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1. Introduction

Lawful Interception (LI) is a legal requirement in most of the countries. It enables the legal authorities to obtain communications network data for analysis or evidence. It is a method of intercepting certain data-streams of end-users in both directions, and tunnel the intercepted traffic to a Mediation Device (MD) with information about direction of capture and reference to the intercepted connection.

Leaf node is the Point of Interception (POI) and MD is the final Point of Collection (POC).

1.1. Supported Hardware Platforms

LI is supported on the following hardware platform:

  • Broadcom’s Qumran Switch

1.2. Components of Lawful Interception

The figure below shows the different components of the LI solution.

li network diagram

Leaf node in the POD which is connected to subscribers.


Spine and Border Leaf in the POD, which can be replaced with just one node.

LI Box

Lawful Intercept Box, which communicates to Law Enforcement Agency (LEMF) and relays mirrored traffic. Two LI boxes per POD are connected for redundancy.


POD Access Orchestrator, which configures the LI Box and network nodes with LI configurations.


Destination node for traffic from subscribers.

Abbreviation Definition


Lawful Interception


Point of Interception


Point of Collection


Pod Access Orchestrator


Lawful Interception Management System


Virtual Routing Instance


Lawful Enforcement Monitoring Facility


Access node


Point to Point Protocol over Ethernet


Layer 2 Tunnelling Protocol


Multi Protocol Label Switching

2. LI Encapsulation

Qumran-MX (BCM) supports LI with 32 bits shim header: SHIMoUDPoIPoETH

2.1. Packet Format Encoding

li packet format encoding
Figure 1. Packet Format Encoding

2.1.1. Payload Direction

Value Payload Direction


Reserved for keepalive mechanism


Intercepted data or event was sent to target (downstream)


Intercepted data or event was sent from target (upstream)

2.1.2. Mapping Payload Format

Value Payload Format


Reserved (unused)


Unknown, Not able to decide the PT (used for upstream flow)


IPv4 packet (not used)


IPv6 packet (not used)


Ethernet Frame (used for downstream flow) Sub-payload Format (Type)

The sub-payload formats are:

  1. Single VLAN tag

  2. Double VLAN tag

  3. Untagged

3. Configuring Lawful Interception

Note RBFS hides information about lawful intercepts from all but the most privileged users. An administrator must set up access rights to enable privileged users to access lawful intercept information.

The following example shows the li_request_object that allows you to create an add or a delete request.

   "object": {
       "codepoint"   : 1302,
       "name"        : "li_request_object",
       "module"      : "subscriberd",
       "description" : "An Object for LI add/delete request"
       "attribute": [

               "mandatory"  : false,
               "codepoint"  : 1,
               "type"       : "uint64",
               "name"       : "subscriber_id",
               "description": "Subscriber Identifier"
               "mandatory"  : true,
               "codepoint"  : 2,
               "type"       : "uint32",
               "name"       : "li_id",
               "description": "LI Identifier (1-4194303(0x1FFFF))"
               "mandatory"  : false,
               "codepoint"  : 3,
               "type"       : "li_direction_map",
               "name"       : "li_direction",
               "description": "LI direction up(ingress)/down(egress)/both"
               "mandatory"  : true,
               "codepoint"  : 4,
               "type"       : "string",
               "name"       : "med_instance",
               "description": "VRF instance to lookup LI destination"
               "mandatory"  : true,
               "codepoint"  : 5,
               "type"       : "ipv4addr",
               "name"       : "med_ip",
               "description": "IP address of MD(LIBox)"
               "mandatory"  : true,
               "codepoint"  : 6,
               "type"       : "uint16",
               "name"       : "med_port",
              "description": "UDP port(MD)(49152-65535), mirrored traffic is forwarded"

The table below lists the parameters of li_request_object.

Parameter Name Description


Subscriber identifier that is generated by RBFS, for example, 72339069014638701.


Identifier for Lawful Interception. The range can be between 1 to 4194303.


LI direction. Values are: INGRESS, EGRESS, BOTH.


VRF instance through the which the mediation device is reachable.


IPv4 address of the mediation device


UDP port(MD)(49152-65535), mirrored traffic is forwarded

3.1. LI Request Object

The li_request_object resides in the global.access.1.li_request table.

The LI Request Object configuration is just a wrapper for the actual LI request table (global.access.1.li_request) which is filled via RADIUS attributes. The required RADIUS attributes are already defined in the RADIUS dictionary. The global.access.1.li_request table is protected by the secure management plane.

3.2. Configuration Example

The following example shows REST/JSON way of configuration LI.

    "table": {
        "table_name": "global.access.1.li_request"
    "objects": [
            "attribute": {
                "subscriber_id": "72339069014639042",
                "li_id": "66666",
                "li_direction": "BOTH",
                "med_instance": "libox",
                "med_ip": "",
                "med_port": "49153"

3.3. Verification

The following commands allow you to view the table information. These are platform-specific tables.

show datastore table dump local.bcm.qmx.mirror

show datastore table dump local.bcm.qmx.acl

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