Sify Ltd., an Internet service provider (ISP) based in Chennai, has deployed Internet Protocol Version 6 (IPv6) on its network in perhaps the first move by an Indian ISP to adopt the next-generation Internet protocol.

Designed to eventually replace IPv4 (Internet Protocol Version 4), IPv6 has a 128-bit address space compared to the 32-bit addresses available in IPv4 networks. Hence IPv6 supports a far greater number of unique IP addresses for assigning to PCs, phones and other networked devices.

Sify supports IPv6 at the core of its network through an implementation of IPv6 over Multi Protocol Label Switching (MPLS ) and at the edge of the network through a dual stack supporting both IPv4 and IPv6, Rustom Irani, Sify’s chief technology officer, said Wednesday. It will be some time before the ISP moves entirely to IPv6 as most of the demand from customers is still for IPv4, he added.

Sify had about 725,000 subscribers as of September last year, giving it about 14 per cent of India’s total Internet subscriber base of 5.3 million, according to data from the Telecom Regulatory Authority of India (TRAI) in Delhi.

The availability of more IP addresses will benefit customers because they will be able to do away with workarounds such as Network Address Translators (NATs) for sharing IP addresses, according to Irani. Mandatory use of Internet Protocol Security (IPSec) on IPv6 will also ensure a higher degree of security for users, he said.

Sify expects initial demand to come from corporate customers who already support IPv6 on their networks or intend to move to IPv6, Irani said. Later, as IPv6 becomes more widespread and as applications are migrated to IPv6, the company will also focus on retail customers.

The Indian government announced last year that its aim is to have the country migrate to IPv6 by 2006, and other Indian ISPs are expected to announce plans in this direction soon.