There are two IIPMs in Kolkata. You are refering to which one! Both are the best and reputed institutes. Ranking is not known but these are the best in there respective areas and one of the kind in India.
Indian Institute of Personnel Management (IIPM) was the first voluntary organisation focussed on the field of human resources in India, formed by a voluntary association of professionals in the year 1948. In 1980, IIPM merged with the National Institute of Labour Management and gave rise to the National Institute of Personnel Management, the "only all - India body of professional managers engaged in the profession of personnel management, industrial relations, labour welfare, training and HRD in the country."
Indian Institute of Ports Management, IIPM, is an educational institution set up as a registered society under the Societies Registration Act, XXI of 1860 by the Major Ports of India, a government of India body. IIPM was initially set up with an objective to undertake training programmes, consulting and additional research services for the ports and shipping industry. On 14 November 2008, under a government covenant that came into action on the passing of The Indian Maritime University Act, IIPM was formally merged with seven other Indian maritime academic institutions—National Maritime Academy-Chennai, T S Chanakya-Mumbai, Lal Bahadur Shastri College of Advanced Maritime Studies & Research-Mumbai, Marine Engineering Research Institute-Mumbai, Marine Engineering Research Institute-Kolkata, Indian Institute of Port Management-Kolkata and National Ship Design & Research Centre-Visakhapatnam — to form India's single largest ports and shipping institution, namely, the Indian Maritime University (IMU).  Currently, IIPM continues to operate as a division of the IMU, which—while allowing IIPM to retain its original name—refers to IIPM as IMU's Kolkata campus.