N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 4 - ATM Technology                                                                                                                      Slide 20 of 46 _________________                                                                                  __________

                             How Information is Placed into Cells

_________________                                                                                  __________

The ATM cell header contains information for routing, identification, and error control. The header elements are:

Virtual Path Identifier (VPI) - VPI in conjunction with Virtual Channel Identifier establishes node (switch) to node communications channel

Virtual Channel Identifier (VPI) - VCI in conjunction with Virtual Path Identifier establishes node to node communications channel

Generic Flow Control (GFC) - Provides equal access to the shared public network

Call Loss Priority (CLP) - Prioritizes cells for periods of network congestion

Payload Type (PT) - Indicates whether user or service information is contained in the payload (information field) of the cell

Header Error Control (HEC) - Provides error checking of the header