which to begin parsing and the number of bytes remaining in the wan link frame from the point at which parsing is to begin to the end of the wan link frame in turn as is indicated at 314 each of the protocol specific identification procedures 310 may call one another if necessary using appropriately modified arguments fig4 is a block diagram illustrating how the system 300 of fig3 may be implemented using a general purpose computer 410 general purpose computer may be any system capable of executing compiled code for example general purpose computer 410 may be a unix based system with high processing speed or a windows or dos based system with perhaps lower processing speed but greater physical portability in order to capture wan link frames from the wan link general purpose computer system 410 should be interfaced with the wan link using conventional wan link interface 412 running on general purpose computer system 412 should be software 414 for implementing decode engine 302 software 416 for implementing main auto identification and location procedure 304 and software 418 for implementing protocol specific identification procedures 310 fig5 is a pseudo code listing illustrating a preferred method for implementing the main auto identification and location procedure of fig3 preferably the code is written in the form of two nested loops the.