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Printable Version: RFC2975.PDF
RFC 2975 Introduction to Accounting Management October 2000 Support for notifications makes it possible to implement the event- driven, event-driven polling and event-driven batching models. This makes it possible to notify domains of available data rather than requiring them to poll for it, which is critical in shared use networks and roaming. Given the SNMPv3 security enhancements, it is desirable for SNMP- based intra-domain accounting implementations to upgrade to SNMPv3. Such an upgrade is virtually mandatory for inter-domain applications. In inter-domain accounting, the burden of managing SNMPv3 shared secrets can be reduced via the localized key capability or via implementation of a Proxy Forwarder. In the long term, alternative security models such as the Kerberos Security Model may further reduce the effort required to manage security and enable streamlined inter-domain operation. SNMP-based accounting has limitations in terms of efficiency and latency that may make it inappropriate for use in situations requiring low processing delay or low overhead. This includes usage sensitive billing applications where fraud detection may be required. These issues can be addressed via proposals under discussion in the IRTF Network Management Research Group (NMRG). The experimental SNMP over TCP transport mapping may prove helpful at reducing latency. Depending on the volume of data, some form of compression may also be worth considering. However, since these proposals are still in the research stage, and are not on the standards track, these capabilities are not readily available, and the specifications could change considerably before they reach their final form. SNMP supports separation of accounting data by domain, using either of two general approaches with the VACM access control model. The domain as index approach can be used if the desired MIB module supports domain indexing, or it can implemented using an additional table. The domain-context approach can be used in agents which support dynamic logical contexts and a domain-to-context and context-to-instrumentation mapping mechanism. Either approach can be supported using SNMPv1, SNMPv2c, or SNMPv3 messages, by utilizing the snmpCommunitytable [11] to provide a community-to-context mapping. 4. Review of Accounting Data Transfer In order for session records to be transmitted between accounting servers, a transfer protocol is required. Transfer protocols in use today include SMTP, FTP, and HTTP. For a review of accounting attributes and record formats, see [45]. Aboba, et al. Informational [Page 43]