Jan. 30: India’s digital pathway has shrunk by half because of a Mediterranean undersea cable snag, affecting Internet services and businesses with clients in the US and Europe.

“Nearly 50 per cent of India’s Internet bandwidth capacity has been hit,” said Rajesh Chharia, the president of the Internet Service Providers Association of India. “The worst hit will be IT companies, call centres and companies with clients in the US and Europe,” he said.

The damaged undersea cable — initial reports said it got cut — lies between Egypt and Greece. Egypt, among the worst-affected countries, said it was not known how the cable was cut.

Sources said a “degraded” service would be activated by late tonight but full restoration could take 10 to 15 days.

India was also affected because the damaged cable was a conduit for traffic to the US east coast and Europe. The Mediterranean cable is linked to another in the Atlantic to complete the traffic circuit.

The other parts of the US, including Silicon Valley in the west, and the world are serviced from India through other cables across the Pacific and Atlantic oceans.

When one cable becomes unavailable, the Internet traffic is routed to the others that get overloaded. “Overload causes performance degradation even when the new load is lower than the maximum capacity of a cable,” said Bijendra Jain, a professor of computer science at the Indian Institute of Technology, New Delhi.

Performance has deteriorated even when a channel with a capacity of 100 voice calls is used for 80 calls instead of the usual 60 calls. “The lower the fraction of the capacity of a cable used, the better the performance,” Jain said.

Chharia said the worst hit are likely to be organisations that generate heavy Internet traffic such as software firms and business process outsourcing companies.

Internet browsing may still be possible with the available capacity, he said. Till 9pm on Wednesday, most airlines and banks said their operations had not been affected.

The IT industry in Calcutta was among those hit. “All Internet service providers (ISP) are diverting traffic through other cables, leading to congestion that has slowed down work,” said Kalyan Kar, the managing director of Acclaris, a BPO firm.

“We have three ISPs. So, we have not been affected as badly as those who are dependent on one ISP. But our productivity has suffered because of the sluggish traffic,” Kar added.

Shankar Ghosh of Tech Mahindra also said work had been affected to a certain extent.

Some companies are worried about the fallout on customers. “Customer support service goes down and the customer who does not realise the problem will not come back. This is a major setback,” said S.P. Mukherjee, the managing director of BPO firm Data Bazaar.