The Sensex gained over 211 points in opening trade on the Bombay Stock Exchange today on fresh buying by funds. It was trading at 17,958, up by over 230 points a short while ago. Brokers said the investor sentiment was boosted by a firming trend in Asia following a higher close in the US market on the weekend.Japan's Nikkei index was up by 0.86 per cent and Hong Kong's Hang Seng Index by 0.73 per cent in early trade today. In the US, the Dow Jones Industrial Average ended 0.36 per cent higher in the previous session on Friday.