Data Communications Networking Devices - 4th Ed.pdf

1.15 THE DATA LINK LAYER ______________________________________________________ 133Figure 1.75YMODEM-G protocol ®le transfer example1.74,it becomes obvious that the streaming nature of YMODEM-G andYMODEM-G BATCH increases transmission throughout,resulting in a decreasein the time required to transmit a ®le or group of ®les.ZMODEMThe development of the ZMODEM protocol was funded by Telenet which is nowoperated by Sprint as SprintNet. This packet switching vendor turned to MrChuck Forsberg,the author of the original YMODEM protocol,to develop a ®letransfer protocol that would provide a more suitable mechanism for transferringinformation via packet networks. The resulting ®le transfer protocol,which wascalled ZMODEM,corrected many of the previously described constraintsassociated with the use of the XMODEM and YMODEM protocols. Signi®cant