CPE as Subscriber in Cable Environment
Revised: February 29, 2012, OL-21080-06
This module deals with the special case when the Customer Premise Equipment (CPE) is considered as the subscriber in the Cisco Service Control Solution for a cable environment.
The cable market presents special issues in terms of subscribers, in addition to the normal subscriber management issues that exist in other markets, such as DSL and Wireless.
Note This module is not relevant for the more common case where the cable modem with all the CPEs behind it is considered the subscriber.
Information About the CPE as a Subscriber in a Cable Environment
•Cable Support Module
•CM and CPE in the SM
•Static and Dynamic CMs
Cable Support Module
The Subscriber Manager (SM) includes a special cable support module (p3cable) for dealing with the special case where the CPE is considered as a subscriber in a cable environment. The cable support module functions as a translator between the cable world (DHCP events) and the Cisco SM, for this special case. It provides an API on top of the basic SM API functionality. This API is accessible using the Java/C/C++ APIs by calling the cableLogin and cableLogout methods.
To ensure the correct behavior of the cable support module, certain configuration steps are necessary, such as the correct domain configuration and the static/dynamic CM configuration.
The cable support module, which translates between the SM and the DHCP events in the cable world, performs the following functions:
•Associates between CPEs and CMs
•Makes CPEs inherit application policy from their CM
•Allows/denies the introduction of CPEs whose CM is unfamiliar to the SM
For additional information regarding the functions of the cable support module, see Information About the p3cable Utility.
The cable support module uses the hardware (MAC) addresses of the CM as its subscriber name. The subscriber name of the CPE is the hardware address of its CM followed by the hardware address of the CPE.
CM and CPE in the SM
In the special case when CPEs are considered as subscribers, cable modems are not delegated to the SCE in any way, and are not considered as subscribers in the Cisco Service Control Solution. However, for ease of integration and for the sake of simplicity, CMs are saved as subscribers in the SM only (but are never introduced to the SCE).
Cable modem SM subscribers are saved in special hidden subscriber domains called CM domains. These CM domains do not contain any SCE and are created automatically upon an insertion of a CM. For a CPE in a given subscriber domain, its CM will reside in a CM domain having the same name as the CPE domain but with the prefix CM_.
Because CM domains are hidden, they cannot be configured by the configuration file. However, it is possible to run subscriber-related commands (p3subs and p3subsdb) on these domains.
A CM subscriber name has the following form: <CM MAC> (the MAC of the CM as sent in the DHCP protocol).
A CPE subscriber name (for such a CM) has the following form: <CM MAC>__<CPE MAC> (the MAC of the CM, followed by two underscore signs, followed by the MAC of the CPE).
The p3cable command imports and exports cable modems, similar to importing and exporting subscribers, except that it is unnecessary to import the CM with an IP address.
When importing cable modems, the full CM domain name (CM_ plus the domain name of its CPEs) must be provided.
In the configuration of this example, the SM has a domain called DomainA. We want CPEs arriving from CMTS with IP 188.8.131.52 to reach this domain; therefore, we have configured 184.108.40.206 as an alias of DomainA.
During operation, because of a DHCP request-response, the DHCP LEG event sends a login event of a cable modem with MAC 0X0Y0Z from CMTS 220.127.116.11.
In the login event, the alias sent was 18.104.22.168 (the alias of domain DomainA), so the cable modem subscriber will be entered into domain CM_DomainA with the name 0X0Y0Z.
When a login event of its CPE with MAC 0A0B0C is sent with the same alias (as the CPE that arrived from the same CMTS), the CPE subscriber will be entered into domain DomainA with the name 0X0Y0Z__0A0B0C.
Static and Dynamic CMs
Login and logout events of CPEs whose CM does not exist in the subscriber database will be ignored, since no subscriber will be created in the SM and aggregated to the SCE. This CPE traffic will be treated as default subscriber.
The SM supports two modes of integrating with cable modems. Editing and loading the p3sm.cfg configuration file controls these modes. (Configuring dynamic CM support is described in Configuration File Options. Use the CLU p3cable to view the current status.
•Deny dynamic CM—In this mode, login/logout events of cable modems that were not imported using the p3cable command will be ignored. Consequently, the CPE traffic of these CMs will be treated as default subscriber.
•Allow Dynamic CM—In this mode, login/logout events of cable modems that were not imported using the p3cable command will result in automatic addition of the cable modem to the subscriber database. These cable modems will receive the application tuneables that were defined in the domain tunable template section of the configuration file. For a description of application tuneables, see Cisco Service Control Application for Broadband User Guide.