Managing Subscriber-Level Policies on MX Series Routers Overview
The Juniper Networks MX Series Ethernet Services Router supports a feature known as packet-triggered subscribers and policy control (PTSP). This feature allows dynamic policy and profile changes to be applied on a per-subscriber basis. The PTSP in the MX Series router signals the SRC policy manager when a new IP address flow is detected or when an existing flow is idle, and allows the policy manager to dynamically apply new policies associated with the IP address flow.
The SRC software uses the Diameter protocol for communications between the local SRC peer on a Juniper Networks routing platform, such as the MX Series router, and the service activation engine (SAE). The local SRC peer in the MX Series router is known as the PTSP.
The PTSP device driver has the following responsibilities:
Manage the logical connection to the MX Series router Diameter peer (PTSP).
Receive IP address notifications from the MX Series router and dynamically activate, modify, or deactivate policies for existing subscriber sessions.
Send subscriber identification information to the MX Series router.
Push subscriber policy changes to MX Series router.
Retrieve accounting information for active service sessions.
Terminate a subscriber session.
Synchronize the state of a single subscriber session or all sessions.
The PTSP device driver responds to requests from the MX Series router, which signals subscribers logging in and logging out. The driver publishes interface tracking events, performs interface classification to determine any default policies, and initiates SAE subscriber session login and logout processing.
Multiple instances of the device driver for the same device (MX Series router) can be configured in the network. The instances communicate with each other to provide redundancy. Only one driver for a given device is active at the same time.
The SAE activates, modifies and deactivates subscriber policies. The SAE can control only those resources that have been provisioned through the SAE. Therefore, the SAE receives information about only those subscribers (IP address flows) for whom PTSP has requested provisioning from the SAE. Similarly, the SAE can control only the subscriber policies that it has activated.