Cross-Straits Cable Network (CSCN)

Cross-Straits Cable Network (CSCN): connecting China and Taiwan across a short distance

The Cross-Straits Cable Network (CSCN) is a submarine telecommunications cable linking mainland China and Taiwan. With a total length of just 21 kilometers, it is among the shortest international submarine cables in operation. This cable is jointly owned by China Mobile, China Telecom, China Unicom, and Chunghwa Telecom, reflecting collaboration between major telecom operators on both sides of the Taiwan Strait.

What makes CSCN interesting is its geopolitical context and technical simplicity. Despite the short distance covered, the cable represents a rare instance of cooperation across the politically sensitive Taiwan Strait. However, public information about its design capacity, fiber pairs, supplier, and technology is notably absent, leaving certain technical aspects of the cable undocumented in open sources.

Quick facts

Route

The CSCN connects four landing points: Dadeng Island and Guanyin Mountain in mainland China, and Guningtou and Lake Ci in Taiwan. These locations are situated near the narrow Taiwan Strait, which separates the two regions. The cable's short length reflects the proximity of the landing points, making it a relatively simple route compared to transoceanic systems.

Dadeng Island, located near Xiamen in Fujian Province, is strategically close to Taiwan, while Guanyin Mountain is another mainland landing site in the same region. On the Taiwan side, Guningtou and Lake Ci are situated in Kinmen County, an area historically significant due to its closeness to the mainland.

Why it was built and what it carries

The CSCN was built to facilitate telecommunications between mainland China and Taiwan, providing a direct and high-speed connection across the Taiwan Strait. This cable supports internet traffic, voice calls, and other data services between the two regions. Given the political sensitivity of cross-strait relations, the cable's construction represents a pragmatic approach to improving connectivity despite broader geopolitical tensions.

While the cable's exact design capacity is not publicly disclosed, its short length suggests it is primarily intended for regional traffic rather than serving as a major international hub. The involvement of major telecom operators from both sides indicates its importance for commercial and personal communication needs.

History: what can be established

The GeoCables database records the CSCN's ready-for-service year as 2012, and no conflicting industry sources are currently known to suggest a different date. This timeline aligns with broader trends in the early 2010s, when many regional submarine cables were being developed to meet growing demand for internet bandwidth.

Details about the cable's construction, including its supplier and specific project milestones, are not publicly available. This lack of documentation is not uncommon for shorter regional cables, which often receive less attention compared to larger transoceanic systems.

Capacity and technology

Publicly available data does not confirm the CSCN's design capacity, number of fiber pairs, supplier, or underlying technology. Without operator documentation, attributing specific values to these parameters would be speculative. Given the cable's short length, it likely uses a straightforward design optimized for regional traffic rather than cutting-edge technologies designed for long-haul systems.

Short cables like CSCN typically require fewer repeaters and simpler terminal equipment compared to longer systems. However, the exact configuration of this cable remains unknown.

Latency: the physics

Based on the cable's length of 21 kilometers, the theoretical one-way light propagation time is approximately 0.1 milliseconds, assuming light travels at 200,000 to 204,000 kilometers per second in optical fiber. This results in a theoretical round-trip time (RTT) floor of roughly 0.2 milliseconds for the wet segment alone.

Real-world latency is higher due to additional factors such as land tails, terminal equipment delays, and routing inefficiencies. As no live measurements are currently available for CSCN, the actual end-to-end latency cannot be precisely stated.

Redundancy: what happens if it breaks

If the CSCN were to experience a fault, redundancy would depend on alternative cables in the region or satellite communication links. Publicly available data does not specify other submarine cables directly connecting mainland China and Taiwan, but broader regional systems such as Asia-Pacific cables might provide indirect routes. Repairing a cable of this length would likely involve standard industry practices, including vessel deployment, fault localization, and cable splicing.

The short distance of the CSCN simplifies repair logistics compared to longer cables, as the affected segment would be relatively easy to access and restore.

Bottom line

• The CSCN spans 21 kilometers, connecting mainland China and Taiwan across the Taiwan Strait.
• Its ready-for-service year is recorded as 2012, with no known conflicting sources.
• Ownership is shared by China Mobile, China Telecom, China Unicom, and Chunghwa Telecom.
• Design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
• Theoretical latency for the wet segment is approximately 0.2 milliseconds RTT, but real-world latency is higher.
• Redundancy would rely on regional alternatives or satellite links, with repair logistics simplified by the cable's short length.