Equity benchmarks started the trade on a firm note on Monday, with the Sensex jumping nearly 311 points in early deals, amid mixed trends from Asian markets. The 30-share BSE benchmark Sensex jumped 310.91 points to 54,637.30. The broader NSE Nifty gained 83.35 points to 16,349.50. From the Sensex firms, Maruti, M&M, Asian Paints, Titan and Kotak Mahindra Bank were the early gainers. In contrast, Tata Steel, ITC, Power Grid and Reliance Industries were among the laggards.