The country's largest stock bourse NSE on Friday said it stuck to the primary site for carrying out trading on Wednesday and did not switch to the disaster recovery site after a considered view while dealing with telecom connectivity issues which led to the nearly four-hour halt in trading earlier this week.
It can be noted that Sebi had asked the exchange, which also trades the highest derivative volumes in the world, as to why it did not switch to the Disaster Recovery (DR) site.
"Post shut down of trading on NSE, we considered all the available alternatives on hand including invocation of DR to decide on the course of action that would bring up the market at the earliest with least disruption to market participants and post evaluation, a decision was taken to bring up the systems at the primary site," a statement from NSE said.
NSE regularly tests its DR readiness in line with Sebi regulations wherein quarterly drills are conducted and live trading sessions from DR site are conducted twice a year, it added.
There are multiple telecom links with two service providers to ensure redundancy and a communication about instability of the links was received from both the service providers on Wednesday, as per the statement.
"While there was no impact on the trading system, the instability of telecom links mentioned above resulted in an impact to the online risk management system of NSE Clearing and other systems.
"Critical systems such as the risk management system are configured with redundancies such that there is no single point of failure," it explained.
The stock bourse said it was working on resolution of the problem continuously and announced re-opening of the markets to its members at 3:17 pm after the same was resolved.
Meanwhile, reacting to news reports of low spend on technology, the statement said the exchange has tripled its investments on technology in the last three-four years and infused over Rs 900 crore on the same during the time period.
The exchange said it has a strong technology governance process wherein the technology infrastructure is reviewed on a regular basis by panels like the Standing Committee on Technology which has technology experts and also multiple types of audits by various firms/ institutions with specialised expertise.
It has a strong technology workforce of approximately 1,500 people, which include employees and also vendor staff, the statement said.
The exchange said multiple transformational projects have been completed and are ongoing to ensure that its systems continue to be robust, resilient, secure and state of the art.
"NSE constantly endeavours to provide a glitch free environment.
"However, the complex technology architecture has significant external and vendor dependencies in terms of connectivity and hardware," the statement said, adding that in the last two years, there have been trading outages in many markets such as Australia, New Zealand, Japan, Germany and UK.
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