3Com CoreBuilder 9000, User Manual

Page: 441 / 468

Operation and Maintenance (OAM) 441
The virtual channel connection (VCC) operation information is carried via
the F5 flow OAM cells. These cells have the same VPI/VCI values as the
user-data cells but are identified by preassigned code points of the PT
field. Two unique PT values are used for every VCC. PT 100 identifies the
connection between user and network on both sides of the UNI while PT
101 identifies the connection between user end stations.
End-to-end OAM cells are passed by all intermediate nodes. The nodes in
the path may monitor these cells. They can only be removed by the
endpoint of the VPC (F4 flow) or VCC (F5 flow). User to network OAM
cells (segment) are removed at the end of a segment.
The OAM cell handles the following functions:
Fault management
Performance management
Activation/deactivation
Figure 33
Common OAM Cell Format