INTERNET DRAFT Jari Arkko Category: Standards Track Oy LM Ericsson Ab Title: draft-calhoun-diameter-accounting-02.txt Pat R. Calhoun Date: December 1999 Sun Microsystems, Inc. Pankaj Patel Convergys Corporation Glen Zorn Microsoft Corporation DIAMETER Accounting Extension Status of this Memo This document is an individual contribution for consideration by the AAA Working Group of the Internet Engineering Task Force. Comments should be submitted to the diameter@ipass.com mailing list. Distribution of this memo is unlimited. This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at: http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at: http://www.ietf.org/shadow.html. Copyright (C) The Internet Society 1999. All Rights Reserved. Abstract The DIAMETER protocol provides Authentication and Authorization for dial-up PPP clients [2] and for Mobile-IP [3]. The ROAMOPS WG has Arkko et al. expires May 2000 [Page 1]
INTERNET DRAFT December 1999 been working on an accounting data format, called Accounting Data Interchange Format (ADIF) [10], as a method to transfer accounting information over a wide variety of transports. This extension describes how accounting records can be securely transmitted over the DIAMETER protocol. When combined with the Strong Security [9] extension, accounting records MAY traverse intermediate proxies in a secure fashion and is compatible with the referral broker model. This extension allows for both real-time and batched accounting transfers. Table of Contents 1.0 Introduction 1.1 Requirements language 1.2 Authorization-Server Directed Model 1.3 Protocol Messages 1.4 Fault Resilience 1.5 Session Records 1.6 Accounting in brokering environments 2.0 Command-Codes AVP Values 2.1 Accounting-Request (ACR) Command 2.2 Accounting-Answer (ACA) Command 2.3 Accounting-Poll-Ind (ACP) Command 3.0 Mandatory AVPs 3.1 Accounting-Record-Type AVP 3.2 ADIF-Record AVP 3.3 Accounting-Interim-Interval AVP 3.4 Accounting-Delivery-Max-Batch AVP 3.5 Accounting-Delivery-Max-Delay AVP 3.6 Accounting-Record-Number AVP 4.0 IANA Considerations 5.0 Security Considerations 6.0 Acknowledgments 7.0 References 8.0 Authors' Addresses 9.0 Full Copyright Statement 1.0 Introduction This accounting protocol is based on an authorization-server directed model with capabilities for both efficient batch and fast real-time delivery of accounting information. Several fault resilience methods [11] have been built in to the protocol in order minimize loss of accounting data in various fault situations and under different assumptions about the capabilities of the used devices. Arkko et al. expires May 2000 [Page 2]
INTERNET DRAFT December 1999 1.1 Requirements language In this document, the key words "MAY", "MUST, "MUST NOT", "optional", "recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as described in [6]. 1.2 Authorization-Server Directed Model The authorization-server directed model means that at authorization time, the device generating the accounting data gets information from the authorization server regarding the way accounting data shall be forwarded. This information includes accounting record timeliness requirements. As discussed in [11], batch transfer of accounting data is more CPU- and bandwidth efficient than real-time transfer. However, there are many applications where real-time transfer is a requirement for at least some of the accounting records. These applications include roaming, where most (local) accounting records can be transferred in batch mode, but roaming (visiting) accounting records should be transferred fast due to the needs of credit limit checks and fraud detection. For these reasons this accounting protocol defines both batch and real-time transfer modes, and allows their use simultaneously. The authorization server (chain) directs the selection of proper transfer strategy, based on its knowledge of the user and relationships of roaming partnerships. The server (or proxies in between) use the Accounting-Delivery-Max-Batch, Accounting-Delivery-Max-Delay, and Accounting-Interim-Interval AVPs to control the operation of the DIAMETER peer operating as a client. The first two attributes set the requirements in terms of number of records and maximum delay before accounting data transfer for this session SHOULD begin. The DIAMETER peer acting as a client MAY deliver the data earlier due to a full batch of records, device reboot, lack of memory, or explicit configuration. The DIAMETER client MUST begin the transfer in the given limits unless prevented from doing so by network partitions, failures of peers, network congestion, or client overload. The Accounting-Interim-Interval AVP, when present, instructs the DIAMETER node acting as a client to produce accounting records continuously even during a session. Typically, the authorization server uses a few batching/real-time classes, such as the local users whose data might be transferred once in an hour and the roaming users whose data would be transferred immediately. Each Accounting-Delivery-Max-Batch / Accounting- Delivery-Max-Delay AVP pair with different values forms one pool of Arkko et al. expires May 2000 [Page 3]
INTERNET DRAFT December 1999 accounting data in the DIAMETER node acting as a client. That is, a new record is placed to same pool as the previous one if the authorization server returned same values for both AVPs and the pool has not been emptied in between. The Extension number for this draft is five (5). This value is used in the Extension-Id Attribute value Pair (AVP) as defined in [7]. 1.3 Protocol Messages The DIAMETER peer, acting as a client, generating the accounting data will use the Accounting-Request message to send one or more accounting records to its peer. The receiver (server) MUST reply with the Accounting-Answer message with appropriate confirmations. It is possible that a DIAMETER Proxy breaks up a batch of accounting records and sends them towards different DIAMETER Home servers. In this case, it is possible that a separate Accounting-Answer message contain the response for each block. Therefore, a DIAMETER node MUST be prepared to handle this scenario. Upon receipt of an Accounting-Request, a home DIAMETER server MUST generate a response. A home server is the node that "owns" the realm portion of the user's NAI. The response includes the Result-Code, which MAY contain an error if the ADIF-Record, or some other AVP, is not acceptable. Each DIAMETER Accounting protocol message MAY be compressed using IPComp [12] in order to reduce the used network bandwidth. DIAMETER peers MUST use a negotiation mechanisms such as IKE [13] in order to ensure that both peers are able to handle IPComp. 1.4 Fault Resilience DIAMETER Base protocol [11] mechanisms are used to overcome small message loss and network faults of temporary nature. DIAMETER peers acting as clients MUST implement the use of alternate servers to guard against server failures and certain network failures. DIAMETER peers acting as servers or related off-line processing systems MUST detect duplicate accounting records caused by the sending of same record to several servers and duplication of messages in transit. This detection MUST be based on the inspection of the Session-Id [1] and Accounting-Record-Number AVP pairs. DIAMETER clients MAY have non-volatile memory for the safe storage of accounting records over reboots or extended network failures, network Arkko et al. expires May 2000 [Page 4]
INTERNET DRAFT December 1999 partitions, and server failures. If such memory is available the client SHOULD store new accounting records there as soon as the records are created and until a positive acknowledgement of their reception from the DIAMETER Server has been received. Upon a reboot, the client MUST starting sending the records in the non-volatile memory to the accounting server with appropriate modifications in termination cause, session length, and other relevant information in the records. A further extension of this protocol may include AVPs to control how many accounting records may at most be stored in the DIAMETER client without committing them to the non-volatile memory or transferring them to the DIAMETER server. The client SHOULD NOT remove the accounting data from any of its memory areas before the correct Accounting-Answer has been received. The client MAY remove oldest, undelivered or yet unacknowledged accounting data if it runs out of resources such as memory. It is an implementation dependent matter for the client to accept new sessions under this condition. 1.5 Session Records In all accounting records the Session-Id AVP, ADIF-Record AVP, and User-Name AVPs MUST be present. If strong authentication is required, as described in [9], the CMS-Data AVP may be used to authenticate the ADIF-Record AVP. It is not typically necessary, nor recommended, that the strong authentication cover any additional AVPs since the ADIF- Record, and associated CMS-Data, MAY need to be submitted to a third party (see section 1.6 below). However, if the accounting records are being in sent in batch mode, the sender can create several "blocks" of accounting records by making use of the AVP Tag field (bit 'T' [1]). Each block has a unique tag value, and an optional CMS-Data AVP. If it is known that multiple ADIF-Records are being sent to the same home DIAMETER server, it is possible to have one CMS-Data AVP cover multiple the ADIF-Records. This optimization reduces the crypto computation that would otherwise be necessary. Different types of session records are sent depending on the actual type of accounted service and the authorization server's directions for interim accounting. If the accounted service is a one-time event, meaning that the start and stop of the event are simultaneous, then the Accounting-Record-Type AVP MUST be present and set to the value EVENT_RECORD. Arkko et al. expires May 2000 [Page 5]
INTERNET DRAFT December 1999 If the accounted service is of a measurable length, then the AVP MUST use the values START_RECORD, STOP_RECORD, and possibly, INTERIM_RECORD. If the authorization server has directed interim accounting to be enabled for the session, but no interim interval was specified, two accounting records MUST be generated for each service of type session. When the initial Accounting-Request is sent for a given session is sent, the Accounting-Record-Type AVP MUST be set to the value START_RECORD. When the last Accounting-Request is sent, the value MUST be STOP_RECORD. If a specified interim interval exists, the DIAMETER client MUST produce additional records between the START_RECORD and STOP_RECORD, marked INTERIM_RECORD. The production of these records is directed both by Accounting-Interim-Interval as well as any re-authentication or re-authorization of the session. If a batch size of greater than 1 has been specified by the authorization server, then the DIAMETER client MUST ensure that new interim records overwrite previous interim records for the same session and batch as this reduces the amount of memory required to store the records. In effect, this means that interim records are delivered at least as often as dictated by Accounting-Delivery-Max-Delay. 1.6 Accounting in brokering environments The DIAMETER base protocol [1] describes brokers that provide redirect services, by allowing AAA servers within a roaming consortium to directly communicate. Referral services can be secured using the strong security extension defined in [9]. Since brokers can also provide settlement services, they typically need to be aware of the accounting information exchange, and since they are no longer part of the message exchange, the DIAMETER protocol MUST allow the broker to receive the accounting record. The strong security [9] provides the broker with the assurances it needs that both parties agreed with the accounting information submitted. When the local AAA server issues an Accounting-Request to the home AAA server, it includes an ADIF-Record AVP as well as a CMS-Data AVP [9], which contains the signature of the local AAA server. The home server MUST add it's own signature to the CMS-Data AVP, that covers both the ADIF-Record and the local AAA's signature. The whole is submitted to the local AAA server in the Accounting-Answer. The local AAA server MUST submit the ADIF-Record, and associated CMS-Data AVP to the broker. The broker can verify that both parties participated and accepted the accounting record, by validating the signatures. 2.0 Command-Codes AVP Values Arkko et al. expires May 2000 [Page 6]
INTERNET DRAFT December 1999 This section defines new Command-Code [1] values that MUST be supported by all DIAMETER implementations that conform to this specification. 2.1 Accounting-Request (ACR) Command The Accounting-Request command, indicated by the Command-Code AVP set to 271, is sent by a DIAMETER node, acting as a client, in order to exchange accounting information with a peer. The Accounting information is contained within an ADIF record, as described in [10]. The Accounting-Request command MAY contain accounting information for more than a single session, which allows it to send batched accounting information. When the batch mode is used, the session-Id AVP [1] MUST be present and the CMS-Data AVP [9] MAY be present, and MUST have a tag of the same value as the ADIF-Record AVP. When the Accounting-Request is being submitted to a broker, and includes the CMS-Data AVP [9], the CMS-Data AVP MUST be signed by both the local and home DIAMETER server using the countersignature procedures described in [9]. Message Format <Accounting-Request> ::= <DIAMETER Header> <Command-Code AVP = 271> <Host-IP-Address AVP> [<Host-Name AVP>] (<Session-Id AVP> && <Accounting-Record-Type> && <Accounting-Record-Number> && <User-Name AVP> && <ADIF-Record AVP> && <CMS-Data AVP>) [<Timestamp AVP> <Nonce AVP> <Integrity-Check-Value AVP>] 2.2 Accounting-Answer (ACA) Command The Accounting-Answer command, indicated by the Command-Code AVP set to 272, is used to acknowledge an Accounting-Request command. The Accounting-Answer command contains the same Session-Id and ADIF- Record AVPs that were sent in the Accounting-Request command. This can be signed using the CMS-Data AVP for strong AVP authentication, which MAY be used for the purposes of repudiation. Arkko et al. expires May 2000 [Page 7]
INTERNET DRAFT December 1999 Only the target DIAMETER Server, known as the home DIAMETER Server, SHOULD respond with the Accounting-Answer command. If the Accounting-Request command contained more than one ADIF-Record AVP, the Accounting-Answer SHOULD contain the same number of ADIF- Record AVPs. However, it is possible for the DIAMETER Server to acknowledge each ADIF-Record in a separate response. This allows the sender of the ADIF-Records to send a batch of records, whose final destination are different. Message Format <Accounting-Answer> ::= <DIAMETER Header> <Command-Code AVP = 272> <Result-Code AVP> <Host-IP-Address AVP> (<Session-Id AVP> && <Accounting-Record-Number> && <ADIF-Record AVP> && <CMS-Data AVP>) [<Timestamp AVP> <Nonce AVP> <Integrity-Check-Value AVP>] 2.3 Accounting-Poll-Ind (ACP) Command The Accounting-Poll-Ind command, indicated by the Command-Code AVP set to 273, is sent by a DIAMETER Server in order to force the peer to send current accounting data. This data MUST include not yet sent accounting records from completed sessions, as well as INTERIM_RECORD records from all ongoing sessions. The receiver MUST use the Accounting-Request command to send the accounting data. The use of Accounting-Poll-Ind is useful in situations where a DIAMETER server comes up after an unscheduled downtime, and wishes to synchronize with the client(s) sooner than at the end of the next INTERIM_RECORD or at the end of a session. Warning: The use of the Accounting-Poll-Ind message is discouraged in roaming networks, since it is unfeasible for a server to attempt to poll all of it's roaming partner's DIAMETER peers. Message Format <Accounting-Poll-Ind> ::= <DIAMETER Header> Arkko et al. expires May 2000 [Page 8]
INTERNET DRAFT December 1999 <Command-Code AVP = 273> <Host-IP-Address AVP> [<Host-Name AVP>] [<Timestamp AVP> <Nonce AVP> <Integrity-Check-Value AVP>] 3.0 Mandatory AVPs The following table describes the DIAMETER AVPs defined in the Mobie IP extension, their AVP Code values, types, possible flag values and whether the AVP MAY be encrypted. Irregular AVP Flag rules +-----+-----+------+-----+----+ Attribute Section Value | | |SHOULD| MUST|Encr| Attribute Name Code Defined Type | MUST| MAY | NOT | NOT|Cand| --------------------------------------------------+-----+------+-----+----+ Accounting-Record 480 3.1 Integer32| M | T,P | | V | Y | Type | | | | | | ADIF-Record 481 3.2 Data | M | T,P | | V | Y | Accounting-Interim- 482 3.3 Integer32| M | P | | T,V | Y | Interval | | | | | | Accounting-Delivery-483 3.4 Integer32| M | P | | T,V | Y | Max-Batch | | | | | | Accounting-Delivery-484 3.5 Integer32| M | P | | T,V | Y | Max-Delay | | | | | | Accounting-Record 485 3.6 Integer32| M | P | | T,V | Y | Number | | | | | | 3.1 Accounting-Record-Type AVP The Accounting-Record-Type AVP (AVP Code 480) is of type Interger32 and contains the type of accounting record that can be found in the corresponding ADIF-Record AVP. The following values are currently defined for the Accounting-Record-Type AVP: EVENT_RECORD 1 An Accounting Event Record is used to indicate a service of indivisible nature has occurred. This record contains all information relevant to the service, and is the only record of the service. START_RECORD 2 An Accounting Start, Interim, and Stop Records are used to Arkko et al. expires May 2000 [Page 9]
INTERNET DRAFT December 1999 indicate that a service of a measurable length has been given. An Accounting Start Record is used to initiate an accounting session, and contains accounting information that is relevant to the initiation of the session. INTERIM_RECORD 3 An Interim Accounting Record contains cumulative accounting information for an existing accounting session. Interim Accounting Records SHOULD be sent every time a re- authentication or re-authorization occurs. The selection of whether to use INTERIM_RECORD records is directed by the Accounting-Interim-Interval AVP. STOP_RECORD 4 An Accounting Stop Record is sent to terminate an accounting session and contains cumulative accounting information relevant to the existing session. 3.2 ADIF-Record AVP The ADIF-Record AVP (AVP Code 481) is of type Data and contains the ADIF payload, as defined in [10]. 3.3 Accounting-Interim-Interval AVP The Accounting-Interim-Interval AVP (AVP Code 482) is of type Integer32 and is sent from the DIAMETER authenticating/authorizing server to the DIAMETER client. The client uses information in this AVP to decide how and when to produce accounting records. With different values in this AVP, service sessions can result in one, two, or two+N accounting records, based on the needs of the home- organization. The following accounting record production behaviour is directed by the inclusion of this AVP: 1. The omission of the Accounting-Interim-Interval AVP or its inclusion with Value field set to 0 means that EVENT_RECORD, START_RECORD, and STOP_RECORD are produced, as appropriate for the service. 2. The inclusion of the AVP with Value field set to a non-zero value means that INTERIM_RECORD records MUST be produced between the START_RECORD and STOP_RECORD records. The Value field of this AVP is the nominal interval between these records in seconds. The DIAMETER node that originates the accounting information, known as the client, MUST produce the first INTERIM_RECORD record roughly at the time when this nominal Arkko et al. expires May 2000 [Page 10]
INTERNET DRAFT December 1999 interval has elapsed from the START_RECORD, the next one again as the interval has elapsed once more, and so on until the session ends and a STOP_RECORD record is produced. The client MUST ensure that the interim record production times are randomized so that large accounting message storms are not created either among records or around a common service start time. 3.4 Accounting-Delivery-Max-Batch AVP The Accounting-Delivery-Max-Batch AVP (AVP Code 483) is of type Integer32 and is included in an Accounting-Answer. This AVP controls how accounting data is transferred to the accounting server. The AVP sets the requirements in terms of number of locally collected records before accounting data transfer SHOULD begin. The DIAMETER node that receives this AVP MAY deliver the data earlier due to satisfying requirements set by Accounting-Delivery-Max-Delay, device reboot, lack of memory, or explicit configuration. The DIAMETER node MUST begin the transfer in the given limits unless prevented from doing so by network partitions, client or server failures, network congestion, or client overload. 3.5 Accounting-Delivery-Max-Delay AVP The Accounting-Delivery-Max-Delay AVP (AVP Code 484) is of type Integer32 and is included in an Accounting-Answer. This AVP controls how accounting data is transferred to the authorization request. The AVP sets the requirements in terms of maximum delay before accounting data transfer SHOULD begin. The DIAMETER node that receives this AVP MAY deliver the data earlier due to satisfying requirements set by Accounting-Delivery-Max-Batch, device reboot, lack of memory, or explicit configuration. The DIAMETER node MUST begin the transfer in the given limits unless prevented from doing so by network partitions, client or server failures, network congestion, or client overload. 3.6 Accounting-Record-Number AVP The Accounting-Record-Number AVP (AVP Code 485) is of type Integer32 and identifies this record within one session. As Session-Id AVPs are globally unique, the combination of Session-Id and Accounting- Record-Number AVPs is also globally unique, and can be used in matching accounting records with confirmations. An easy way to produce unique numbers is to set the value to 0 for records of type Arkko et al. expires May 2000 [Page 11]
INTERNET DRAFT December 1999 EVENT_RECORD and START_RECORD, and set the value to 1 for the first INTERIM_RECORD, 2 for the second, and so on until the value for STOP_RECORD is one more than for the last INTERIM_RECORD. 4.0 IANA Considerations The values for the Command-Code AVPs (section 2) is taken from the numbering space defined for Command Codes in [1]. The numbers for the various AVPs defined in section 3 were taken from the AVP numbering space defined in [1]. The numbering for the AVP and Command-Code AVP MUST NOT conflict with values specified in [1] and other DIAMETER related Internet Drafts. This document introduces the Accounting-Record-Type AVP, which contains pre-defined values. This document defines the values 1-3. All remaining values are available for assignment via a Designated Expert [8]. 5.0 Security Considerations This DIAMETER extension assumes that the accounting data is secured either through a hop-by-hop authentication mechanism, as described in [1], or using a strong authentication mechanism as defined in [9]. 6.0 Acknowledgments The authors would like to thank Nenad Trifunovic, Tony Johansson and Pankaj Patel for their participation in the Document Reading Party. Thanks to the various people that have contributed to accounting related requirements at the IETF's AAA Working Group and other related WGs. 7.0 References [1] P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, "DIAMETER Base Protocol", draft-calhoun-diameter-11.txt (work in progress), December 1999. [2] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "DIAMETER NASREQ Extension", draft-calhoun-diameter-nasreq-00.txt (work in progress), December 1999. [3] P. Calhoun, C. Perkins, "DIAMETER Mobile IP Extension", draft- calhoun-diameter-mobileip-04.txt (work in progress), December 1999. [4] C. Rigney, A. Rubens, W. Simpson, S. Willens, "Remote Arkko et al. expires May 2000 [Page 12]
INTERNET DRAFT December 1999 Authentication Dial In User Service (RADIUS)." RFC 2138, April 1997. [5] C. Rigney, "RADIUS Accounting." RFC 2139, April 1997. [6] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [7] G. Zorn, P. Calhoun, "Limiting Fraud in Roaming", draft-ietf- roamops-fraud-limit-00.txt (work in progress), May 1999. [8] Narten, Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998 [9] P. Calhoun, W. Bulley, S. Farrell, "DIAMETER Strong security Extension", draft-calhoun-diameter-strong-crypto.txt (work in progress), December 1999. [10] B. Aboba, D. Lidyard, "The Accounting Data Interchange Format (ADIF)", draft-ietf-roamops-actng-06.txt (work in progress), August 1999. [11] B. Aboba, J. Arkko. "Introduction to Accounting Management", draft-aboba-acct-01.txt (work in progress), June 1999. [12] A. Shacham, R. Monsour, R. Pereira, M. Thomas, "IP Payload Compression Protocol (IPComp)", RFC 2393, December 1998. [13] D. Harkins, D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. 8.0 Authors' Addresses Questions about this memo can be directed to: Jari Arkko Oy LM Ericsson Ab 02420 Jorvas Finland Phone: +358 40 5079256 E-Mail: Jari.Arkko@ericsson.com Pat R. Calhoun Network and Security Research Center, Sun Labs Sun Microsystems, Inc. 15 Network Circle Menlo Park, California, 94025 USA Phone: 1-650-786-7733 Fax: 1-650-786-6445 E-mail: pcalhoun@eng.sun.com Arkko et al. expires May 2000 [Page 13]
INTERNET DRAFT December 1999 Pankaj Patel Convergys Corporation 4600 Montgomery Road Cincinnati, OH 45212 USA Phone: 1-513-723-2018 E-Mail: pankaj.patel@convergys.com Glen Zorn Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA Phone: 1-425-703-1559 E-Mail: gwz@acm.org 9.0 Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this docu- ment itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Inter- net organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permis- sions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WAR- RANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Arkko et al. expires May 2000 [Page 14]