Method and apparatus for providing integral cell payload integrity verification in ATM Telecommunication devices

An ATM telecommunication device for use in an ATM packet switching network, the ATM telecommunications device comprising:

• (a) an ingress, an egress, and a data path extending between the ingress and the egress;
• (b) a payload integrity verification code calculator at a first location on the data path for generating a first payload integrity verification code from a payload of an ATM cell;
• (c) a payload integrity verification code writing circuit connected to write the first payload integrity verification code to the ATM cell at the first location;
• and,
• (d) a payload integrity verification circuit at a second location on the data path downstream from the first location.

A method for passing information from an upstream location in a cell stream in an ATM telecommunication device to a downstream location in the ATM telecommunication device, the method comprising:

• a) receiving at an ATM telecommunication device an ATM cell having VPI and VCI fields in an ATM cell header;
• b) at an upstream location within the ATM telecommunication device, adding a connection identifier to the ATM cell and recording information in at least a portion of the VPI and VCI fields of the ATM cell;
• c) passing the cell to a downstream location along a data path in the ATM telecommunication device;
• d) at the downstream location retrieving the recorded information;
• and,
• e) before the cell egresses from the ATM telecommunication device, if the information is recorded in any portion of the VPI field, writing a VPI value to the VPI field of the cell and, if the information is recorded in any portion of the VCI field, writing a VCI value to the VCI field of the cell and removing the connection identifier.