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The security of international submarine cable networks has been called into question once again after cable cuts in the Mediterranean Sea severely disrupted internet and phone services between Europe, the Middle East and South Asia.

In a dubious coincidence, four separate undersea cables - including the Flag Europe-Asia and the SeaMeWe-4 cables (owned by a consortium of 15 cable carriers) - were cut within the same week in late January and early February.

According to TeleGeography Research, the damage to FEA and SeaMeWe-4 were the most significant because the two cables, with 620 Gbps in capacity, are the prime direct links between Europe, the Middle East and South Asia. The outage on these two systems reduced the capacity between Europe and Middle East by 76%.

The outages were less severe than the devastating cable breakdowns caused by the Taiwan earthquake in December 2006, which snapped seven undersea cables serving Asia. However, the damage raises increased concerns about the threat of sabotage of submarine cable systems, which carry over 95% of the world's cross-border internet and telephone traffic.

It has not been made clear what caused some of the cable breaks and whether the separate events were related. There has been speculation that so many cable cuts over such a short period were too much of a coincidence and that sabotage must have been involved. This came as an AFP newswire report quoted an ITU official as saying that the damage could have been due to an act of sabotage.

'We do not want to pre-empt the results of ongoing investigations, but we do not rule out that a deliberate act of sabotage caused the damage to the undersea cables,' said Sami Al-Murshed, the UN agency's head of development. 'Some experts doubt the prevailing view that the cables were cut by accident, especially as the cables lie at great depths under the sea and are not passed over by ships.'

While Reliance Flag, formerly Flag Telecom, revealed that the cut to its Falcon Cable was caused by an abandoned ship anchor, mystery shrouds what caused the other three reported damage.Matt Walker, a senior analyst at Ovum RHK, pointed out that while cable owners have been working hard to minimize accidental damage with different methods, there is an unspoken assumption that the networks are safe from deliberate human sabotage. However, he added, the recent spate of cable failures has raised doubts on this assumption.

Walker said there is the possibility of human attack, whatever the motivation, given the location of the undersea cables and the fact that they are a target for those who want to wreak havoc on international communications.

This poses the need for cable owners to consider protection against sabotage in addition to having multiple independent operators of ring- or mesh-based networks that have built-in restoration capabilities and multiple redundant links between cable stations and city gateways.

'If ports, railways, gas pipelines and other types of networks are being secured against possible sabotage, we must similarly increase the security of undersea optical highways,' Walker said. 'Guaranteeing reliability is impossible, but an improvement on current hands-off approach is long overdue.'

Alan Mauldin, research director of TeleGeography Research, disagreed. He said cable operators are acutely aware of all of the potential risks to their systems, including the deliberate act of sabotage or terrorist attacks, but suggests such a threat is largely theoretical.

Natural causes

'If someone really wanted to intentionally damage a cable, I am sure they could,' Mauldin said. 'But focusing on issues like this shifts the focus off the real culprits of cable damage - fishermen, anchors and earthquakes.'

He said cables being damaged because of these three causes 'occur all the time' and are thus what worries cable operators the most.According to the Submarine Cable Improvement Group, about 70% of all cable faults are from fishing and anchoring while natural hazards such as chafing and earthquakes account for 12% of faults. Most faults occur in depths of less than 200 meters.

Mauldin also insists there is no need for government involvement or any new security issues emerging as a result of the recent disruptions.

Frank Cuccio, managing director of marine services at Tyco Telecommunications, agreed. He said that while it is almost impossible to eliminate the risk of damage to submarine cables caused by human and natural forces, cable owners and operators have been adopting multiple strategies to protect their systems and avoid service interruptions. Proper design and installation is the first-order mechanism to prevent damage to a cable network.

'The most important consideration in helping submarine cable owners to improve reliability and security of their undersea cable networks is the upfront design, engineering, manufacture and installation of the systems,' Cuccio said. 'Each cable system is 100% surveyed from beach landing to beach landing; this allows the route engineers and cable engineers to select the most cable-friendly route and select the proper cable armoring.'

In areas where fishing and anchoring threaten undersea cable networks, a sea plow is used during the installation to bury the cable under the seafloor. Sea plows are towed behind the cable ship during installation and new cables are typically buried at depths of 1.5-3 meters. As much as possible, cable routes deliberately avoid hazards such as earthquake-prone zones and rocky seabed.

In addition, all major networks are covered by maintenance programs that include one or more cable ships that are fully-equipped with spare cable, spare amplifiers and joint kits along with the equipment and trained personnel required to find and repair a faulty submarine cable.

Cuccio said these ships and cable depots are strategically located around the world. Typically, a repair ship will leave port within 24 hours when notified by the cable maintenance authority.

Another strategy is to use ring architecture and mesh network architecture, which allow a properly engineered network to suffer the inevitable fault on one part of the network without impacting client traffic. In such a network, terminal equipment located at the cable station automatically routes the traffic around the damaged segment.Added precautions

TeleGeography Research's Mauldin said many cable operators have also been trying to diversify the routes for transmissions, especially in the aftermath of the cable breakdowns caused by an earthquake in Taiwan in December 2006. Operators continue to build new cables along different routes to provide diversity in case of localized damages to several cables.

For instance, the new Trans-Pacific Express and Asia America Gateway cable will link the US to Asia through more southerly routes instead of via Japan as most other modern cables do.

In the next few years, four new cables will be laid between Europe and Egypt, including Telecom Egypt's TE North cable, Orascom's MENA cable, the IMEWE consortium cable and another from Reliance Flag. The new cables will be able to transmit up to 10.24 Tbps for TE North, 5.76 Tbps for MENA, 3.84 Tbps for IMEWE and 2.56 Tbps for FLAG.

'If FEA and SeaMeWe-4 were to be damaged in 2009, it would probably go largely unnoticed due to the other cables in place,' Mauldin said. 'These new cables were all planned before the recent outage, so it is not as though that really changed any plans that were already in place.'