Batam Dumai Melaka (BDM)

BDM: A Short Cable in the World's Most Hazardous Strait for Cables

Batam Dumai Melaka, or BDM, is a short international submarine cable system connecting Indonesia's Batam and Dumai with Malaysia's Melaka through the Strait of Malacca. In terms of length, it is one of the shortest cables in our database: approximately 353 km according to our data and around 400 km according to industry publications, which account for both routes. The Batam-Melaka segment, which we monitor, measures only about 240 km.

However, the interest in BDM lies not in its length. It is laid through the strait considered the most hostile place on the planet for submarine cables: a narrow channel, depths of no more than 60 meters, strong tidal currents, and one of the densest shipping lanes in the world. Here, the cable exists not in the calm depths of the ocean but beneath the hulls of thousands of ships, each carrying an anchor.

The second notable aspect of BDM is revealed through our own measurements. The latency in one direction is 9.3 ms, while in the reverse direction along the same route, it is 93.4 ms. A tenfold difference on a cable only 240 km long.

Key Facts

Show Batam Dumai Melaka (BDM) on the interactive cable map

Two Discrepancies Worth Noting

For this system, our data differs from industry sources in two areas, and it is worth acknowledging these discrepancies rather than glossing over them.

Commissioning date. Our database lists 2009 as the commissioning year, while industry publications cite December 2011 as the date the system became operational. A two-year gap is too significant to overlook. Plausible explanations include the possibility that 2009 refers to the start of construction, the signing of the contract, or the commissioning of the first segment, while 2011 refers to the commercial readiness of the entire system. Without the consortium's acceptance documentation, it is prudent to list both dates.

Ownership composition. Our records list Moratelindo and Telekom Malaysia as owners, while project descriptions in industry sources identify the consortium as comprising three participants: Telekom Malaysia, XL Axiata, and Moratelindo. The absence of the third participant in our database is most likely due to incomplete information on our part rather than a change in ownership.

Route and Challenges

BDM crosses the Strait of Malacca, a narrow waterway between Sumatra and the Malay Peninsula, which serves as a major conduit for maritime trade between the Indian and Pacific Oceans.

Several adverse conditions converge in this region, making it particularly challenging for submarine cables:

• Shallow waters-no more than 60 meters deep along the route, making it vulnerable to large ship anchors that can reach the seabed at such depths;
• Extremely dense maritime traffic, including anchorage areas and emergency moorings;
• Strong tidal currents that shift seabed sediments and expose previously buried sections of cable;
• A high density of existing submarine cables, which the new system must cross.

The engineering response to these conditions is evident in the system's specifications: the cable is buried three meters deep into the seabed. This depth is significantly greater than the typical burial depth in calmer areas and directly addresses the risk posed by anchors. The project was executed by Huawei Marine Networks as a turnkey solution.

While burial reduces risk, it does not eliminate it. A heavy anchor dragged along the seabed can still reach the cable even at this depth, and currents may eventually erode the protective sediment layer.

Purpose of the Cable

Batam is an Indonesian island located just a few dozen kilometers from Singapore, serving as an industrial and offshore zone closely tied to Singapore's economy. Dumai, situated on Sumatra's eastern coast, is a port and oil refining hub.

For Indonesian operators, direct access to the Malaysian network offers an alternative to the traditional route through Singapore. For Telekom Malaysia, the system provides connectivity to the rapidly growing Indonesian market without routing through third countries.

The system's capacity of 2.56 Tbps may seem modest by modern standards, but it reflects the technology of its time: a configuration of 64 channels at 10 Gbps each across four fiber pairs was typical for the early 2010s. As with most submarine systems, the actual activated capacity and potential for terminal equipment upgrades are not publicly disclosed.

Physics: What to Expect from a 240 km Segment

The distance between Batam and Melaka along the great circle is approximately 240 km. Given the speed of light in optical fiber is about 204,000 km/s, the lower bound for latency on this segment is as follows:

• approximately 1.2 ms one-way;
• approximately 2.4 ms round-trip.

This is the theoretical minimum for an ideal direct path. On such short distances, the contribution of equipment to overall latency becomes significant: terminal transponders, switching, terrestrial segments from the station to the operator's network, and packet processing by routers all add delays comparable to the time taken for light to travel through the fiber.

What Measurements Show

Over the past 30 days, the following data has been collected for two directions along the same corridor:

The minimum of 9.3 ms in the Batam-Melaka direction is roughly four times the physical limit of the segment. For a short line, this is a normal result: at a distance of 240 km, fixed equipment delays contribute a larger relative share than on transoceanic routes.

However, the minimum of 93.4 ms in the reverse direction cannot be explained by the cable's properties. The same pair of points, the same submarine crossing-yet a tenfold difference in the best result. This suggests that the return path is physically different and does not mirror the forward path.

Why Forward and Return Paths Differ

In the internet, routes are not required to be symmetrical. Forward and return paths between two points are chosen independently, each determined by its own network and routing policies. A packet may take a short regional route to its destination but return via a distant transit node-due to different agreements, transit costs, or routing priorities on the other end.

The 84 ms difference between the best results for the two directions corresponds to several thousand kilometers of additional distance on the return path. The most likely scenarios involve a return route through Singapore, Kuala Lumpur, or a more distant hub instead of a direct crossing of the strait.

The practical takeaway for readers is this: if a service is fast in one direction and slow in the other, the cause may lie not in congestion or the cable itself but in route asymmetry, which can only be observed through measurements from both ends.

What Traceroutes Reveal

Traceroutes for the Melaka-bound direction, captured during our tests, show a path passing through Singaporean networks, then Malaysian nodes near Cyberjaya and Kampung Baru Subang, and ending near Port Dickson with a latency of approximately 9.4 ms.

This leads to an important caveat. The measured path traverses Singaporean and mainland Malaysian terrestrial networks, so it cannot be definitively stated that our packets traverse the BDM system. The 9.3 ms latency is physically plausible for the region, but its attribution to this specific submarine system is unproven. Strict attribution requires identification of operator interfaces and routing data at the autonomous system level.

This is a general characteristic of measurements in dense regions: the shorter the cable and the more alternative routes around it, the harder it is to attribute observed latency to a specific system.

Risks and Resilience

The primary threat to BDM is evident from its geography-anchors and fishing activities. Industry statistics show that most submarine cable damage occurs in shallow waters, and the Strait of Malacca combines shallow depths with record-high vessel traffic.

The second factor is the density of cable infrastructure. The system crosses several existing lines. Repair work on one cable increases the risk of damaging neighboring cables, and an incident in such a narrow corridor could affect multiple systems simultaneously.

The third factor is seabed mobility. Strong tidal currents shift sediments, meaning that burial depth achieved during installation may decrease over time in certain areas.

As for redundancy, the situation is mixed. The region is rich in cables, and alternative routes between Indonesia and Malaysia do exist. However, as with any region, the presence of neighboring systems does not guarantee automatic redundancy: purchased capacity, configured routing, and independent terrestrial segments are all required. On the other hand, the BDM system's dual routes-to Batam and Dumai-provide some internal redundancy: damage to one branch does not necessarily disable the other.

Conclusion

• BDM is a short international system crossing the Strait of Malacca, linking Indonesia's Batam and Dumai with Malaysia's Melaka; its length is approximately 353 km according to our data and around 400 km according to industry publications.
• There is a discrepancy regarding the commissioning date: our data states 2009, while industry sources cite December 2011. This issue cannot be resolved without consortium documentation.
• The consortium composition in industry descriptions is broader than in our records: in addition to Telekom Malaysia and Moratelindo, XL Axiata is also a participant.
• The system comprises four fiber pairs, has a system capacity of 2.56 Tbps, was built by Huawei Marine Networks, and is buried three meters deep in waters up to 60 meters deep.
• The burial depth is a direct response to anchor threats: the strait combines shallow waters, strong currents, and one of the world's densest shipping lanes.
• Our measurements reveal a sharp asymmetry: 9.3 ms in the Batam-Melaka direction versus 93.4 ms in the reverse. This cannot be explained by the cable's properties and indicates different physical paths for the two directions.
• Traceroutes show that the measured path traverses Singaporean and Malaysian terrestrial networks, making it impossible to definitively attribute the observed latency to the BDM system without further routing verification.