Packet classification is one of the key elements of a routers to implement traffic control techniques.
As an example, let us consider an IPv6 packet such as the following one :
What are the fields of the packet that you can match if you want to implement Layer-2 classification ?
Destination IP address
Ethernet destination address
Internet protocol version
TLS record type
Ethernet source address
Ethernet type
Destination port
Source IP address
Hop Limit
Source port
Next header
Traffic class
What are the fields of the packet that you can match if you want to implement Layer-3 classification ?
What are the fields of the packet that you can match if you want to implement Layer-4 classification ?
What are the fields of the packet that you can match if you want to implement application-level (or layer 7) classification ?