Cogent Communications Holdings, Inc.

Zayo operates one of the most comprehensive fiber backbones across North America, offering dense metro fiber, extensive intercity dark fiber routes, and scalable 10G to 400G+ wavelength transport optimized for enterprise data center interconnect and hyperscale workloads.

Lumen maintains an expansive North American ultra-low-loss fiber footprint and Tier-1 IP backbone, offering high-capacity point-to-point wavelength services up to 400G and customizable dark fiber for enterprise WAN, AI workloads, and mission-critical cloud interconnects.

Operating AS1299—one of the world's most connected Tier-1 global IP backbones—Arelion provides carrier-grade DWDM wavelength services, global IP transit, and high-performance inter-data center transport across major North American metropolitan and long-haul corridors.

Crown Castle provides dense metro dark fiber assets and managed optical wavelength connectivity across major top-tier US metropolitan markets, delivering dedicated Layer 1 capacity between carrier hotels, enterprise sites, and data centers.

Uniti provides extensive long-haul and regional dark fiber and high-capacity wavelength transport across the Central and Southeastern United States, specifically tailored for enterprise DCI, carrier wholesale, and AI network interconnects.

AT&T Business provides ubiquitous enterprise optical infrastructure across North America, featuring metro and long-haul wavelength services up to 400G and private optical line services connecting enterprise sites to key carrier-neutral data centers and cloud on-ramps.

Verizon offers high-availability optical wave services, dark fiber, and Tier-1 IP transit across a vast US footprint, engineered to support latency-sensitive enterprise WAN architectures and high-throughput data center replication workloads.

FiberLight designs and operates custom, high-strand-count metro and regional dark fiber and wavelength transport networks throughout Texas and the Southeast, offering low-latency, physically diverse paths between key data centers and enterprise campuses.

FirstLight provides dense optical infrastructure and carrier-grade transport across the Northeast and Mid-Atlantic regions, offering low-latency wavelength and dark fiber links connecting key regional enterprise locations and colocation facilities.

Operates one of the largest global Tier 1 IP backbones with dense enterprise fiber reach across all 50 U.S. states, providing dedicated internet access backed by 100% uptime SLAs and fully integrated enterprise WAN solutions.

Maintains an extensive Tier 1 network infrastructure across the United States, delivering high-performance Dedicated Internet Access, carrier Ethernet, and managed SD-WAN/private IP networking for multi-location enterprises.

Controls an expansive ultra-long-haul and metro fiber network spanning hundreds of thousands of route miles in the U.S., offering high-bandwidth DIA, MPLS/IP-VPN, and bandwidth-on-demand capabilities for enterprise WANs.

Features ubiquitous commercial last-mile reach across major U.S. metro markets through its business services unit, delivering scalable dedicated fiber internet up to 100 Gbps alongside managed SD-WAN and multi-site WAN services.

Provides dense national fiber infrastructure across 41 states with symmetrical dedicated fiber internet, Carrier Ethernet, and managed SD-WAN tailored for distributed enterprise commercial sites.

Operates an extensive North American independent fiber backbone with deep metro and long-haul reach, delivering high-capacity dedicated internet access, wavelengths, and Layer 2/3 private WAN interconnectivity.

Delivers symmetrical high-capacity dedicated internet access up to 400 Gbps, Metro Ethernet, and managed SD-WAN across extensive regional and national commercial footprints.

Operates a global Tier 1 IP backbone specializing in multinational and distributed U.S. enterprise WAN deployments, combining cloud-connected DIA, managed SD-WAN, and MPLS services.

Provides enterprise-grade fiber dedicated internet access, Carrier Ethernet 2.0 services, and managed network WAN solutions across substantial U.S. regional and suburban service territories.

Operates extensive long-haul and metro dark fiber across North America and Western Europe, offering high-count dark fiber pairs and 400G+ wavelength transport purpose-built for hyperscale and enterprise data center interconnect.

Controls one of North America's largest intercity fiber backbones with extensive transatlantic routes, providing next-generation ultra-low-loss dark fiber and 400G optical wavelengths connecting thousands of commercial and colocation data centers.

Provides dense pan-European long-haul networks and metro fiber rings connecting over 1,000 data centers, supporting both raw dark fiber IRUs and fully transparent high-speed optical wavelength services across Europe and transatlantic paths.

Operates a global Tier-1 optical backbone across North America and Europe, delivering point-to-point 400GE/DWDM wavelength connectivity and selective long-haul dark fiber routes optimized for low latency between carrier-neutral facilities.

Specializes heavily in Western European data center interconnect, engineering custom high-count dark fiber superhighways and long-haul wavelength infrastructure connecting major cloud clusters across cities like Frankfurt, London, Amsterdam, and Paris.

Maintains dedicated European and transatlantic digital infrastructure, supplying hyperscalers and wholesale carriers with extensive long-haul dark fiber routes, subsea cable connectivity, and 400G wavelength capacity.

Delivers comprehensive national long-haul and regional dark fiber and high-capacity wavelength transport across the United States, linking tier-1 and tier-2 data center clusters, subsea landing stations, and enterprise aggregation points.

Maintains an extensive footprint of metro and regional optical infrastructure across the United States, offering high-availability dark fiber leases and dedicated 100G/400G wavelengths to connect distributed multi-tenant data centers.

Maintains a massive global optical network supplying dedicated long-haul optical wavelength links up to 400G and selective dark fiber infrastructure for hyperscale interconnects, enterprise private backbones, and carrier handoffs.

Operates AS1299, consistently ranked among the world's top Tier-1 IP backbones with extensive reach across North America and Europe, delivering wholesale IP transit up to 400 Gbps and underlying optical wavelength transport.

Operates AS3356 (formerly Level 3), one of the most interconnected Tier-1 backbones in the world, offering high-speed IP transit with native 100G/400G ports and long-haul optical transport across North America, Europe, and Asia-Pacific.

Provides the Tier-1 Global IP Network (AS2914) under NTT DATA, distinguished by its transpacific backbone capacity, tight routing controls, and peering density connecting North America, Europe, and Asia.

Operates Tier-1 backbone AS6453, handling a significant share of global internet routes and subsea cable connectivity spanning major Asian hubs, Europe, and the Americas.

Operates global Tier-1 IP network AS3257, delivering wholesale IP transit and high-capacity optical wavelengths with deep metro and long-haul footprints across North America and Europe.

Combines a dense dark fiber and 400G optical transport network across North America and Western Europe with wholesale IP transit on Tier-1 backbone AS6461.

Operates the Seabone Tier-1 IP backbone (AS6762), providing high-capacity wholesale transit and optical subsea transport bridging Europe, the Mediterranean basin, the Americas, and Asia.

Wholesale infrastructure subsidiary of Telefónica operating Tier-1 backbone AS12956, underpinned by an extensive transoceanic subsea fiber mesh linking the Americas and Europe.

Operates AS6939, maintaining the world's most connected IPv6 backbone and one of the largest IPv4 peering meshes across exchange points globally, making it a standard choice for multihomed transit blends.