Cable Complications

Greenland receives international Internet connectivity via the Greenland Connect submarine cable, linking the country to Iceland and Canada through landing points in Nuuk and Qaqortaq. In December 2018, the submarine cable link between these two cities suffered damage, disrupting Internet connectivity for users in Greenland. TELE-POST, a subsidiary of national telecommunications company TELE Greenland, has been tracking cable repair efforts over the last several months — efforts that have been slowed due to weather and ice cover.

Some repairs took place in early May, stabilizing Internet connectivity for users in North Greenland. However, disruptions to Internet connectivity in Greenland were also observed during this time frame, as seen in the figures below. While it has not been definitively confirmed that these disruptions were, in fact, due to cable repair efforts, TELE-POST has noted on the status site that connectivity for some customers may be turned on/off while repair efforts are underway.

A similar disruption was also observed on May 22, as shown in the figures below. That day, TELE-POST noted that it would be postponing repair work until August due to ice conditions. It is likely that similar disruptions will continue to occur over the coming months, as the update states: “However, in the coming period, until the important repair work next to Qaqortoq has been completed, there will be an increased risk of operational disturbances, particularly of the Internet service.”

On May 4, Globe Telecom subscribers in several regions of the Philippines experienced Internet service disruptions due to damaged fiber optic cables. A submarine cable was damaged by a 5.5-magnitude earthquake, while another cable was damaged by a vehicle dragging the cable at a road crossing. The figure below shows the impact of the cable damage to connectivity for AS4775 (Globe Telecom) – a minor change was seen in BGP, while successful active probing was impacted for just over three hours; measured darknet traffic dropped briefly at the start of the event, but appeared to recover quickly.

Apparently a popular day for Internet disruptions, Haiti also experienced an issue during the afternoon of May 4, as shown in the figure below. According to a number of Twitter responses from Digicel Haiti (@DigicelHT) to user complaints, the brief disruption was related to issues with a submarine cable.

The figure below shows that connectivity to Digicel Haiti through Digicel Jamaica was disrupted. The Fibralink submarine cable connects the two countries, so it may have been the cable referenced (but not named) in the @DigicelHT Tweets.

Just over two weeks later on May 19, AS15964 (Cameroon Telecommunications Network) experienced a connectivity disruption. As shown in the figure below, the number of traceroutes to endpoints in the network going through Tata dropped significantly for several hours, with Telxius and Orange picking up the slack.

This disruption impacted downstream networks in different ways. The figures below illustrate the impact of the disruption to two of those networks – AS30992 (MTN Cameroon) and AS37620 (VIETTEL CAMEROUN SARL). The number of successful traceroutes to endpoints in MTN declined by approximately half during the disruption period, while the number of traceroutes to endpoints in VIETTEL going through Cameroon Telecommunications Network unexpectedly increased during that period, although that shift also brought a significant increase in latency.

In a Tweet from @MTNCameroon that was subsequently deleted, the company acknowledged the apparent connectivity issues. The deleted Tweet was in response to a user complaint that included what appeared to be a screenshot of a text message that reads (via Google Translate) “Dear customer, following an incident on the optical fiber provided to us, our network is momentarily disrupted. MTN sexcuse for possible inconvenience.” This same (original) text was also Tweeted by several other users (1, 2) that same day. However, it is also worth noting that the text appears in Tweets from February 2019 and October/September/June/April 2018, so it may just be a stock customer support response from MTN Cameroon, rather than a definitive root cause.

On May 21 & 22, Malawi held elections to name a President, new members of Parliament, and local councilors. After the polls closed, Internet connectivity was disrupted across multiple providers in the country, reportedly due to damage to a cable owned by Malawi Telecommunications Limited. The figure below shows the impact to Internet connectivity for AS36969 (Malawi Telecommunications Limited) – successful active probing trended lower for several hours, and darknet activity was reduced as well.

The disruption also impacted local media outlets, as seen in the Facebook post below from Mibawa TV.

Satellite Suspicions

During May 2019, several Internet disruptions were observed that appear to be related to a reliance on satellite connectivity by major telecommunications providers in the impacted countries. In each case, the observed country-level disruption is coincident with a drop in the number of completed traceroutes reaching endpoints on the providers’ networks through satellite connectivity providers. In the figures below, the disruptions in South Sudan, Solomon Islands, Kiribati, and Cook Islands appear to be related to issues with O3b, while in Eritrea, connectivity through Asia Broadcast Satellite was problematic.

Wayward Weather

Damage caused by severe weather events frequently wreaks havoc on electrical and communications infrastructure. In early May, a storm in the U.S. Virgin Islands impacted Internet connectivity for users across multiple networks within the territory. Reduced levels of successful traceroute completions and active probing can be seen late in the day (UTC) on May 1 in the figures below.

These disruptions were also visible in network-level graphs for local network providers, as seen in the figures below. A Facebook thread highlighted issues with Broadband VI, and a Facebook Messenger response from a representative of Virgin Islands Next Generation Network noted “Our IT Team has indicated that there was a storm affecting the island of St. Croix on Wednesday, May 1. We were able to confirm with Broadband VI that they experienced a lightning strike. This appears to correspond with what you observed.”

The highly localized impact of extreme weather was highlighted by CAIDA’s IODA team towards the end of the month. In the Tweet embedded below, the team shared graphs of disruptions in active probing to endpoints in two Ohio counties on May 28, with the disruption timeframes correlating with reports of a tornado in those areas.

Other Outages

In addition to the disruptions discussed above that had frequently seen (probable) underlying causes, several additional disruptions were observed in May that were significant enough to mention here as well.

On May 5, the @BGPStream Twitter feed posted 70 “outage” alerts for autonomous systems (ASNs) associated with the United States Department of Defense, all at 01:51 UTC. BGPStream maintainer Andre Toonk explained what happened in the Tweet embedded below, highlighting the risk of single-homing multiple networks behind a single provider.

Just over a week later, on May 13 a significant Internet disruption was observed in China, apparently due to an issue at China Telecom. This event was explored in more detail in a previous post: “Multi-Hour Disruption at China Telecom”.

On May 22, published reports (The Straits Times, The Independent) indicated that thousands of fiber broadband subscribers of Singapore provider M1 (MobileOne) experienced a multi-hour Internet disruption, but M1 did not say what caused the disruption. Interestingly, it occurred a day after hundreds of customers of three local providers – Singtel, StarHub and M1 – had Internet connectivity disrupted by a fiber cut at Netlink Trust, which owns Singapore’s fiber network and resells fiber connectivity to these telecommunications providers.

Conclusion

Physical damage to terrestrial and submarine cables has long been a cause of Internet disruptions, as has problems with satellite communications for those regions underserved with wired connectivity. The continued growth in both submarine cable buildout and satellite Internet services should help provide redundancy and resiliency, reducing the frequency and severity of large-scale Internet disruptions. However, these additional avenues of connectivity will not change the likelihood that government-directed Internet disruptions will continue to occur (probably becoming more targeted and frequent), nor will they mitigate transient disruptions impacting local areas or individual network providers.