Handling data packets received at a routing node

A method applied in a routing node, and a forwarding engine implemented in a routing node, are provided for handling data packets received at the routing node. A N-tuple comprising N elements is extracted from a first header of a data packet. A default meta-field is added to the N elements, providing a N+1-tuple. The N+1-tuple is used to make a first lookup of inspection rules. The default meta-field makes the inspection rules apply to the first header. The data packet is handled according to a result of the first lookup, wherein a possible outcome is a finding of a second header within the data packet. If a second header is found, a new meta-field value is set and a second lookup is made. The second lookup of the inspection rules is made according to N elements from the second header and the new value of the meta-field.