Whenever an IP packet arrives on a subscriber-facing SAP on which Enhanced Subscriber Management (ESM) is enabled, a lookup is done in the subscriber host table using as the index the SAP, source IP address, and source MAC address.
If there is no entry, this means that the host is not using the assigned IP address, so the packet is dropped.
If there is an entry, this refers to the subscriber profile and SLA profile to be used.