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Subscriber Secure Policy Overview

Subscriber secure policy enables you to mirror traffic on a per-subscriber basis. You can mirror the content of subscriber traffic as well as monitor events related to the subscriber session that is being mirrored.

Subscriber secure policy (SSP) mirroring can be based on information provided by either RADIUS or Dynamic Tasking Control Protocol (DTCP), and can mirror both IPv4 and IPv6 traffic. Configuration of subscriber secure policy mirroring is independent of the actual mirroring session—you can configure the mirroring parameters at any time. Also, you can use a single RADIUS or DTCP server to provision mirroring operations on multiple routers in a service provider’s network. To provide security, the ability to configure, access, and view the subscriber secure policy components and configuration is restricted to authorized users.

After subscriber secure policy is triggered, the subscriber’s incoming and outgoing traffic are both mirrored. The original traffic is sent to its intended destination and the mirrored traffic is sent to a mediation device for analysis. The actual mirroring operation is transparent to subscribers whose traffic is being mirrored. A special UDP/IP header is prepended to each mirrored packet sent to the mediation device. The mediation device uses the header to differentiate multiple mirrored streams that arrive from different sources.


This feature requires a license. To understand more about Subscriber Access Licensing, see, Subscriber Access Licensing Overview. Please refer to the Juniper Licensing Guide for general information about License Management. Please refer to the product Data Sheets at MX Series 5G Universal Routing Platform for details, or contact your Juniper Account Team or Juniper Partner.

Support for Intercepting Both Layer 2 and Layer 3 Datagrams

When DTCP- or RADIUS-initiated SSP intercepts traffic on logical subscriber interfaces and VLAN subscriber interfaces, it sends both Layer 2 and Layer 3 datagrams to the mediation device. When you enable subscriber secure policy for these interfaces, traffic for all configured families (inet, inet6) including Layer 2 and Layer 3 control traffic is mirrored.

Traffic Filtering for DTCP-Initiated Subscriber Secure Policy Mirrored Traffic

You can filter mirrored traffic before it is sent to a mediation device. With this feature, service providers can reduce the volume of traffic sent to a mediation device. For some types of traffic, such as IPTV or video on demand, you do not need to mirror the entire content of the traffic because the content may already be known or controlled by the service provider.

Mirroring-Related Event Reporting

Subscriber secure policy also supports the use of SNMPv3 traps to report events related to the mirroring operation to an external device. Types of information sent in traps include identifying information for subscribers, such as username or IP address, and subscriber session events, such as login or logout events or mirroring session activation or deactivation. The traps map to messages defined in the Lawfully Authorized Electronic Surveillance (LAES) for IP Network Access, American National Standard for Telecommunications.

Starting in Junos OS Release 16.1R1, you must configure the target parameters for mediation devices so that the SNMPv3 traps are sent with privacy (encrypted). Targets without privacy configured cannot receive the notifications.

In earlier releases, you can configure target parameters without privacy, allowing unencrypted notifications to be sent to the mediation devices. You also cannot restrict the traps to specific targets.

Support for L2TP Subscribers

Both DTCP-initiated and RADIUS-initiated SSP can be applied to Point-to-Point Protocol (PPP) subscribers whose traffic is tunneled with Layer 2 Tunneling Protocol (L2TP). DTCP SSP supports subscribers only at the L2TP network server (LNS), whereas RADIUS-initiated SSP supports subscribers at the L2TP access concentrator (LAC) or the LNS.

At the LAC, both subscriber ingress traffic (from the subscriber into the tunnel) and subscriber egress traffic (from the tunnel to the subscriber) are mirrored at the subscriber-facing ingress interface. The ingress traffic is mirrored after PPPoE decapsulation and before L2TP encapsulation. The egress traffic is mirrored after L2TP decapsulation. The mirrored packet includes the complete HDLC frame sent to the LNS rather than only the IP datagram.

At the LNS, both subscriber ingress traffic (from the LAC to the LNS) and subscriber egress traffic (from the LNS to the LAC) are mirrored at the inline services (si) interface corresponding to the subscriber. Ingress traffic is mirrored after decapsulation of L2TP, HDLC, and PPP headers. The egress traffic is mirrored before the IP datagram is encapsulated. The mirrored traffic contains only the IP datagram belonging to the subscriber.

There is no specific L2TP SSP configuration.

Junos OS Service for Subscriber Secure Policy Traffic Mirroring

Subscriber secure policy mirroring requires the use of the radius-flow-tap service, configured at the [edit services radius-flow-tap] hierarchy level. This service is used only for subscriber secure policy mirroring and only on MX Series routers.

There are other Junos OS services with similar names, but they are not used for subscriber secure policy mirroring:

  • The flow-tap service, configured at the [edit services flow-tap] hierarchy level, is an older Junos OS service for packet mirroring. This service uses Dynamic Tasking Control Protocol (DTCP) requests from mediation devices to intercept IPv4 packets in an active flow monitoring station (router). The router uses DTCP to send a copy of packets that match filter criteria to one or more content destinations. The flow-tap service is supported only on M Series and T Series routers using Adaptive Services PICs. For information about the flow-tap service, see Understanding Flow-Tap Architecture.

  • The FlowTapLite service is a lightweight version of the flow-tap service for packet mirroring. It is also configured at the [edit services flow-tap] hierarchy level. The FlowTapLite service resides on the Packet Forwarding Engine rather than a line card. The intercepted packets are sent to a tunnel logical interface (vt-) for encapsulation, so you must allocate and assign tunnel interfaces for the service. It is supported on MX Series routers and on M320 routers with Enhanced III Flexible PIC Concentrators (FPCs). You cannot run FlowTapLite and the flow-tap service on the same router concurrently. For information about FlowTapLite, see Configuring FlowTapLite on MX Series Routers and M320 Routers with FPCs.

Protection of SSP Data when a Core Error is Generated

When the authd, bbe-smgd, or dfcd processes generate a core error, the core dump file contains information related to whatever the process is involved with, including SSP. The error files contain SSP information that might identify the subscriber whose traffic is mirrored or the mediation device that receives the mirrored traffic. For example, the files include information such as the source and destination IP address for the mediation device, device ports, and intercept ID.

Starting in Junos OS Release 18.4R1, SSP-related information is automatically encrypted in core dump files to prevent this information from being seen by unauthorized persons in the event of a core error. Encryption is enabled by default; no configuration is required or possible. The dfcd core error files may contain traffic mirroring information that does not identify subscribers or devices; this information is not masked. FlowTapLite information is not masked.


Information related to SSP is not encrypted when it is in a transient state; for example, if the core error occurs when the data has been received from a RADIUS or DTCP server, but is not yet encrypted.

Subscriber Secure Policy Licensing Requirements

To enable and use subscriber secure policy, you must install and properly configure the Subscriber Secure Policy license.

Release History Table
Starting in Junos OS Release 18.4R1, SSP-related information is automatically encrypted in core dump files to prevent this information from being seen by unauthorized persons in the event of a core error.