One document matched: draft-ietf-aaa-accounting-attributes-00.txt
Network Working Group Nevil Brownlee
INTERNET-DRAFT The University of Auckland
Category: Informational Alan Blount
<draft-ietf-aaa-accounting-attributes-00.txt> MetraTech Corp.
13 January 2000
Accounting Attributes and Record Formats
Status of this Memo
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Abstract
This draft summarises IETF and 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 draft discusses service definition independence, extensibility,
and versioning. Compound service definition capabilities are
described.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Notation . . . . . . . . . . . . . . . . . . . 3
3. Architecture Model . . . . . . . . . . . . . . . . . . . . . . 4
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4. IETF Documents . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1. RADIUS Attributes . . . . . . . . . . . . . . . . . . . . 5
4.2. DIAMETER . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2.1. DIAMETER Attributes . . . . . . . . . . . . . . . . . . . 7
4.3. ROAMOPS . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4. RTFM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4.1. RTFM Attributes . . . . . . . . . . . . . . . . . . . . . 8
4.5. ISDN MIB . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.5.1. ISDN Attributes . . . . . . . . . . . . . . . . . . . . . 10
4.6. AToMMIB . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.6.1. AToMMIB Attributes . . . . . . . . . . . . . . . . . . . . 11
4.7. QoS: RSVP and DIFFSERV . . . . . . . . . . . . . . . . . . . 11
4.7.1. QoS: RSVP and DIFFSERV Attributes . . . . . . . . . . . . 12
5. ITU-T Documents . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Q.825: Call Detail Recording . . . . . . . . . . . . . . . . 13
5.2. Q.825 Attributes . . . . . . . . . . . . . . . . . . . . . . 13
6. Other Documents . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. TIPHON: ETSI TS 101 321 . . . . . . . . . . . . . . . . . . 17
6.2. MSIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7. Accounting File and Record Formats . . . . . . . . . . . . . . 18
7.1. ASN.1 Records . . . . . . . . . . . . . . . . . . . . . . . 18
7.1.1. RTFM and AToMMIB . . . . . . . . . . . . . . . . . . . . . 18
7.1.2. Q.825 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.2. Binary Records . . . . . . . . . . . . . . . . . . . . . . . 18
7.2.1. RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.2.2. DIAMETER . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.3. Text Records . . . . . . . . . . . . . . . . . . . . . . . . 19
7.3.1. ROAMOPS . . . . . . . . . . . . . . . . . . . . . . . . . 19
8. AAA Requirements . . . . . . . . . . . . . . . . . . . . . . . 20
8.1. A Well-defined Set of Attributes . . . . . . . . . . . . . . 20
8.2. A Simple Interchange Format . . . . . . . . . . . . . . . . 21
9. Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.1. Record Format vs. Protocol . . . . . . . . . . . . . . . . . 22
9.2. Tagged, Typed Data . . . . . . . . . . . . . . . . . . . . . 22
9.2.1. Standard Type Definitions . . . . . . . . . . . . . . . . 22
9.3. Transaction Identifiers . . . . . . . . . . . . . . . . . . 23
9.4. Service Definitions . . . . . . . . . . . . . . . . . . . . 23
9.4.1. Service Independence . . . . . . . . . . . . . . . . . . . 23
9.4.2. Versioned Service Definitions . . . . . . . . . . . . . . 25
9.4.3. Relationships Among Usage Events . . . . . . . . . . . . . 25
9.4.4. Service Namespace Management . . . . . . . . . . . . . . . 26
10. Encodings . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11. Security Considerations . . . . . . . . . . . . . . . . . . . 27
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
13. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 30
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1. Introduction
This draft summarises IETF and ITU-T documents related to Accounting.
For those documents which describe Accounting Attributes (i.e. quan-
tities which can be measured and reported), an Attribute Summary is
given. Although several of the documents describe Attributes which
are similar, no attempt is made to identify those which are the same
in several documents. An extensible classification scheme for AAA
Accounting Attributes is proposed; it is a superset of the attributes
in all the documents summarised.
Many existing accounting record formats and protocols [RAD-ACC]
[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-ACC], none provide iden-
tification, type checking, or versioning support for defined group-
ings of attributes (service definitions). This draft makes a case
for well-defined services.
Advantages and disadvantages of integrated versus separate record
formats and transport protocols are discussed. This draft discusses
service definition independence, extensibility, and versioning. Com-
pound service definition capabilities are described.
2. Terminology and Notation
The following terms are used throughout the document.
Accounting Server
A network element that accepts Usage Events from Service Elements.
It acts as an interface to back-end rating and billing systems.
Attribute-Value Pair (AVP)
A representation for a Usage Attribute consisting of the name of
the Attribute and a value.
Property
A component of a Usage Event. A Usage Event describing a phone
call, for instance, might have a "duration" Property.
Service
A type of task that is performed by a Service Element for a Ser-
vice Consumer.
Service Consumer
Client of a Service Element. End-user of a network service.
Service Definition
A specification for a particular service. It is composed of a
name or other identifier, versioning information, and a collection
of Properties.
Service Element
A network element that provides a service to Service Consumers.
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Examples include RAS servers, voice and fax gateways, conference
bridges.
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.
3. Architecture Model
Service Elements provide Services to Service Consumers. Before,
while, and/or after services are provided, the Service Element
reports Usage Events to an Accounting Server. Alternately, the
Accounting Server may query the Service Element for Usage Events.
Usage events are sent singly or in bulk.
+------------+ +-----------+ +------------+
| Service |<----->| Service | Usage Events | Accounting |
| Consumer | +-->| Element |------------->| Server |
+------------+ | +-----------+ +------------+
|
+------------+ |
| Service |<--+
| Consumer |
+------------+
4. IETF Documents
In March 1999 there were at least 19 Internet Drafts and 8 RFCs con-
cerned with Accounting. These are summarised (by working group) in
the following sections.
4.1. RADIUS
The RADIUS protocol [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 informa-
tion 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-ACC].
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 now very widely used, and a number of significant new
extensions to it have been proposed. For example [RAD-EXT] discusses
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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.
4.1.1. RADIUS Attributes
Each RADIUS attribute is identified by an 8-bit number, referred to
as the RADIUS Type field. Up-to-date values of this field are speci-
fied in the most recent Assigned Numbers RFC [ASG-NBR], but the cur-
rent list is as follows:
RADIUS Attributes [RAD-PROT] 60 CHAP-Challenge
61 NAS-Port-Type
1 User-Name 62 Port-Limit
2 User-Password 63 Login-LAT-Port
3 CHAP-Password
4 NAS-IP-Address RADIUS Accounting Attributes
5 NAS-Port [RAD-ACC]
6 Service-Type
7 Framed-Protocol 40 Acct-Status-Type
8 Framed-IP-Address 41 Acct-Delay-Time
9 Framed-IP-Netmask 42 Acct-Input-Octets
10 Framed-Routing 43 Acct-Output-Octets
11 Filter-Id 44 Acct-Session-Id
12 Framed-MTU 45 Acct-Authentic
13 Framed-Compression 46 Acct-Session-Time
14 Login-IP-Host 47 Acct-Input-Packets
15 Login-Service 48 Acct-Output-Packets
16 Login-TCP-Port 49 Acct-Terminate-Cause
17 (unassigned) 50 Acct-Multi-Session-Id
18 Reply-Message 51 Acct-Link-Count
19 Callback-Number
20 Callback-Id RADIUS Extension Attributes
21 (unassigned) [RAD-EXT]
22 Framed-Route
23 Framed-IPX-Network 52 Acct-Input-Gigawords
24 State 53 Acct-Output-Gigawords
25 Class 54 Unused
26 Vendor-Specific 55 Event-Timestamp
27 Session-Timeout
28 Idle-Timeout 70 ARAP-Password
29 Termination-Action 71 ARAP-Features
30 Called-Station-Id 72 ARAP-Zone-Access
31 Calling-Station-Id 73 ARAP-Security
32 NAS-Identifier 74 ARAP-Security-Data
33 Proxy-State 75 Password-Retry
34 Login-LAT-Service 76 Prompt
35 Login-LAT-Node 77 Connect-Info
36 Login-LAT-Group 78 Configuration-Token
37 Framed-AppleTalk-Link 79 EAP-Message
38 Framed-AppleTalk-Network 80 Signature
39 Framed-AppleTalk-Zone
84 ARAP-Challenge-Response
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RADIUS Tunneling Attributes
[RAD-TACC]
51 Acct-Link-Count
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
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4.2. DIAMETER
The DIAMETER framework [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 vari-
ety of ways, the most useful feature is the ability to "proxy" mes-
sages across a set of DIAMETER servers (known as a proxy chain).
The DIAMETER Policy and Accounting Extension for SIP (Session Initia-
tion Protocol) document [DIAM-SIP] extends DIAMETER by adding a pol-
icy and accounting information exchange mechanism between a DIAMETER
policy server and a SIP proxy server.
A DIAMETER server is responsible for maintaining a user policy and
accounting database and a means to update it. A SIP proxy server
needs to contact a DIAMETER server during multimedia session setup
and teardown time to perform admission control and accounting tasks.
The exchange mechanism protocol does not make any assumption about
policy and billing algorithms at DIAMETER servers.
4.2.1. DIAMETER Attributes
DIAMETER AVPs are identified by a 16-bit number defined in [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 facil-
itate deployment. To this end, DIAMETER inherits the RADIUS
attributes, and only adds 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, *)
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33 (unassigned, *)
280 Filter-Rule
281 Framed-Password-Policy
600 SIP-Sequence
601 SIP-Call-ID
602 SIP-To
603 SIP-From
4.3. ROAMOPS
[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 com-
pactly 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.
4.4. RTFM
The RTFM Architecture [RTFM-ARC] provides a general method of measur-
ing 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 col-
lected 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.
4.4.1. RTFM Attributes
RTFM attributes are identified by a 16-bit attribute number.
The RTFM Attributes are:
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0 Null
1 Flow Subscript Integer Flow table info
4 Source Interface Integer Source Address
5 Source Adjacent Type Integer
6 Source Adjacent Address String
7 Source Adjacent Mask String
8 Source Peer Type Integer
9 Source Peer Address String
10 Source Peer Mask String
11 Source Trans Type Integer
12 Source Trans Address String
13 Source Trans Mask String
14 Destination Interface Integer Destination Address
15 Destination Adjacent Type Integer
16 Destination Adjacent Address String
17 Destination AdjacentMask String
18 Destination PeerType Integer
19 Destination PeerAddress String
20 Destination PeerMask String
21 Destination TransType Integer
22 Destination TransAddress String
23 Destination TransMask String
26 Rule Set Number Integer Meter attribute
27 Forward Bytes Integer Source-to-Dest counters
28 Forward Packets Integer
29 Reverse Bytes Integer Dest-to-Source counters
30 Reverse Packets Integer
31 First Time Timestamp Activity times
32 Last Active Time Timestamp
33 Source Subscriber ID String Session attributes
34 Destination Subscriber ID String
35 Session ID String
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)
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4.5. ISDN MIB
The ISDN MIB [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.
4.5.1. ISDN Attributes
The relevant object in the MIB is the ISDN bearer table, which has
entries in the following form:
IsdnBearerEntry ::=
SEQUENCE {
isdnBearerChannelType INTEGER,
isdnBearerOperStatus INTEGER,
isdnBearerChannelNumber INTEGER,
isdnBearerPeerAddress DisplayString,
isdnBearerPeerSubAddress DisplayString,
isdnBearerCallOrigin INTEGER,
isdnBearerInfoType INTEGER,
isdnBearerMultirate TruthValue,
isdnBearerCallSetupTime TimeStamp,
isdnBearerCallConnectTime TimeStamp,
isdnBearerChargedUnits Gauge32
}
4.6. AToMMIB
The "ATM Accounting Information MIB" document [ATM-ACT] describes a
large set of accounting objects for ATM connections. An administra-
tor 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 set-
ting bits in "list," which is an octet string. For example, the set
containing the number of received cells for the first eight ATM con-
nections 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].
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4.6.1. AToMMIB Attributes
Accounting data objects within the AToMMBIB are identified by the
last integer in their object identifiers.
The ATM accounting data objects are:
1 atmAcctngConnectionType
2 atmAcctngCastType
3 atmAcctngIfName
4 atmAcctngIfAlias
5 atmAcctngVpi
6 atmAcctngVci
7 atmAcctngCallingParty
8 atmAcctngCalledParty
9 atmAcctngCallReference
10 atmAcctngStartTime
11 atmAcctngCollectionTime
12 atmAcctngCollectMode
13 atmAcctngReleaseCause
14 atmAcctngServiceCategory
15 atmAcctngTransmittedCells
16 atmAcctngTransmittedClp0Cells
17 atmAcctngReceivedCells
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
4.7. QoS: RSVP and DIFFSERV
As we move towards providing more than simple "best effort" connec-
tivity, there has been a tremendous surge of interest in (and work
on) protocols to provide managed Quality of Service for Internet ses-
sions. This is of particular interest for the provision of "Inte-
grated Services," i.e. the transport of audio, video, real-time, and
classical data traffic within a single network infrastructure.
Two approaches to this have emerged so far:
- the Integrated Services architecture (intserv) [IIS-ARC], with its
accompanying signaling protocol, RSVP [RSVP-ARC], and RSVP's
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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 sub-
jected 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].
4.7.1. RSVP and DIFFSERV Attributes
A set of parameters for specifying a requested Quality of Service are
given in [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
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for that usage.
5. ITU-T Documents
5.1. Q.825: Call Detail Recording
ITU-T Recommendation Q.825 specifies how CDRs (Call Detail Records)
are produced and managed in Network Elements for POTS, ISDN and IN
(Intelligent Networks).
Uses of Call Detail information for various purposes are discussed.
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 speci-
fied 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.
5.2. Q.825 Attributes
The following attributes are defined. The explanations given are
very brief summaries only, see [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
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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 ele-
ment 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
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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
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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 dialled 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.
6. Other Documents
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6.1. TIPHON: ETSI TS 101 321
TIPHON [TIPHON] is an XML-based protocol, carried by HTTP, which han-
dles 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
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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.
6.2. MSIX
MSIX [MSIX-SPEC] is an XML-based open protocol transported by HTTP
that is used to make accounting service definitions and transmit ser-
vice 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.
7. Accounting File and Record Formats
7.1. ASN.1 Records
7.1.1. RTFM and AToMMIB
RTFM and AToMMIB use ASN.1 Basic Encoding Rules (BER) to encode lists
of attributes into accounting records. RTFM uses SNMP to retrieve
such records as BER strings, thus avoiding having to have an object
identifier for every object.
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.
7.1.2. Q.825
A Q.825 Call Record is an ASN.1 SET containing a specified group of
the Q.825 attributes. Call records would presumably be encoded as
BER strings before being collected for later processing.
7.2. Binary Records
7.2.1. RADIUS
Radius packets carry a sequence of attributes and their values, as
(Type, Length, Value) triples. The format of the value field is one
of four data types.
string 0-253 octets
address 32 bit value, most significant octet first.
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integer 32 bit value, most significant octet first.
time 32 bit value, most significant octet first -- seconds
since 00:00:00 GMT, January 1, 1970. The standard
Attributes do not use this data type but it is presented
here for possible use within Vendor-Specific attributes.
7.2.2. DIAMETER
Each DIAMETER message consists of multiple AVP's that are 32-bit
aligned, with the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Length | AVP Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (AVP contents) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code
Identifies the AVP; values of this field are defined below.
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
0x01: Mandatory-Support
0x02: SS-Encrypted-Data
0x03: PK-Encrypted-Data
0x04: Vendor-Specific-AVP
7.3. Text Records
7.3.1. ROAMOPS
ADIF (Accounting Data Interchange Format [ROAM-ADIF]) presents a gen-
eral, text-based format for accounting data files, described in a
straightforward BNF grammar. Its file header contains a field indi-
cating 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
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device: server3
description: Accounting Server 3
date: 02 Mar 1998 12:19:01 -0500
defaultProtocol: radius
#NAS-IP-Address
4: 204.45.34.12
#NAS-Port
5: 12
#NAS-Port-Type
61: 2
#User-Name
1: fred@bigco.com
#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
8. AAA Requirements
8.1. A Well-defined Set of Attributes
AAA needs a well-defined set of attributes whose values are to be
carried in records to or from accounting servers.
Most of the existing sets of documents described above include a set
of attributes, identified by small integers. It is likely that these
sets overlap, i.e. that some of them have attributes which represent
the same quantity using different names in different sets. This sug-
gests it might be possible to produce a single combined set of "uni-
versal" accounting attributes, but such a "universal" set does not
seem worthwhile.
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The ADIF approach of specifying a default protocol (from which
attributes are assumed to come) and identifying any exceptions seems
much more practical. We therefore propose that AAA should use the
ADIF convention (or something like it) to identify attributes,
together with all the sets of attributes covered by the [ASG-NBR]
document.
8.2. A Simple Interchange Format
AAA needs a simple interchange file format, to be used for accounting
data. Several schemes for packaging and transporting such data have
been described above.
The SNMP-based ones fit well within the context of an SNMP-based net-
work management system. RTFM and AToMMIB provide ways to reduce the
SNMP overhead for collecting data, and AToMMIB defines a complete
file format. Both provide good ways to collect accounting data.
As an interchange format, however, ASN.1-based schemes suffer from
being rather complex binary structures. This means that one requires
suitable tools to work with them, as compared to plain-text files
where one can use existing text-based utilities.
The binary schemes such as RADIUS and DIAMETER have simpler struc-
tures, but they too need purpose-built tools. For general use they
would need to be extended to allow them to use attributes from other
protocols.
From the point of view of being easy for humans to understand, ADIF
seems very promising. Of course any processing program would need a
suitable ADIF input parser, but using plain-text files makes them
much easier to understand.
TIPHON's record format is specified by an XML DTD. While XML repre-
sentations have the advantages of being well-known, they are limited
by XML's inability to specify type or other validity checking for
information within the tags. This situation will likely be improved
by the XML Schema [XML-SCHM] efforts that are underway, but a stable
reference is not yet available.
9. Issues
It is generally agreed that there is a need for a standard record
format and transport protocol for communication between Service Ele-
ments and Accounting Servers.
There is less agreement on the following issues:
o Separate or integral record format and transport protocol
o Standard set of base data types
o Service definitions: part of the protocol or separately defined
o Service definition namespace management
The following sections address these issues.
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9.1. Record Format vs. Protocol
All known Internet-centric billing protocols to date have an integral
record format. That is, the collection of Properties that describe a
Usage Event are specified as an integral part of the protocol, typi-
cally as a part of a "submit" message that is used to transmit a
Usage Event from a Service Entity to an Accounting Server.
It may be worthwhile to define a record format that is independent of
the transport protocol. Such a record format should support both
representation of individual records and records in bulk, as Usage
Events are often aggregated and transmitted in bulk.
A separate record format is useful for temporary file storage and for
archival purposes. Multiple transport protocols may be defined with-
out affecting the record format. The task of auditing is made easier
if a standard file format is defined. If a canonical format is used,
bulk records may be hashed with MD5 [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.
9.2. Tagged, Typed Data
Each Property is named by a textual identifier and carries 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. ETSI's TIPHON [TIPHON] specification takes this
approach. TS 101 321 also carries an Increment field, which denomi-
nates the Property's Unit of Measure field. Whether this additional
convenience is necessary is a matter for discussion.
9.2.1. Standard Type Definitions
It is useful to define a standard set of primitive data types to be
used by the record format and protocol. Looking at the prior art,
Diameter supports Data (arbitrary octets), String (UTF-8), Address
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(32 or 128 bit), Integer32, Integer64, and Time (32 bits, seconds
since 1970). MSIX [MSIX-SPEC] supports String, Unistring, Int32,
Float, Double, Boolean, and Timestamp. SNMP [SNMP] offers OBJECT
IDENTIFIER, NULL, OCTET STRING, IpAddress, NetworkAddress, Counter,
Gauge, TimeTicks, and Opaque.
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.
9.3. Transaction Identifiers
Each Usage Event requires its own unique identifier.
It is expedient to allow Service Elements to create their own unique
identifiers. In this manner, Usage Events can be created and
archived without the involvement of an Accounting Server.
A number of methods for creating unique identifiers are well known.
One popular identifier is an amalgamation of a monotonically increas-
ing sequence number, a large random value, a network element identi-
fier, and a timestamp. Another possible source of entropy is a hash
value of all or part of the record itself.
RFC 822 [MAIL], RFC 1036 [NEWS], and RFC 2445 [ICAL-CORE] give guid-
ance on the creation of good unique identifiers.
9.4. Service Definitions
A critical differentiator in accounting record formats and protocols
is their capability to account for arbitrary service usage. To date,
no accounting record format or protocol that can handle arbitrary
service definitions has achieved broad acceptance on the Internet.
This section analyzes the issues in service definition and makes a
case for a record format and protocol with the capability to carry
Usage Events for rich, independently-defined services.
9.4.1. Service Independence
It is informative to survey a number of popular Internet protocols
and examine their capacities for extension. These protocols can be
categorized into two broad categories--"complete" protocols that have
little provision for extension and "framework" protocols that are
incomplete, but coupled with extension or application documents pro-
vide only a basis for future extension.
Examples of "complete" protocols are NTP [NTP], NNTP [NNTP], RADIUS
Accounting [RAD-ACC], and HTML [HTML].
Network Time Protocol [NTP] defines everything. Aside from leaving
some field values "reserved for future use," all the fields are
fixed-width and completely defined. This is appropriate for a simple
protocol that solves a simple problem. The notion of "time" is
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unlikely to be extended (we hope).
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-ACC]. Perhaps
the second biggest 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.
HTML/2.0 [HTML] is mostly a "complete" protocol, but with W3C's
HTML/4.0, it 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 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-Encod-
ing, Accept-Encoding, and Transfer-Encoding header fields. New types
of content can be designated and carried by HTTP/1.1 without modifi-
cation to the HTTP protocol.
XML [XML] is the king-hell 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
or even involve the SNMP standard itself. From "An Overview of SNMP"
[SNMP-OVER]:
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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 "complete" protocols, with either a
completely defined service or set of services (RADIUS Accounting) or
with one or more services defined and provision for "extension" ser-
vices to be added to the protocol later (TIPHON). While the latter
is preferable, it would be better to have a more SNMP-like approach
where the accounting record format and protocol merely provide a
framework for service definition, and leave the task of service defi-
nition (and optionally standardization) to separate efforts. In this
manner, the accounting protocol itself would not have to be modified
to handle new services.
9.4.2. Versioned Service Definitions
Versioning is a naming and compatibility issue. Separate version
identifiers are useful in service definition because they enables
service definitions to be upgraded without a possibly awkward name
change. They also enable possible compatibility between different
versions of the same service.
An example could be the service definition of a phone call. Version
1 might define Properties for the start time, duration, and called
and calling party numbers. Later, version 2 is defined, which aug-
ments the former Service with a byte count. An Accounting Server,
aware of only Version 1, may accept Version 2 records, discarding the
additional information (forwards compatibility). Alternately, if an
Accounting Server is made aware of version 2, it could optionally
still accept version 1 records from Service Elements, provided it
does not require the additional information to properly account for
service usage (backwards compatibility).
9.4.3. Relationships Among Usage Events
A case that accounting record formats and protocols to date have
failed to sufficiently address is that of "compound" service descrip-
tion.
A compound service is a service that is described as a composition of
other services. A conference call, for example, is well described as
a number of point-to-point calls to a conference bridge. It is
important to account for the individual calls, rather than just sum-
ming up an aggregate, both for auditing purposes and to enable dif-
ferential rating. If these calls are to be reported to the Account-
ing Server individually, the Usage Events require a shared identifier
that can be used by the Accounting Server and other backend systems
to group the records together.
For a Service Element to report compound events over time as a
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succession of individual Usage Events, the accounting protocol
requires a facility to communicate that the compound event has
started and stopped. The "start" message can be implicit--the trans-
mission of the first Usage Event will suffice. An additional
semaphore is required to tell the Accounting Server that the compound
service is complete and may be further processed. This is necessary
to prevent the Accounting Server from prematurely processing compound
events that overlap the end of a billing period.
RADIUS Accounting has some provision for this sort of accounting with
its "Acct-Multi-Session-Id" field. Unfortunately, RADIUS Account-
ing's other shortcomings preclude it from being used in general pur-
pose service usage description.
9.4.4. Service Namespace Management
"Framework" protocols, as previously mentioned, do not define com-
plete schema for their payload. For interoperability to be achieved,
it must be possible for:
(1) content definers to specify definitions without conflicting with
the names of other definitions
(2) protocol users to find and use content definitions
Condition (1) can be readily managed through IANA assignment or by
using an existing namespace differentiator (for example, DNS).
Condition (2) is harder, and places considerable burden on the imple-
mentors. Their clients and servers must be able, statically or
dynamically, to find and validate definitions, and manage versioning
issues.
As previously mentioned, XML provides no facility for DTD discovery
or namespace management. XML, however, specifies only a document
format, and as such does not need to specify support for more "proto-
col" oriented problems.
For an accounting record format and protocol, an approach closer to
SNMP's is useful. SNMP uses an ISO-managed dotted-decimal namespace.
An IANA-managed registry of service types is a possibility. Another
possibility, used by MSIX [MSIX-SPEC], is for Service Element cre-
ators 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 possi-
ble for Service Element creators to directly supply accounting system
managers with the required definitions, via the network or by other
means.
10. Encodings
It may be useful to define more than one record encoding.
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A "verbose" XML encoding is useful in that it is easily implemented
and records can be syntactically verified with existing tools.
"Human-readable" protocols tend to have an edge on "bitfield" proto-
cols where ease of 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. 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 encod-
ing.
11. Security Considerations
This draft summarises many existing IETF and ITU documents; please
refer to the original documents for security considerations for their
particular protocols.
Security is of paramount concern in accounting. It must be possible
for the accounting protocol to be carried by a secure transport. A
canonical record format is useful so that regeneration of secure
record hashes is possible.
When dealing with accounting data files, one must of course take care
that their integrity and privacy are preserved. This document, how-
ever, is only concerned with the format of such files.
12. References
[ACC-BKG] Mills, C., Hirsch, G. and Ruth, G., "Internet
Accounting Background", RFC 1272, November 1991.
[ASG-NBR] Reynolds, J., Postel, J., "Assigned Numbers,"
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 Prasad,
A., "Accounting Information for ATM Networks,"
RFC 2512, February 1999.
[ATM-COLL] McCloghrie, K., Heinanen, J., Greene, W. and Prasad,
A., " Managed Objects for Controlling the Collection
and Storage of Accounting Information for Connection-
Oriented Networks," RFC 2513, February 1999.
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[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-AUTH] Calhoun, P.R. and Bulley, W., "DIAMETER User
Authentication Extensions," Internet Draft (Work in
progress), draft-calhoun-diameter-authent- ..
[DIAM-FRAM] Calhoun, P.R., Zorn, G. and Pan, P., "DIAMETER
Framework Document," Internet Draft (Work in
progress), draft-calhoun-diameter-framework- ..
[DIAM-SIP] Pan, P. and Clahoun, P., "DIAMETER: Policy and
Accounting Extension for SIP Framework Document,"
Internet Draft (Work in progress), draft-pan-diameter-sip-
[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., D. Connolly, "Hypertext Markup Language -
2.0", RFC 1866, November 1995.
[HTTP] Fielding, R., J. Gettys, J. Mogul, H. Frystyk, and
T. Berners-Lee. "Hypertext Transfer Protocol--HTTP/1.1",
RFC 2068, January 1997.
[ICAL-CORE] Dawson, F., D. Stenerson, "Internet Calendaring and
Scheduling Core Object Specification", RFC 2445, November
1998.
[IIS-ARC] Braden, R., Clark, D. and Shenker, S., "Integrated
Services in the Internet Architecture: an Overview",
RFC 1633, June 1994
[IIS-SPEC] Shenker, S., Partridge, C., Guerin, R.: "Specification of
Guaranteed Quality of Service," RFC 2212, 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", RFC 822, August 1982.
[MD5] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[MSIX-SPEC] Blount, A., D. Young, "Metered Service Information Exchange
1.2", Work in Progress, <draft-blount-acct-msix-00.txt>,
Brownlee, Blount [Page 28]
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July 1999.
[NEWS-MSGS] Horton, M., R. Adams, "Standard for Interchange of USENET
Messages", RFC 1036, December 1987.
[NEWS-PROT] Kantor, B., P. Lapsley, "Network News Transfer Protocol"
RFC 977, Febuary 1986.
[NTP] Mills, D.L., "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-ACC] Rigney, C., "RADIUS Accounting," RFC 2139, April 1997.
[RAD-EXT] Rigney, C., Willats, W. and Calhoun, P., "RADIUS
Extensions," Internet Draft (Work in progress),
draft-ietf-radius-ext- ..
[RAD-PROT] Rigney, C., Rubens, A., Simpson, W. and Willens, S.,
"Remote Authentication Dial In User Service (RADIUS),"
RFC 2138, April 1997.
[RAD-RECX] Calhoun, P.R. and Beadles, M.., "RADIUS Accounting
Interim Accounting Record Extension," Internet Draft
(Work in progress), draft-ietf-radius-acct-interim- ..
[RAD-TACC] Zorn, G., Mitton, D. and Aboba, A.,"RADIUS Accounting
Modifications for Tunnel Protocol Support,"
(Work in progress), draft-ietf-radius-tunnel-acct- ..
[RAP-COPS] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan, R.
and Sastry, A., "The COPS (Common Open Policy Service)
draft-ietf-rap-cops- ..
[ROAM-ADIF] Aboba, B and Lidyard, D., "The Accounting Data
Interchange Format (ADIF)," Internet Draft (Work
in progress), draft-ietf-roamops-actng- ..
[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. and Braden, R., "Interoperation of RSVP/Intserv
and Diffserv Networks," Internet Draft (Work in Progress),
draft-ietf-issll-diffserv-rsvp- ..
[RSVP-ARC] Braden, R., Zhang, L., Berson, S., Herzog, S. and
Jamin, S., "Resource Reservation Protocol (RSVP) Version 1
Functional Specification", RFC 2205, September 1997
Brownlee, Blount [Page 29]
INTERNET-DRAFT January 2000
[RSVP-MIB] Baker, F., Krawczyk, J. and Sastry, A., "RSVP Management
Information Base," Internet Draft (Work in Progress),
draft-ietf-rsvp-mib-v2- ..
[RTFM-ARC] Brownlee, N., Mills, C., and Ruth, G., "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 Stibler, S.,
"New Attributes for Traffic Flow Measurement",
RFC 2724, October 1999.
[SIP-PROT] Handley, M.,Schulzrinne, H.,Schooler, E. and
Rosenberg, J., "SIP: session initiation protocol,"
RFC 2543, March 1999.
[SNMP] Case, J., M. Fedor, M. Schoffstall, J. Davin, "A Simple
Network Management Protocol (SNMP)", RFC 1157, May 1990
[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-SCHM] "XML Schema Part 1: Structures", W3C Working Draft 17,
December 1999.
13. Authors' Addresses
Alan Blount
MetraTech Corp.
330 Bear Hill Road
Waltham, MA 02451
Email: blount@alum.mit.edu
Nevil Brownlee
Information Technology Systems & Services
The University of Auckland
Phone: +64 9 373 7599 x8941
E-mail: n.brownlee@auckland.ac.nz
Brownlee, Blount [Page 30]
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