Shallow Packet Inspection (SPI, but usually just called Packet Inspection) is a technology that has been developed and used in the firewall and security fields to investigate type of traffic based on ports.
It inspects IP packets only up to the layer 4 (TCP/UDP layer) of the OSI model, extracts basic protocol information such as IP addresses (source, destination) and other low-level connection states. This information typically resides in the packet header and reflects only rudimentary information about the communication.
Shallow Packet Inspection applied to mobile OSS can provide KPIs and metrics on accessibility, throughput, port usage, data volume, data retransmission and loss, etc ...
Today SPI is widely used by simple firewalls to block ports.
