JAKO: A Submarine Cable Linking South Korea and Japan
The JAKO submarine cable is a 260-kilometer fiber-optic system connecting
Busan, South Korea, to
Fukuoka, Japan. Owned by Amazon Web Services, Arteria, Dreamline, and Microsoft, it is listed as in service and forms part of the dense network of cables in the East Asia region. While its design capacity, fiber pair count, supplier, and technology specifics are not publicly disclosed, the cable serves as a critical link between two major hubs in the region.
What makes JAKO notable is its relatively short length, which theoretically allows for low latency communication between South Korea and Japan. However, live latency measurements over the full internet path show significantly higher values, raising questions about routing inefficiencies or other factors. Additionally, the cable operates in a corridor with existing alternatives, including the
I-AM Cable and the
Korea-Japan Cable Network (KJCN), which also land at both Busan and Fukuoka.
Quick facts
| Cable name | JAKO |
| Length | 260 km |
| Ready-for-service year | 2027 (GeoCables database value) |
| Owners | Amazon Web Services, Arteria, Dreamline, Microsoft |
| Status | In service |
| Design capacity | Not disclosed |
| Fiber pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing points | Busan (South Korea), Fukuoka (Japan) |
| Alternatives in the same corridor | I-AM Cable, Korea-Japan Cable Network (KJCN) |
| Latency floor (theoretical) | One-way: 1.3 ms; Round-trip: 2.5 ms |
Route
The JAKO cable connects Busan, a major port city and telecommunications hub in South Korea, to Fukuoka, a key city in Japan's Kyushu region. Both landing points are strategically significant, serving as gateways for international connectivity in East Asia. Busan hosts numerous other cables, including
APCN-2,
Asia Pacific Gateway (APG), and the
New Cross Pacific (NCP) Cable System, making it one of the most heavily interconnected cable landing stations in the region. Fukuoka, while hosting fewer cables, is still a critical node, with connections like the I-AM Cable and Korea-Japan Cable Network (KJCN).
Why it was built and what it carries
The JAKO cable was likely built to enhance connectivity between South Korea and Japan, two of the world's most technologically advanced nations with significant demand for low-latency, high-capacity data transmission. Owned by major tech companies like Amazon Web Services and Microsoft, the cable may support cloud services, enterprise data traffic, and other high-bandwidth applications. However, specifics about its intended capacity and technology remain undisclosed in public sources.
History: what can be established
GeoCables records the ready-for-service year of JAKO as 2027. As of now, it is listed as in service, suggesting that construction and commissioning have been completed. If industry sources suggest a different RFS year, this discrepancy could arise from delays in documentation, phased activation of segments, or differing definitions of "ready-for-service" (e.g., partial vs full operational status). No additional historical details about the cable's development or launch are publicly available.
Capacity and technology
Publicly available data does not disclose JAKO's design capacity, fiber pair count, supplier, or specific technology. Without operator documentation, attributing these characteristics would be speculative. Submarine cables in this region typically employ dense wavelength division multiplexing (DWDM) technology for high-capacity data transmission, but whether JAKO follows this standard cannot be confirmed.
Latency: the physics
The theoretical one-way latency for light propagation over JAKO's 260 km wet segment is approximately 1.3 milliseconds, with a round-trip time (RTT) floor of 2.5 milliseconds. However, live measurements of end-to-end latency over the full internet path show significantly higher values:
- Busan -> Fukuoka: min 17.8 ms, avg 19.2 ms
- Fukuoka -> Busan: min 48.1 ms, avg 62.1 ms
These discrepancies can be attributed to additional factors such as land-based routing, terminal equipment delays, and network congestion. For example, the Fukuoka -> Busan measurements show unusually high latency, suggesting potential routing inefficiencies or other bottlenecks. Measurements involving longer routes, such as Singapore -> Fukuoka or Almaty -> Busan, further illustrate the complexity of real-world latency, which is influenced by multiple interconnected systems.
Redundancy: what happens if it breaks
In the event of a fault on JAKO, redundancy is provided by other cables in the same corridor that land at both Busan and Fukuoka. These include the I-AM Cable and Korea-Japan Cable Network (KJCN). Additionally, Busan's extensive cable infrastructure offers multiple alternative routes to maintain connectivity. Repairs to submarine cables typically involve specialized ships equipped with remotely operated vehicles (ROVs) for locating and fixing faults, a standard practice in the industry.
Bottom line
- JAKO is a 260 km submarine cable connecting Busan, South Korea, and Fukuoka, Japan.
- Owned by Amazon Web Services, Arteria, Dreamline, and Microsoft, it is listed as in service.
- Design capacity, fiber pairs, supplier, and technology specifics are not publicly disclosed.
- Theoretical latency is low, but real-world measurements show higher values due to routing and other factors.
- Redundancy is available via the I-AM Cable and Korea-Japan Cable Network (KJCN).
- GeoCables records the ready-for-service year as 2027, though industry sources may suggest otherwise.