The subscriber identification policy contains the URL definitions for the Programmable Subscriber Configuration Policy (PSCP) scripts used for DHCP ACK message processing. Up to three URLs can be defined per subscriber identification policy. These are designated as primary, secondary and tertiary. Each URL can be individually enabled or disabled. Only one script (the URL with the highest priority active script) is used at any one time to process DHCP ACK messages. If the system detects an error with a specified script, the URL is placed in an operationally down state. If the script is shut down, it is placed in an administratively down state. A script that is operationally or administratively down is considered inactive. The system automatically reverts to the highest priority active script. If a script becomes operationally down, it must be cycled through the administratively down then administratively up states for the system to attempt to reactivate the script.
Multiple subscriber identification policies are provided for the event that access nodes (such as DSLAMs) from different vendors are attached to the same router. Each policy’s active script can be explicitly defined to process the various DHCP message formats or idiosyncrasies of each vendor.
If a script is changed, it must be reloaded by disabling and re-enabling any URL which refers to the changed script (a shutdown command followed by a no shutdown command).
Each subscriber identification policy can also contain a subscriber profile map and an SLA profile map. The subscriber profile map creates a mapping between the sub-profile-strings returned from the active script with an existing subscriber profile name. The SLA profile map is used to create a mapping between the sla-profile-strings returned from the active script with an existing SLA profile name.
The subscriber identification policy is designed to accept a DHCP ACK message destined for a subscriber host and return up to three string values to the system;
The subscriber identification string (mandatory)
The subscriber profile string (optional)
The SLA profile string (optional).
These strings are used to derive the subscriber profile and the SLA profile to be used for this host See Using scripts for dynamic recognition of subscribers.