1. A method, performed in, by or for a networking device having a router core, of performing one or more core virtual router functions for a packet responsive to one or more abstracted virtual identifiers abstracted from one or more virtual identifiers derived from the packet, thus insulating the router core from changes in the one or more virtual identifiers, the method comprising the steps of: receiving a packet having VLAN, VMAN, and ingress port fields; forming a key from the VLAN, VMAN and ingress port fields; masking the key with a key type determined responsive to the ingress port field; mapping the masked key into an abstracted VLAN identifier (AVID) and abstracted virtual port identifier (AVPT) using a two-step indirection mapping process, comprising a first step and a second step, wherein the first step comprises accessing a table having a plurality of entries, each having a content value and an index value, and locating an entry having a content value that matches the masked key, and the second step comprises mapping the index value of the matching entry into the AVID and AVPT by using the index value to identify an entry in an associated data store element containing or including the AVID and AVPT; performing one or more core virtual router functions responsive to the AVID, the one or more core virtual router functions selected from the group consisting of: qualifying OSI layer two MAC addresses; limiting OSI layer two broadcasting or flooding domains; performing OSI layer three indirection; performing router MAC address detection; and generating a CAM key in support of a packet processor operation; and looking up a spanning tree state responsive to the AVPT.