{"id":98449,"date":"2024-05-27T11:44:53","date_gmt":"2024-05-27T09:44:53","guid":{"rendered":"https:\/\/firstcolo.net\/glossary\/dark-fiber\/"},"modified":"2026-05-08T11:08:07","modified_gmt":"2026-05-08T09:08:07","slug":"dark-fiber","status":"publish","type":"glossary","link":"https:\/\/firstcolo.net\/en\/glossary\/dark-fiber\/","title":{"rendered":"Dark Fiber"},"content":{"rendered":"\t\t
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Dark Fiber<\/h1>\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\tDark fiber is an unlit fiber-optic line that, as passive infrastructure, provides an exclusive and physical metro\/long-haul connection between two locations. Since this line has not yet been \u201clit\u201d with optical signals by the provider\u2019s active network components, it remains \u201cdark\u201d and gives the tenant full control over the transmission technology and bandwidth. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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What is Dark Fiber? <\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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A dark-fiber connection<\/strong> consists of fiber-optic pairs that are already installed underground but remain unused until a company rents or leases them. Unlike standard internet connections, the provider only supplies the physical fiber without active hardware (such as routers or switches). <\/p>

The user is responsible for \u201clighting\u201d the endpoints using their own hardware. This is often done with DWDM technology (Dense Wavelength Division Multiplexing) to transmit multiple data streams simultaneously over different wavelengths on a single fiber. At the same time, the customer must consider route length and characteristics, including attenuation, optical power margins, and dispersion.This setup maximizes capacity and minimizes latency, since there are no intermediary provider nodes delaying signal processing. <\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Distinction: Dark Fiber vs. Lit Fiber<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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To fully answer the question \u201cWhat is Dark Fiber?\u201d, it is important to distinguish it from conventional \u201clit\u201d connections (Lit Fiber). For dark fibers not provided by firstcolo as the provider, no guarantees can be made regarding route separation from external dark fibers.Um die Frage \u201ewas ist Dark Fiber\u201c vollst\u00e4ndig zu beantworten, ist die Unterscheidung zu herk\u00f6mmlichen, \u201ebeleuchteten\u201c Leitungen (Lit Fiber) entscheidend. Bei Darkfibern, die nicht durch firstcolo als Provider bereitgestellt werden, k\u00f6nnen keine Garantien hinsichtlich der Kreuzungsfreiheit zu externen Darkfibern \u00fcbernommen werden. <\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t

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Feature<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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Dark Fiber<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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Lit Fiber (Managed Services)<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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Hardware control<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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User provides own optics & routers<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Provider supplies hardware<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Scalability<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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Virtually unlimited (hardware-dependent)<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Limited by service plan<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Maintenance<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\tUser maintains active equipment \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t
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Provider handles end-to-end maintenance<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Cost structure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t
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Fixed rental costs per route<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Costs usually depend on bandwidth<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Practical Example: Data Center Interconnect (DCI)<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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In practice, companies use dark fiber for Data Center Interconnect (DCI). For example, a financial institution may connect two sites in Frankfurt via a dark-fiber line to perform real-time data replication. Because the institution controls encryption and routing itself, it achieves a level of security and speed that would not be possible over public networks. <\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

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Sovereignty Through Hardware Independence<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
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A key advantage of dark fiber is independence from the provider\u2019s innovation cycle. Customers using standard connections must wait for their provider to upgrade to new standards (e.g., 400G or 800G). A dark-fiber user, however, can increase capacity at any time simply by replacing the SFP modules at the endpoints.This reduces long-term costs and provides strategic flexibility in network design. <\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t

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\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tGlossary<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Dark Fiber Dark fiber is an unlit fiber-optic line that, as passive infrastructure, provides an exclusive and physical metro\/long-haul connection between two locations. Since this line has not yet been \u201clit\u201d with optical signals by the provider\u2019s active network components, it remains \u201cdark\u201d and gives the tenant full control over the transmission technology and bandwidth. […]<\/p>\n","protected":false},"author":43,"featured_media":97249,"menu_order":0,"template":"","meta":{"content-type":"","footnotes":""},"glossary-categories":[],"glossary-tags":[],"class_list":["post-98449","glossary","type-glossary","status-publish","has-post-thumbnail","hentry"],"yoast_head":"\nWhat is Dark Fiber | firstcolo Glossary<\/title>\n<meta name=\"description\" content=\"Dark Fiber explained: Discover the benefits and responsibilities of using unlit fiber optic connections.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/firstcolo.net\/en\/glossary\/dark-fiber\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Dark Fiber\" \/>\n<meta property=\"og:description\" content=\"Dark Fiber explained: Discover the benefits and responsibilities of using unlit fiber optic 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