a method and apparatus for dynamically adjusting the window size in a session between a sender and a receiver over a link of a packet transmission network . this invention discloses a dynamic window adjustment scheme to determine the optimum window size with a minimum number of iterations . this invention also covers a method and apparatus for sharing pacing credits among a number of sessions during which packets are transmitted over the network . with this invention sessions having no packets to transmit will send pacing credits to a shared credit pool while pacing credits will be distributed to those session having packets to transmit .