What each country and landing point keeps if PLDT Domestic Fiber Optic Network (DFON) goes down. A calculation from our cable and landing-point database, not a forecast.
Legazpi City, Philippines: no other cable lands within 50 km.
Ozamiz City, Philippines: no other cable lands within 50 km.
On an island this means losing the submarine link; on the mainland traffic can still go over land.
No alerts from our monitoring on this cable in the last 180 days. Events feed →
Counted: other international cables landing in the same country (domestic cables between points of one country are not a way out), other cables at landing points within 50 km, and whether the country has land links. Not counted: cable capacity, operator contracts and satellite. Use as a first look at dependence, not as a statement of what would happen.
Live Performance
99
measurements
5
probes
88
days monitored
217.3
ms avg RTT
0
anomalies
Monitored from 2026-07-17 through 2026-10-14 - live ICMP round-trip time measurements via our monitoring probes. All values below are recomputed daily from raw probe data. ✓ No anomalies detected in the monitored period.
Measurement sources
Probe
Location
Samples
Avg
Min-Max
Last seen
#6410 own probe
Sao Paulo BR
33
337.4 ms
319.2-409.2
2026-10-14
#6427 own probe
Sydney AU
33
250.9 ms
137.8-309.4
2026-10-14
#6568 own probe
Singapore SG
24
56.8 ms
51.4-73.7
2026-10-14
#6487
control probe
8
49.4 ms
44.9-61.8
2026-08-20
own probe
Almaty KZ
1
336.8 ms
336.8-336.8
2026-09-20
About the PLDT Domestic Fiber Optic Network (DFON) Cable System
PLDT Domestic Fiber Optic Network (DFON): a key submarine cable interconnecting the Philippines
The PLDT Domestic Fiber Optic Network (DFON) is a submarine cable system spanning approximately 11,100 kilometers, designed to interconnect multiple regions within the Philippines. Owned and operated by PLDT, one of the country's leading telecommunications providers, DFON links 13 landing points across the Philippine archipelago, facilitating domestic communication and data transfer. The cable has been listed as in service since 1997 according to GeoCables records.
What stands out about DFON is its extensive reach within the Philippines, connecting cities and towns across multiple islands. However, many technical details about the cable, such as its design capacity, fiber pair count, supplier, and specific technology, remain undisclosed in public sources. This lack of transparency makes it difficult to assess its full capabilities and role in the broader network infrastructure. Additionally, the recorded ready-for-service year of 1997 has not been universally corroborated by industry sources, leaving room for potential discrepancies in its operational timeline.
Quick facts
Length
11,100 km
Ready for Service
1997 (GeoCables database; industry sources may differ)
The PLDT DFON connects 13 landing points distributed across the Philippines, including major urban centers such as Cebu and Cagayan de Oro, as well as smaller cities like Masbate City and Pinamalayan. This extensive network spans multiple islands, reflecting the geographic challenges of interconnecting an archipelago nation. Each landing point serves as a critical node for regional connectivity, supporting both local and national telecommunications infrastructure.
Why it was built and what it carries
The DFON was constructed to enhance domestic connectivity within the Philippines, addressing the need for reliable and high-capacity communication links across the country's islands. It supports a range of services, including voice, data, and internet traffic, helping to bridge the digital divide between urban and rural areas. While exact details about its design capacity and technological specifications are not publicly disclosed, its role in PLDT's network suggests it is a core component for domestic data traffic.
History: what can be established
GeoCables records indicate the DFON became ready for service in 1997. However, it is worth noting that industry sources may not universally confirm this date, and discrepancies could arise due to differences in documentation or updates to the cable over time. Possible explanations for such conflicts include phased deployments, upgrades, or delays in public announcements. Despite this uncertainty, the cable has been consistently listed as operational and remains a key component of PLDT's domestic network.
Capacity and technology
Publicly available data does not disclose the design capacity, fiber pair count, supplier, or specific technology used in the DFON. Without operator documentation, attributing these details would be speculative. Given its age, it is likely that the cable has undergone upgrades to remain competitive with newer systems, but such developments are not confirmed in public sources.
Latency: the physics
The computed theoretical one-way light propagation latency for the DFON's 11,100 km length is approximately 54.4 milliseconds, with a round-trip time (RTT) floor of 108.8 milliseconds. This calculation assumes ideal conditions, such as light traveling at 200,000 to 204,000 km/s in fiber. Real-world latency is higher due to land tails, terminal equipment, and routing.
Live measurements taken from remote probes, which reflect the full internet path rather than the cable itself, show significant variation. For example:
Singapore to Cebu: Minimum 46.4 ms, average 48.9 ms (the minimum is an artifact below the physical floor and should not be interpreted as real cable latency).
Sydney to Cebu: Minimum 140.2 ms, average 140.8 ms.
Sao Paulo to Cebu: Minimum 338.1 ms, average 342.7 ms.
These values highlight the complexity of measuring cable latency, as intermediate network factors can distort results.
Redundancy: what happens if it breaks
In the event of a failure, redundancy for the DFON is supported by several other cables landing at overlapping points. For example:
Standard industry practices for submarine cable repair, such as deploying cable ships for fault localization and splicing, would apply to the DFON. However, repair times can vary depending on the nature of the fault and weather conditions.
Bottom line
The PLDT Domestic Fiber Optic Network spans 11,100 km and connects 13 landing points across the Philippines.
GeoCables lists its ready-for-service year as 1997, though industry sources may not universally confirm this.
Technical details such as design capacity, fiber pairs, supplier, and technology remain undisclosed.
Latency measurements based on live probes reflect the full internet path, not the cable itself, with some artifacts below the physical latency floor.
Redundancy is supported by several other cables landing at overlapping points, ensuring continued connectivity in case of failure.