US 7042839

I'll search for authoritative information on this specific patent number, including any litigation activity.

Let me check for litigation activity and any CAFC docket references.

US Patent 7,042,839 — Analyst Summary

Search scope and caveats up front: I ran web searches against public patent databases (Google Patents, Justia, FreePatentsOnline) and open-web queries aimed at USPTO records and CAFC 2026 dockets. I did not find any litigation, CAFC appeal, PTAB proceeding, or 2026 court docket referencing U.S. Patent No. 7,042,839. I could not directly query the CAFC docket system or a live USPTO PatentCenter session in this environment, so I cannot rule out a filing that isn't indexed publicly — treat "no litigation found" as "nothing surfaced," not as a certification. I also did not auto-correct any identifiers; everything below is taken literally from the record returned.

Bibliographic Data

Legal status discrepancy (flag as uncertain): The Google Patents header lists status "Expired – Fee Related" with an "adjusted expiration" of 2024-10-21. However, the same page's Legal Events timeline shows a maintenance-fee reminder (2009-12-14), a lapse event (2010-05-09), and an explicit "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362" (2010-06-07), with a lapse effective 2010-05-09. These two records conflict. The events log indicates the patent actually lapsed in 2010 for non-payment of maintenance fees; the "2024-10-21" figure appears to be a computed/adjusted-term date rather than an actual expiration event. I would verify against USPTO PatentCenter before relying on either date.

Abstract (as issued)

A scalable protection method for connection-oriented networks includes a source, a destination, and primary nodes interconnected by working path segments. A point-to-multipoint connection with multiple destinations and additional primary nodes is also supported. Each of a number of backup nodes is interconnected with an associated primary node by pre-provisioned shunt segments, and the backup nodes are interconnected among themselves by pre-provisioned protection path segments. Upon a failure, the primary node upstream of the failure directs input traffic to a shunt segment, and its associated backup node directs that traffic onto an output protection segment. Downstream of the failure, a backup node directs traffic from an input protection segment to a shunt segment, and its associated primary node forwards that traffic to a downstream working segment — so traffic is routed around failures via local switching operations.

Plain-Language Overview of the Independent Claims

Claim 1 — Protected network (apparatus).
A network with two parallel paths between a source and a destination:

• A chain of primary nodes joined by pre-provisioned working path segments (the normal traffic path).
• A set of backup nodes joined by pre-provisioned protection path segments, where each backup node also connects to its own associated primary node through a pre-provisioned bidirectional shunt segment (a two-way side connection).

The primary node must be able to do three things: normally pass traffic from its input working segment to its output working segment; if the upstream working segment fails, take traffic in from the shunt segment and put it out on the working segment; and if the downstream working segment fails, take traffic in from the working segment and send it out on the shunt segment.

The backup node must do two things: if the downstream working segment of its paired primary node fails, take traffic from the shunt segment and send it down the protection path; and if the upstream working segment fails, take traffic off the protection path and send it onto the shunt segment to feed the primary node.

In short: claim 1 covers the paired primary/backup node architecture with pre-provisioned working, protection, and bidirectional shunt segments, and the specific local traffic-steering behaviors triggered by upstream vs. downstream failures.

Claim 8 — Method of operating a protected network.
The method counterpart to claim 1. It recites the same steps: (a) interconnecting backup nodes with pre-provisioned protection segments and connecting each backup node to a corresponding primary node via a pre-provisioned bidirectional shunt segment; (b) at each primary node, performing the normal / upstream-failure / downstream-failure switching behaviors; and (c) at each backup node, performing the downstream-failure and upstream-failure switching behaviors. Substantively it mirrors claim 1's functional requirements as method steps.

Note on the remaining claims (dependent): Claim 2 (and method claim 9) adds routing around a failed primary node itself (protection-in → protection-out). Claims 3 and 10 limit the segments to label-switched paths (MPLS). Claims 4/11 require a one-to-one primary-to-backup pairing; claims 5/12 allow one backup node to serve multiple primary nodes; claims 6/13 require direct connection with no intervening segment-terminating nodes. Claim 7 covers the point-to-multipoint branch case (branching primary/backup nodes and additional primary/backup nodes for a second destination). Dependency structure is consistent across the apparatus and method sets.

Prior Art Cited on the Face (11 references)

Representative earliest references include US 4,956,835 (Alberta Telecommunications Research Centre, 1990), US 5,146,452 (Alcatel Network Systems, 1992), US 5,179,548 (Bellcore, 1993), US 5,835,482 (MCI, 1998), US 6,047,331 (MIT, 2000), and US 6,163,525 (Nortel, 2000), plus several 2001–2002 published applications (Thompson, Kinoshita, Montgomery, Lakshminarayana, Oda). The examiner also cited Falkenstein et al. US 7,016,379 among the "similar documents"/citing family.

Bottom Line

• The patent is a Fujitsu (originally Fujitsu Network Communications) MPLS/ATM-oriented, line-based local protection switching scheme using pre-provisioned protection segments plus bidirectional shunt segments between each primary node and a paired backup node, with defined switching rules for upstream failures, downstream failures, and primary-node failure.
• No CAFC or district-court activity for this number surfaced in my searches; I found no 2026 docket entry.
• Confidence: High on bibliographic data, claims, and abstract (multiple consistent sources). Lower/uncertain on the true legal status due to the conflicting maintenance-fee-lapse (2010) vs. "expires 2024-10-21" records, and on the definitive absence of litigation given I could not directly query the CAFC/USPTO live systems.

I'll search for litigation involving US patent 7042839. Let me run several targeted searches.

Let me search litigation-specific databases for this exact patent number.

Summary answer

I found no litigation (district court, ITC, or PTAB) specifically asserting or involving US Patent No. 7,042,839. Treat this as "none known" rather than a definitive negative — see the caveats below.

What I verified about the patent itself (to avoid number confusion)

From the authoritative full text at https://patents.google.com/patent/[US7042839](/patent/US7042839)/en:

• US 7,042,839 B2 — "Scaleable line-based protection for connection oriented communications protocols"
• Application US 10/071,712, filed 2002-02-07, granted 2006-05-09
• Inventors: Mark A.W. Stewart, David Peck
• Assignee: Fujitsu Limited (originally Fujitsu Network Communications, Inc.; reassigned 2005)
• Pre-grant publication: US 2003/0147344 A1 (2003-08-07)
• No "Cited By" litigation-related listings; the citation lists are prior art and later patents (Corrigent, Tellabs, Ericsson, Cisco, ZTE, etc.), not cases
• Legal status: Google Patents flags it "Expired – Fee Related," but the Legal Events show "Lapse for failure to pay maintenance fees," effective 2010-05-09 (docket entries 2009-12-14 reminder, 2010-05-09 lapse, 2010-06-07 discontinuation, 2010-06-29 lapsed). This early lapse is itself consistent with a patent that was never asserted.

Why search results looked like "hits" (they are false positives)

Database and web searches for "7042839" / "'839" returned cases involving different patents abbreviated as '839:

None of these cite or assert US 7,042,839 (the Fujitsu line-based protection patent). No hit matched the patent title, inventors, or assignee.

Caveats on completeness

• I could not directly query PACER or the Unified Patents litigation portal case list in this session; my searches were web-based. A definitive negative would require running the patent number in Docket Navigator, Lex Machina, Unified Patents' Portal, and PACER/PTAB (and checking the ITC EDIS Section 337 database).
• The patent's owner (Fujitsu) is a large, active litigant, so absence of found cases should not be read as proof that none ever existed — only that no case naming this patent number appeared in any source I could reach.
• Related Fujitsu networking litigation that did surface in searches (e.g., Fujitsu v. Tellabs re US 6,473,737; Fujitsu v. Nanya; Fujitsu v. Netgear re the Ozawa patent) involves different patents and should not be attributed to 7,042,839.

Bottom line: On the available evidence, no known litigation involves US 7,042,839, and it appears the patent lapsed in 2010 for non-payment of maintenance fees — a profile typical of a never-asserted patent.

PTAB Proceedings — U.S. Patent No. 7,042,839

"Scaleable line-based protection for connection oriented communications protocols"
Assignee: Fujitsu Limited (originally Fujitsu Network Communications, Inc.) · Inventors: Mark A. W. Stewart, David Peck · Filed 2002-02-07 · Granted 2006-05-09 · App. No. 10/071,712

Proceedings overview

Total AIA trial proceedings on file: 0 — zero IPRs, zero PGRs, zero CBMs; consequently zero claims invalidated, zero sustained, zero settlements, and zero institution denials, which for a defendant means there is no PTAB-based invalidity shortcut and no estoppel to leverage, but also that every invalidity ground remains untouched and available — and, more importantly, that the real defensive leverage here is not PTAB at all but the patent's expiry.

Two caveats on that "zero," stated plainly:

1. The canonical structured source for this task (the USPTO Open Data Portal "PTAB proceedings on file" block) returns no AIA trial proceedings for US 7,042,839 as of the most recent ingest. Consistent with my instructions, that is the controlling list, and I have not invented any proceeding numbers to fill it.
2. I ran open-web searches (Google Patents, PTAB/PTACTS document text, CourtListener-hosted briefs, and litigation coverage) for the patent number and title on 2026-10-01 and surfaced no IPR/PGR/CBM petition, no institution decision, no Final Written Decision, and no Federal Circuit appeal involving this patent. That is a negative search result, not an affirmative confirmation that no petition was ever filed — PTAB filings from the 2012–2018 window are not uniformly indexed by general web search, and I could not query the PTAB E2E / PTABIS docket directly from this environment. Treat "no PTAB activity" as the strong default and verify on PTAB E2E (Patent Trial and Appeal Board End-to-End) before you commit to it in a brief or an opinion letter.

Bottom-line defensive posture: this is not the "hardened by surviving two IPRs" scenario, and it is not the "claims 1–5 canceled — the troll has no case" scenario. It is a third scenario: an unasserted-in-AIA Fujitsu portfolio patent that has been dead since 2010-05-09 for failure to pay maintenance fees. No one has ever needed to file an IPR against it, and the reason is almost certainly that no one has been able to.

Proceedings

None to itemize.

There are no proceeding entries to run through the required template (type / filed / status / panel / grounds / institution / FWD / settlement / appeal). I am deliberately not reconstructing a "typical" IPR narrative for this patent, because fabricating a proceeding number, a panel, or a claim-level disposition would be exactly the kind of error this report exists to prevent.

For completeness on the absence: the patent's own prosecution record shows 11 references cited (including US 4,956,835; US 5,146,452; US 5,179,548; US 5,835,482; US 6,047,331; US 6,163,525; and pre-filing publications by Montgomery, Thompson, Kinoshita, Lakshminarayana), and the patent is cited by later work (7 third-party/examiner citations in the "Cited By" set, plus 27 family members citing it), including P2MP-protection art in MPLS-TP rings (US 9,450,778 / US 9,838,216) and Cisco's open-ended UPSR work (US 8,078,756). That citation traffic shows the disclosure is squarely in the middle of a crowded field — which is why, had the patent still been alive and asserted, an IPR would have been an obvious and probably attractive play. It is not a substitute for a proceeding.

Strategic summary

Claim status: every claim of the patent is UNTESTED at the PTAB, and the patent is expired. Claims 1–13 stand exactly as they issued (subject to a certificate of correction recorded 2007-02-27). Nothing was canceled; nothing was confirmed through an adversarial PTAB record. That cuts both ways. On the one hand, there is no FWD you can hand a court to show claim 1 is dead. On the other hand, there is also no PTAB record preserving the patent — no panel has ever construed "primary node," "backup node," "shunt segment," or "pre-provisioned" in this patent's claims. Any construction fight would start from a blank slate, which is usually bad for a patent owner in a § 103 case, not good.

The controlling fact is expiry, not PTAB. The USPTO record reproduced on Google Patents shows a maintenance-fee lapse: "2010-05-09 — LAPS — Lapse for failure to pay maintenance fees," followed by "2010-06-07 — PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362" and "2010-06-29 — Lapsed due to failure to pay maintenance fee, Effective date: 20100509." (That effective date is consistent with the 3.5-year maintenance window running from the 2006-05-09 grant.) Separately, the ODP legal-status line reads "Expired - Fee Related, expires 2024-10-21," which appears to be a term-adjustment-derived expiry date rather than the operative lapse date. Flag the discrepancy and pull the fee record from PatentCenter before relying on either date. Either way, as of 2026-10-01 the patent is expired. Practical consequences for a defendant receiving a demand now:

• No injunction is available for current or future conduct; an expired patent cannot be infringed going forward.
• Damages exposure is limited to pre-expiration acts within the § 286 six-year lookback measured from the complaint date — i.e., a window that closed roughly 16 years ago on the lapse theory, and at the very latest in late 2024 on the ODP theory. If a demand letter is asserting live products against this patent, that is a serious problem with the demand letter itself.
• An IPR petition filed today would be a poor use of money even if the Board would take it: the Board routinely weighs whether a patent has expired, and there is nothing left to protect. A § 101 / § 102 / § 103 invalidity or non-infringement defense in litigation (or a declaratory-judgment posture), plus an unenforceability/laches-style attack and a § 285 fee motion, is the far better play than a post-grant petition.

Estoppel landscape: there is none, and that is the only clean thing here. Because no IPR/PGR has gone to a Final Written Decision on this patent, no petitioner and no privy of a petitioner is barred under 35 U.S.C. § 315(e)(2) from raising any prior-art ground. Any defendant is free to run the full § 102/§ 103 playbook, including the Montgomery, Thompson, Kinoshita, and Lakshminarayana references cited on the face of the patent and the KSR-style combinations that post-date them (BLSR/UPSR restoration art from Nortel, MCI, Bellcore, and Alberta Telecom in the cited set is directly on point for "line-based protection with pre-provisioned backup paths"). The only estoppel risk is prospective: if a defendant or a defensive aggregator does file an IPR now and the Board institutes and issues an FWD, § 315(e)(2) will bite in the parallel district court case — so pick one lane.

Pattern signals. There is no pattern to report: no serial petitioner, no defensive aggregator (no Unified Patents or RPX filing on this patent appears anywhere in the record or in my searches), no PTAB appeal history, and no Federal Circuit docket entry. The patent's litigation history in my searches is Fujitsu on the offensive side of unrelated patents (the long-running Fujitsu v. Tellabs optical-amplifier case in N.D. Ill., which involved the '737, '163, '418, '686, '006, and '681 patents — not this one), and Fujitsu as a defendant in third-party suits (Realtime Data, Zond, USEI). I found no district court complaint asserting US 7,042,839 itself. A patent that issues in 2006, is cited by the MPLS-TP protection literature, and still never draws a single IPR petition is normally a patent that was never worth attacking — which fits the maintenance-fee lapse perfectly.

Recommended next steps

If you are a defendant and you have been threatened or sued on US 7,042,839:

1. Lead with expiry, not invalidity. Get the maintenance-fee record and the current legal status from USPTO PatentCenter for application 10/071,712 and confirm whether the 2010-05-09 lapse was ever petitioned for revival under 37 CFR 1.378 (no revival event appears in the record I reviewed, and revival is not available for fee lapses of this vintage in any event). If the patent is expired, damages are limited to the § 286 lookback window and prospective relief is off the table. Quote the legal-events entry verbatim in your demand response.
2. Do not file an IPR. With no FWD on file and an expired patent, a petition buys you nothing and creates § 315(e)(2) exposure if you are also a district court defendant. There is no estoppel currently blocking any ground — keep it that way, or litigate invalidity in court where you can run § 101 as well (the claims recite generic network-node selection circuitry and pre-provisioned paths, which invites an Alice step-one argument that the PTAB cannot reach in an IPR).
3. If the patent owner claims the patent is still alive, demand the fee record and the basis for the "expires 2024-10-21" ODP entry, and note the two dates cannot both be right.
4. Verify the negative before you rely on it. The absence of PTAB activity is the default per the structured ODP block and is consistent with every search I ran, but I could not query PTAB E2E directly. Run the patent number through PTAB E2E and CourtListener's docket search before filing anything that asserts "no post-grant proceedings exist." If E2E does turn up a petition, send it to me and I will rebuild this report around the actual institution decision and FWD.
5. Treat the absence of IPRs as a signal, not a comfort. Well-asserted, economically live patents attract IPRs — often by a defensive aggregator, and this patent has none. Combined with a 2010 maintenance-fee lapse, the most likely explanation is that the patent was never a meaningful assertion asset. That is useful context if a demand letter arrives from an assignee or a broker claiming a 2002-vintage MPLS protection patent is a licensing priority.

Items I could not confirm and am therefore not asserting: whether any petition was filed and denied institution without a public decision reaching general web indices; the exact operative expiry date (2010-05-09 lapse vs. 2024-10-21 adjusted expiration); and whether any district court complaint ever named this patent. Each is flagged rather than resolved.

I'll verify the assignment records and check for any downstream NPE activity before writing up the chain.

Let me check for any litigation or assertion history, and verify the fee-status discrepancy in the record.

Assignment & Ownership Analysis — US 7,042,839 B2

Patent: "Scaleable line-based protection for connection oriented communications protocols"
App. No. 10/071,712 · Filed 2002-02-07 · Issued 2006-05-09
Assignee of record at issue: Fujitsu Limited (Japan) — per Google Patents legal events (USPTO assignment data)
Status per record: Expired–Fee Related; maintenance-fee lapse events dated 2009-12-14 / 2010-05-09 / 2010-06-07

Inventors

Pattern notes: Both inventors executed the assignment to FNC in April 2002 (signing dates on the face of Reel 012879/0737 run 2002-04-01 to 2002-04-22), i.e. contemporaneously with filing — the normal employee-invention practice of a vertically integrated telecom-equipment maker. I found no evidence of either inventor departing FNC within 12 months of filing, nor any inventor-initiated assignment (which is the pattern that would precede a fire-sale). I could not independently verify either inventor's post-filing employment history; treat that as unverified, not as a negative finding. There is only one inventor pair and no continuations asserted — nothing anomalous.

Original assignee

Original assignee (as filed): Fujitsu Network Communications, Inc. ("FNC"), a Texas corporation based in Richardson, TX, and a wholly-owned U.S. subsidiary of Fujitsu Limited (Tokyo; TSE: 6702). This is confirmed by the April 2002 assignment, which conveys the inventors' rights to FNC (Reel 012879/0737).

At issuance (2006-05-09) ownership of record had already moved up to the parent: Fujitsu Limited.

Business: FNC is the U.S. optical/telecom transport arm of Fujitsu — SONET/SDH and later ROAM/OTN transport platforms (FLASHWAVE family) plus network-services integration. Fujitsu Limited is a large, publicly traded operating company (ICT services, computing, networking, semiconductors).

Product practice: The patent sits squarely in FNC's technical lane (MPLS/ATM LSP-based protection switching), and FNC shipped carrier transport gear with path/line protection features. However, I have not verified that any specific shipped product practiced the claimed shunt-segment/backup-node architecture. Mark the specific "embodiment" claim unverified; the corporate and technical fit is nonetheless direct — this is not a paper patent.

Current status: Fujitsu Limited is operating. FNC remains a Fujitsu U.S. subsidiary. (Fujitsu has restructured its optical-networking business in recent years; I am not confident about the current branding of the FNC entity, so I flag that as uncertain rather than assert it.)

Assignment timeline

Two recorded assignments appear in the USPTO/Google Patents legal-event record. Nothing after 2005.

• 2002-04-01 to 2002-04-22 (executed) / recorded 2002-05-07 — Reel 012879/0737

  • Conveyance: Assignment
  • Assignor: Mark A. W. Stewart; David Peck (individually)
  • Assignee: Fujitsu Network Communications, Inc. (Richardson, Texas)
  • Correspondent: Not exposed in the sources I could retrieve. The Google Patents legal-event record shows the reel/frame and the "Owner name: FUJITSU NETWORK COMMUNICATIONS, INC., TEXAS" field, but omits the correspondent/attorney of record. I could not pull the cover-sheet correspondent from the Assignment Center page in this session — do not treat as absent, treat as un-verified. (Flag: no recurrence can be assessed without it.)
  • Context: Original employment/obligation assignment — inventors → their employer, contemporaneous with filing.

• effective 2005-06-28 (executed) / recorded 2005-06-30 — Reel 016454/0339

  • Conveyance: Assignment
  • Assignor: Fujitsu Network Communications, Inc.
  • Assignee: Fujitsu Limited (Japan)
  • Correspondent: Not exposed in the sources I could retrieve (same limitation as above).
  • Context: Internal corporate reorg / subsidiary-to-parent consolidation — FNC transfers the asset to its ultimate parent. No consideration paid to a third party; no change of beneficial control.

• (non-assignment event) recorded 2007-02-27 — Certificate of Correction (prosecution/issuance housekeeping, not an ownership event).

• (non-assignment event) 2009-12-14 → 2010-05-09 → 2010-06-07 — maintenance-fee reminder, lapse for nonpayment, and "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362." Data inconsistency to flag: Google Patents' header simultaneously shows "Adjusted expiration 2024-10-21," which conflicts with the 2010 lapse events. I am reporting both verbatim and not resolving which governs; the legal-event chain reads as a 2010 lapse.

There are no post-issuance transfers to any third party, no security interests, no licenses, and no NPE-linked instruments in the record. No entity beyond Fujitsu and its subsidiary has ever held record title.

Timeline diagram

timeline
    title Ownership of US 7042839
    2002 : Filed by Fujitsu Network Communications
         : Assigned to Fujitsu Network Comm
    2005 : Assigned to Fujitsu Limited
    2006 : Patent issued
    2007 : Certificate of Correction
    2010 : Lapsed for unpaid maintenance fee

NPE / troll-pattern signals

1. Shell-entity transfer — not present. No transfer to any "IP / Holdings / Licensing / Ventures" entity; the only two assignees are a named operating subsidiary and its public parent (Reels 012879/0737 and 016454/0339).

2. Known asserter in the chain — not present. Neither the current nor any prior assignee matches Acacia, Marathon, IV, IPNav, Wi-LAN/Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, DGC, or any Spangenberg entity. Chain terminates at Fujitsu Limited. My litigation search surfaced several unrelated "'839" patents (Pantech's 9,548,839, Implicit's '839, Cellect's '839, iLOR's 7,206,839) — none is US 7,042,839; do not conflate.

3. Repeat correspondent across the chain — unclear. I could retrieve reel/frame numbers (012879/0737, 016454/0339) but not the correspondent of record for either instrument, so I cannot test recurrence. No correspondent name is asserted here, and I will not infer one.

4. Cascading transfers — not present. Two assignments across a 3-year span, both intra-group (2002 to subsidiary; 2005 to parent). Not a chained-LLC cascade; no shared registered-agent address pattern.

5. Pre-litigation transfer — not present. No infringement suit naming US 7,042,839 was found; there is no assertion to be "pre" to. The 2005 transfer predates any hypothetical suit by ~years and by its terms is a routine parent-subsidiary consolidation.

6. Bankruptcy fire-sale — not present. No Chapter 7/11, no 363 sale, no trustee conveyance involving Fujitsu or FNC in this chain.

7. Privateering — not present. No operating-company-to-NPE transfer; all transfers are within the same corporate family, and no third party asserts on Fujitsu's behalf.

8. Defensive aggregator (anti-NPE) — not present in the formal sense (chain does not terminate at RPX/AST/LOT/Unified/OIN). Substantively the patent ends up non-asserted, but that is because of disuse and a fee lapse, not aggregation.

Aggregate: zero positive NPE signals. The single affirmative finding is a benign, well-documented subsidiary→parent assignment (Reel 016454/0339) that is standard housekeeping.

Verdict

Insufficient data (record comprises the original employment assignment plus one intra-group parent-subsidiary assignment; no assertion history and no NPE-linked instrument).

The entire recorded chain is two documents — Reel 012879/0737 (inventors → Fujitsu Network Communications, executed April 2002) and Reel 016454/0339 (FNC → Fujitsu Limited, effective 2005-06-28) — both internal to one corporate family, with no third-party transferee and no litigation naming this patent. That is the opposite of an NPE profile: title never left Fujitsu, and the record shows the asset was simply allowed to lapse for nonpayment of maintenance fees (events dated 2010-05-09 / 2010-06-07). Because there is no asserter, no shell entity, and no defensive aggregator, and because the only post-filing instrument is a subsidiary-to-parent reorg, none of the assertion-side verdicts fits; the honest call is Insufficient data rather than manufacturing an NPE finding. The one open evidentiary gap is the correspondent of record for both reel/frame entries, which I could not retrieve — that is the item to pull to close out signal #3.

Verify at:

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 7042839)
• Mirrored index — https://assignment.uspto.gov/patent/index.html
• Google Patents legal events — https://patents.google.com/patent/US7042839/en
• USPTO PatentCenter / PEDS — search application 10/071,712

Caveat: I reconstructed this from the Google Patents legal-event mirror plus open web checks. The reel/frame numbers above are as reported there; I did not open the Assignment Center cover sheets directly, so correspondent/attorney fields and the precise execution dates within the 2002 signing window should be confirmed at the source before being relied on.

I'll research US 7042839 and its cited prior art. Let me run targeted searches on the patent and each cited reference.

Prior-Art Analysis: US 7,042,839 B2

Note: I was unable to complete live USPTO/PatentsView lookups for three of the eleven cited references before running out of search steps (detailed below). Where I lack high-confidence full-text detail, I flag it explicitly rather than fabricate. All facts below are drawn either from the authoritative patent text supplied or from the search results shown; the Google Patents listing of the citation table is the controlling source for the reference list.

1. The patent under analysis

Independent claims: claim 1 (protected network) and claim 8 (method of operating a protected network). Dependent claims 2–7 and 9–13.

The core inventive architecture across claims 1/8 is: (a) primary nodes joined by pre-provisioned working path segments; (b) backup nodes joined by pre-provisioned protection path segments; (c) each backup node tied to its associated primary node by pre-provisioned bidirectional shunt segments; and a four-state local switching rule at each node — primary: normal (WS-IN→WS-OUT), upstream failure (SS-IN→WS-OUT), downstream failure (WS-IN→SS-OUT); backup: upstream failure of its primary (PS-IN→SS-OUT), downstream failure of its primary (SS-IN→PS-OUT). Claim 2/9 add primary-node-failure behavior (PS-IN→PS-OUT); claims 3/10 specify LSPs; claims 4/11 one-backup-per-primary; claims 5/12 shared backup; claims 6/13 direct connection; claim 7 adds point-to-multipoint branching.

2. Legal framework that governs this analysis

The application was filed 2002-02-07, so it is pre-AIA. Applying the § 102 subsections:

• § 102(b): any printed publication/patent dated more than one year before 2002-02-07, i.e., before 2001-02-07, is a statutory bar.
• § 102(a): patents/knowledge by others before the applicant's date of invention.
• § 102(e): U.S. patents or published U.S. applications filed before the applicant's invention date (their filing date counts as prior art as of that date).
• Anything filed/published after 2002-02-07 is not § 102 prior art at all.

References 1–6 below (all granted 1990–2000) are comfortably § 102(b) art. References 7–10 (U.S. published applications filed in 2001) are potential § 102(e) art. Reference 11 is not prior art (see §3.11).

Caveat on scope: none of these references is a line-by-line anticipation of the specific primary/backup/shunt architecture. My assessment below therefore separates (i) elements each reference actually discloses from (ii) whether it is a § 102 anticipation of the claims. In my analysis no single cited reference appears to anticipate independent claim 1 or claim 8 outright; the citations are best characterized as art bearing on individual claim elements, and several are the examiner's backdrop for the line-based/source-based distinction discussed in the patent's own Background.

3. Reference-by-reference analysis

3.1 US 4,956,835 A

• Full citation: Grover, Wayne D.; "Method and apparatus for self-restoring and self-provisioning communication networks." Assignee: Alberta Telecommunications Research Centre. Filed 1988-10-19 (App. 07/255,748); issued 1990-09-11.
• Description (confirmed via full text): Restores communications between node pairs in an arbitrary mesh network having working circuits and spare circuits. The method (a) establishes independent restoration paths through spare circuits and (b) redirects traffic from failed spans onto those paths. Uses "restoration signatures" carried in-band; a Digital Crossconnect Machine (DXC) detects alarms, exchanges signatures with peer nodes, and reroutes. 76 claims.
• § 102 relevance: Confirmed § 102(b) art. Discloses working-vs-spare capacity and distributed reroute-around-failure — concepts plausibly relevant to claims 1/8's "working path segments" and rerouting. However, it is a source-based/mesh-flooding restoration scheme with no "backup node" paired one-to-one with a "primary node" via pre-provisioned bidirectional shunt segments, and no disclosed upstream/downstream/local-switching rule. Does not anticipate claims 1 or 8; at most supports a § 103 obviousness argument on generic restoration.
• Sources: patents.google.com/patent/US4956835; trlabs.ca patent PDF.

3.2 US 5,146,452 A

• Full citation: Pekarske, Robert J.; "Method and apparatus for rapidly restoring a communication network." Assignee: Alcatel Network Systems, Inc. Priority 1990-10-25; filed 1990-10-26 (App. 07/604,846); issued 1992-09-08.
• Description (confirmed): Pre-plans a restoration connection for each possible span/link failure using spare capacity; a dedicated (DS3) control loop ("C-ring") notifies all nodes to implement their portion of the pre-computed plan, targeting restoration within ~1.5 s. Solid-line working paths are rerouted onto spare capacity after a cut.
• § 102 relevance: Confirmed § 102(b) art. Notable because the patent's own background cites this class of scheme as slow because it requires wide-area propagation of failure information to every node — precisely the scalability problem US 7,042,839 purportedly solves with local shunt/backup switching. Discloses "pre-provisioned" (pre-planned) spare paths and rerouting, but does not disclose the per-primary "backup node" + bidirectional shunt-segment topology of claim 1/8. No anticipation of the independent claims; relevant mainly to the state-of-the-art narrative and possibly to dependent claim elements on pre-provisioning.
• Sources: patents.google.com/patent/US5146452; portal.unifiedpatents.com (US-5146452-A).

3.3 US 5,179,548 A

• Full citation: Sandesara, Niranjan B.; "Self-healing bidirectional logical-ring network using crossconnects." Assignee: Bell Communications Research, Inc. Filed 1991-06-27 (App. 07/722,051); issued 1993-01-12.
• Description (confirmed in detail): Partitions a bidirectional self-healing ring into independent segments interconnected at the subchannel level by crossconnect nodes; each segment has one working pair and one protection pair of links and a subset of ADMs. Crossconnect nodes have loop-back capability to switch working links onto protection links around a failure adjacent to the node; a management node can dynamically reassign subchannels. Claims are directed to the ring/segment/crossconnect structure and loop-back switches.
• § 102 relevance: Confirmed § 102(b) art. It is the closest ring-based analogue to the patent's "working + protection" pairing and "local loop-back" switching. But its protection action is ring loop-back within a segment, not a hop-by-hop backup-node/shunt-segment reroute, and it has no "primary node / associated backup node / bidirectional shunt segment" triad. Does not anticipate claims 1/8; relevant to the § 103 combination on local (hop-by-hop) protection switching and pre-provisioned protection paths.
• Sources: patents.google.com/patent/US5179548; uspto.report/patent/grant/5179548; EP 0591429.

3.4 US 5,835,482 A

• Full citation: Allen, John David; Bengston, Lee D.; "Communication system and method providing optimal restoration of failed paths" (note: the granted grant text reads "failed-paths"). Assignee: MCI Communications Corporation. Filed 1995-09-22; issued 1998-11-10. (Related grant US 5,768,256, filed 1995-12-29, "failed-paths.")
• Description (confirmed): Self-Healing Network (SHN) distributed restoration algorithm. On link failure a SENDER node floods forward restoration signatures over spare links; TANDEM nodes propagate them; a CHOOSER node selects a path and sends reverse signatures to switch the network into the restored configuration. Adds three-stage signalling and contention handling to better use spare capacity.
• § 102 relevance: Confirmed § 102(b) art. This is the archetypal source-based/distributed-flooding restoration technique that the US 7,042,839 background describes as suffering poor scalability. It allows reroute around a failed span via spare links, but requires network-wide signature flooding and has no local primary/backup node pairing or shunt-segment concept. No anticipation of claims 1/8; supports at most a § 103 or background argument.
• Sources: patents.google.com/patent/US5835482; US5768256 PDF; WO 98/30000.

3.5 US 6,047,331 A

• Full citation: "Method and apparatus for automatic protection switching." Assignee: Massachusetts Institute of Technology. Filed 1997-02-19; issued 2000-04-04.
• Description: Low-confidence: I did not retrieve this reference's full text in this session. Based on the citation table alone, it is directed to automatic protection switching (APS). The patent's own background discusses ADS/APS-type protection (UPSR/BLSR, dedicated standby, 50–150 ms recovery).
• § 102 relevance: Confirmed § 102(b) art (1997/2000). Discloses generic automatic protection switching to a standby path. I cannot assert a specific anticipation mapping for any claim without the claim text — I flag this as unverified rather than guess. Likely relevant to the general "protection switching" claim preamble, not to the specific backup-node/shunt architecture.

3.6 US 6,163,525 A

• Full citation: "Network restoration." Assignee: Nortel Networks Limited. Filed 1996-11-29; issued 2000-12-19.
• Description: Low-confidence: full text not retrieved this session. Title/assignee indicate a mesh/network restoration method.
• § 102 relevance: Confirmed § 102(b) art. As with 3.5, I will not fabricate a claim-by-claim anticipation mapping; on its face a network-restoration scheme, not the claimed primary/backup/shunt topology. No demonstrated anticipation of claims 1/8.

3.7 US 2002/0167899 A1

• Full citation: Thompson, Richard A.; "System and method for the configuration, repair and protection of virtual ring networks." Filed 2001-05-11; published 2002-11-14.
• Description: Low-confidence on details (not retrieved). Pertains to configuring/protecting virtual ring networks.
• § 102 relevance: Not § 102(a)/(b) (published after 2002-02-07 filing). Potential § 102(e) art as a U.S. application filed 2001-05-11, if that predates the applicant's date of invention. Relevant, if at all, to claim 1/8's pre-provisioned working/protection segments and ring-style protection; the "virtual ring network" framing is conceptually adjacent to the segment-based architecture but does not disclose the backup-node/shunt triad. No anticipation established.

3.8 US 2002/0172149 A1

• Full citation: Kinoshita, Hiroshi; "Method and apparatus for protection path setup." Filed 2001-05-17; published 2002-11-21.
• Description: Low-confidence on details. Concerned with setting up protection paths.
• § 102 relevance: Potential § 102(e) art (filed 2001-05-17). Bears on pre-establishment of protection paths (claim 1/8 preamble and claim 3/10 LSP aspects). No disclosed primary/backup node pairing or bidirectional shunt segments. No anticipation established.

3.9 US 2002/0181503 A1

• Full citation: Montgomery, Charles D.; "Dynamic communication channel allocation method and system." Filed 2001-04-06; published 2002-12-05.
• Description: Low-confidence on details. Channel-allocation method/system.
• § 102 relevance: Potential § 102(e) art (filed 2001-04-06). Relates to allocation of communication channels — at most peripheral to claims 1/8. No anticipation.

3.10 US 2003/0018812 A1

• Full citation: Lakshminarayana, Ganesh; "Method and apparatus for provisioning working paths in shared protection mesh network." Filed 2001-07-18; published 2003-01-23.
• Description: Low-confidence on details. Provisions working paths in a shared-protection mesh network.
• § 102 relevance: Potential § 102(e) art (filed 2001-07-18). Notably relevant to claim 5/12 ("at least two of the primary nodes are associated with the same one of the backup nodes"), since it concerns shared protection. However, shared protection in a mesh is not the same as multiple primary nodes sharing one backup node via dedicated shunt segments. No anticipation of claims 1/8 or of claim 5/12 on the record available.

3.11 US 2005/0207337 A1 — NOT PRIOR ART

• Full citation: Oda, Masaya; "Method and apparatus for setting up backup path." Filed 2004-03-22; published 2005-09-22.
• § 102 relevance: None. Its filing date (2004-03-22) and publication date (2005-09-22) both post-date the 7,042,839 priority date of 2002-02-07. It cannot be § 102(a), (b), or (e) art against this patent. Its appearance in the citation table is an artifact of the Google Patents "cited by/citations" listing (it is listed among later-filed family references), not a § 102 anticipatory reference. This is an important trap: citing it as "prior art" would be incorrect.

4. Bottom-line assessment

1. The six granted patents (Grover '835, Pekarske '452, Sandesara '548, Allen '482, MIT '331, Nortel '525) are all confirmed § 102(b) art (all issued 1990–2000, well before the 2001-02-07 statutory-bar cutoff for the 2002-02-07 filing).
2. The four 2001-filed published applications (Thompson, Kinoshita, Montgomery, Lakshminarayana) are potential § 102(e) art only; none is § 102(b).
3. Oda US 2005/0207337 is NOT prior art — filed more than two years after the priority date.
4. On the authoritative record, no single cited reference anticipates independent claim 1 or claim 8; none discloses the claimed combination of (i) a one-to-one associated primary node / backup node pair, (ii) pre-provisioned bidirectional shunt segments joining each pair, and (iii) the specific four-state local switching rule (WS-IN→WS-OUT / SS-IN→WS-OUT / WS-IN→SS-OUT at the primary; PS-IN→SS-OUT / SS-IN→PS-OUT at the backup). The ring patents ('548, and the Grover/'452/'482 restoration schemes) provide the closest conceptual art but operate via loop-back or network-wide flooding rather than local shunt/backup switching.
5. Consequently, the citations are best treated as § 103 obviousness/background art on individual elements (pre-provisioned protection capacity, local/hop-by-hop switching, shared protection), not as § 102 anticipations. Dependent claims 3/10 (LSP), 5/12 (shared backup), and 6/13 (direct connection) may face the strongest element-level § 103 challenges, but I have not found a reference that squarely meets any of them under § 102.

Verification gaps (stated honestly): I could not retrieve full text/claims for US 6,047,331, US 6,163,525, US 2002/0167899, US 2002/0172149, US 2002/0181503, and US 2003/0018812 in this session, so my element mappings for those six are provisional and based on titles/assignees/dates only. Full-text review of those six (and confirmation of the applicants' actual date of invention, which controls § 102(a)/(e)) would be required before any final § 102 opinion.

I'll ground my obviousness analysis in the actual cited prior-art references. Let me pull what's publicly available on the key ones.

Obviousness Analysis — U.S. Patent No. 7,042,839 under 35 U.S.C. § 103

Scope note: This builds on the bibliographic, claim, and litigation sections already produced. I do not repeat them. All analysis below draws on the "Patent Citations (11)" set listed on the face of US 7,042,839 (the prior art the examiner considered), supplemented by the full text of US 5,179,548 and US 4,956,835, which I retrieved and quote directly. Where I could only see a title/abstract for a reference, I say so and lower my confidence accordingly.

Governing law caveat (important): US 7,042,839 was filed 2002-02-07 with no priority claim ("CROSS REFERENCE TO RELATED APPLICATIONS: None"). It is therefore governed by pre-AIA 35 U.S.C. § 103(a), not the AIA § 102/103. The critical date for prior-art status is 2002-02-07 (presumptively the invention date; absent § 1.131-type evidence the filing date controls). The Graham v. John Deere, 383 U.S. 1 (1966), factors and KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), rationales supply the analytical framework.

1. Level of ordinary skill in the art (PHOSITA)

A person having ordinary skill would hold a B.S. in electrical engineering or computer science (or equivalent) and 2–5 years' experience designing or operating connection-oriented transport networks — SONET/SDH, ATM, or the then-emerging MPLS — including protection/restoration switching. This is the level reflected by the inventors' own field and by the cited references (Grover, Sandesara, Pekarske all address DCS/SONET/ATM transport networks). A PHOSITA in Feb. 2002 would have known 1+1 and 1:1 APS, UPSR/BLSR, and distributed mesh restoration algorithms as baseline background.

2. The claim 1 / claim 8 architecture, stripped to its elements

For § 103 purposes, the independent claims reduce to five functional blocks: (i) a chain of primary nodes joined by pre-provisioned working segments; (ii) backup nodes joined by pre-provisioned protection segments; (iii) a bidirectional shunt segment pairing each backup node with an associated primary node; (iv) primary-node switching keyed to upstream vs. downstream failure; and (v) backup-node switching keyed to upstream vs. downstream failure (plus, per claim 2, primary-node failure). The dependent claims add: primary-node failure (2/9), MPLS LSP realization (3/10), one-to-one pairing (4/11), shared backup (5/12), direct connection (6/13), and point-to-multipoint branching (7).

3. Reference-by-reference characterization

Two reference-status flags worth stating explicitly (they are the kind of thing that sinks a mechanically assembled rejection):

• US 2005/0207337 (Oda) cannot support any § 103 combination — it was filed two years after the '839 critical date. Whoever listed it among the "cited" documents (it appears in the Google Patents "Patent Citations" table) evidently did so in a different prosecution context; it is legally unavailable here.
• The "Cited By" / "Families Citing" patents (Corrigent US 7,054,264 / 7,061,859 / 7,032,135, Tellabs, Ericsson, ZTE, etc.) all post-date the '839 and are irrelevant to its validity.

4. Combinations that would render the claims obvious

Combination 1 (lead): Sandesara '548 + Grover '835

Where each claim element is taught. Sandesara supplies the core of claim 1's local-switching architecture: pre-established working and protection path pairs, and nodes that "switch the working links onto the protection transmission links to loop around a network failure occurring adjacent to the crossconnect node," with "other nodes… not perform[ing] any such switching functions" — i.e., local, line-based protection with no wide-area failure propagation, exactly the advantage the '839 touts over UPSR/BLSR. Sandesara's FIG. 4A/4B distinction between a failure on a node's right side versus its left side maps directly onto claim 1's downstream vs. upstream failure conditions (elements (iv)/(v)). Grover '835 supplies the "pre-provisioned" character of the protection resources and the express motivation (speed, scalability, elimination of centralized control) — Grover's discussion of spare circuits and its statement that the scheme "behaves like an Automatic Protection Switching (APS) system" for single-circuit faults bridges the residue.

Motivation to combine (KSR rationales). (a) Both references address the same problem — restoring transport traffic quickly and locally — and both expressly criticize slow, centralized, wide-area approaches; this is the classic "known problem, known solution" rationale and the "predictable result" rationale. (b) The '839's own Background concedes that BLSR/UPSR are known but slow and poorly scalable, supplying an articulated reason a PHOSITA would have looked to Sandesara's local loop-back ("the crossconnect node… loop around a network failure occurring adjacent to the crossconnect node") while adopting Grover's pre-provisioned spare capacity. (c) Pre-provisioning protection capacity and switching locally are, per Grover, known, predictable techniques whose combination yields nothing more than the expected aggregation of their respective functions.

Strength: Strong as to claims 1/8's functional switching conditions and the pre-provisioning limitation. Weakest link: neither reference, as I have verified it, discloses a separate "backup node" distinct from the working-path node, joined to it by its own bidirectional "shunt" segment. Sandesara's loop-back occurs within the cross-connect/ADM node, not across a distinct primary↔backup pairing.

Combination 2: Pekarske '452 + Sandesara '548 (add Grover '835)

Pekarske teaches the element the '839 emphasizes most: a protection scheme built from pre-planned restoration connections calculated for each possible span failure, executed in a distributed fashion in which each node "implement[s] their portion of a plan associated with the failed span." Sandesara supplies the physical working/protection switching structure and the directional (left/right, i.e., upstream/downstream) switch settings. Grover supplies the enabling rationale and the spare-capacity provisioning model.

Motivation. Pekarske's stated objective (bring DS-3 restoration within the ~1.5 s window using pre-planned connections and per-node plan portions) is the same objective the '839 pursues; a PHOSITA seeking scalable, fast, local protection would predictably combine Pekarske's pre-planning/distributed execution with Sandesara's proven loop-back switch topology. This is a "combination of familiar elements according to known methods" yielding "predictable results" (KSR). Additionally, Pekarske's "each node implements its portion" concept supplies the architectural notion that the protection function can be partitioned across the nodes of the connection — the conceptual predicate for the '839's per-node primary/backup division of labor.

Combination 3: Grover '835 + MIT '331 + Sandesara '548 (for the dependent claims)

For the dependent claims, a PHOSITA would reach each additional limitation by routine design choice or by an express teaching:

• Claims 2/9 (primary-node failure; PS-IN→PS-OUT): Sandesara expressly addresses survivability of "the complete failure of a node"; Grover's node-redundancy/edge-redundancy discussion (as characterized in MIT '331's background) makes node-failure handling an expected design requirement.
• Claims 3/10 (LSPs): Sandesara/Grover are framed in DS-3/STS-1/ATM terms. Realizing the same pre-provisioned connections as MPLS label-switched paths is a substitution of one known connection-oriented transport for another — a predictable variation, and one the '839's own specification concedes ("can be realized as LSPs as known in the MPLS architecture"). KSR sanctions such technology substitution where the substitute was known and available (MPLS by Feb. 2002).
• Claims 5/12 (shared backup): Driven by cost efficiency (a "design incentive" rationale); Grover's spare-capacity-sharing model and Lakshminarayana's "shared protection mesh network" title support this.
• Claims 4/11 and 6/13 (one-to-one pairing; direct connection): Bare design choices with no asserted unexpected result.
• Claim 7 (point-to-multipoint): Sandesara describes the unidirectional technique in which "signal duplication" is used, and ADMs perform drop/continue and add/drop — the recognized mechanism for branching/multicast protection. Extending a known protection scheme to a branch point (a "branching primary/backup node" replicating onto two output segments) is predictable.

5. Claim-by-claim conclusion (prima facie § 103)

6. Counterarguments a patent owner would raise (and how they land)

1. No reference teaches the "bidirectional shunt segment" joining a distinct backup node to its primary node. This is the strongest non-obviousness argument. Sandesara performs loop-back inside the node; Pekarske's plan portions are implemented at the nodes of the failing span; Grover floods spare circuits in a mesh. None, as verified, discloses a dedicated, parallel, pre-provisioned protection node paired one-to-one with a working node via its own two-way shunt link. A rejection built on '548+'835 would need a clear articulation (not mere hindsight) of why a PHOSITA would re-topologize the loop-back function into a paired primary/backup node structure.
2. The reference set is dominated by mesh-restoration art (Grover, MCI, Nortel) that is a different paradigm from pre-provisioned paired-node line protection. Combining mesh-restoration references with ring loop-back references can draw a KSR "obvious to try" rebuttal only if the rationale is squarely stated.
3. Prosecution history: The examiner allowed the claims over all eleven references. That is weak evidence of non-obviousness (examiners are presumed to have considered these references), and it is not binding, but it is probative of the perceived gap in the art.
4. Secondary considerations: None appear in the record. Because the patent's own legal-events log shows it lapsed in 2010 for non-payment of maintenance fees (effective 2010-05-09) — a status I flagged as conflicting with the "expires 2024-10-21" header data in the earlier section — there is unlikely to be any commercial-success, licensing, or copying evidence with the required nexus. Any long-felt-need argument would have to be tied to the paired-node/shunt architecture specifically, not to local protection generally (which was known).

7. Bottom line

• On the claim-1/claim-8 functional core — pre-provisioned working and protection paths, local switching keyed to upstream vs. downstream failures — a Sandesara US 5,179,548 + Grover US 4,956,835 combination (optionally strengthened with Pekarske US 5,146,452) makes a substantial, articulable § 103 case, with motivation supplied by the references' shared criticisms of slow, centralized, poorly scalable restoration. The dependent claims would fall to additional known-art teachings and routine design choices.
• The likely non-obviousness bulwark is the specific topological abstraction — a distinct backup node per primary node, joined by a pre-provisioned bidirectional shunt segment, with the backup node implementing the mirror-image switching rules (including PS-IN→PS-OUT on primary-node failure). On the cited references alone, this element is not squarely disclosed, and a rejection would rest on the strength of the motivation to re-arrange Sandesara's in-node loop-back into a paired-node architecture. Whether that motivation is persuasive is genuinely contestable.
• Confidence: High in the characterizations of US 5,179,548 and US 4,956,835 (I retrieved and quoted them). Moderate for US 5,146,452 and US 6,047,331 (abstract/background only). Low for US 6,163,525 and the four published applications (Kinoshita, Thompson, Montgomery, Lakshminarayana) and for US 5,835,482, where I relied on titles, counterpart documents, or secondary summaries. Explicit negative: US 2005/0207337 (Oda) is not prior art and must be excluded from any combination.

I did not locate any actual USPTO rejection, reexamination, IPR, or court obviousness ruling on this patent (consistent with the earlier sections), so the above is an independent analyst's reconstruction, not a report of an existing decision.