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ADD (DTCP)

Syntax

Description

Specify the DTCP attributes that do one of the following:

  • Trigger the router to initiate traffic mirroring.

  • Provide instructions to populate fields in the encapsulation header for packets sent to the mediation device

The DTCP ADD message can be sent either before or after subscribers log in through the interface.

The following attributes are added to the packet header of mirrored packets that the router sends to the mediation device. These attributes are required in the DTCP ADD message.

  • X-JTap-Cdest-Dest-Address

  • X-JTap-Cdest-Dest-Port

  • X-MD-Intercept-Id

This DTCP message is supported for both FlowTapLite and radius-flow-tap services.

Note:

Starting with Junos OS Release 12.3, DTCP ADD requests are validated for the IP version. The source IP and destination IP addresses must contain a matching IP address family, which must match with the value of the IPVersion field if it is available in the ADD message.

Note:

Consult the documentation for your mediation device to learn how to configure DTCP messages on the device.

Best Practice:

The Account Session ID, Interface Identifier, and Subscriber User Name trigger attributes are optimized for a scaled subscriber management environment. Forwarding of mirrored traffic begins almost immediately when you include one or more of these three attributes and none of the non-optimized attributes in DTCP ADD messages.

If you include any of the non-optimized trigger attributes in the DTCP ADD message in a scaled subscriber management environment, some delay might be observed between the time when the DTCP ADD message is sent and the time when forwarding starts for the mirrored traffic. For example, if there are 10,000 subscriber sessions on the router, forwarding of the mirrored traffic might be delayed for less than one minute. This delay occurs when you specify any non-optimized attribute, with or without any optimized attribute. The delay occurs regardless of the order of attributes in the DTCP packet.

When a subscriber matches more than one of the DTCP mirroring triggers in an ADD message, the router processes the triggers in the following order:

  1. X-Act-Sess-Id

  2. X-Call-Sta-Id

  3. X-IP-Addr

  4. X-Interface-Id

  5. X-NAS-Port-Id

  6. X-RM-Circuit-Id

  7. X-UserName

Best Practice:

When you have DHCPv4/DHCPv6 subscribers over VLANs, two sessions are created for each subscriber— one for the Layer 2 VLAN, and one for DHCP. In this case do not use a trigger, such as X-RM-Circuit-Id, that applies to both the VLAN and the DHCP sessions. If the DHCP and VLAN sessions match the same trigger, the DHCP subscriber login fails and subscriber secure policy is not triggered. You need to select a traffic mirroring trigger that matches only one of these sessions.

Options

Csource-ID: user-name

Username on the router. This username must be configured as a DTCP user on the router using the set system login class or set system login user statements.
Cdest-ID: variable

ID of the mediation device.

Flags: flag

STATIC is the only flag supported.
Priority: priority-number

This implementation of DTCP does not use the priority number.

X-Drop-Policy policy-name

Name of the policy used to determine which mirrored packets are no longer sent to the mediation device.
X-JTap-Cdest-Dest-Address: ipv4-address

Destination IPv4 address of the mediation device to which intercepted packets are sent. You must include this attribute in your ADD messages. It is used in the header of mirrored traffic that is sent to the mediation device.
X-JTap-Cdest-Dest-Port: udp-port

Destination port of the mediation device to which intercepted packets are sent. You must include this attribute in your ADD messages. It is used in the header of mirrored traffic that is sent to the mediation device.
X-JTap-Cdest-Source-Address: ipv4-address

Source IPv4 address. You must include this attribute in your ADD messages. If the value entered does not match the value configured on the router using the set services radius-flow-tap source-ipv4-address source-ipv4-address statement, it is replaced by configured value.
X-JTap-Cdest-Source-Port: port-number

Source port. You must include this attribute in your ADD messages. If the value entered does not match the value of X-Jtap-Cdest-Dest-Port, it is ignored.
X-JTap-Cdest-TTL: time-to-live

TTL value to be used in the forwarded packet.
X-MD-Intercept-Id 4-byte-id or 8-byte-id

An Id that is used to identify a subscriber. You must include this attribute in your ADD messages. This ID is used in the header of mirrored traffic that is sent to the mediation device to allow the device to track a subscriber. The X-MD-Intercept-ID attribute must be provided in hexadecimal format, it can be prepended with 0x or 0X, but this prepend is optional. The X-MD-Intercept-ID attribute can consist of only 4 bytes or 8 bytes. If 4 bytes format is used, the two most significant bits must be 01. If 8 bytes format is used, the two most significant bits must be 00.
Dtcp-trigger: trigger-value

DTCP attribute used to trigger traffic mirroring.

  • X-Act-Sess-Id—Text string of the accounting session ID associated with the subscriber session. The intercept terminates when the subscriber logs out.

    Best Practice:

    We recommend that you include other triggers to ensure that all sessions for a subscriber are intercepted.

  • X-Call-Sta-Id—Text string of the calling station ID associated with the subscriber. If the subscriber is not logged in, the policy is applied at any current or subsequent subscriber log in.

  • X-IP-Addr—IPv4 address that is associated with the interface for a subscriber.

    If the subscriber is not using the default logical system, you must also include the X-Logical-System attribute in your DTCP message. If the subscriber is not using the default routing instance, you must also include the X-Router-Instance attribute in your DTCP message.

  • X-Interface-Id—Interface description string on which traffic mirroring is performed. Traffic is mirrored for all subscribers that use this interface; for example, ge-0/0/0.1 or demux0.107472834.

  • X-NAS-Port-Id—Text string of the NAS port ID associated with the subscriber.

  • X-RM-Circuit-Id—For PPPoE subscribers, the agent circuit ID (ACI) in the PPPoE Intermediate Agent (PPPoE IA) tag.

    For DHCP subscribers, use X-RM-Circuit-Id with the agent remote ID (ARI), X-RM-Agent-Id, to completely specify a trigger for the DHCP option 82 value that is associated with this session.

  • X-RM-Agent-Id—For PPPoE subscribers, the agent remote ID (ARI) in the PPPoE IA tag.

    For DHCP subscribers, X-RM-Agent-Id is the option 82 Agent-Remote-ID suboption and you can use it alone as a trigger. You can also use it with the ACI, X-RM-Circuit-Id, to completely specify a trigger for the DHCP option 82 value that is associated with this session.

  • X-Logical-System—Include in addition to the X-IP-Addr or X-UserName attribute for subscribers that use anything other than the default logical system. X-Logical-System is ignored if neither of those attributes is included in the message. The default logical system is assumed when X-Logical-System is not included in the ADD message.

  • X-Router-Instance—Include in addition to the X-IP-Addr or X-UserName attribute for subscribers that use anything other than the default routing instance. X-Router-Instance is ignored if neither of those attributes is included in the message. The default routing instance is assumed when X-Router-Instance is not included in the ADD message.

  • X-UserName—Subscriber’s user name. For subscribers not using the default logical system or routing instance, you can also include the X-Logical-System or X-Router-Instance attributes.
Seq: sequence-number

Number added by the mediation device. DTCP messages contain a monotonically increasing sequence number for each successive message.

Authentication-Info: ssh-authentication-string

String used when you are using SSH to connect to the router.

Required Privilege Level

Not applicable.

Sample Output

command-name

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