Virtual Private Routed Network Services
7750 SR OS Services Guide Page 1019
The QinQ and TopQ SAP PBit marking follows the default behavior devined in Table 4 when qinq-
mark-top-only is not specified.
The dot1p dot1p-value command must be configured without the qinq-mark-top-only parameter to 
remove the TopQ PBits only marking restriction.
Dot1Q Preserved Dot1P bits Preserved tag PBits remarked 
using dot1p-value
TopQ No preserved Dot1P bits TopQ PBits marked using dot1p-
value
TopQ Preserved Dot1P bits (used as TopQ 
and BottomQ PBits)
TopQ PBits marked using dot1p-
value, BottomQ PBits preserved
QinQ No preserved Dot1P bits TopQ PBits and BottomQ PBits 
marked using dot1p-value
QinQ Preserved Dot1P bits (used as TopQ 
and BottomQ PBits)
TopQ PBits and BottomQ PBits 
marked using dot1p-value
Table 5: QinQ Mark Top Only Explicit Marking Actions
Egress SAP 
Type
Ingress Packet Preserved 
Dot1P State
Marked (or Remarked) PBits
Null No preserved Dot1P bits None
Null Preserved Dot1P bits Preserved tag PBits remarked 
using dot1p-value
Dot1Q No preserved Dot1P bits New PBits marked using dot1p-
value
Dot1Q Preserved Dot1P bits Preserved tag PBits remarked 
using dot1p-value
TopQ No preserved Dot1P bits TopQ PBits marked using dot1p-
value
TopQ Preserved Dot1P bits (used as TopQ 
and BottomQ PBits)
TopQ PBits marked using dot1p-
value, BottomQ PBits preserved
QinQ No preserved Dot1P bits TopQ PBits PBits marked using 
dot1p-value, BottomQ PBits 
marked with zero
QinQ Preserved Dot1P bits (used as TopQ 
and BottomQ PBits)
TopQ PBits PBits marked using 
dot1p-value, BottomQ PBits 
marked using preserved value
Table 4: Default Dot1P Explicit Marking Actions  (Continued)
Egress SAP 
Type
Ingress Packet Preserved 
Dot1P State
Marked (or Remarked) PBits