the SmartCast question

why we need to open the classification and marking together?
because incoming traffic needs classification first, before continue to marking (for outgoing traffic)
When the marking will work?
marking is the action that you want to change tos/dot1p value for outgoing traffic L3 packets always have ToS field, that you always can mark with ToS value

Why we have ToS nonzero Marking this function?
L3 packets always have ToS field

If you want insert a packet to voice queue
1. packet will match with heuristics rule for voice (mean matching packet gap and packet length)
2. packet can be matched voice TOS value
3. packet can match Port matching filter rule...

packet from queue want to go out
you have 2 ways to process with it:
1. You don't want to change anything, just leaving(traffic will not change anything)
2. You want to change tos value (or dot1p value)

you know why we only mark using tos/dot1p value
because that a field using for QoS
we only classify packet based on the ToS filed (or dot1p filed), because the purpose of that field is for QoS