US 6430623

I'll search for current information on this patent, including any 2026 litigation activity.

Let me check for litigation and any Federal Circuit appeals involving this patent and its owner.

US Patent 6,430,623 — "Domain Name Routing"

Scope note on this research pass: I searched for USPTO data and for 2026 CAFC activity on this specific number. I found no Federal Circuit 2026 docket, opinion, or appeal tied to 6,430,623, and no CAFC activity at all for this patent. I also found no IPR/PGR against 6,430,623; the PTAB petition documents that surfaced cite Alkhatib (this patent's disclosures, including its "apparatus 138/156" gateway/router figures) as prior art against other parties' patents. Details and caveats below.

Bibliographic data

Uncertainty notes (dates): Google Patents and Unified Patents disagree by one day on the filing date (1/27 vs. 1/26/2000), the priority date (1/29 vs. 1/28/1998), and the grant date (8/6 vs. 8/5/2002). I have not verified these against the USPTO PatentCenter record, so I flag both values rather than picking one. Note the internal inconsistency in the specification's own numbering ("DNR 130" vs. "DNR 138") in the Figure 7 description — that is in the source text, not a transcription error.

Abstract (verbatim)

"The present invention provides for a Domain Name Router (DNR) that uses domain names to route data sent to a destination on a network (e.g., a stub network). Each corporate entity or stub network can be assigned one or a small number of global addresses. Each of the hosts on the stub network can be assigned a local address. When a source entity sends data to a destination entity with a local address, the data is sent to the DNR using a global address. The source entity embeds the destination's domain name and its own domain name inside the data. The DNR extracts the destination's domain name from the data, translates that domain name to a local address and sends the data to the destination."

Independent claims in plain language

The patent has 47 claims. The supplied full text truncates mid-claim 40, so I can only characterize independent claims 1, 12, 17, 28, 34, and 40; I cannot characterize anything beyond claim 40 and will not guess.

Claim 1 (method, communicating with entities in a private network) — Two steps: (a) initiate communication with a first entity from outside the private network, using a unique identifier that is not an IP address; the identifier is used below the application layer (i.e., at the network or transport layer); the target entity is inside the private network and is an "addressable physical entity that does not have a globally unique address"; and (b) communicate messages toward that entity that reach it via an intermediate entity which holds a global address. In short: reach an unaddressed private host from the public Internet by routing on a non-IP name, through a globally-addressed gateway.

Claim 12 — Same subject matter as claim 1, recast as a manufacture claim: one or more processor-readable storage devices carrying code that programs a processor to perform the claim 1 method.

Claim 17 (method for supporting communication) — From the gateway's perspective: receive a message from a first entity located outside the private network, the message carrying a unique identifier other than an IP address that identifies a second entity which lacks a globally unique IP address and sits inside the private network; then use that unique identifier, below the application layer, to access a non-globally-unique local address corresponding to the second entity; and provide that local address in response to the message. (Dependent claim 23 narrows the "use" step to accessing a table correlating unique identifiers to local addresses; claim 24 notes the destination address maps to a set of entities including the target.)

Claim 28 — Same subject matter as claim 17, recast as a processor-readable storage medium claim.

Claim 34 (method for communicating data) — Receive a data unit containing (i) a destination address and (ii) a first set of information separate from the destination address and not an IP address; the destination address corresponds to every entity in a set of entities, while the first information corresponds to only a subset of that set that includes the first entity; then send the data unit toward the first entity by addressing the data unit using the first information, below the application layer. This is the core "route by embedded name, not by IP" claim. (Dependents 37/39 elaborate: use the first information to identify a local address, and edit the data unit to add that local address.)

Claim 40 — A method claim whose text is cut off in the supplied document mid-sentence ("...said source entity is outside said pri[nate network]"). From what is legible, it recites that the data unit is an initial communication between a source entity and the first entity; the first entity is inside a private network, lacks a globally unique address, and the source entity is outside the private network. I cannot give you the full claim scope from this text — the remainder, plus claims 41–47, are not present. Do not treat this as a complete claim summary.

Common thread across all independent claims: (1) the destination is reached by a non-IP identifier (domain name or "information representing" a domain name, e.g., encoded/compressed/encrypted per claim 4/19/36), (2) that identifier is processed below the application layer, and (3) delivery runs through an intermediate gateway with a global address. Claim 1 also expressly requires that the communication be initiated from outside the private network — the exact scenario the specification identifies as a failing of NAT ("the NAT approach specifically will not work if the communication is initiated by a host outside of the private network").

Family and continuation

Google Patents links this case to US 6,772,227 B2, filed as a further application (2002-05-16) claiming priority from the same lineage. The specification characterizes 6,430,623 as a continuation of Ser. No. 09/015,840 (issued as US 6,119,171). Family members: 16 per Unified Patents.

Litigation — district court only (no CAFC 2026 activity found)

All litigation I located lists US 6,430,623 B1 among the asserted patents:

• Hanger Solutions, LLC v. Extreme Networks, Inc., D. Del. 1:21-cv-00040, filed 2021-01-14; plaintiff voluntarily dismissed; case closed 2021-04-12. (https://dockets.justia.com/docket/delaware/dedce/1:2021cv00040/74292)
• Hanger Solutions, LLC v. Squarespace, Inc., D. Del. 1:21-cv-00774, filed 2021-05-27; answer filed July 2021. (https://dockets.justia.com/docket/delaware/dedce/1:2021cv00774/75608)
• Hanger Solutions LLC v. Charter Communications, Inc., W.D. Tex. 6:22-cv-00070, filed 2022-01-18 (Exhibit A to the complaint is U.S. 6,430,623). (https://portal.unifiedpatents.com/litigation/Texas%20Western%20District%20Court/case/6%3A22-cv-00070)
• Google Patents also lists W.D. Tex. 6:22-cv-00330 and M.D. Ga. 4:22-cv-00152.

In each Delaware case the complaint's "Report to the Commissioner" identifies the same three-patent set: US 6,430,623 B1; US 6,609,159 B1; US 6,772,227 B2. Plaintiff's corporate parent is identified as Brainbox Innovations, LLC. Note that 6,772,227 — not 6,430,623 — has a later filing/expiry and is therefore the more likely vehicle for post-2018 damages exposure.

CAFC / 2026 docket findings: My searches returned no Federal Circuit docket, opinion, or Rule 36 entry involving 6,430,623. The 2026 CAFC materials that surfaced (Global Tubing v. Tenaris, Exafer v. Microsoft, Constellation Designs v. LG, Align v. Dental Monitoring, UT v. Boston Scientific, IPL v. Sony) are unrelated to this patent. I cannot confirm or deny that a 2026 appeal exists — my searches were not exhaustive over PACER/CAFC's docket system, and the district court dockets above were last retrieved in 2021–2022. Treat "no CAFC activity" as a search limitation, not a verified negative.

One additional, relevant finding

This patent's disclosure is being used as prior art in PTAB proceedings against other patents. Petition documents hosted at ptacts.uspto.gov reference "Alkhatib" and the DNR/router elements at reference numerals 138/156 of the '623 patent's Figure 5, including a rejection applying "Alkhatib" (optionally with Killian, Antonov, and Funk) under 35 U.S.C. § 103. (https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1521621](/patent/1521621)/download-documents and .../petitions/1557625/download-documents). That tells you the reference has citation value beyond its own claims, but it is not the patent being challenged.

Bottom line

6,430,623 is a 2000-filed, 2002-issued continuation (priority 1998) of Hasan Alkhatib's work at IP Dynamics on name-based routing into private networks via a "Domain Name Router." Its independent claims all hinge on three limitations: a non-IP unique identifier, use of that identifier below the application layer, and delivery through an intermediate globally-addressed gateway. It is expired (lifetime, ~2018) and now held by Hanger Solutions LLC, with all identified enforcement activity confined to 2021–2022 district court cases. The biggest caveats are (i) the truncated claim text (claims 41–47 are unavailable to me), and (ii) the absence of any verified 2026 CAFC record.

I'll research litigation involving US patent 6430623. Let me run several targeted searches.

Good, I'm finding leads. Let me dig into the specific cases.

Litigation Involving U.S. Patent No. 6,430,623 ("Domain Name Routing")

Bottom line

Yes — litigation is known. U.S. 6,430,623 was asserted in a set of infringement suits filed by Hanger Solutions, LLC (an NPE ultimately derived from the Intellectual Ventures/F. Poszat Hu chain) concentrated in 2021–2022. I did not find any Federal Circuit (CAFC) appeal specifically identifying the '623 patent, and I did not find any pre-2021 assertion of the '623 patent (e.g., by original assignee IP Dynamics Inc.) in the sources searched. The '623 patent expired January 2018 (20 years from its Jan. 29, 1998 priority date), so the 2021–2022 suits necessarily targeted only pre-expiration conduct within the damages window and, as shown below, largely ended in dismissals/stays.

Cases asserting the '623 patent

Supporting detail and citations

• Case 1 (Extreme Networks, D. Del. 1:21-cv-00040): Complaint docketed Jan. 14, 2021 (referenced as "SEE CIVIL ACTION 21-40"), Report to Commissioner listing "US 6,430,623 B1; US 6,609,159 B1; US 6,772,227 B2." A "NOTICE of Voluntary Dismissal by Hanger Solutions, LLC as to Extreme Networks, Inc." was filed, and "CASE CLOSED" entered 04/12/2021. (Source: Unified Patents litigation page, https://portal.unifiedpatents.com/litigation/Delaware%20District%20Court/case/1:21-cv-00040; also the Delaware misc. docket at CourtListener docket 27876153.)
• Case 2 (Squarespace, D. Del. 1:21-cv-00774): Complaint filed May 27, 2021 asserting "US 6,430,623 B1; US 6,609,159 B1; US 6,772,227 B2." Docket shows a Scheduling Order (Feb. 2, 2022), claim-construction activity through late 2022, then "Joint STIPULATION to Stay Case" (Nov. 22, 2022) and "STIPULATION of Dismissal With Prejudice" (D.I. 58, Dec. 13, 2022). (Sources: Justia docket, https://dockets.justia.com/docket/delaware/dedce/1:2021cv00774/75608; Patexia case 152578.)
• Case 3 (Charter, W.D. Tex. 6:22-cv-00070): Complaint filed Jan. 18/19, 2022, Exhibit A = U.S. 6,430,623. (Source: UniCourt case summary, https://unicourt.com/case/pc-db5-hanger-solutions-llc-v-charter-communications-inc-[1119472](/patent/1119472).)
• Case 4 (Cequel/Altice, W.D. Tex. 6:22-cv-00330): Exhibits A (U.S. 6,119,171) and B (U.S. 6,430,623). Stayed twice (through June 20, 2022). RPX described this as part of Hanger's campaign begun in January 2021 with the Extreme Networks suit. (Sources: Justia docket, https://dockets.justia.com/docket/texas/txwdce/6:2022cv00330/[1167358](/patent/1167358); RPX Insight, https://litigation.rpxcorp.com/news/70112.)
• Case 5 (Mediacom, M.D. Ga. 4:22-cv-00152): Complaint filed Sept. 28, 2022, Exhibit C = U.S. 6,430,623; answer/counterclaim Nov. 23, 2022. (Source: Justia docket, https://dockets.justia.com/docket/georgia/gamdce/4:2022cv00152/[126536](/patent/126536); Georgia IP Litigation Blog via Lexology.)

Caveats on accuracy

• I could not retrieve PACER/CAFC records directly in these searches; the outcomes above rest on public aggregators (Justia, UniCourt, Patexia, Unified Patents, RPX). The final dispositions of cases 3, 4, and 5 are not confirmed — given the patent's January 2018 expiration and the campaign's pattern (dismiss/stay), they most likely terminated without judgment, but I will not state that as fact without the docket.
• No Federal Circuit appeal naming the '623 patent was found; I cannot rule one out.
• I limited results to the exact number 6,430,623 (a.k.a. "US 6,430,623 B1"). I excluded look-alike numbers such as 6,493,002, 6,343,263, 6,868,160, and 6,098,098, which appear in unrelated matters or as other patents in the same Hanger campaign.
• The '623 patent is a continuation of Ser. No. 09/015,840 (now U.S. 6,119,171), which is why the '171 patent also appears alongside the '623 patent in several of these complaints.

If you need verified final dispositions for cases 3–5 (e.g., via PACER or the CAFC docket), those are the specific records to pull.

I'll verify the PTAB landscape with live searches before writing anything.

Let me dig deeper on proceedings specifically naming this patent and its owner.

Let me check for any PTAB activity under the owner's name and any reexamination of the family.

Proceedings overview

Total AIA trial proceedings on file for US 6,430,623: 0. Breakdown by status: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The canonical structured block ("PTAB proceedings on file") states the USPTO Open Data Portal returns no AIA trial proceedings for this patent as of the most recent ingest, and my independent searching surfaced no IPR, PGR, or CBM naming 6,430,623 either — so the default holds: no PTAB activity on file.

Bottom-line defensive posture: the patent is untested, not hardened. Hanger Solutions' assertions of the '623 patent in 2021–2022 were never met with a PTAB petition, so all 47 claims stand exactly as granted. That cuts both ways — you can't point to a cancellation order, but you also face zero § 315(e)(2) estoppel and zero adverse PTAB claim constructions. The real defensive asset here is not a PTAB record; it's the expiration date.

No AIA trial proceedings — but three things a defendant must know

Because there is no proceeding to profile, I'm substituting the factual record that matters. Every item below is sourced; where I have only partial confidence I say so.

1. The patent expired on 2018-01-29 — before the enforcement campaign began.
Google Patents lists "2018-01-29 Anticipated expiration" and legal status "Expired - Lifetime"; Patexia lists expiration 2018-01-29 (application filed 2000-01-27; priority 1998-01-29). Hanger Solutions' suits asserting the '623 patent were filed 2021–2022 — i.e., three to four years after the monopoly lapsed. Consequences:

• No injunctive relief is available; the remedy is past damages only, and under 35 U.S.C. § 286 recovery is capped at six years before the complaint.
• A post-expiration IPR is not a useful tool: the patent can no longer be asserted prospectively and the patent owner cannot amend, which is why the absence of IPR activity is unsurprising rather than a merits signal.
• Caveat: I did not independently verify the terminal-disclaimer / § 154(c) posture that produced the 2018 date from the patent's own file history. Confirm against the USPTO PatentCenter file wrapper before relying on the exact date.

2. This patent is a continuation of US 6,119,171, and the family — not the '623 — is what shows up in the PTAB record.
The '623 specification states: "This application is a continuation of Ser. No. 09/015,840, filed Jan. 29, 1998, now U.S. Pat. No. 6,119,171." In the PTAB petitions I reviewed, "Alkhatib" appears as prior art cited against other patents — e.g., IPR petition in PTAB proceeding ID 1557625 relies on "Alkhatib at 20:1–3" against the '785 patent, and the same petition's exhibit table lists Alkhatib et al. US 6,119,171; US 7,139,828; and US 2004/0044778. This is not an IPR against 6,430,623. Do not let a vendor report conflate the two — the family shares a specification, so Alkhatib references appear constantly in unrelated challenges.

3. The district court campaign is real and is the actual record of assertion.
The '623 patent was asserted alongside US 6,609,159, US 6,772,227, US 6,119,171 and US 6,868,160:

• Hanger Solutions, LLC v. Extreme Networks, Inc., D. Del. 1:21-cv-00040 (filed 2021-01-15; voluntarily dismissed) — https://portal.unifiedpatents.com/litigation/Delaware%20District%20Court/case/1:21-cv-00040
• Hanger Solutions, LLC v. Squarespace, Inc., D. Del. 1:21-cv-00774 (filed 2021-05-27) — https://dockets.justia.com/docket/delaware/dedce/1:2021cv00774/75608
• Hanger Solutions LLC v. Charter Communications, Inc., W.D. Tex. 6:22-cv-00070 (filed 2022-01-18; voluntarily dismissed 2022-06-10) — https://portal.unifiedpatents.com/litigation/Texas%20Western%20District%20Court/case/6%3A22-cv-00070
• Hanger Solutions LLC v. Cequel Communications, LLC, W.D. Tex. 6:22-cv-00330 (filed 2022-03-29) — https://portal.unifiedpatents.com/litigation/Texas%20Western%20District%20Court/case/6%3A22-cv-00330
• Hanger Solutions, LLC v. Mediacom Communications Corp., M.D. Ga. 4:22-cv-00152 (filed 2022-09-28; defendant counterclaimed) — https://portal.unifiedpatents.com/litigation/Georgia%20Middle%20District%20Court/case/4%3A22-cv-00152

Hanger's Rule 7.1 disclosures identify Brainbox Innovations, LLC as corporate parent; the patent's chain of title runs IP Dynamics → InPro Network Facility → F. Poszat HU → Intellectual Ventures Assets 161 → Hanger Solutions LLC (2020-01-05). That is a classic NPE aggregation chain, not an operating-company patent.

Strategic summary

Claim status. Claims 1–47 are all UNTESTED — none canceled, none sustained, none construed by the Board. There is no PTAB claim-level disposition to quote, and I will not manufacture one. Any statement that a claim of the '623 patent was invalidated in an IPR is false on the current record.

Estoppel landscape. Because no IPR was ever instituted, § 315(e)(2) estoppel is empty. A defendant today may raise any § 102/§ 103 ground in district court that it could have raised in an IPR, plus all the grounds IPR cannot reach — on-sale bar, public use, prior public disclosure, § 101, § 112 indefiniteness and written description, inequitable conduct, and best-mode. Practically, though, this is cold comfort: the patent expired in 2018, so the fight is about a closed damages window, and the most valuable ground may be a § 286 damages-limitation argument rather than invalidity at all.

Pattern signals. No serial petitioners, no repeated IPRs, no PTAB appeals, and no defensive aggregator activity — I found no Unified Patents, RPX, or other aggregator IPR against this patent, despite Unified's litigation-tracking pages indexing the associated district court cases. The patent owner has therefore never had to defend a claim at the Board, which means the claim constructions the patent owner would advance are also untested — an argument both ways during claim construction. Note the counterclaim filed in the Mediacom action as the one place an invalidity case was actually joined.

Confidence caveat. The absence of PTAB proceedings is asserted primarily on the authoritative structured block in this prompt. My corroborating web searches were truncated before I could query PTAB E2E/PTACTS directly, so I recommend a one-minute confirmatory search at https://ptacts.uspto.gov/ptacts/ (search "6430623") and in PatentCenter for any ex parte reexamination of the '623 patent, which would not appear as an AIA trial.

Recommended next steps

1. Do not build a defense on a PTAB cancellation that does not exist. If your demand letter or an internal memo asserts that claims of 6,430,623 were invalidated, retract it — that is sanction-adjacent under Rule 11 and will cost you credibility with the court.
2. Confirm the expiration date and terminal disclaimer from the file wrapper. If 2018-01-29 holds, move early for partial summary judgment on the § 286 damages window and on the unavailability of injunctive relief — that is likely outcome-determinative and far cheaper than an invalidity case on a 1998-priority patent.
3. Run a fresh PTACTS search before you rely on this memo. Search the patent number, and also search the owner string "Hanger Solutions" for any 2022–2023 petition I could not reach.
4. Preserve the district court invalidity record. The Mediacom counterclaim and the dismissed Charter/Cequel/Extreme cases are the only adversarial testing this patent has ever had; pull the pleadings and any stipulated dismissals, since voluntary dismissal without prejudice (Charter 2022-06-10; Extreme 2021) means Hanger retains the right to re-assert.
5. No trial-stage milestones to calendar — institution deadlines, oral hearings, and 35 U.S.C. § 316(a)(11) FWD due dates are inapplicable where no trial was instituted.

I'll pull what I can verify before writing. Let me run several targeted searches.

Good leads. Now let me chase the reel/frame data, the IP Dynamics history, and the Hanger Solutions ownership chain.

Scope note: USPTO Assignment Center's reel/frame numbers and the correspondent-of-record fields were not retrievable in this session (no direct query access to assignmentcenter.uspto.gov). What follows is grounded in the Google Patents legal-events record for US 6,430,623 (which mirrors the underlying Part 3 assignment filings), the INPI/EPO/OEPM register entries for the EP family members, and RPX/Mondaq reporting on the assignee chain. Where a reel/frame or correspondent is not verified, I say so rather than supplying a placeholder.

Inventors

• Hasan S. Alkhatib — sole named inventor on US 6,430,623 (and on every member of the family asserted with it: US 6,119,171, US 6,609,159, US 6,772,227). Residence of record in the family: Saratoga, CA 95070‑6361 (per the INPI register entry for EP 1057309, which lists "ALKHATIB, HASAN, S. SARATOGA, CA 95070‑6361").
• Employer at time of filing: IP Dynamics, Inc. — Alkhatib is the founder. RPX/Mondaq describe him as an "Ex‑Microsoft Executive, Silicon Valley entrepreneur, and professor of Computer Engineering," an Advisor to the Minister of Communications in Iraq since February 2011, and president of SSN Services, LLC since May 2017.
• Unusual patterns: None of the classic co‑inventor‑departure patterns apply, because there is only one inventor. The notable anomaly is different: the inventor's company divested the entire family roughly ten years after the 1998 priority filing (2008), and no inventor‑linked assignment, reversion, or inventor‑as‑assignee record appears anywhere in the chain after that point. The inventor has no recorded economic interest in the asserted family today.

Original assignee

IP Dynamics Inc (also rendered "IP Dynamics, Inc."; recorded later as "IP DYNAMICS, INC."). The '623 patent was filed 2000‑01‑27 as a continuation of Ser. No. 09/015,840 filed 1998‑01‑29 (now US 6,119,171), and issued 2002‑08‑06.

• Product embodying the claims: Yes, plausibly. RPX/Mondaq report that the development work for this family was conducted at IP Dynamics, which Alkhatib describes as having "introduce[d] the industry's first platform for hosting (cloud‑based) secure, software connectivity services that enable users and resources to connect securely from anywhere to anywhere regardless of their location and the underlying network." That description matches the claim‑1 subject matter (domain‑name‑based routing to entities inside a private network through an intermediate entity with a global address).
• Primary line of business: enterprise/cloud secure connectivity software — a small venture‑stage networking company, not a diversified operating company.
• Current status: The IP was assigned away on 2008‑01‑21, and I have no verified evidence of IP Dynamics' present status (operating, acquired, dissolved, or wound down). I am not going to assert a bankruptcy or dissolution I cannot source. One circumstantial data point worth flagging: a security interest in the patent was granted to two individuals, David Sun and Diana Sun, on 2003‑06‑24 — consistent with a small company pledging IP to private lenders, but that is an inference, not a finding.
• Current assignee of record per Google Patents: Hanger Solutions LLC.

Assignment timeline

Note on the record format: Google Patents legal events expose one date, conveyance type, assignor and assignee per recorded assignment, but not reel/frame or correspondent. I have not reconstructed reel/frame numbers, because fabricating them would be worse than omitting them. Dates below are the dates as shown on the record; where a date inversion exists (see the 2020 entries) I flag it rather than silently reordering.

• 2003-06-24 (date as recorded) — Reel/Frame not available in this session

  • Conveyance: Security Interest (recorded as "SECURITY INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: IP Dynamics Inc
  • Assignee: David Sun and Diana Sun (individuals)
  • Correspondent: not available in this session — not exposed by Google Patents legal events.
  • Context: securitization / IP‑collateralized private financing by the original assignee.

• 2008-01-21 — Reel/Frame not available in this session

  • Conveyance: Assignment of assignors' interest
  • Assignor: IP Dynamics, Inc.
  • Assignee: Inpro Network Facility, LLC
  • Correspondent: not available in this session. (This is exactly the field that would answer whether the 2008, 2016 and 2020 recordings share a filing attorney — I could not retrieve it.)
  • Context: portfolio sale / fire‑sale — the small operating company divests the whole family; RPX's account characterizes this transfer as the family going to Intellectual Ventures ("IP Dynamics assigned the family to IV in 2008").

• 2016-01-14 — Reel/Frame not available in this session

  • Conveyance: Merger
  • Assignor: Inpro Network Facility, LLC
  • Assignee: F. Poszat Hu, L.L.C.
  • Correspondent: not available in this session.
  • Context: internal reorg — a holding‑entity merger, not an arm's‑length sale. F. Poszat Hu, L.L.C. is registered at 2711 CenterVille Road, Suite 400, Wilmington, DE 19808, the standard registered‑agent suite address (confirmed on the INPI, Luxembourg and OEPM registers for its EP properties).

• 2020-02-15 — Reel/Frame not available in this session

  • Conveyance: Assignment of assignors' interest
  • Assignor: F. Poszat Hu, L.L.C.
  • Assignee: Intellectual Ventures Assets 161 LLC
  • Correspondent: not available in this session.
  • Context: transfer into IV's divestiture vehicle — IV Assets 161 LLC is one of IV's numbered single‑purpose asset LLCs used for bulk dispositions.

• 2020-01-05 — Reel/Frame not available in this session

  • Conveyance: Assignment of assignors' interest
  • Assignor: Intellectual Ventures Assets 161 LLC
  • Assignee: Hanger Solutions, LLC
  • Correspondent: not available in this session.
  • Context: transfer‑to‑asserter — part of the late‑2019/early‑2020 IV divestiture to Georgia entities tied to IPinvestments Group LLC; RPX reports six entities received over 3,800 patents from IV in November and December 2019, with the vast majority assigned to Hanger Solutions.
  • Date inversion flagged: as listed on Google Patents, the Hanger assignment (2020‑01‑05) precedes the F. Poszat Hu → IV Assets 161 assignment (2020‑02‑15), which is logically impossible if both are execution dates. The most likely explanation is that one date is a recording date and the other an execution date, or that IV internally recorded a bulk transfer out of order. I am not asserting a corrected ordering.

• Family‑level, post‑chain (not confirmed for the '623 itself): RPX reports that Hanger Solutions assigned former IV patents to an Equitable IP Corporation entity (Dynadex Data LLC / Zodex Data Systems LLC) in March 2021, and separately passed patents to Kioba Processing, LLC and 21ST CENTURY GARAGE LLC. The record before me does not confirm the '623 was among those onward transfers.

Assignment‑related sibling facts (not assignments of the '623): US 10/147,442 was filed 2002‑05‑16 as a continuation‑in‑part/continuation claiming priority to this family and issued as US 6,772,227 — it appears in the Google Patents event list only as a "priority to" event, not as a title transfer.

Timeline diagram

timeline
    title Ownership of US 6430623
    1998 : Filed by Hasan Alkhatib
         : Assigned to IP Dynamics Inc
    2002 : Issued as US 6430623
    2003 : Security interest to David and Diana Sun
    2008 : Assigned to Inpro Network Facility LLC
    2016 : Merged into F Poszat Hu LLC
    2020 : Assigned to IV Assets 161 LLC
         : Assigned to Hanger Solutions LLC
    2021 : First suit filed against Extreme Networks
    2022 : Suits filed against Charter and Cequel

NPE / troll-pattern signals

1. Shell-entity transfer — PRESENT. Two clean links. (a) 2008-01-21: IP Dynamics, Inc., a small operating software company, assigns the family to Inpro Network Facility, LLC. (b) 2020-01-05: Intellectual Ventures Assets 161 LLC assigns to Hanger Solutions, LLC, a Georgia LLC. Hanger's own complaint in Hanger Solutions LLC v. Charter Communications, Inc., No. 6:22‑cv‑00070 (W.D. Tex.) states at ¶ 31: "Plaintiff does not sell, offer to sell, make, or use any products itself, so it does not have any obligation to mark any of its own products." Hanger's Rule 7.1 disclosure names Brainbox Innovations, LLC as its corporate parent, and RPX ties the entity to Atlanta monetization firm IPinvestments Group LLC. Non‑practicing status is admitted on the record, not inferred from the name.

2. Known asserter in the chain — PRESENT. Intellectual Ventures Assets 161 LLC appears as assignee in the 2020-02-15 entry (IV is on the public NPE list). Hanger Solutions, LLC is the current assignee and the asserting plaintiff in all five suits listed on Google Patents (D. Del. 1:21‑cv‑00040 and 1:21‑cv‑00774; W.D. Tex. 6:22‑cv‑00070 and 6:22‑cv‑00330; Ga. M.D. 4:22‑cv‑00152). RPX describes Hanger as one of the top recipients of IV's divestitures, which is a public NPE‑directory characterization, not a naming inference.

3. Repeat correspondent across the chain — UNCLEAR / NOT VERIFIABLE HERE. The correspondent‑of‑record field was not retrievable, so I cannot say whether one attorney filed the 2003, 2008, 2016 and 2020 recordings. Reporting as "present" on the basis of naming would be exactly the error the brief warns against. For completeness, the litigation counsel is highly recurrent across Hanger's cases — Stamatios Stamoulis / Richard C. Weinblatt (Stamoulis & Weinblatt) as Delaware counsel, and James F. McDonough, III, Jonathan R. Miller, Travis E. Lynch and Jonathan L. Hardt as pro hac vice counsel in the 2021 Delaware and 2022 Texas actions — but litigation counsel appearing repeatedly is normal in patent enforcement and is not the same signal as a repeat recording correspondent.

4. Cascading transfers — PRESENT (limited). Two consecutive LLC‑to‑LLC hops (F. Poszat Hu, L.L.C. → Intellectual Ventures Assets 161 LLC → Hanger Solutions, LLC) appear on the record within roughly six weeks of each other in early 2020, and both terminal entities are single‑purpose holding/monetization vehicles. The earlier hops are spaced widely (2008 → 2016), so the compression is confined to the 2020 IV divestiture, not the whole chain. The date inversion between the two 2020 entries is flagged above.

5. Pre-litigation transfer — NOT PRESENT. The transfer into Hanger Solutions is dated/recorded 2020‑01‑05 (with the underlying IV bulk deal reported as November–December 2019). The first infringement suit naming this patent is 2021‑01‑14 (Hanger Solutions, LLC v. Extreme Networks, Inc., D. Del. 1:21‑cv‑00040). That is roughly 12–13 months, outside the six‑month window. The acquisition was clearly made with assertion in mind, but the specific "docket‑driven transfer" timing signal does not fire.

6. Bankruptcy fire-sale — NOT PRESENT ON THIS RECORD. No Chapter 7/11 proceeding for IP Dynamics appears in the evidence I could reach. The 2008 divestiture is a distressed‑looking asset sale by a small company (and follows a 2003 security interest to individual lenders), but I will not characterize it as a bankruptcy sale without a docket.

7. Privateering — NOT PRESENT. Classic privateering requires an operating company funding assertion against its own competitors. IP Dynamics sold in 2008; the suits were filed 2021–2022 against Extreme Networks, Squarespace, Charter Communications and Cequel/Suddenlink — none of which is plausibly an IP Dynamics competitor, and IP Dynamics is not reported as a beneficiary. The assertion is IV/IPinvestments‑driven, not originator‑driven.

8. Defensive aggregator (anti‑NPE) — NOT PRESENT. The chain terminates at an asserting NPE, and RPX reports Hanger onward transfers to further asserting entities (Equitable IP's Dynadex Data LLC / Zodex Data Systems LLC in March 2021; Kioba Processing, LLC; 21ST CENTURY GARAGE LLC). The patent has been re‑monetized, not neutralized. Note the secondary caveat: the '623 is expired — Google Patents shows "Anticipated expiration 2018‑01‑29" and status "Expired – Lifetime," so the 2021–2022 campaigns ran on an expired patent and all five cases were resolved by voluntary dismissal, stay-and-dismiss, or are otherwise terminated.

Verdict

NPE — high confidence.

Two independent strong signals are documented rather than inferred. First, a shell‑entity transfer: the 2008‑01‑21 assignment to Inpro Network Facility, LLC and the 2020‑01‑05 assignment to Hanger Solutions, LLC move the patent from an operating software company to entities whose own court filings state they make and sell no products (Hanger's Rule 7.1 parent is Brainbox Innovations, LLC, and RPX links it to IPinvestments Group LLC). Second, a known asserter in the chain: Intellectual Ventures Assets 161 LLC is the assignee in the 2020‑02‑15 entry, and IV is a perennial fixture on public NPE directories. The weak signals are the compressed 2020 cascade and the Wilmington registered‑agent address (2711 CenterVille Road, Suite 400) used by F. Poszat Hu, L.L.C. The principal limitation on this analysis is that reel/frame numbers and correspondents of record could not be retrieved in this session — that gap does not change the verdict, but it does block signal 3 (repeat correspondent) from being scored either way.

Verification links: USPTO Assignment Center · USPTO Patent Assignment Search · Google Patents legal events for US 6,430,623

I'll research this systematically. Let me pull the patent's front-page citations and related records from multiple sources.

I have the authoritative front-page citation list. Let me verify details on the most technically relevant references.

Prior‑Art Analysis — U.S. Patent No. 6,430,623 B1 (“Domain name routing”)

Prepared: 2026‑04‑26 · Analyst note: all identifiers reproduced literally, as found.

0. Important caveats before the analysis

1. Source of the citation list. I could not pull the USPTO Patent Center / PTO‑892 image for application 09/492,565 in this session. The reference list below is taken from the patent’s own front‑page “References Cited” data as mirrored on Google Patents (patents.google.com/patent/US6430623B1/en), uspto.report/patent/grant/6430623, Unified Patents (portal.unifiedpatents.com/patents/patent/6430623), and Patexia (patexia.com/us/patent/06430623). These are USPTO‑derived mirrors and agree with each other (25 U.S. patent references; 4–5 non‑patent references).
2. “Cited” ≠ “applied.” Everything below is art the Examiner cited/considered. For US 6,430,623 I did not retrieve the examiner’s substantive § 102/§ 103 rejections, so I cannot say the Office ever relied on a given reference against these claims. The § 102 mapping below is my own element‑by‑element screening, not an Office position, and the patent issued over all of this art.
3. Confidence flags. Where I state a reference’s title/subject matter, it is marked [verified] if I confirmed it from a search hit in this session. Items marked [unverified] are references whose bibliographic data (number/date/inventor) I have from the front page but whose title/abstract I could not confirm — I will not invent one.

1. Identification of the patent (literal, per the record)

Because the effective filing date is 1998‑01‑29, a reference is only § 102 prior art if its publication/issue or (for § 102(e) art) its filing date predates that date (or the inventor’s actual date of invention).

2. Executive summary — the most relevant prior art

Ranked by closeness to the claims of the ’623 patent:

3. U.S. patent references (front‑page “References Cited”)

Format: Number — Inventor — Issue date · Filing date: (where known) · Description · § 102 candidate claims · Confidence.

Tier A — potentially material to §§ 102/103

1. US 5,751,961 — Smyk — 1998‑05‑12 · Filings: US 31 Jan 1996; priority via WO 9728553 (07‑08‑1997); EP 0878018 A1 (18‑11‑1998) [verified]
Description: Integrated Internet system using an Integrated Service Control Point (ISCP) that translates logical addresses of Internet documents (e.g., hyperlink/logical addresses) into physical addresses and returns the physical address to the requesting browser (uses Internet CPRs / MSAP / ISCP gateway; HTTP/TCP/IP interface). Assignee: Bell Communications Research.
§ 102 candidates: claims 17, 23, 25 (receive message containing a non‑IP identifier → look up/return an address corresponding to the identified entity) and 34 (data unit with destination address plus separate identifying information used to route). It is a plausible anticipation candidate only if one can read “logical address” as the recited “unique identifier” and the translation as occurring “below an application layer.” On the face of the reference the request/translation is an application‑layer (HTTP/browser) transaction, which is the principal gap to claims 1, 17, and 34 as issued.
Confidence: medium‑high on citation content; low on anticipation (likely § 103 only).

2. US 6,031,196 — Monier — 2000‑02‑29 · Filing date [not retrieved in this session; must be checked for § 102(e)]
Description: [unverified] — my recollection is that this reference concerns translating a static identifier into a dynamically assigned network address (i.e., resolving a stable, non‑address identifier to an address that is assigned on the fly). Please treat the description as provisional and verify against the printed patent.
§ 102 candidates: claims 1, 6, 7, 12, 17, 23, 26, 28, 34, 40 — potentially the closest cited art, because it can implicate “unique identifier other than an IP address,” “does not have a globally unique address,” and “using said unique identifier to access a local address.” Whether the identifier is used “below an application layer” and whether the second entity is “in a private network” with a first entity outside it are the decisive, likely‑missing limitations.
Confidence: low‑medium — verify the title and specification before relying on this row.

3. US 5,793,763 — Mayes et al. — 1998‑08‑11 · [not independently verified this session]
Description: [unverified] — commonly identified as a NAT security system (address translation gateway with translation table and access validation).
§ 102 candidates: claims 10, 16, 21, 24, 25, 37, 39, 42, 44, 45 (intermediate device that determines/adds a local address and forwards). Fails claim 1 because the identifier is an IP address, not a non‑IP unique identifier, and because inbound, externally‑initiated communication to a host lacking a global address is precisely what NAT is conceded (in the ’623 specification) not to do.
Confidence: medium that it is NAT‑related; low on any § 102 anticipation.

4. US 5,781,550 — Templin et al. — 1998‑07‑14 · [not independently verified this session]
Description: [unverified] — transparent/secure network gateway architecture with address translation (Digital Equipment lineage).
§ 102 candidates: claims 10, 16, 21 (transparent gateway that rewrites addressing). Same claim‑1 gap as item 3.
Confidence: low‑medium.

5. US 5,790,548 — Sistanizadeh et al. — 1998‑08‑04 · Title verified: “Universal access multimedia data network” (Sistanizadeh appears in the same title family; Bell Atlantic) [verified via citation hits]
Description: Broadband access architecture (ATM/DSL line‑card/portal) that multiplexes subscriber traffic and uses address/portal translation between a public backbone and subscriber networks.
§ 102 candidates: claim 24/31 (“destination address corresponds to each entity in a set of entities”) and claim 34/42 framing; not claim 1 (no non‑IP unique identifier used below the application layer).
Confidence: medium.

6. US 5,764,906 — Edelstein et al. — 1998‑06‑09 · Title verified: “Universal electronic resource denotation, request and delivery system”; filed 1995‑11‑07 (parent 08/554,775); WO 97/19564 [verified]
Description: Distributed registry (client, local server, central registry, value‑added, root servers) mapping short mnemonic Resource Aliases/Source Aliases to physical locations such as URLs, with personal aliasing, “see also,” mirroring and update features.
§ 102 candidates: at most claims 2, 3, 35, 36 (identifier includes a string/domain name) and the lookup concept of claim 23 — but it maps aliases to URLs at the application layer, not to non‑globally‑unique local addresses. Not anticipatory of claims 1, 17, 34.
Confidence: high on content; low on anticipation.

7. US 5,937,162 — Funk et al. — 1999‑08‑10 · Title verified: “Method and apparatus for high volume e‑mail delivery” (Enactis.com; filed 1996‑09‑24; CIP of 08/431,254) [verified]
Description: High‑volume e‑mail “newspaper” delivery system that hashes outbound messages onto parallel transmission queues based on destination MX hosts; appends a unique job number to each message.
§ 102 candidates: none of claims 1–47. It is a message‑batching/hashing teaching; it is in this list as a general “unique ID appended to a message” and will be asserted, if at all, only under § 103 for ancillary features (e.g., an appended identifier field).
Confidence: high.
Cross‑check note: this same reference appears as a secondary reference in the prosecution of a different application (Callon et al., app. 09/444,921, cited against Alkhatib’s US 6,119,171) — do not conflate that record with the ’623 record.

8. US 5,361,256 — Doeringer et al. — 1994‑11‑01 · Title verified: “Inter‑domain multicast routing” (IBM) [verified]
Description: Inter‑domain multicast routing for IBM’s Multiprotocol Transport Networking (MPTN); gateways join NetBIOS/SNA/TCP‑IP subnetworks into one logical network; IDRP‑based routing, multicast group addressing, single‑copy‑per‑subnetwork rules.
§ 102 candidates: none (no name‑based addressing, no private/global address split). Relevant only under § 103 as background for “an intermediate entity” that routes between networks (claims 1, 12, 42).
Confidence: high on content.

9. US 5,623,605 — Keshav et al. — 1997‑04‑22 · [restricted confidence]
Description: [unverified] — I associate this number with interprocess communication / inter‑network data transfer work of AT&T lineage; the data‑unit handling concepts could be cited against the “data unit” claims. Verify before use.
§ 102 candidates: possibly claims 34, 42 (receiving/sending a data unit); low likelihood of reading on the identifier‑based addressing steps.
Confidence: low.

Tier B — cited art with no identified claim‑1‑level disclosure

For the following, I have the front‑page bibliographic data but could not verify titles/abstracts in this session. I will not fabricate descriptions. Each is plausibly § 103‑only background in the internetworking/address‑translation/security space, and none is a credible § 102 candidate for independent claims 1, 17, 34, or 42 on the information available.

§ 102(e) reminder for items 21–24: several of these issued after 1998‑01‑29 but may have been filed before it. Under pre‑AIA 35 U.S.C. § 102(e), such a U.S. patent is prior art as of its filing date. Their filing dates are the controlling fact and must be verified in Patent Center before they can be charged against claims 1/17/34.

Tier C — the parent (listed, but legally not prior art)

25. US 6,119,171 — Alkhatib — 2000‑09‑12 · Ser. No. 09/015,840, filed 1998‑01‑29
Description: “Domain name routing,” the parent application of the ’623 patent, same inventor, same disclosure (DNR, domain names carried in IP/TCP options or as a trailer, DNR table of domain names → local addresses).
§ 102 candidates: superficially all of claims 1–47 (the disclosures are the same). However, it is disqualified: US 6,430,623 is a continuation of 09/015,840 under § 120, so US 6,119,171 shares the same effective filing date and the same inventive entity. It cannot be § 102 prior art against its own continuation. Its appearance on the front page is an artifact of the continuation relationship.
Confidence: high.

4. Non‑patent references (front page)

A. RFC 1631, “The IP Network Address Translator (NAT),” K. Egevang and P. Francis, May 1994.
The canonical NAT specification. It translates IP addresses/ports at a gateway, only for sessions initiated from inside the private network. § 102: none — claim 1 affirmatively requires a non‑IP unique identifier and externally initiated communication to a host without a globally unique address. § 103: principal backdrop for claims 10/16/21 and for the specification’s own admission of NAT’s shortcomings.

B. Computer Networks, Third Edition, Andrew S. Tanenbaum, 1996, pp. 643–670, 685–691.
Textbook treatment of TCP/IP, DNS and routing — a printed publication under § 102(a)/(b), but no single embodiment anticipatory. § 103 background; also confirms that domain‑name→address translation (DNS) was a notoriously well‑known application‑layer service, which is central to the “below an application layer” language that distinguishes the ’623 claims.

C. Inside AppleTalk, Second Edition, G. Sidhu, R. Andrews, A. Oppenheimer, 1990.
[verified] as a real 1990 Apple Computer book. AppleTalk’s Name Binding Protocol (NBP) maps human‑readable object names to network addresses below the application layer — conceptually aligned with claim elements “unique identifier … not an IP address” and “used below an application layer.” § 102 candidates to study: claims 1, 3, 8, 17, 27, 34, 41. The likely defeating distinctions are the private‑network/globally‑unique‑address framework and the “intermediate entity has a first global address” requirement, which are products of the IPv4 Internet, not AppleTalk. Worth a dedicated read.

D. Excerpts from the Help section of Microsoft Outlook pertaining to rules and forwarding email (Microsoft Corporation, no date).
Message‑forwarding/rules functionality. § 102: none. At most § 103 support for “forwarding a message toward an entity.”

5. Bottom line on § 102

• No cited reference, as described, discloses the full combination of independent claim 1 (synonymous language in independent claims 12, 17, 28, 34, 42): (i) communication initiated from outside a private network; (ii) using a unique identifier that is not an IP address; (iii) used below an application layer; (iv) to an entity in the private network without a globally unique address; (v) reaching it via an intermediate entity having a first global address.
• The three limitations that most of the cited art cannot supply are (ii) + (iii) — non‑IP identifier used below the application layer — and (iv) the private‑address/global‑address topology combined with (i) inbound initiation.
• The best § 102 candidates to run down are US 6,031,196 (Monier) and US 5,751,961 (Smyk), with US 5,793,763 / US 5,781,550 as translation‑step candidates for dependent claims 10/16/21/37/39/44/45 — but all are better characterized as § 103 art.
• US 6,119,171 should be removed from any prior‑art chart as a matter of law (continuation/§ 120, common inventorship).
• A meaningful number of the front‑page references (items 10–24) have filing dates I could not verify; for those issued in 1999–2000, § 102(e) eligibility turns on filing date and should be checked in USPTO Patent Center before any assertion.

Recommended next steps: (1) pull the actual PTO‑892 and all Office actions for 09/492,565 to see which references the Examiner substantively applied; (2) verify titles, filing dates and § 102(e) status for rows 10–24 and for US 6,031,196; (3) obtain the claim charts from the Hanger Solutions litigations (Del. 1:21‑cv‑00040 / 1:21‑cv‑00774; W.D. Tex. 6:22‑cv‑00070 / 6:22‑cv‑00330; M.D. Ga. 4:22‑cv‑00152) to see what the parties treat as the governing prior art.

I'll research the prior art landscape for this patent before building the obviousness analysis.

Let me get the front-page cited references and search for the key prior art in this field.

Let me find the actual cited prior art references on the front page of this patent.

Obviousness Analysis — U.S. Patent No. 6,430,623 under 35 U.S.C. § 103

Scope note / caveats up front. This build shares the search budget with the earlier summary and litigation sections, so I did not retrieve the complete front‑page PTO‑892 list ("References Cited") for the '623 from a primary source in this pass. The reference set below therefore mixes (i) references verified in the sources I did retrieve (URLs given), (ii) references that appear on the face of family members or in related proceedings, and (iii) references whose existence I can state but whose precise content I have not re‑verified this pass — those are labeled. I do not assert claim‑by‑claim anticipation content that I have not seen. For the claim‑element mapping I rely on the full text in the record plus the claim list at Patexia (https://patexia.com/us/patent/06430623), which confirms 47 claims and confirms that claim 42 is an apparatus claim ("An apparatus used to communicate data, comprising:"). Claims 41 and 43–47 remain unavailable in the supplied text and are not analyzed.

1. Governing framework

Pre‑AIA § 103 applies (filed 2000‑01‑27; priority to Ser. No. 09/015,840 filed 1998‑01‑29). The '623 is a continuation of that parent under § 120, so its effective U.S. filing date is 1998‑01‑29 (Google Patents) / 1998‑01‑28 (Unified Patents), and the § 102(b) critical date is therefore on the order of 1997‑01‑28/29. The Graham v. John Deere factors control: scope/content of the prior art, differences, PHOSITA level, and objective indicia. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) governs the combination inquiry ("a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions," id. at 417).

PHOSITA: a person with a B.S. in EE/CS (or equivalent) and roughly 2–3 years of experience designing or operating TCP/IP internetworks, familiar with RFC‑style protocol specifications, NAT, DNS, and firewall/proxy gateways. This is a lower skill level than a protocol designer — relevant because the claimed advance is an architectural arrangement of known pieces.

2. The limitations that must be met

Reduced to elements (cross‑referencing the earlier claim summary rather than restating it); this is the chart the grounds below are built against:

E1/E5/E7 are the classic NAT architecture. E2/E3/E6 are the "route on a name" twist. E4 is the express inverse of NAT's acknowledged limitation.

3. Prior‑art reference set

Explicit non‑reference. The parent US 6,119,171 (Alkhatib) is not available as prior art against the '623. It is the same inventive entity and the same disclosure; the '623 is its § 120 continuation. This matters because the earlier sections note that PTAB petitions apply "Alkhatib" at DNR numerals 138/156 as § 103 art — that is Alkhatib used against third‑party later patents, not against the '623. Anyone importing those petition charts into a § 103 attack on the '623 would commit a legal error. The "apparatus 138/156" language in those petitions is the Examiner's treatment of the Alkhatib family disclosure, which is exactly the subject matter the '623 claims.

4. Grounds

Ground 1 — Egevang (RFC 1631) in view of DNS (RFC 1034/1035; Huitema '512 and/or Kapoor '038)

Mapping. RFC 1631 alone supplies E1, E5 and E7 almost verbatim: private local addresses reused across networks, a gateway holding the scarce global address, a translation table, destination‑address rewriting, and mandatory checksum correction — which is precisely the patent's Fig. 11 steps 518/520. DNS supplies E2: the domain name is the one identifier that is globally unique for a host that has no globally unique IP address, and it is resolved via a table of resource records correlating a name to an address (the patent's own Table 1, col. 9). Combining them to carry the name in the packet and have the gateway look the name up in a local table yields E3, E4 and E6.

Motivation (why a PHOSITA would combine). It is supplied by the art itself, not by hindsight:

1. RFC 1631 and the '623 specification agree on the deficiency. The specification states in terms: "One problem with the NAT approach is that it only works for communication initiated by a host within the network… The NAT approach specifically will not work if the communication is initiated by a host outside of the private network and is directed to a host with a local address" (Background, § 2). A reference that frames its own limitation creates the design pressure; solving a problem the art articulates is not hindsight.
2. The only viable identifier is the name. If a host has no globally unique address, the IP layer has nothing to route on. The finite, identified, predictable option is the identifier the Internet already treats as globally unique — the domain name. KSR, 550 U.S. at 421 ("a finite number of identified, predictable solutions").
3. The mechanism is unchanged. The gateway performs the identical table‑lookup‑and‑rewrite it already performed for outbound NAT; only the key changes from a global‑address/port tuple to a name. This is the "predictable use of prior art elements according to their established functions." The specification's Fig. 11 confirms this: it is a NAT table lookup with a domain‑name key.

Where to carry the name (E3). The precise placement is a design choice among a finite number of known vessels — the IPv4 Options field 22, the TCP Options field 80, or a trailer in the payload — all of which the patent itself lists as alternatives, and all of which Stevens documents as existing, variable‑length fields designed to carry extra information (the "record route"/"suggested routing path" options already carry routing data). KSR at 417 ("if a technique has been used to improve one device… using the technique is obvious"). Placing a name in an IP option is exactly such a predictable variation.

Ground 2 — RFC 1928 (SOCKS) in view of RFC 1631 (NAT)

Mapping. SOCKS supplies the pieces NAT lacks: a client sends a destination domain name to a proxy/gateway that owns the globally reachable address, and the proxy connects onward to the internal host (E2, E3, E4, E5). SOCKS is implemented as a shim between the application and the socket/transport layer — i.e., below the application layer — which directly satisfies E3, and it is protocol‑agnostic across TCP and UDP. NAT supplies E1 and E7 (the non‑globally‑unique local address and the checksum‑correcting address rewrite). Claim 34's "data unit … destination address … [information] separate from said destination address" maps to a SOCKS request carrying the name alongside the proxy's address.

Motivation. SOCKS is host‑centric: it forwards to a resolved address, so a private, unaddressable host cannot be the target of an inbound SOCKS connect unless the proxy can map the name itself. NAT supplies exactly that mapping machinery and the private‑address regime. A PHOSITA seeking to let public clients reach hosts behind a NAT while preserving the clients' ability to use names — which is how users and applications already refer to resources, per the specification itself ("Users and software applications rarely refer to hosts… by their numerical IP address") — would combine the two with a reasonable expectation of success. Both references are § 102(b) printed publications well before the 1997 critical date.

Ground 3 — Wesinger firewall ('830/'788) and/or Nordman ('346) in view of DNS/'512

A transparent intercepting gateway that accepts externally initiated traffic on its own global address and forwards to protected hosts supplies E5 and the "transparency" motivation; the DNS/name lookup supplies E2/E6. Motivation: firewalls already needed to decide which internal host a request was for; using the name (rather than a scarce global address) is the predictable economy. The nearer‑art-possessing device (a firewall/VPN gateway that terminates external sessions) makes the combination particularly natural.

Ground 4 — Sun '777 ("Communicating between address spaces") in view of NAT/DNS

To the extent '777 describes an intermediary routing between address spaces on an identifier, it supplies E4/E5/E6 between distinct address domains; NAT/private addressing per RFC 1918 supplies E1. ⚠️ I have not re‑verified '777's disclosure this pass, so I treat this ground as plausible and supported by its citation on the face of the family, not as established. It should be confirmed from the '777 text before being relied on.

5. Dependent claims

Because every independent claim falls under Grounds 1–3, the dependents are highly vulnerable as routine combinations/design choices:

• Claims 2, 13, 18, 29, 35 ("unique identifier includes a domain name") — DNS, express.
• Claim 3 ("a string") — the name is an ASCII string (specification, col. 1).
• Claims 4, 19, 36 ("information representing said domain name") — compression/encoding is squarely conventional: RFC 1035 already compresses domain names in DNS messages; encryption for security and compression for efficiency are stated alternatives in the specification with obvious motivations.
• Claims 8, 9, 11, 15, 27, 33 (used at network/transport layer) — IP Options = network layer; SOCKS/TCP Options = transport layer.
• Claims 10, 16, 21, 23, 25, 31, 37, 39 (lookup table; add local address; send) — the NAT translation table and DNS resource records.
• Claims 24, 31 ("destination address corresponds to each entity in a set of entities") — this is NAT itself: one global gateway address shared by many private hosts.
• Claims 26, 32, 40 ("initial communication") — the inbound‑initiation scenario; supplied by static NAT entries and SOCKS.
• Claim 42 and 43–47 — unanalyzed (text unavailable).

6. Why no single reference anticipates

RFC 1631's inbound identifier is a global address/port pair (an IP‑based identifier), so it fails E2/E3. SOCKS forwards to a resolved address in v4 and, even in the domain‑name variants, does not itself disclose the NAT‑style private‑address regime of E1 or the E7 rewrite/checksum step. Neither reference alone meets all of E1–E7. The case is a § 103 case, not a § 102 case — which is the correct posture given the claim drafting ("information representing," "below an application layer").

7. Anticipated rebuttals and where they are weak

8. Bottom line

The '623 claims read as a NAT architecture keyed on a domain name instead of an address/port tuple. NAT (RFC 1631 — cited on the family's own face), private addressing (RFC 1918), name‑based identifiers and lookup tables (DNS, Huitema '512, Kapoor '038), name‑carrying proxy gateways (SOCKS/RFC 1928), and transparent intercepting gateways (Wesinger '830/'788, Nordman '346) collectively disclose or suggest every element E1–E7, and the motivation to combine is express in RFC 1631's and the specification's shared statement of NAT's inbound‑initiation failure. Under KSR, the arrangement is the predictable use of known elements for their established functions, with the placement of the name among a finite set of known packet fields (IP options, TCP options, trailer). The most defensible § 103 grounds are (1) Egevang + DNS, (2) SOCKS/RFC 1928 + Egevang, and (3) Wesinger/Nordman + DNS/'512, with (4) Sun '777 + Egevang as a supplementary ground contingent on verifying '777's disclosure.

Two flags for the reader. (a) Do not use the "Alkhatib" PTAB petition charts (DNR numerals 138/156) against the '623 itself — that is the same family and is not prior art here; those charts are valid only against later, third‑party patents. (b) The '623 patent expired 2018‑01‑29, so any current § 103 analysis is retrospective (validity for past damages / IPR‑style challenge purposes only), not an injunction posture.