Network Working Group N. Brownlee Request for Comments: 2924 The University of Auckland Category: Informational A. Blount MetraTech Corp. September 2000 Accounting Attributes and Record Formats Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved.
AbstractThis document summarises Internet Engineering Task Force (IETF) and International Telecommunication Union (ITU-T) documents related to Accounting. A classification scheme for the Accounting Attributes in the summarised documents is presented. Exchange formats for Accounting data records are discussed, as are advantages and disadvantages of integrated versus separate record formats and transport protocols. This document discusses service definition independence, extensibility, and versioning. Compound service definition capabilities are described. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology and Notation . . . . . . . . . . . . . . . . . . . 3 3. Architecture Model . . . . . . . . . . . . . . . . . . . . . . 4 4. IETF Documents . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1.1. RADIUS Attributes . . . . . . . . . . . . . . . . . . . . 5 4.2. DIAMETER . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.2.1. DIAMETER Attributes . . . . . . . . . . . . . . . . . . . 7 4.3. ROAMOPS . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.4. RTFM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.4.1. RTFM Attributes . . . . . . . . . . . . . . . . . . . . . 9 4.5. ISDN MIB . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.5.1. ISDN Attributes . . . . . . . . . . . . . . . . . . . . . 10 4.6. AToMMIB . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.6.1. AToMMIB Attributes . . . . . . . . . . . . . . . . . . . . 11
4.7. QoS: RSVP and DIFFSERV . . . . . . . . . . . . . . . . . . . 12 4.7.1. RSVP and DIFFSERV Attributes . . . . . . . . . . . . . . . 13 5. ITU-T Documents . . . . . . . . . . . . . . . . . . . . . . . 13 5.1. Q.825: Call Detail Recording . . . . . . . . . . . . . . . . 13 5.2. Q.825 Attributes . . . . . . . . . . . . . . . . . . . . . . 14 6. Other Documents . . . . . . . . . . . . . . . . . . . . . . . 18 6.1. TIPHON: ETSI TS 101 321 . . . . . . . . . . . . . . . . . . 18 6.2. MSIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7. Accounting File and Record Formats . . . . . . . . . . . . . . 19 7.1. ASN.1 Records . . . . . . . . . . . . . . . . . . . . . . . 19 7.1.1. RTFM and AToMMIB . . . . . . . . . . . . . . . . . . . . . 19 7.1.2. Q.825 . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.2. Binary Records . . . . . . . . . . . . . . . . . . . . . . . 20 7.2.1. RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.2.2. DIAMETER . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.3. Text Records . . . . . . . . . . . . . . . . . . . . . . . . 21 7.3.1. ROAMOPS . . . . . . . . . . . . . . . . . . . . . . . . . 21 8. AAA Requirements . . . . . . . . . . . . . . . . . . . . . . . 22 8.1. A Well-defined Set of Attributes . . . . . . . . . . . . . . 22 8.2. A Simple Interchange Format . . . . . . . . . . . . . . . . 23 9. Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 9.1. Record Format vs. Protocol . . . . . . . . . . . . . . . . . 24 9.2. Tagged, Typed Data . . . . . . . . . . . . . . . . . . . . . 24 9.2.1. Standard Type Definitions . . . . . . . . . . . . . . . . 25 9.3. Transaction Identifiers . . . . . . . . . . . . . . . . . . 26 9.4. Service Definitions . . . . . . . . . . . . . . . . . . . . 26 9.4.1. Service Independence . . . . . . . . . . . . . . . . . . . 27 9.4.2. Versioned Service Definitions . . . . . . . . . . . . . . 29 9.4.3. Relationships Among Usage Events . . . . . . . . . . . . . 29 9.4.4. Service Namespace Management . . . . . . . . . . . . . . . 30 10. Encodings . . . . . . . . . . . . . . . . . . . . . . . . . . 30 11. Security Considerations . . . . . . . . . . . . . . . . . . . 31 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 13. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 35 14. Full Copyright Statement . . . . . . . . . . . . . . . . . . 36
Many existing accounting record formats and protocols [RAD-ACT] [TIPHON] are of limited use due to their single-service descriptive facilities and lack of extensibility. While some record formats and protocols support extensible attributes [RAD-ACT], none provide identification, type checking, or versioning support for defined groupings of attributes (service definitions). This document makes a case for well-defined services. Advantages and disadvantages of integrated versus separate record formats and transport protocols are discussed. This document discusses service definition independence, extensibility, and versioning. Compound service definition capabilities are described.
Usage Attribute A component of a Usage Event that describes some metric of service usage. Usage Event The description of an instance of service usage. RAD-PROT] carries authentication, authorization and configuration information between a Network Access Server (NAS) and an authentication server. Requests and responses carried by the protocol are expressed in terms of RADIUS attributes such as User- Name, Service-Type, and so on. These attributes provide the information needed by a RADIUS server to authenticate users and to establish authorized network service for them. The protocol was extended to carry accounting information between a NAS and a shared accounting server. This was achieved by defining a set of RADIUS accounting attributes [RAD-ACT].
RADIUS packets have a short header containing the RADIUS packet type and authenticator (sixteen octets) and length, followed by a sequence of (Type, Length, Value) triples, one for each attribute. RADIUS is very widely used, and a number of significant new extensions to it have been proposed. For example [RAD-EXT] discusses extensions to implement the Extensible Authentication Protocol (EAP) and the Apple Remote Access Protocol (ARAP). [RAD-TACC] discusses extensions to permit RADIUS to interwork effectively with tunnels using protocols such as PPTP and L2TP. ASG-NBR], but the current list is as follows: RADIUS Attributes [RAD-PROT] 36 Login-LAT-Group 37 Framed-AppleTalk-Link 1 User-Name 38 Framed-AppleTalk-Network 2 User-Password 39 Framed-AppleTalk-Zone 3 CHAP-Password 4 NAS-IP-Address 60 CHAP-Challenge 5 NAS-Port 61 NAS-Port-Type 6 Service-Type 62 Port-Limit 7 Framed-Protocol 63 Login-LAT-Port 8 Framed-IP-Address 9 Framed-IP-Netmask RADIUS Accounting Attributes 10 Framed-Routing [RAD-ACT] 11 Filter-Id 12 Framed-MTU 40 Acct-Status-Type 13 Framed-Compression 41 Acct-Delay-Time 14 Login-IP-Host 42 Acct-Input-Octets 15 Login-Service 43 Acct-Output-Octets 16 Login-TCP-Port 44 Acct-Session-Id 17 (unassigned) 45 Acct-Authentic 18 Reply-Message 46 Acct-Session-Time 19 Callback-Number 47 Acct-Input-Packets 20 Callback-Id 48 Acct-Output-Packets 21 (unassigned) 49 Acct-Terminate-Cause 22 Framed-Route 50 Acct-Multi-Session-Id 23 Framed-IPX-Network 51 Acct-Link-Count 24 State 25 Class RADIUS Extension Attributes 26 Vendor-Specific [RAD-EXT] 27 Session-Timeout 28 Idle-Timeout 52 Acct-Input-Gigawords
29 Termination-Action 53 Acct-Output-Gigawords 30 Called-Station-Id 54 Unused 31 Calling-Station-Id 55 Event-Timestamp 32 NAS-Identifier 33 Proxy-State 70 ARAP-Password 34 Login-LAT-Service 71 ARAP-Features 35 Login-LAT-Node 72 ARAP-Zone-Access 73 ARAP-Security 74 ARAP-Security-Data 75 Password-Retry 76 Prompt 77 Connect-Info 78 Configuration-Token 79 EAP-Message 80 Message-Authenticator 84 ARAP-Challenge-Response 85 Acct-Interim-Interval 87 NAS-Port-Id 88 Framed-Pool RADIUS Tunneling Attributes [RAD-TACC] 64 Tunnel-Type 65 Tunnel-Medium-Type 66 Tunnel-Client-Endpoint 67 Tunnel-Server-Endpoint 68 Acct-Tunnel-Connection 69 Tunnel-Password 81 Tunnel-Private-Group-ID 82 Tunnel-Assignment-ID 83 Tunnel-Preference 90 Tunnel-Client-Auth-ID 91 Tunnel-Server-Auth-ID DIAM-FRAM] defines a policy protocol used by clients to perform Policy, AAA and Resource Control. This allows a single server to handle policies for many services. The DIAMETER protocol consists of a header followed by objects. Each object is encapsulated in a header known as an Attribute-Value Pair (AVP).
DIAMETER defines a base protocol that specifies the header formats, security extensions and requirements as well as a small number of mandatory commands and AVPs. A new service can extend DIAMETER by extending the base protocol to support new functionality. One key differentiator with DIAMETER is its inherent support for Inter-Server communication. Although this can be achieved in a variety of ways, the most useful feature is the ability to "proxy" messages across a set of DIAMETER servers (known as a proxy chain). The DIAMETER Accounting Extension document [DIAM-ACT] extends DIAMETER by defining a protocol for securely transferring accounting records over the DIAMETER base protocol. This includes the case where accounting records may be passed through one or more intermediate proxies, in accordance with the 'referral broker' model. The DIAMETER accounting protocol [DIAM-ACT] defines DIAMETER records for transferring an ADIF record (see below). It introduces five new attributes (480..485) which specify the way in which accounting information is to be delivered between DIAMETER servers. DIAM- AUTH]. Since most of the AVPs found in that document were copied from the RADIUS protocol [RAD-PROT], it is possible to have both RADIUS and DIAMETER servers read the same dictionary and users files. The backward compatibility that DIAMETER offers is intended to facilitate deployment. To this end, DIAMETER inherits the RADIUS attributes, and adds only a few of its own. In the list below attribute numbers which are used for RADIUS attributes but not for DIAMETER are indicated with a star (*). RADIUS attributes used by DIAMETER are not listed again here. The DIAMETER attributes are: 4 (unassigned, *) 17 (unassigned) 21 (unassigned) 24 (unassigned, *) 25 (unassigned, *) 27 (unassigned, *) 32 (unassigned, *) 33 (unassigned, *) 280 Filter-Rule 281 Framed-Password-Policy
480 Accounting-Record-Type 481 ADIF-Record 482 Accounting-Interim-Interval 483 Accounting-Delivery-Max-Batch 484 Accounting-Delivery-Max-Delay 485 Accounting-Record-Number 600 SIP-Sequence 601 SIP-Call-ID 602 SIP-To 603 SIP-From ROAM-IMPL] reviews the design and functionality of existing roaming implementations. "Roaming capability" may be loosely defined as the ability to use any one of multiple Internet service providers (ISPs), while maintaining a formal customer-vendor relationship with only one. One requirement for successful roaming is the provision of effective accounting. [ROAM-ADIF] proposes a standard accounting record format, the Accounting Data Interchange Format (ADIF), which is designed to compactly represent accounting data in a protocol-independent manner. As a result, ADIF may be used to represent accounting data from any protocol using attribute value pairs (AVPs) or variable bindings. ADIF does not define accounting attributes of its own. Instead, it gives examples of accounting records using the RADIUS accounting attributes. RTFM-ARC] provides a general method of measuring network traffic flows between "metered traffic groups". Each RTFM flow has a set of "address" attributes, which define the traffic groups at each of the flow's end-points. As well as address attributes, each flow has traffic-related attributes, e.g. times of first and last packets, counts for packets and bytes in each direction. RTFM flow measurements are made by RTFM meters [RTFM-MIB] and collected by RTFM meter readers using SNMP. The MIB uses a "DataPackage" convention, which specifies the attribute values to be read from a flow table row. The meter returns the values for each
required attribute within a BER-encoded sequence. This means there is only one object identifier for the whole sequence, greatly reducing the number of bytes required to retrieve the data.
36 Source Class Integer "Computed" attributes 37 Destination Class Integer 38 Flow Class Integer 39 Source Kind Integer 40 Destination Kind Integer 41 Flow Kind Integer 50 MatchingStoD Integer PME variable 51 v1 Integer Meter Variables 52 v2 Integer 53 v3 Integer 54 v4 Integer 55 v5 Integer 65-127 "Extended" attributes (to be defined by the RTFM working group) ISDN-MIB] defines a minimal set of managed objects for SNMP-based management of ISDN terminal interfaces. It does not explicitly define anything related to accounting, however it does define isdnBearerChargedUnits as The number of charged units for the current or last connection. For incoming calls or if charging information is not supplied by the switch, the value of this object is zero. This allows for an ISDN switch to convert its traffic flow data (such as Call Connect Time) into charging data.
isdnBearerCallConnectTime TimeStamp, isdnBearerChargedUnits Gauge32 } ATM-ACT] describes a large set of accounting objects for ATM connections. An administrator may select objects from this set using a selector of the form (subtree, list) where "subtree" specifies an object identifier from the AToMMIB. For each subtree there is a table holding values for each ATM connection. The required connections are indicated by setting bits in "list", which is an octet string. For example, the set containing the number of received cells for the first eight ATM connections would be selected by (atmAcctngReceivedCells, 0xFF). The Connection-Oriented Accounting MIB document [ATM-COLL] defines a MIB providing managed objects used for controlling the collection and storage of accounting information for connection-oriented networks such as ATM. The accounting data is collected into files for later retrieval via a file transfer protocol. Records within an accounting file are stored as BER strings [ASN1, BER].
18 atmAcctngReceivedClp0Cells 19 atmAcctngTransmitTrafficDescriptorType 20 atmAcctngTransmitTrafficDescriptorParam1 21 atmAcctngTransmitTrafficDescriptorParam2 22 atmAcctngTransmitTrafficDescriptorParam3 23 atmAcctngTransmitTrafficDescriptorParam4 24 atmAcctngTransmitTrafficDescriptorParam5 25 atmAcctngReceiveTrafficDescriptorType 26 atmAcctngReceiveTrafficDescriptorParam1 27 atmAcctngReceiveTrafficDescriptorParam2 28 atmAcctngReceiveTrafficDescriptorParam3 29 atmAcctngReceiveTrafficDescriptorParam4 30 atmAcctngReceiveTrafficDescriptorParam5 31 atmAcctngCallingPartySubAddress 32 atmAcctngCalledPartySubAddress 33 atmAcctngRecordCrc16 IIS-ARC], with its accompanying signaling protocol, RSVP [RSVP-ARC], and RSVP's Common Open Policy Service protocol, COPS [RAP-COPS] - the Differentiated Services architecture (diffserv) [DSRV-ARC] RSVP is a signaling protocol that applications may use to request resources from the network. The network responds by explicitly admitting or rejecting RSVP requests. Certain applications that have quantifiable resource requirements express these requirements using intserv parameters [IIS-SPEC]. Diffserv networks classify packets into one of a small number of aggregated flows or "classes", based on the diffserv codepoint (DSCP) in the packet's IP header. At each diffserv router, packets are subjected to a "per-hop behavior" (PHB), which is invoked by the DSCP. Since RSVP is purely a requirements signalling protocol it can also be used to request connections from a diffserv network [RS-DS- OP].
IIS-SPEC]. These have been turned into accounting attributes within RTFM [RTFM-NEWA] and within the RSVP MIB [RSVP- MIB]. The RTFM QoS attributes are: 98 QoSService 99 QoSStyle 100 QoSRate 101 QoSSlackTerm 102 QoSTokenBucketRate 103 QoSTokenBucketSize 104 QoSPeakDataRate 105 QoSMinPolicedUnit 106 QoSMaxPolicedUnit The RSVP MIB contains a large number of objects, arranged within the following sections: General Objects Session Statistics Table Session Sender Table Reservation Requests Received Table Reservation Requests Forwarded Table RSVP Interface Attributes Table RSVP Neighbor Table The Session tables contain information such as the numbers of senders and receivers for each session, while the Reservation Requests tables contain details of requests handled by the RSVP router. There are too many objects to list here, but many of them could be used for accounting. In particular, RSVP Requests contain the specification of the service parameters requested by a user; these, together with the actual usage data for the connection make up an accounting record for that usage.
Each call produces one or more records describing events that occurred during the life of a call. Data may be produced in real time (single CDRs), near real-time (blocks of CDRs), or as batch files of CDRs. The information model for Call Detail Recording is formally described in terms of an Entity-Relationship model, and an object model specified in terms of GDMO templates (Guidelines for the Definition of Managed Objects). Note that this model includes the ways in which CDRs are transported from the (NE) Network Element where they are generated to the OS (Operations System) where they are used. Q-825] for the complete text. 1 accessDelivery Indicates that the call was delivered to the called subscriber 2 accountCodeInput Account code (for billing), supplied by subscriber. 78 additionalParticipantInfo (No details given) 5 b-PartyCategory Subscriber category for called subscriber. 4 bearerService Bearer capability information (only for ISDN calls). 13 cDRPurpose Reason for triggering this Call Data Record. 70 callDetailDataId Unique identifier for the CallDetailData object. 79 callDuration Duration of call 6 callIdentificationNumber Identification number for call; all records produced for this call have the same callIdenfificationNumber. 73 callStatus Identifies whether the call was answered or not.
9 calledPartyNumber Telephone number of the called subscriber (may be a "diverted-to" or "translated" number. 7 callingPartyCategory Calling subscriber category. 8 callingPartyNumber Telephone number of the calling party. 10 callingPartyNumberNotScreened An additional, user-provided (not screened) number to the calling party. 11 callingPartyType Calling subscriber type. 74 carrierId Carrier ID to which the call is sent. 12 cause Cause and location value for the termination of the call. 14 chargedDirectoryNumber Charged directory number (where the charged participant element can't indicate the number). 16 chargedParticipant Participant to be charged for the usage. 15 chargingInformation Charging information generated by a Network Element which is capable of charging. 17 configurationMask Time consumption, e.g. from B-answer to termination time, between partial call records, etc. 18 conversationTime Time consumption from B-answer to end of call. 19 creationTriggerList List of trigger values which will create Call Detail data objects. 75 dPC Destination point code (for analysis purposes).
20 dataValidity Indicates that the NE is having problems, contents of the generated Call Detail record is not reliable. 23 durationTimeACM Time consumption from seizure until received ACM. 21 durationTimeB-Answer Time consumption from seizure until B-answer. 22 durationTimeNoB-Answer Time from seizure to termination when no B-answer was received. 25 exchangeInfo Identity of exchange where Call Detail record was generated. 26 fallbackBearerService Fallback bearer capability information for a call. 27 glare Indicates if a glare condition was encountered. 31 iNServiceInformationList Contains information about the use of IN (Intelligent Network) services. 32 iNSpecificInformation Contains information about the use of one IN service. 33 iSUPPreferred Indicate whether an ISUP preference was requested. 28 immediateNotificationForUsageMetering Indicates that the Call Detail records requires immediate data transfer to the Operations System. 34 maxBlockSize Maximum number of Call Detail records in a block. 35 maxTimeInterval Maximum latency allowable for near-real-time Call Detail data delivery. 36 networkManagementControls Indicates which Traffic Management Control has affected the call.
37 networkProviderId Indicates the Network Provider for whom the CDR is generated. 76 oPC Originating point code for a failed call (for analysis purposes). 38 operatorSpecific1AdditionalNumber 40 operatorSpecific2AdditionalNumber 42 operatorSpecific3AdditionalNumber Operator-defined additional participant information. 39 operatorSpecific1Number 41 operatorSpecific2Number 43 operatorSpecific3Number Operator-defined participant information. 44 originalCalledNumber Telephone number of the original called party. 45 partialGeneration Included if the CDR (Call Detail record) output is partial. Such CDRs have a field indicating their partial record number. 77 participantInfo (No details given). 46 percentageToBeBilled Percentage to be billed when normal billing rules are not to be followed. 47 periodicTrigger Defines the intervals at which the CDR file should be created. 48 personalUserId Internationally unique personal User Identity (for UPT calls). 49 physicalLineCode Identifies the call subscriber's physical line. 50 progress Describes an event which occurred during the life of a call. 51 queueInfo Used to record usage of queueing resources with IN calls.
52 receivedDigits The digits dialed by the subscriber. (Normally only included for customer care purposes). 53 recordExtensions Information elements added by network operators and/or manufacturers in addition to the standard ones above. TIPHON] is an XML-based protocol, carried by HTTP, which handles accounting and authorization requests and responses. The following are elements selected from TIPHON's DTD that are used for accounting. <!ELEMENT Currency (#PCDATA)> <!ELEMENT Amount (#PCDATA)> Identifies a numeric value. Expressed using the period (.) as a decimal separator with no punctuation as the thousands separator. <!ELEMENT CallId (#PCDATA)> Contains a call's H.323 CallID value, and is thus used to uniquely identify individual calls. <!ELEMENT Currency (#PCDATA)> Defines the financial currency in use for the parent element. <!ELEMENT DestinationInfo type ( e164 | h323 | url | email | transport | international | national | network | subscriber | abbreviated | e164prefix ) Gives the primary identification of the destination for a call. <!ELEMENT Increment (#PCDATA)> Indicates the number of units being accounted. <!ELEMENT Service EMPTY> Indicates a type of service being priced, authorized, or reported. An empty Service element indicates basic Internet telephony service, which is the only service type defined by V1.4.2 of the specification. The specification notes that "Later revisions of this standard are expected to specify more enhanced service definitions to represent quality of service, availability, payment methods, etc."
<!ELEMENT DestinationInfo type ( e164 | h323 | url | email | transport | international | national | network | subscriber | abbreviated | e164prefix) Gives the primary identification of the source of a call. <!ELEMENT Timestamp (#PCDATA)> A restricted form of [ISO-DATE] that indicates the time at which the component was generated. <!ELEMENT TransactionId (#PCDATA)> Contains an integer, decimal valued identifier assigned to a specific authorized transaction. <!ELEMENT Unit (#PCDATA)> Indicates the units by which pricing is measured or usage recorded. It shall contain one of the following values: s seconds p packets (datagrams) byte bytes <!Element UsageDetail ( Service, Amount, Increment, Unit ) > Collects information describing the usage of a service. MSIX-SPEC] is an XML-based protocol transported by HTTP that is used to make accounting service definitions and transmit service usage information. As its service definitions are parameterized and dynamic, it makes no definition of services or attributes itself, but allows implementors to make their own. It specifies only the base data types that attributes may take: STRING, UNISTRING, INT32, FLOAT, DOUBLE, BOOLEAN, TIMESTAMP.
AToMMIB carries this a stage further by defining an accounting file format in ASN.1 and making it available for retrieval by a file transfer protocol, thereby providing a more efficient alternative to simply retrieving the records using SNMP.
Code The AVP Code identifies the attribute uniquely. If the Vendor- Specific bit is set, the AVP Code is allocated from the vendor's private address space. The first 256 AVP numbers are reserved for backward compatibility with RADIUS and are to be interpreted as per RADIUS [RAD-PROT]. AVP numbers 256 and above are used for DIAMETER, which are allocated by IANA. AVP Length A 16-bit field contains the total object length in bytes. Must always be a multiple of 4, and at least 8. AVP Flags P Protected bit T Tag bit V Vendor-ID bit R Reserved (MUST be set to 0) M Mandatory bit ROAM-ADIF]) presents a general, text-based format for accounting data files, described in a straightforward BNF grammar. Its file header contains a field indicating the default protocol from which accounting attributes are drawn. If an attribute from another protocol is to be used, it is preceded by its protocol name, for example rtfm//27 would be RTFM's "forward bytes" attribute. Comments in an ADIF file begin with a cross-hatch. Example: An ADIF file encoding RADIUS accounting data version: 1 device: server3 description: Accounting Server 3 date: 02 Mar 1999 12:19:01 -0500 defaultProtocol: radius rdate: 02 Mar 1999 12:20:17 -0500 #NAS-IP-Address 4: 22.214.171.124 #NAS-Port 5: 12 #NAS-Port-Type
61: 2 #User-Name 1: firstname.lastname@example.org #Acct-Status-Type 40: 2 #Acct-Delay-Time 41: 14 #Acct-Input-Octets 42: 234732 #Acct-Output-Octets 43: 15439 #Acct-Session-Id 44: 185 #Acct-Authentic 45: 1 #Acct-Session-Time 46: 1238 #Acct-Input-Packets 47: 153 #Acct-Output-Packets 48: 148 #Acct-Terminate-Cause 49: 11 #Acct-Multi-Session-Id 50: 73 #Acct-Link-Count 51: 2
o Service definition namespace management The following sections address these issues. MD5] or a similar function, for reliability and security purposes. +------------+ | transport | | header | +------------+ +------------+ | | | | | Usage | | Usage | | Event(s) | | Event(s) | | | | | | | | | +------------+ +------------+ | trailer | +------------+ record format transport protocol If the protocol is written such that it can transmit Usage Events in the record format, no record rewriting for transport is required. RFC822], for instance, defines a header block composed of several Attribute-Value Pairs, followed by a message body. Each header field is explicitly
tagged, but the order of the AVPs is undefined. The message body is not tagged (except with an additional preceding blank line), and is found through its position in the message, which must be after all header fields. Some record formats make no use of tags--data elements are identified only by their position within a record structure. While this practice provides for the least amount of record space overhead, it is difficult to later modify the record format by adding or removing elements, as all record readers will have to be altered to handle the change. Tagged data allows old readers to detect unexpected tags and to detect if required data are missing. If the overhead of carrying explicit tags can be borne, it is advantageous to use explicitly tagged data elements where possible. An AVP approach has proven useful in accounting. RADIUS [RADIUS] uses numeric data type identifiers. ETSI's TIPHON [TIPHON] uses XML markup. For an AAA accounting record format, the authors suggest that each Property be named by a textual or numeric identifier and carry a value and a data type indicator, which governs interpretation of the value. It may also be useful for each Property to carry a units of measure identifier. The TIPHON specification takes this approach. TS 101 321 also carries an Increment field, which denominates the Property's Unit of Measure field. Whether this additional convenience is necessary is a matter for discussion. It is not strictly necessary for each data record to carry data type, units of measure, or increments identifiers. If this information is recorded in a record schema document that is referenced by each data record, each record may be validated against the schema without the overhead of carrying type information. MSIX-SPEC] supports String, Unistring, Int32, Float, Double, Boolean, and Timestamp. SMIv2 [SMI-V2] offers ASN.1 types INTEGER, OCTET STRING, and OBJECT IDENTIFIER, and the application-defined types Integer32, IpAddress, Counter32, Gauge32, Unsigned32, TimeTicks, Opaque, and Counter64.
An appropriate set would likely include booleans, 32 and 64 bit signed integers, 32 and 64 bit floats, arbitrary octets, UTF-8 and UTF-16 strings, and ISO 8601:1988 [ISO-DATE] timestamps. Fixed- precision numbers capable of representing currency amounts (with precision specified on both sides of the decimal point) have proven useful in accounting record formats, as they are immune to the precision problems that are encountered when one attempts to represent fixed-point amounts with floating point numbers. It may be worthwhile to consider the datatypes that are being specified by the W3C's "XML Schema Part 2: Datatypes" [XML-DATA] document. That document specifies a rich set of base types, along with a mechanism to specify derivations that further constrain the base types. RFC 822 [MAIL], RFC 1036 [NEWS], and RFC 2445 [ICAL-CORE] give guidance on the creation of good unique identifiers.
NTP], NNTP [NNTP], RADIUS Accounting [RAD-ACT], and HTML [HTML]. Aside from leaving some field values "reserved for future use", all of Network Time Protocol's fields are fixed-width and completely defined. This is appropriate for a simple protocol that solves a simple problem. Network News Transfer Protocol [NEWS-PROT] specifies that further commands may be added, and requests that non-standard implementations use the "X-" experimental prefix so as to not conflict with future additions. The content of news is 7-bit data, with the high-order bit cleared to 0. Nothing further about the content is defined. There is no in-protocol facility for automating decoding of content type. We pay particular attention to RADIUS Accounting [RAD-ACT]. Perhaps the second most frequently heard complaint (after security shortcomings) about RADIUS Accounting is its preassigned and fixed set of "Types". These are coded as a range of octets from 40 to 51 and are as follows: 40 Acct-Status-Type 41 Acct-Delay-Time 42 Acct-Input-Octets 43 Acct-Output-Octets 44 Acct-Session-Id 45 Acct-Authentic 46 Acct-Session-Time 47 Acct-Input-Packets 48 Acct-Output-Packets 49 Acct-Terminate-Cause 50 Acct-Multi-Session-Id 51 Acct-Link-Count These identifiers were designed to account for packet-based network access service. They are ill-suited for describing other services. While extension documents have specified additional types, the base
protocol limits the type identifier to a single octet, limiting the total number of types to 256. HTML/2.0 [HTML] is mostly a fully-specified protocol, but with W3C's HTML/4.0, HTML is becoming more of a framework protocol. HTML/2.0 specified a fixed set of markups, with no provision for addition (without protocol revision). Examples of "framework" protocols and document encodings are HTTP, XML, and SNMP. HTTP/1.1 [HTTP] is somewhat similar to NNTP in that it is designed to transport arbitrary content. It is different in that it supports description of that content through its Content-Type, Content- Encoding, Accept-Encoding, and Transfer-Encoding header fields. New types of content can be designated and carried by HTTP/1.1 without modification to the HTTP protocol. XML [XML] is a preeminent general-purpose framework encoding. DTD publishing is left to users. There is no standard registry of DTDs. SNMP presents a successful example of a framework protocol. SNMP's authors envisioned SNMP as a general management protocol, and allow extension through the use of private MIBs. SNMP's ASN.1 MIBs are defined, published, and standardized without the necessity to modify the SNMP standard itself. From "An Overview of SNMP" [SNMP-OVER]: It can easily be argued that SNMP has become prominent mainly from its ability to augment the standard set of MIB objects with new values specific for certain applications and devices. Hence, new functionality can continuously be added to SNMP, since a standard method has been defined to incorporate that functionality into SNMP devices and network managers. Most accounting protocols are fully-specified, with either a completely defined service or set of services (RADIUS Accounting) or with one or more services defined and provision for "extension" services to be added to the protocol later (TIPHON). While the latter is preferable, it may be preferable to take a more SNMP-like approach, where the accounting record format and protocol provide only a framework for service definition, and leave the task of service definition (and standardization) to separate efforts. In this manner, the accounting protocol itself would not have to be modified to handle new services.
RADIUS Accounting has some provision for this sort of accounting with its "Acct-Multi-Session-Id" field. Unfortunately, RADIUS Accounting's other shortcomings preclude it from being used in general purpose service usage description. MSIX-SPEC], is for Service Element creators to identify their services by concatenation of a new service name with existing unique identifier, such as a domain name. A standard record format for service definitions would make it possible for Service Element creators to directly supply accounting system managers with the required definitions, via the network or other means.
implementation is paramount and the application can tolerate any additional processing required to generate, parse, and transport the records. A alternative "compressed" encoding that makes minimal use of storage and processing may be useful in many contexts. There are disadvantages to supporting multiple encodings. Optionally-supported multiple encodings mandate the requirement for capabilities exchange between Service Element and Accounting Server. Also, implementations can tend to "drift apart", with one encoding better-supported than another. Unless all encodings are mandatory, implementors may find they are unable to interoperate because they picked the wrong encoding. [ACC-BKG] Mills, C., Hirsch, G. and G. Ruth, "Internet Accounting Background", RFC 1272, November 1991. [ASG-NBR] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700, October 1994. [ASN1] Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization, International Standard 8824, December 1987. [ATM-ACT] McCloghrie, K., Heinanen, J., Greene, W. and A. Prasad, "Accounting Information for ATM Networks", RFC 2512, February 1999.
[ATM-COLL] McCloghrie, K., Heinanen, J., Greene, W. and A. Prasad, " Managed Objects for Controlling the Collection and Storage of Accounting Information for Connection-Oriented Networks", RFC 2513, February 1999. [BER] Information processing systems - Open Systems Interconnection - Specification of Basic Encoding Rules for Abstract Notation One (ASN.1), International Organization for Standardization, International Standard 8825, December 1987. [DIAM-ACT] Arkko, J., Calhoun, P.R., Patel, P. and Zorn, G., "DIAMETER Accounting Extension", Work in Progress. [DIAM-AUTH] Calhoun, P.R. and Bulley, W., "DIAMETER User Authentication Extensions", Work in Progress. [DIAM-FRAM] Calhoun, P.R., Zorn, G. and Pan, P., "DIAMETER Framework Document", Work in Progress. [DSRV-ARC] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z. and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998. [HTML] Berners-Lee, T. and D. Connolly, "Hypertext Markup Language - 2.0", RFC 1866, November 1995. [HTTP] Fielding, R., Gettys, J., Mogul, J. Frystyk, H. and T. Berners-Lee, "Hypertext Transfer Protocol--HTTP/1.1", RFC 2068, January 1997. [ICAL-CORE] Dawson, F. and D. Stenerson, "Internet Calendaring and Scheduling Core Object Specification", RFC 2445, November 1998. [IIS-ARC] Braden, R., Clark, D. and S. Shenker, "Integrated Services in the Internet Architecture: an Overview", RFC 1633, June 1994. [IIS-SPEC] Shenker, S., Partridge, C. and R. Guerin, "Specification of Guaranteed Quality of Service", RFC 2212, September 1997. [ISDN-MIB] Roeck, G., "ISDN Management Information Base using SMIv2", RFC 2127, March 1997.
[ISO-DATE] "Data elements and interchange formats -- Information interchange -- Representation of dates and times", ISO 8601:1988. [MAIL] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES", STD 11, RFC 822, August 1982. [MD5] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April 1992. [MSIX-SPEC] Blount, A. and D. Young, "Metered Service Information Exchange 1.2", Work in Progress. [NEWS-MSGS] Horton, M. and R. Adams, "Standard for Interchange of USENET Messages", RFC 1036, December 1987. [NEWS-PROT] Kantor, B. and P. Lapsley, "Network News Transfer Protocol", RFC 977, February 1986. [NTP] Mills, D., "Network Time Protocol (NTP)", RFC 958, September 1985. [Q-825] "Specification of TMN applications at the Q3 interface: Call detail recording", ITU-T Recommendation Q.825, 1998. [RAD-ACT] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000. [RAD-EXT] Rigney, C., Willats, W. and Calhoun, P., "RADIUS Extensions", RFC 2869, June 2000. [RAD-PROT] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000. [RAD-TACC] Zorn, G., Mitton, D. and A. Aboba, "RADIUS Accounting Modifications for Tunnel Protocol Support", RFC 2867, June 2000. [RAP-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. [ROAM-ADIF] Aboba, B. and D. Lidyard, "The Accounting Data Interchange Format (ADIF)", Work in Progress. [ROAM-IMPL] Aboba, B., Lu, J., Alsop, J., Ding, J. and W. Wang, "Review of Roaming Implementations", RFC 2194, September 1997.
[RS-DS-OP] Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L., Speer, M., Braden, R., Davie, B., Wroclawski, J. and E. Felstaine, "A Framework For Integrated Services Operation Over Diffserv Networks", Work in Progress. [RSVP-ARC] Braden, R., Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource Reservation Protocol (RSVP) Version 1 Functional Specification", RFC 2205, September 1997. [RSVP-MIB] Baker, F., Krawczyk, J. and A. Sastry, "RSVP Management Information Base using SMIv2", RFC 2206, September 1997. [RTFM-ARC] Brownlee, N., Mills, C. and G. Ruth, "Traffic Flow Measurement: Architecture", RFC 2722, October 1999. [RTFM-MIB] Brownlee, N., "Traffic Flow Measurement: Meter MIB", Measurement: Architecture", RFC 2720, October 1999. [RTFM-NEWA] Handelman, S., Brownlee, N., Ruth, G. and S. Stibler, "New Attributes for Traffic Flow Measurement", RFC 2724, October 1999. [SIP-PROT] Handley, M., Schulzrinne, H., Schooler, E. and J. Rosenberg, "SIP: Session Initiation Protocol", RFC 2543, March 1999. [SMI-V2] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [SNMP-OVER] "AN OVERVIEW OF SNMP V2.0", Diversified Data Resources, Inc., http://www.ddri.com, 1999. [TIPHON] "Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON); Inter-domain pricing, authorization, and usage exchange", TS 101 321 V1.4.2, December 1998. [XML] Bray, T., J. Paoli, and C. Sperberg-McQueen, "Extensible Markup Language (XML) 1.0", W3C Recommendation, February 1998.
[XML-DATA] "XML Schema Part 2: Datatypes", W3C Working Draft 07 April 2000, April 2000. [XML-SCHM] "XML Schema Part 1: Structures", W3C Working Draft 7 April 2000, April 2000.
Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society.