N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 7 - LAN, WAN, VPN, WLAN, MAN, FDDI and Optical MANS                                                      Slide 14 of 45 _________________                                                                                  __________

                                                Token Passing LANs

                                        Architecture

                                        Token Ring Frames

                                        Token Passing Protocol

                                        Baseband Transmission at either 4 M bps or 16 M bps

_________________                                                                                  __________

CSMA / CD methodology LANs involve a certain contention between workstations trying to transmit data at the same time. Token Passing LANs provide a different approach to access the channel. Access is determined by which station has the token. Only one station at a time can have the token. The one with the token is allowed to transmit on the channel. The token is passed from one idle station to another idle station until a station with data to transmit receives it. After the data is transmitted the station passes the token to the next station.

Architecture: Token Passing Rings and Token Passing Buses.

Token Frame: Token frames are different than the information and command frames.

Transmission Speed: IBM's has 4 M bps and 16 M bps LANs