Filter
Top Products
Line Interface Hardware Interface
6-10
Centillion 1200N ATM Switch User Manual
NTP 297-8103-903
Figure 6-11: ATM Cell Format
UNI: User-Network Interface
NNI: Network-Network Interface
GFC: Generic Flow Control
VPI: Virtual Path Identifier
VCI: Virtual Channel Identifier
PT: Payload Type
CLP: Cell Loss Priority
HEC: Header Error Control
UNI
MSB LSB
GFC(4)
VPI(4)
VPI(4)
VCI(4)
VCI(4)
VCI(8)
PT(3)
HEC(8)
User Information
(1)
CLP
NNI
VPI(4)
VCI(4)
VPI(8)
MSB LSB
VCI(4)
VCI(8)
PT(3)
HEC(8)
User Information
(1)
CLP
payload 48Byte header 5Byte
cell 53Byte
GFC VPI VCI
0 0
1
2
3
4
5
16
x
x
x
x
x
x
use
unassigned cell
meta signalling (default VPI=0)
general broadcast signalling (default VPI=0)
segment OAM F4
end-to-end OAM F4
end-to-end OAM F5
reserved for traffic cont. and resource man.
point-to-point signalling (default VPI=0)
ILMI (Interim Local Management Interface)
segment OAM F5
user data cell, no congestion, SDU-type=0
user data cell, congestion, SDU-type=1
user data cell, congestion, SDU-type=0
user data cell, no congestion, SDU-type=1
reserved
PT
0
0
0
0
0
0
0
0
0
0
x
any
value
other
than
0
x
0,2
0,2
0,2
7
0-3
0-3
CLP
1
normal priority
lower priority
0
1
2
3
4
5
6
*
*
*
*
*
*
*
*
*
*
*
*
*
*