent bankruptcy proceedings.

7. Privateering — unclear

   • While the initial operating company (Orckit Communications Ltd.) transferred its patents to IP holding entities (Orckit IP, LLC), there is no explicit public documentation (e.g., SEC filings) to confirm whether Orckit is privately backing or directing QUICKER CONNECTIONS LLC in its assertion efforts against competitors.

8. Defensive aggregator (anti-NPE) — not present

   • The current assignee, QUICKER CONNECTIONS LLC, is engaged in patent litigation and is not a known defensive aggregator.

Verdict

NPE — high confidence

The assignment chain clearly demonstrates a pattern consistent with NPE activity. This includes multiple transfers to shell entities such as Orckit IP, LLC (Reel 038541/0984), SUCA LTD (Reel 070953/0085), and QUICKER CONNECTIONS LLC (Reel 071087/0641), cascading transfers between these entities in late 2022, and securitization to an IP financing entity (IP LITFIN US 2024 LLC, Reel 069230/0593). Most importantly, the current assignee, QUICKER CONNECTIONS LLC, is explicitly noted as being involved in litigation concerning this patent, solidifying its role as an asserting entity.

For verification, refer to the USPTO Assignment Center search for US6834038.

Here's an analysis of the most relevant prior art cited in US Patent 6834038, focusing on potential anticipation under 35 U.S.C. § 102. The independent claims of US6834038 (Claims 1 and 14) are central to this analysis, particularly the concept of a master sub-system with active and standby master units, where the standby unit is coupled through the active unit's interface to slave units for transparent failover.

Cited Patent Analysis

1. US5283782A

• Full Citation: US5283782A, Inventors: Takeshi Oshima, Kazuhiro Takaya, Kenichi Imai, Hirofumi Nakano, Atsushi Takahashi; Assignee: Hitachi, Ltd.; Publication Date: February 1, 1994.
• Filing Date: August 17, 1990.
• Brief Description: This patent describes a system switching method and apparatus for an asynchronous transfer mode (ATM) cell switching system. It focuses on switching between active and standby systems without signal loss during a failure. The system uses a common cell queue and selectively sends cells from the active or standby system to the output buffer. It includes a cell detection circuit for detecting cell loss or insertion in the active system and a switch to select the output of the standby system upon detection of a failure.
• Potential Anticipation: US5283782A describes redundant ATM switching systems with failover mechanisms. While it addresses master/standby redundancy and transparent switching at the ATM layer, it does not explicitly disclose the specific architecture of a remote slave unit communicating with master units via assigned links through a second public network (e.g., PDH) and, critically, the standby master unit being coupled through the first master unit's subscriber link interface to those links, as claimed in US6834038. Therefore, it likely does not fully anticipate claims 1 or 14, but it is highly relevant for redundancy in ATM systems.

2. US5436886A

• Full Citation: US5436886A, Inventors: Michael G. W. Hall, John R. Jones, Dennis G. Smith; Assignee: Northern Telecom Limited; Publication Date: July 25, 1995.
• Filing Date: July 14, 1994.
• Brief Description: This patent describes an ATM switch operating in a dual switch plane configuration for fault tolerance. It features two independent switch planes (primary and backup) that both receive incoming ATM cells. In the event of a failure in the primary switch plane, the backup plane takes over. It employs mechanisms to ensure that the backup plane maintains synchronization with the primary and can seamlessly transition to active operation.
• Potential Anticipation: Similar to US5283782A, this patent addresses ATM redundancy and failover in a switch. However, it focuses on dual switch planes rather than a master/standby unit configuration with remote slave units connected via specific subscriber links through a second public network where the standby is coupled through the active unit's interface. While highly relevant to general fault tolerance in ATM networks, it doesn't appear to anticipate the specific "coupling" and remote access architecture of US6834038's claims 1 and 14.

3. US5663949A

• Full Citation: US5663949A, Inventor: Masataka Muto; Assignee: Fujitsu Limited; Publication Date: September 2, 1997.
• Filing Date: November 15, 1994.
• Brief Description: This patent describes a line protection switching system in a duplexed fiber interface shelf, primarily for synchronous digital hierarchy (SDH) networks. It details a system with active and standby optical fiber interface units and line termination units that allows for switching between them in case of failure. The goal is to prevent communication disruption by automatically switching to the standby system.
• Potential Anticipation: This patent pertains to line protection switching, particularly in SDH, which is mentioned in US6834038 as a known protection standard for network trunks (ITU-T G.783). However, US6834038 explicitly states there is "no standardized method of protection against failures in the IMA links between slave units 30 and master unit 20" and aims to provide a solution for this. US5663949A does not appear to describe the specific remote DSLAM architecture, the IMA links, or the unique "coupled through the first subscriber link interface" mechanism for master unit redundancy over these remote links. Therefore, it is unlikely to anticipate claims 1 or 14.

4. US5796717A

• Full Citation: US5796717A, Inventors: Tsuyoshi Sakamoto, Takeshi Oshima, Kenichi Imai; Assignee: Fujitsu Limited; Publication Date: August 18, 1998.
• Filing Date: January 7, 1986.
• Brief Description: This patent describes a system for switching from working units to stand-by units in a communication system. It involves monitoring the working unit, and upon detection of a fault, activating the stand-by unit and switching communication paths to it. The focus is on providing high reliability for common equipment by immediately switching to a spare unit upon detection of a failure.
• Potential Anticipation: US5796717A provides a general concept of active/standby redundancy and switching in communication systems. While relevant to the problem of ensuring reliability, it lacks the specific details of a multi-shelf DSLAM system, remote slave units, IMA links, and the unique coupling of the standby master unit through the active master unit's interface as defined in claims 1 and 14 of US6834038.

5. WO1999004596A1

• Full Citation: WO1999004596A1, Inventors: David P. P. Recker, Scott H. Wood, Robert H. K. Yu; Assignee: Ameritech Corporation; Publication Date: January 28, 1999.
• Filing Date: July 17, 1997.
• Brief Description: This international application describes a method and apparatus for providing broadband access conferencing services. It involves a network access device that multiplexes various types of signals (e.g., voice, video, data) from subscribers to a broadband network. It discusses providing different access technologies like DSL but focuses on conferencing services rather than redundancy mechanisms for master unit failure in a remote access multiplexing context.
• Potential Anticipation: While it touches upon broadband access and multiplexing, WO1999004596A1 does not disclose a redundant master sub-system with active/standby units or the specific coupling mechanism for failover as claimed in US6834038. Therefore, it is unlikely to anticipate claims 1 or 14.

6. EP1006702A2

• Full Citation: EP1006702A2, Inventors: Timothy M. Whalen, Peter E. F. Biron; Assignee: Nortel Networks Corporation; Publication Date: June 7, 2000.
• Filing Date: December 4, 1998.
• Brief Description: This patent application describes a method and apparatus for providing an improved Virtual Router Redundancy Protocol (VRRP). VRRP is a protocol used to provide automatic assignment of available IP routers to hosts on a local area network, ensuring high availability by allowing a backup router to take over if the primary fails.
• Potential Anticipation: EP1006702A2 addresses network redundancy at the IP layer using VRRP. While it ensures high availability, it operates at a different layer and concerns router redundancy rather than the specific physical layer/data link layer (IMA over PDH) redundancy for remote DSLAM master units, especially not the physical coupling arrangement claimed in US6834038. It does not anticipate claims 1 or 14.

7. US6075767A

• Full Citation: US6075767A, Inventors: Akio Itokawa, Kazuhiro Takaya, Kenichi Imai, Hirofumi Nakano; Assignee: Hitachi, Ltd.; Publication Date: June 13, 2000.
• Filing Date: March 19, 1996.
• Brief Description: This patent describes an Asynchronous Transmission Mode (ATM) handler that performs cell transmission and reception. It includes a cell transmission unit and a cell reception unit, with focus on efficient handling of ATM cells, including flow control and error handling. It does not primarily focus on redundancy or failover mechanisms in a multi-shelf access system.
• Potential Anticipation: US6075767A deals with ATM cell handling but does not appear to describe the specific redundant master unit architecture, remote slave units, or the unique coupling for transparent failover as claimed in US6834038. Therefore, it is unlikely to anticipate claims 1 or 14.

8. US6314102B1

• Full Citation: US6314102B1, Inventors: Dirk Peschi, M. J. Van Aken, Emmanuel F. Borowski, Peter P. F. Reusens, Herman L. R. Verbueken, Frank Ryckebusch, Koen A. G. De Wulf; Assignee: Alcatel; Publication Date: November 6, 2001.
• Filing Date: July 10, 1997.
• Brief Description: This patent describes a telecommunications system for providing both narrowband and broadband services to subscribers, including ADSL (Asymmetric Digital Subscriber Line) technology. It focuses on the system architecture for delivering various services over copper pairs. While it involves DSL and access multiplexing, its primary contribution is not master unit redundancy with transparent failover for remote slave units.
• Potential Anticipation: While US6314102B1 relates to DSL services, it does not detail a redundant master sub-system with the specific "coupled through" arrangement for failover that is central to US6834038's independent claims. It likely does not anticipate claims 1 or 14.

9. US6351452B1

• Full Citation: US6351452B1, Inventors: Donald C. Johnson, Michael H. Clark; Assignee: Carrier Access Corporation; Publication Date: February 26, 2002.
• Filing Date: January 19, 1999.
• Brief Description: This patent describes a telecommunication device with centralized processing, redundancy protection, and on-demand insertion of signaling bits. It focuses on redundancy for common control elements and processing resources within a telecommunications device, allowing a standby processor to take over upon failure of the active one.
• Potential Anticipation: US6351452B1 discusses redundancy for internal components and processing within a telecommunication device. However, it does not describe the specific architecture of redundant master units in a DSLAM system, particularly the coupling of a standby master unit through the active master unit's subscriber link interface to remote slave units over a second public network for transparent failover, as specified in US6834038's claims 1 and 14.

10. US6438144B1

• Full Citation: US6438144B1, Inventors: Menahem Kaplan, Eli Aloni, Ron Sdayor, David Zelig; Assignee: Eci Telecom Ltd.; Publication Date: August 20, 2002.
• Filing Date: March 11, 1999.
• Brief Description: This patent, notably sharing inventors with US6834038, describes a communication system with two-stage multiplexing, particularly for DSLAMs. It focuses on the efficient multiplexing and demultiplexing of signals between subscriber lines and a core network using a concentrator and line cards. It addresses traffic management but does not explicitly detail the master unit redundancy and failover mechanism that is the focus of US6834038.
• Potential Anticipation: While related by inventors and field (DSLAMs), US6438144B1 focuses on the multiplexing architecture. Without specific disclosure of the dual master unit redundancy with the unique "coupled through the first subscriber link interface" mechanism, it is unlikely to anticipate claims 1 or 14 of US6834038.

11. US6466576B2

• Full Citation: US6466576B2, Inventors: Kenichi Imai, Hirofumi Nakano, Takeshi Oshima; Assignee: Fujitsu Limited; Publication Date: October 15, 2002.
• Filing Date: October 20, 1997.
• Brief Description: This patent describes an ATM switching unit designed for efficient processing of ATM cells, including mechanisms for handling virtual paths and virtual channels. It focuses on hardware architecture for high-speed ATM switching.
• Potential Anticipation: US6466576B2 is an ATM switching unit patent. It primarily focuses on the internal architecture and operation of an ATM switch for processing cells, not on redundant master units providing access to remote slave units via specific types of links (like IMA over PDH) with a standby unit coupled through an active unit's interface for failover. Thus, it is unlikely to anticipate claims 1 or 14.

12. US6597689B1

• Full Citation: US6597689B1, Inventors: Graham D. Wilson, Robert K. K. P. Wong; Assignee: Nortel Networks Limited; Publication Date: July 22, 2003.
• Filing Date: December 30, 1998.
• Brief Description: This patent describes an SVC (Switched Virtual Circuit) signaling system and method, particularly for ATM networks. It focuses on how switched virtual circuits are established, maintained, and released using signaling protocols. It is related to control plane functionality rather than physical layer redundancy in access networks.
• Potential Anticipation: US6597689B1 deals with signaling for SVCs in ATM networks. It does not address the physical or data link layer redundancy for remote DSLAM master units or the specific "coupled through" architecture of the standby unit as claimed in US6834038. Therefore, it is unlikely to anticipate claims 1 or 14.

13. US6680904B1

• Full Citation: US6680904B1, Inventors: Menahem Kaplan, Eli Aloni, Ron Sdayor, David Zelig; Assignee: Orckit Communications Ltd.; Publication Date: January 20, 2004.
• Filing Date: December 27, 1999.
• Brief Description: This patent, with the same inventors and original assignee as US6834038, describes "Bi-directional chaining of network access ports." It focuses on a multi-shelf access system (e.g., DSLAM) where slave units are connected to a master unit via daisy-chained physical interface lines. In the event of a fault in one of the daisy chains, a pre-switch re-routes data packets through another daisy chain, ideally without requiring switch reconfiguration. The patent discusses "active" and "standby" interfaces and redirection of traffic in a fault scenario. US6834038 explicitly refers to this co-pending application.
• Potential Anticipation: This patent is highly relevant due to shared inventors, assignee, and direct cross-reference in US6834038. It describes a system with master and slave units and fault recovery by re-routing traffic. The concept of "bi-directional chaining" and re-routing in the event of a fault, especially with "active" and "standby" interfaces, closely aligns with the redundancy goals of US6834038. It may anticipate several aspects of the redundancy described in claims 1 and 14, particularly the idea of a backup path for communication between master and slave units. However, it specifically focuses on "re-routing" via another daisy chain rather than the specific architecture where a standby master unit is coupled through the active master unit's subscriber link interface to the same assigned links to the slave units for seamless takeover (without notification to the slave). The specific phrase "coupled through the first subscriber link interface" might be the differentiating factor if not explicitly present in US6680904B1.

14. US6687231B1

• Full Citation: US6687231B1, Inventors: Francis Van-Aken, Peter P. F. Borowski, Emmanuel F. Reusens, Herman L. R. Verbueken, Frank Ryckebusch, Koen A. G. De Wulf; Assignee: Alcatel; Publication Date: February 3, 2004.
• Filing Date: May 28, 1999.
• Brief Description: This patent describes a system and method for ensuring operations of redundant signal paths in a communication system, particularly for enhancing reliability in a central office serving multiple subscribers. It aims to provide 1+1 network interface protection for connections to a wide area network (WAN). It mentions that an active interface receives and sends data, while a standby interface also receives data but only sends it if the active interface fails, with a switch to select the active interface.
• Potential Anticipation: US6687231B1 is highly relevant to the general concept of 1+1 redundancy in network interfaces for a central office. It describes active/standby interfaces and switching upon failure to enhance reliability, which is a core problem US6834038 aims to solve. However, similar to the other patents, the critical distinguishing feature for US6834038's independent claims (1 and 14) is the specific architecture where a "second master unit, coupled through the first master unit to communicate with the slave unit via the assigned link" (claim 1) or "coupling the second master unit through the subscriber link interface of the first master unit to the respective links" (claim 14). While US6687231B1 covers general 1+1 interface protection, it does not explicitly detail this specific coupling through mechanism for a remote DSLAM setup involving IMA links to slave units.

Most Relevant Prior Art

Based on the analysis, US6680904B1 (Bi-directional chaining of network access ports) stands out as the most relevant prior art. It shares the same inventors and assignee, and US6834038 itself refers to it as a co-pending application, indicating a close relationship and likely development from or alongside it. This patent directly addresses multi-shelf access architectures with master and slave units and fault recovery through re-routing.

US6687231B1 (System and method for ensuring operations of redundant signal paths in a communication system) is also highly relevant due to its focus on 1+1 network interface protection in a central office, a general problem that US6834038 is designed to solve in a specific remote access context.

The primary distinguishing feature that US6834038 appears to claim over these, and other general redundancy patents, is the specific architectural detail of the "second master unit, coupled through the first subscriber link interface [of the first master unit] to communicate with the slave units via the assigned links" and the resulting transparent takeover (without notification to the slave unit). This "coupling through" allows both master units to potentially receive upstream traffic and the active unit to control downstream traffic, with the standby unit ready to take over without requiring a separate signaling or reconfiguration process with the remote slave. The other cited patents, while addressing various forms of redundancy, do not explicitly describe this particular physical or logical coupling arrangement between the master units and the shared link to the remote slave units.

Obviousness Analysis of US Patent 6834038 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the independent claims of US Patent 6834038 obvious to a person having ordinary skill in the art (POSA) at the time of the invention (priority date: August 11, 2000). The patent itself notes a known problem: "Unlike the above-mentioned SDH protection standards for the connection between master unit 20 and ATM network 22, there is no standardized method of protection against failures in the IMA links between slave units 30 and master unit 20." The invention purports to solve this by providing redundant master units with a specific coupling mechanism.

Independent Claim 1 (Apparatus)

Claim 1 describes a network access apparatus comprising:

• A multiplicity of slave units, each with subscriber ports and a multiplexer.
• A master sub-system, remote from the slave units, for connection to a first public network.
• A first master unit with a first subscriber link interface (to communicate with slave units via links through a second public network) and a first multiplexer.
• A second master unit with a second multiplexer and a second subscriber link interface, which is coupled through the first subscriber link interface to communicate with the slave units via the assigned links, enabling failover.

Combination of Prior Art:
A combination of Delpapa ("DSLAM-A broadband Digital Subscriber Line Access Multiplexer System," 1999), the ATM Forum AF-PHY-0086.001 ("Inverse Multiplexing for ATM (IMA) Specification Version 1.1," 1999), and US6680904B1 (Orckit Communications Ltd., "Bi-directional chaining of network access ports," filed Dec. 27, 1999) would render Claim 1 obvious.

Disclosure in Prior Art:

1. Delpapa: This reference describes the fundamental architecture of a Digital Subscriber Line Access Multiplexer (DSLAM) system, including master and slave units. It establishes the context of connecting subscribers via slave units to a core network.
2. ATM Forum AF-PHY-0086.001: This standard explicitly defines Inverse Multiplexing for ATM (IMA), which allows data transfer over multiple parallel physical lines (e.g., E1 or T1) to form a virtual ATM port. The patent itself notes that remote slave units communicate with the master unit via IMA links over a Plesiochronous Digital Hierarchy (PDH) network. This reference teaches the use of IMA as the "assigned links through a second public network" (PDH) for communication between master and slave units.
3. US6680904B1: This patent, filed by the same assignee and explicitly incorporated by reference into US6834038, describes "Bi-directional chaining of network access ports" and "1+1 network interface protection." US6834038 further elaborates that its "standby master is daisy-chained to the active master, so that both of them receive upstream packets sent over the link by the slave." It also details that downstream packets are merged by a demultiplexer, and upstream packets are bi-cast and duplicated, with the standby unit discarding redundant upstream packets and refraining from sending downstream packets until a failure occurs, ensuring transparency to the slave unit. This directly teaches the crucial element of the "second subscriber link interface...coupled through the first subscriber link interface" for failover, as well as the functionality of the first and second master units, including their respective multiplexers and communication mechanisms.

Motivation to Combine:
A POSA in the field of high-speed data communication systems, specifically DSLAMs, would have been motivated to combine these references to provide robust and uninterrupted service to remote subscribers. The explicit problem statement in US6834038 highlights the lack of a standardized protection method for IMA links between master and remote slave units.

Knowing that:

• DSLAM architectures with remote slave units were common (Delpapa).
• IMA was the established technology for connecting these remote units over multiple physical lines (ATM Forum IMA Spec).
• Redundancy schemes for network interfaces and active/standby units with transparent failover and bi-directional chaining were already developed by the same entity (US6680904B1), and applied to network access ports.

A POSA would have found it obvious to extend the proven 1+1 protection and bi-directional chaining mechanism described in US6680904B1 to the specific context of IMA links connecting remote slave units in a DSLAM system. The motivation would be to improve the reliability and fault tolerance of the entire DSLAM system by protecting a critical segment (the IMA links) against failures, consistent with the broader goal of ensuring continuous network access. The explicit cross-referencing and shared assignee between US6834038 and US6680904B1 strongly indicate that this was a straightforward application of known techniques by the same inventors to a related problem.

Independent Claim 14 (Method)

Claim 14 describes a method for providing network access, including:

• Connecting first and second master units via respective network interfaces to a first public network.
• Linking multiple remote slave units to multiplex among subscriber lines.
• Establishing links (through a second public network) between a subscriber link interface of the first master unit and the slave units.
• Providing multiplexers in both master units.
• Coupling the second master unit through the subscriber link interface of the first master unit to the links, such that access is provided by the second master unit upon failure in the first master unit's network interface or multiplexer.

Combination of Prior Art:
The same combination of Delpapa, ATM Forum AF-PHY-0086.001, and US6680904B1 would render Claim 14 obvious. Additionally, ITU-T G.783 ("Characteristics of Synchronous Digital Hierarchy (SDH) Equipment Functional Blocks," 1994) provides further evidence for the commonality of 1+1 protection for core network interfaces.

Disclosure in Prior Art:

1. Delpapa: Describes the method steps of linking slave units to subscriber lines and the overall DSLAM system operation.
2. ATM Forum AF-PHY-0086.001: Teaches the method of establishing IMA links as the communication pathway between master and remote slave units, operating through a PDH network.
3. US6680904B1: Discloses the method of providing two master units, with one active and one standby. It details the steps of coupling the standby unit's interface through the active unit's interface, bi-casting upstream packets from slave units to both masters, merging downstream packets, and controlling the standby unit to discard redundant upstream packets and refrain from sending downstream packets until a failure of the active unit. It explicitly teaches the transparent transfer of communication in the event of failure.
4. ITU-T G.783: Describes methods for 1+1 protection for network interfaces, which supports the step of connecting first and second master units via respective network interfaces to a first public network for redundancy.

Motivation to Combine:
The motivation for a POSA to combine these references to arrive at the method of Claim 14 is identical to that for Claim 1. The objective is to apply known and effective redundancy techniques to a recognized vulnerability in remote DSLAM access systems—the IMA links to slave units. The practice of implementing 1+1 protection for various critical components in telecommunications systems was well-established (e.g., ITU-T G.783 for core network interfaces). The development of bi-directional chaining and transparent failover for network access ports by the same assignee (US6680904B1) demonstrates that this method was known and considered desirable for improving system reliability.

A POSA would naturally seek to extend these existing methods to protect the IMA links, which are crucial for remote subscriber access within a DSLAM framework. The combination offers a predictable solution to a known problem by integrating existing elements in a logical and expected manner to achieve enhanced fault tolerance without requiring complex messaging protocols with the remote slave unit.