Payload Type
Indicator (PTI)
8
7
6
5
4
3
2
1
GFC* / VPI
VPI
VPI
VCI
VCI
VCI
PTI
HEC
CLP
One PTI bit is used in AAL 5
User data / control data
Traffic management
0 0 0 User data cell, no
congestion. ATM-user indication = 0
0 0 1 User data cell, no
congestion. ATM-user indication = 1
0 1 0 User data cell, congestion. ATM-user
indication = 0
0 1 1 User data cell, congestion. ATM-user
indication = 1
1 0 0 OAM F5 segment associated
cell
1 0 1 OAM F5 end-to-end associated
cell
1 1 0 Resource management cell
1 1 1 Reserved for future VC functions