
á
PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
263
7.3.2.4
OAM (Operation Administration and Maintenance)
cells, are special cells that are generated by the “Lay-
er Management” entity (within the BISDN Reference
Model), and are typically used to carry maintenance
related information such as:
Virtual Path Connection (VPC)/Virtual Circuit
Connection (VCC) failure reporting
VPC/VCC continuity check information
VPC/VCC continuity verification: OAM Cell
Loopback Testing
VPC/VCC Performance Monitoring
OAM Cell Processing
OAM cells are identified and distinguished from user
cells by their specific cell header byte patterns. ATM
layer entities can typically use one of four types of
OAM cells. These types of OAM cells are listed below.
F4—Segment
F4—End to End
F5—Segment
F5—End to End
F4 type OAM cells usually carry maintenance related
information regarding a specific Virtual Path Connection
(VPC). Whereas F5 type OAM cells usually carry main-
tenance related regarding a specific Virtual Circuit
Connection (VCC). The header byte patterns of each
of these types of OAM cells is tabulated below.
Rx CP User Filter Cell Mask Header—Byte 2 (Address = 5Dh)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx User Cell Mask Header—Byte 2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
Rx CP User Filter Cell Mask Header—Byte 3 (Address = 5Eh)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx User Cell Mask Header—Byte 3
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1
Rx CP User Filter Cell Mask Header—Byte 4 (Address = 5Fh)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
Rx User Cell Mask Heade—Byte 4
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
1
1
1
1
1