At an application executing in conjunction with a vSwitch in a host system, using a processor assigned to the vSwitch in the host system, a flow of a number of packets is received from a VM. At the application, a set of CWND values is computed using a corresponding set of congestion control algorithms. At the application, a determination is made whether any of the CWND values in the set of CWND values match the number of packets in the flow within a tolerance value. In response to a CWND value in the set of CWND matching the number of packets in the flow within the tolerance value, a conclusion is drawn that a type of the congestion control algorithm which computed the matching CWND value is the type of a local congestion control algorithm implemented within the VM.