What if a submarine cable failure occurs in Vietnam? The reality of communication delays and workarounds

Actual "submarine cable outages" occurring in Vietnam and their impact on business operations

When working in Japan, you rarely think about the "undersea cables" that are behind international communications. However, when you are posted to Vietnam, you hear stories of "undersea cables breaking." Undersea cables are the main arteries of international communications. If they are disrupted, it can have an impact on business operations.

There are various causes for this, including cable deterioration and contact with fishing boat anchors. Although the frequency of disconnections has decreased in recent years, they are not completely eliminated. In fact, when a failure occurs, overseas communications often become extremely slow, regardless of which ISP you use.

Teams meetings between Vietnam and Japan may suddenly be interrupted, or when trying to open cloud documents via VPN connection with the Japanese headquarters, they may not open.

Practical workarounds for undersea cable failures and cloud computing

The only realistic option to avoid these risks isGuaranteed bandwidth international lines" Because it provides a minimum guaranteed bandwidth, it is less susceptible to disruptions than regular internet lines. Of course, if the undersea cable itself is physically disconnected, the total bandwidth will decrease, but because priority is given to customers who have selected a bandwidth-guaranteed line, it is easier to maintain stability.

* Guaranteed bandwidth international lines
A dedicated international communication line that guarantees the contracted communication speed (bandwidth) at all times and maintains stable communication quality even during congestion. Unlike best-effort type (using public networks), it is expensive because it uses dedicated equipment, but it is used for business where stability and reliability are essential, such as video conferencing and cloud collaboration, and enables high-capacity, high-speed communication using undersea cables, etc.

This approach is also important when using cloud services such as AWS. As of November 2025, there is no AWS region in Vietnam, and it is common to use the Singapore region, but access delays are unavoidable in the event of an undersea cable failure. The impact can be minimized by combining dedicated lines and guaranteed bandwidth lines.

Meanwhile, it is said that an AWS Local Zone is expected to open in Hanoi in 2026. If this comes to fruition, it will be possible to use key components such as EC2 and EBS within Vietnam without having to extend communications to Singapore.

"Submarine cable risk" is not often discussed in Japan. If you are doing business in Vietnam, the first step to utilizing the cloud is to know your options for communication infrastructure and keep track of future AWS Local Zone trends.