Staff Fiber Network Engineer

About the role

Anthropic is building Anternet — a private, global dark-fiber backbone connecting our data centers, cloud regions, and partners. We light our own glass: long-haul and metro DWDM over leased dark fiber and IRU pairs terminating on our own optical line systems and routers.

We're looking for a Staff Fiber Network Engineer to own the physical layer of this network end-to-end. You'll be the person who decides where the fiber goes and then makes sure it actually shows up, splices clean, and tests to spec. This is equal parts route engineering, vendor management, and field-delivery program management — the connective tissue between "we need N×Tbps between these two metros" and "the span is lit and carrying traffic."

This is a foundational role building Anternet's fiber program from the ground up. You'll define the inventory system, set acceptance standards, and establish the vendor bench yourself.

You'll work closely with our optical/transport engineers (who design the line systems on top of your fiber), our backbone routing team, and our data center and capacity planning teams.

Key responsibilities

• Route engineering and design — Plan terrestrial fiber routes between Anternet PoPs and data centers. Evaluate diversity (SRLG, conduit, ROW, landing-station separation), latency, and OSNR/loss budgets. Produce route KMZs, splice diagrams, and as-built documentation
• Fiber acquisition — Source and qualify dark fiber, IRU, and wavelength options from carriers and infrastructure providers. Run RFPs, compare bids on cost, route quality, diversity, and MTTR, and drive contracts to signature alongside legal and procurement
• Vendor and delivery management — Own the build from PO to acceptance: track splicing, lateral construction, building entries, meet-me-room cross-connects, and CLS access. Hold vendors to schedule and SLA; serve as the escalation point when a span is late or fails OTDR
• Acceptance and characterization — Define and enforce fiber acceptance criteria (OTDR bi-directional, IL/ORL, CD/PMD where relevant). Review test results, reject substandard spans, and sign off on handover to the optical team
• Capacity and lifecycle management — Maintain the source-of-truth fiber inventory (strands, conduits, splice points, leases, IRU terms and renewals). Forecast fiber needs against our PoP and capacity roadmap. Monitor degradation and quality over time
• Operations — Partner with NOC and field-ops on fiber cuts, locates, and repairs. Drive root-cause analysis with vendors and feed lessons back into route-diversity decisions

Minimum qualifications

• Experience in OSP/fiber planning or network delivery at a carrier, hyperscaler, dark-fiber provider, or large enterprise backbone
• Demonstrated experience taking long-haul or metro dark-fiber routes from design through acceptance — can read an OTDR trace and engage substantively with vendors on splice quality
• Solid working knowledge of the vendor landscape: who has conduit where, how IRU vs. lease vs. wavelength pricing behaves, and what's negotiable in an MSA
• Proficiency with GIS/KMZ tooling for route design and comfort maintaining structured inventory data
• Sufficient understanding of optical transport (DWDM, amplifier spacing, span loss, CD/PMD)