East-West Submarine Cable System

Overview

The East-West Submarine Cable System (EWSCS) is a 950-kilometre regional fibre-optic submarine cable connecting Malaysia and Indonesia. Operational since 2004, it is owned and operated by Sacofa Sdn Bhd, a Malaysian telecommunications company based in Kuching, Sarawak. The cable provides connectivity between Mersing on the east coast of Peninsular Malaysia and Penarik on the eastern coast of Sumatra, Indonesia, with additional landing points in Kuching and Terempa. This system serves as a critical link in the regional telecommunications infrastructure, facilitating data transfer between these locations.

While EWSCS is relatively modest in terms of its length and the scope of its connections, its role in linking regional networks makes it an important component of Southeast Asia's communications landscape. The cable’s strategic placement helps bridge the digital divide between Malaysia and Indonesia, contributing to economic and social connectivity in the region. Despite its age and regional focus, EWSCS continues to provide valuable insights into the complexities of submarine cable performance and routing, as evidenced by our monitoring data.

Route and Landings

The EWSCS spans the South China Sea and the Karimata Strait, connecting key locations in Malaysia and Indonesia. Its landing points include Kuching, the capital of Sarawak in Malaysian Borneo; Mersing, a coastal town in Peninsular Malaysia’s Johor state; Penarik, a coastal village in Sumatra, Indonesia; and Terempa, part of the Anambas Islands in Indonesia’s Riau Archipelago. These landing points reflect the cable’s regional focus, linking smaller population centers rather than major international hubs like Singapore or Jakarta.

The route crosses geographically and economically significant waters. The South China Sea is one of the world’s busiest maritime corridors, while the Karimata Strait connects the Java Sea to the South China Sea, making it a vital passage for regional trade. By landing in Kuching and Mersing, the cable enhances connectivity within Malaysia, while its connections to Penarik and Terempa extend its reach into Indonesia, supporting local economies and communities in these areas.

Ownership and History

EWSCS is wholly owned and operated by Sacofa, a telecommunications infrastructure provider based in Kuching, Malaysia. The cable was commissioned in 2004, during a period of regional expansion in submarine cable networks aimed at improving connectivity within Southeast Asia. Unlike trans-oceanic systems designed for global data traffic, EWSCS was built to serve as a regional link, reflecting the growing demand for improved telecommunications infrastructure in Malaysia and Indonesia during the early 2000s.

Its launch came at a time when the telecommunications industry was recovering from the dot-com bubble, with a focus on building sustainable and reliable infrastructure. Over nearly two decades of operation, EWSCS has become an integral part of the regional cable mesh, coexisting with other systems like SEAX-1, B2JS, and MCS. These cables collectively provide redundancy and resilience for data traffic between Malaysia, Indonesia, and nearby regions, ensuring stable connectivity for businesses and communities.

What Our Measurements Show

Our live monitoring of EWSCS has provided valuable insights into its performance. Across 3,101 measured corridors, the best round-trip time (RTT) recorded is 1 millisecond, while the average RTT is 255 milliseconds. Notably, the minimum RTT of 15.76 ms between Mersing and Penarik is close to the theoretical physics floor for a cable of this length, indicating that the forward path likely utilizes the cable efficiently. However, the average RTT of 227 ms and a maximum of 560 ms suggest significant variability, likely due to asymmetric routing and congestion in the return path.

Measurements from distant locations, such as Jerusalem, show a stable RTT of 227 ms with minimal variance, likely due to the dominance of long-haul trans-Asia fibre routes that minimize queuing delays. In contrast, measurements from closer locations like Mersing reveal a 35× spread in RTT, highlighting the impact of last-mile infrastructure and congestion in regional networks. This variability underscores the challenges of maintaining consistent performance in regional submarine cable systems, where complex routing decisions and network congestion play a larger role than in trans-oceanic systems.

EWSCS serves as a case study in the interplay between physical infrastructure and network-layer behavior. Its measurements reveal not only the health of the cable itself but also the broader dynamics of regional telecommunications networks in Southeast Asia.