The publication of ETSI
TS 103 221 marks a step forward
in Lawful Interception. It brings standardized X1, X2 and
X3 interfaces and replaces proprietary interfaces.
X1 is the interface that allows the Lawful Interception system
to provision tasks on an Network Function (NF).
A task represents an intercept on a target. As long as the
task is provisioned, the NF is instructed to intercept
communication. The intercepted communication is delivered using
the X2 and X3 interfaces.
The X1 interface:
The latest version of the ETSI TS 103 221-1 can be downloaded from the ETSI portal. Download the ZIP file to grab a copy of the XSD schema and XML samples.
X2 is the interface that is used to transmit intercepted
signalling, X3 is used for transmission of intercepted content.
An NF initiates one or more X2/X3 connections towards the LI
system to deliver packets.
The volume of packets on these interfaces may be high,
especially on the X3 interface. As such, the format is
optimized for performance. It uses a fixed length TLV format
to allow fast inspection and is also used for X2.
The X2 and X3 interfaces:
Both X2 and X3 are specified in ETSI TS 103 221-2.