Internet Draft Diana Rawlins Expiration: September 2002 WorldCom File: draft-ietf-rap-feedback-frwk-02.txt Amol Kulkarni Intel Martin Bokaemper Unisphere Networks Kwok Ho Chan Nortel Networks Framework of COPS-PR Policy Usage Feedback Last Updated March 1, 2002 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC-2119]. Abstract Common Open Policy Services Protocol [COPS], RFC 2748, defined the capability of reporting information to the PDP. The types of report information are success, failure and accounting of an installed state. This document focuses on the COPS Report Type of Accounting and the necessary framework for the monitoring and reporting of usage feedback for an installed state. Rawlins et al. Expires September 2002 [Page 1] Internet Draft COPS-FEED-FRWK March 2002 Table of Contents 1 Introduction...................................................3 2 Overview.......................................................3 3 Requirements for Normal Operations.............................3 4 Periodic Nature of Policy Usage Feedback.......................4 4.1 Reporting Intervals..........................................4 5 Suspension, Resumption and Halting of Usage Monitoring and Reporting........................................................5 6 Solicited Feedback.............................................5 7 Usage reports on shared objects................................5 8 Context........................................................6 9 Delete Request States..........................................6 10 Failover......................................................6 11 Security Considerations.......................................6 12 Authors' Addresses............................................7 13 References....................................................7 Rawlins et al. Expires September 2002 [Page 2] Internet Draft COPS-FEED-FRWK March 2002 1 Introduction Policy usage reported by the PEP makes a richer set of information available to the PDP for decision-making. This feedback on policy usage can impact future decisions made by the PDP and the resulting policy installed by the PDP at the PEP. For example, a PDP making policy for a SIP signaled multimedia session may need to base the decision in part on usage information related to previously installed QoS policy decisions. Furthermore, the PDP may coordinate this usage information with other external systems to determine the future policy such as the case with the PDP coordinating multimedia session QoS and clearinghouse authorizations [SIP-AAA-QOS.] The scope of this document is to describe the framework for policy usage monitored and reported by the PEP and collected at the PDP. The charging, rating and billing models as well as other accounting or statistics gathering events detectable by the PDP are beyond the scope of this framework. 2 Overview There are three main aspects to define policies for usage feedback: - which objects are monitored - the metrics to be monitored and reported for these objects - when the reports are delivered In the framework a selection criteria policy specifies one or more objects that should be monitored û for example a dropper or the instances of an IP Filter for all its interfaces. A usage feedback class is used to specify which metrics are to be collected for a set of objects - instances of the specified class carry the usage information when it is reported. The valid combinations of monitored object classes and usage feedback classes are reported by the PEP as capabilities. Finally selection criteria policy and usage feedback class are bound together in a linkage policy, which also contains the information when reports are generated. Reports are usually sent periodically but more restrictions can be placed on the generation of reports, like thresholds or a change in the data. 3 Requirements for Normal Operations Per [COPS], the PDP specifies the minimum feedback interval in the Accounting Timer object that is included in the Client Accept message during connection establishment. This specifies the maximum frequency with which the PEP issues unsolicited accounting type report messages. The purpose of this interval is to pace the number of report messages sent to the PDP. It is not the goal of Rawlins et al. Expires September 2002 [Page 3] Internet Draft COPS-FEED-FRWK March 2002 the interval defined by the ACCT Timer value to provide precision synchronization or timing. The selection and the associated usage criteria and intervals for feedback reporting are defined by the PDP. Feedback policies, which define the necessary selection and linkages to usage feedback criteria, are included by the PDP in a Decision message to the PEP. The usage feedback is then periodically reported by the PEP at intervals defined in the linkage policies at a rate no more frequently than specified in the Accounting Timer object. Note that there are exceptions where reports containing feedback are provided prior the Accounting Timer interval in several cases described in sections 6 and 7.) The PDP may also solicit usage feedback which is to be reported back immediately by the PEP. Usage information may be cleared upon reporting. This is specified in the usage policy criteria. The PEP monitors and tracks the usage feedback information. The PDP is the collection point for the policy usage feedback information reported by the PEP clients within the administrative domain. The PDP may also collect other accounting event information that is outside the scope of this document. 4 Periodic Nature of Policy Usage Feedback Generally the policy usage feedback is periodic in nature and the reporting is unsolicited. The unsolicited reports are supplied per the interval defined by the PDP. The periodic unsolicited reports are dictated by timer intervals and use a deterministic amount of network resources. The PDP informs the PEP of the minimal feedback interval during client connection establishment with the Accounting Timer object. The PDP may specify feedback intervals in the specific usage feedback policies as well. The unsolicited monitoring and reporting by the PEP may be suspended and resumed at the direction of the PDP. 4.1 Reporting Intervals The generation of usage feedback by the PEP to the PDP is done under different conditions that include feedback on demand, periodic feedback or feedback when a defined threshold is reached. The periodic feedback for a usage policy can be further defined in terms of providing feedback if there is a change or providing feedback periodically regardless of a change in value. The periodic interval is defined in terms of the Accounting Object, ACCT Timer value. A single interval is equal to the number of seconds specified by the ACCT Timer value. The PDP may define a specific number of intervals, which are to pass before the PEP provides the usage feedback for a specific policy in a report. When the ACCT Timer value is equal to zero there is no unsolicited usage feedback provided by the PEP. However, the PEP still Rawlins et al. Expires September 2002 [Page 4] Internet Draft COPS-FEED-FRWK March 2002 monitors and tracks the usage per the PDP policy and reports it when the PDP solicits the feedback. Reporting may be based on a defined threshold value in the usage PRC that is reached. The PDP may solicit usage feedback in the middle of an interval. The PEP shall provide the requested usage information and clear the usage information if the usage policy requires that the attribute be cleared after reporting. The PEP should continue to maintain the same interval schedule as defined by the PDP in the Accounting Timer object and established at client connection acceptance. 5 Suspension, Resumption and Halting of Usage Monitoring and Reporting The PDP may direct the PEP to suspend usage feedback report messages and then at a later time instruct the PEP to resume the reporting of feedback. The PDP may also instruct the PEP to suspend the monitoring and tracking of usage which also results in the suppression of the feedback reports until the PDP later tells the PEP to resume the monitoring (and reporting). When the PDP suspends monitoring or suspends reporting, it also specifies whether the PEP is to provide an unsolicited feedback report of the current monitored usage of the affected usage policy. The PDP may suspend and resume monitoring and reporting for specific usage policies or for all of the usage feedback policies. 6 Solicited Feedback There may be instances when it is useful for the PDP to control the feedback per an on-demand basis rather than a periodic basis. The PDP may solicit the PEP for usage feedback with a Decision. The PDP may solicit usage feedback at any time during the accounting interval defined by the ACCT Timer. The PEP responds immediately and reports the appropriate usage policies and should continue to follow the usage feedback interval schedule established during connection acceptance. 7 Usage reports on shared objects While some objects in a contextÆs namespace directly represent unique objects of the PEPÆs configuration, other COPS objects can be shared between multiple actual assignments in the PEP. Whenever the PEP creates multiple actual configuration instances from the same COPS objects, these assignments can potentially collect their own statistics independently. Since the individual assignments do not have a direct representation as COPS objects, additional information must be provided to uniquely identify the assignment that generates the usage information. Rawlins et al. Expires September 2002 [Page 5] Internet Draft COPS-FEED-FRWK March 2002 The feedback framework allows this information to be distributed between a selection criteria PRC and the corresponding usage feedback PRC, however both PRCs together always must contain sufficient information for the finest granularity of usage collection supported by the PEP. If all the additional information is not part of the selection criteria PRC, all matching assignments are selected to collect usage information. The necessary data to differentiate these assignments is part of the usage feedback PRC. Implementations based on the feedback framework should always provide a selection criteria PRC that contains a complete set of information to select a unique assignment, while underspecified selection criteria PRCs (together with extended usage feedback PRCs) are optional. 8 Context The monitoring and recording of usage policies is subject to context switches in a manner similar to that of the enforcement policy. Usage policy is monitored, recorded and reported while the associated policy information context is active. When the context is deactivated a report message containing the usage feedback policies for that context is provided to the PDP. The PEP does not perform any monitoring, tracking or reporting of policy usage for a given context while the context is inactive. 9 Delete Request States The PEP MUST send any outstanding usage feedback data monitored during the feedback interval to the PDP via an unsolicited report message immediately prior to issuing a Delete Request State. This is also the case when the PDP initiates the Delete Request State. 10 Failover In the event the connection is lost between the PEP and PDP, the PEP continues to track usage feedback information as long as it continues to enforce installed (cached) policy. When the locally installed policy at the PEP expires, the usage feedback policy data also expires and is no longer monitored. Upon successful reconnection where the PEP is still caching policy, the PDP indicates deterministically to the PEP that the PEP may resume usage feedback reporting. The PEP reports all cached usage and resumes periodic reporting making any needed adjustment to the interval schedule as specified in the reconnection acceptance ACCT Timer. 11 Security Considerations Rawlins et al. Expires September 2002 [Page 6] Internet Draft COPS-FEED-FRWK March 2002 The feedback information is sensitive and requires that authorized messaging occur between the PEP and the PDP. This protection can be accomplished with IPSEC between the PEP and the PDP, TLS [COPS TLS] or using the security mechanisms described in the base COPS protocol. 12 Authors' Addresses Diana Rawlins WorldCom 901 International Parkway Richardson, Texas 75081 Phone: 972-729-1044 Email: Diana.Rawlins@wcom.com Amol Kulkarni JF3-206 2111 NE 25th Ave Hillsboro, Oregon 97124 Phone: 503-712-1168 Email: amol.kulkarni@intel.com Kwok Ho Chan Nortel Networks, Inc. 600 Technology Park Drive Billerica, MA 01821 USA Phone: 978-288-8175 Email: khchan@nortelnetworks.com Martin Bokaemper Unisphere Networks 700 Silver Seven Road Kanata, ON, K2V 1C3, Canada Phone: 613-591-2735 Email: mbokaemper@unispherenetworks.com" 13 References [COPS] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan, R., and A. Sastry, "The COPS (Common Open Policy Service) Protocol" RFC 2748, January 2000. [SIP-AAA-QOS] Gross, G., Sinnreich, H. Rawlins D., Havinis, T. "QoS and AAA Usage with SIP Based IP Communications" draft-gross-sipaq- 00.txt, November 2000. [COPS-TLS], Walker, J., Kulkarni, A.,öCOPS Over TLSö, draft-ietf- rap-cops-tls-02.txt, October 2001. Rawlins et al. Expires September 2002 [Page 7]