Fibralink

Fibralink is a 1,102 km intra-Caribbean submarine cable connecting Jamaica, Haiti, and the Dominican Republic, with five landings across the three countries. Ready for service in 2006, it is owned by Liberty Networks, the wholesale infrastructure arm of Liberty Latin America (which acquired the former Cable & Wireless Caribbean business in 2016). Fibralink exists to link three Caribbean markets that, despite being a few hundred kilometres apart in the Greater Antilles, historically had to route traffic to each other through the United States.

The cable has five landings on 1,102 km of fibre: Montego Bay, Ocho Rios, and Bull Bay on Jamaica (three stations to reach the different sides of the island without terrestrial backhaul), Kaliko on Haiti, and Puerto Plata on the Dominican Republic's north coast. The physical geography it serves is intimate — Montego Bay to Puerto Plata is roughly 700 km of open Caribbean — but the commercial geography it navigates is not.

43 ms between two islands 700 km apart — why so high

Our monitor samples Fibralink between Montego Bay (Jamaica) and Puerto Plata (Dominican Republic). Across thirty days the two directions produced remarkably consistent minimums:

Both directions are tight. The reverse direction is astonishingly tight — 14 measurements in a 2.5 ms window. Symmetry between the two minimums is excellent: 4 ms of gap, both hovering around 45 ms. For a two-hop regional cable, that consistency suggests the path is well-groomed at the IP layer — once the route is chosen, it is stable.

But the absolute number deserves scrutiny. The theoretical physics floor for a 1,102 km fibre path is 10.79 ms round-trip. Our measured minimum of 43 ms is 4.0× that floor. Converting back to fibre distance: 43 ms round-trip corresponds to roughly 4,300 km one-way of light traversal. Our two measured landings are 700 km apart. The measured path is using something like six times as much fibre as the direct cable between them provides.

The Miami hair-pin — a Caribbean routing story

This is not a broken cable. Fibralink is operating as designed. The extra fibre distance is happening at the IP layer, not the submarine layer. Specifically, traffic between Jamaica and the Dominican Republic is being routed through United States peering infrastructure — almost certainly the major peering hubs in Miami — even though a direct regional cable connects the two landing points.

The pattern has a name in Caribbean networking: the "Miami hair-pin." It arose historically because Caribbean internet service providers' cheapest commercial transit options were peering agreements with tier-1 carriers in the United States, not peering with each other. For most of the 2000s and 2010s, a packet from a Jamaican ISP to a Dominican one would leave Jamaica on a US-bound cable, reach a Miami exchange point, change carriers, and return to the Dominican Republic on a different US-bound cable. The direct regional cables that existed — Fibralink, ARCOS, others — were used mostly for in-country backhaul and for the paying wholesale customers of their owner-carriers; general internet traffic preferred the Miami route because that was where the peering was cheap.

The ~35 ms of extra RTT beyond the direct-cable physics floor is the cost of that hair-pin: roughly 2,000 km one-way of extra fibre, plus handoff latency at the US peering point. Thirteen traceroute hops for Montego Bay → Puerto Plata is consistent with multi-carrier transit rather than a single-cable regional path. A direct cable route would produce perhaps six hops, all within two or three autonomous systems.

Things have been shifting. Caribbean regional IXPs — most notably JAIX in Jamaica, DO-IX in the Dominican Republic, and CAR-IX as a regional initiative — have grown since the late 2010s. For domestic content and for some local peering, the hair-pin has weakened. But for internet traffic that traverses multiple ISPs, it remains the default path.

Five landings on 1,102 km

Three Jamaican landings on a 1,102 km cable is unusually dense for such a short system — about one landing per 200 km of Jamaican coastline. The reason is that Jamaica's terrestrial fibre network is not dense enough to make a single landing sufficient; the same cable body reaches Kingston, Ocho Rios, and Montego Bay directly, saving carriers from having to provision island-wide backhaul to reach the cable. Haiti and the Dominican Republic each get one landing — fewer because their national terrestrial networks can carry traffic from a single coastal station inland without the same backhaul bottleneck Jamaica faces.

Liberty Networks and the Caribbean wholesale market

Liberty Networks owns Fibralink as part of a regional cable portfolio that also includes the ARCOS cable (connecting the US through Central America, Caribbean, and northern South America) and the East–West cable around Jamaica. Liberty's commercial model is to provide wholesale capacity to Caribbean ISPs and enterprise customers that do not have the scale to run their own submarine infrastructure. The portfolio competes primarily with Columbus Communications' legacy cables (also now under Liberty ownership after the 2014 merger) and with the remnants of the Cable & Wireless regional network.

A 2006-build cable is no longer new. At 20 years, Fibralink's wet plant is approaching the later portion of its design life, though it has been through capacity upgrades on the dry-plant side. The cable's value today is not its raw capacity — which by 2020s standards is modest — but its landing footprint. Anyone providing regional service to the Greater Antilles benefits from the existence of a cable that lands at Montego Bay, Kingston (via Bull Bay), Ocho Rios, and Puerto Plata; replacing that footprint from scratch would require either a new build (hundreds of millions of dollars) or a patchwork of leases across multiple owners.

What our data proves

• Jamaica ↔ Dominican Republic via Fibralink runs at 43–48 ms. Both directions are stable and symmetric within a few milliseconds.
• 4× the physics floor on a 1,102 km cable. The measured path is roughly 4,300 km of fibre one-way — consistent with a Miami hair-pin rather than direct regional routing.
• The pattern is structural, not temporary. Thirteen traceroute hops and a 35 ms excess over the direct-cable floor reflect historical Caribbean peering economics, not a measurement artefact.

Try it yourself

Live measurements on the Fibralink cable page. Compare with AMX-1, which provides a direct coastal path through Caribbean landings and Puerto Rico, and with South American Crossing's continental loop. The three together show different Caribbean and Latin American routing philosophies: direct regional (Fibralink), coastal multi-country (AMX-1), and continental ring (SAC) — each making different tradeoffs between landing coverage and IP-layer path length.