The present invention relates to a method and a system of flow control in a communication network. The method comprises determining if at least one sender buffer has a sufficient number of credits. The sufficient number of credits informs the sender buffer if the receiver buffer has an available buffer space corresponding to at least one data packet. The method further comprises transmitting the at least one data packet to at least one receiver buffer, if the at least one sender buffer has the sufficient number of credits. If the sufficient number of credits in the at least one sender buffer are absent, a data packet is transmitting speculatively to the at least one receiver buffer. If a negative acknowledgement is received for the transmitted data packet, a copy of the data packet can be retransmitted to the receiver buffer.