HTTP/1.1 200 OK Date: Tue, 09 Apr 2002 05:46:39 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Thu, 02 Mar 2000 18:38:00 GMT ETag: "3049f0-80ba-38beb508" Accept-Ranges: bytes Content-Length: 32954 Connection: close Content-Type: text/plain NASREQ Working Group M. Beadles INTERNET-DRAFT SmartPipes, Inc. Category: Informational D. Mitton 2 March 2000 Nortel Networks Criteria for Evaluating Network Access Server Protocols draft-ietf-nasreq-criteria-04.txt 1. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working docu- ments of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working doc- uments 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. The distribution of this draft is unlimited. It is filed as and expires September 2000. Please send comments to the authors. 2. Copyright Statement Copyright (C) The Internet Society 2000. All Rights Reserved. 3. Abstract This document defines requirements for protocols used by Network Access Servers (NAS). Protocols used by NAS's may be divided into four spaces: Access protocols, Network protocols, AAA protocols, and Management pro- tocols. Primary attention is given to setting requirements for AAA Beadles, Mitton Informational [Page 1] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 protocols, since that space is currently the least well defined. 4. 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 [KEYWORDS]. 5. Introduction This document defines requirements for protocols used by Network Access Servers (NAS). Protocols used by NAS's may be divided into four spaces: Access protocols, Network protocols, AAA protocols, and Device Manage- ment protocols. The primary focus of this document is on AAA protocols. The reference model of a NAS used by this document, and the analysis of the functions of a NAS which led to the development of these require- ments, may be found in [NAS-MODEL]. 6. Access Protocol Requirements There are three basic types of access protocols used by NAS's. First are the traditional telephony-based access protocols, which interface to the NAS via a modem or terminal adapter or similar device. These protocols typically support asynchronous or synchronous PPP [PPP] carried over a telephony protocol. Second are broadband pseudo-telephony access proto- cols, which are carried over xDSL or cable modems, for example. These protocols typically support an encapsulation method such as PPP over Ethernet [PPPOE]. Finally are the virtual access protocols used by NAS's that terminate tunnels. One example of this type of protocol is L2TP [L2TP]. It is a central assumption of the NAS model used here that a NAS accepts multiple point-to-point links via one of the above access protocols. Therefore, at a minimum, any NAS access protocol MUST be able to carry PPP. The exception to this requirement is for NAS's that support legacy text login methods such as telnet [TELNET], rlogin, or LAT. Only these access protocols are exempt from the requirement to support PPP. Beadles, Mitton Informational [Page 2] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 7. Network Protocol Requirements The network protocols supported by a NAS depend entirely on the kind of network to which a NAS is providing access. This document does not impose any additional requirements on network protocols beyond the pro- tocol specifications themselves. For example, if a NAS that serves a routed network includes internet routing functionality, then that NAS must adhere to [ROUTING-REQUIREMENTS], but there are no additional pro- tocol requirements imposed by virtue of the device being a NAS. 8. AAA Protocol Requirements 8.1. General protocol characteristics There are certain general characteristics that any AAA protocol used by NAS's must meet. Note that the transport requirements for authentica- tion/authorization are not necessarily the same as those for account- ing/auditing. An AAA protocol suite MAY use the same transport and pro- tocol for both functions, but this is not strictly required. 8.1.1. Transport requirements 8.1.1.1. Transport independence The AAA protocol MUST be transport independent, and MUST be capable of using both TCP and UDP as a transport. Additionally, the AAA protocol SHOULD be designed to easily support any new transport protocols devel- oped by the Internet standards community. 8.1.1.2. Scalability Very large scale NAS's that serve up to thousands of simultaneous ses- sions are now being deployed. And a single server system may service a large number of ports. This means that, in the extreme, there may be an almost constant exchange of many small packets between the NASes and the AAA server. An AAA protocol transport SHOULD support being optimized for a long-term exchange of small packets in a stream between a pair of hosts. Beadles, Mitton Informational [Page 3] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 The protocol MUST be designed to support a large number of ports, clients, and concurrent sessions. Examples of poor design would include message identifiers which values are so small that queues and reception windows wrap under load, unique session identifier ranges that are so small that they wrap within the lifetime of potential long sessions, counter values that cannot accomodate reasonable current and future bandwidth usage, and computational processes with high overhead that must be performed frequently. 8.1.1.3. Support for Multiple AAA Servers and Failure Recovery In order to operationally support large loads, load balancing and fail- over to multiple AAA servers will be required. The AAA protocol MUST provide for NAS's to balance individual AAA requests between two or more AAA servers. The load balancing mechanism SHOULD be built in to the AAA protocol itself. The AAA protocol MUST be able to detect a failure of the transport pro- tocol to deliver a message or messages within a known and controllable time period, so it can engage retransmission or server fail-over pro- cesses. The reliability and robustness of authentication requests MUST be predicable and configurable. The AAA protocol design MUST NOT introduce a single point of failure during the AAA process. The AAA protocol MUST allow any sessions between a NAS and a given AAA server to fail-over to a secondary server without loss of state information. This fail-over mechanism SHOULD be built in to the AAA protocol itself. 8.1.1.4. Support for Multiple Administrative Domains NAS's operated by one authority provide network access services for clients operated by another authority, to network destinations operated by yet another authority. This type of arrangement is of growing impor- tance; for example, dial roaming is now a nearly ubiquitous service. Therefore, the AAA protocol MUST support AAA services that travel between multiple domains of authority. The AAA protocol MUST NOT use a model that assumes a single domain of authority. The AAA protocol MUST NOT dictate particular business models for the relationship between the administrative domains. The AAA protocol MUST Beadles, Mitton Informational [Page 4] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 support proxy, and in addition SHOULD support other multi-domain rela- tionships such as brokering and referral. The AAA protocol MUST also meet the protocol requirements specified in [ROAMING-REQUIREMENTS]. 8.1.2. Attribute-Value Protocol Model Years of operational experience with AAA protocols and NAS's has proven that the Attribute-Value protocol model is an optimal representation of AAA data. The protocol SHOULD use an Attribute-Value representation for AAA data. This document will assume such a model. Even if the AAA pro- tocol does not use this as an on-the-wire data representation, Attribute-Value can serve as abstraction for discussing AAA information. Experience has also shown that attribute space tends to run out quickly. In order to provide room for expansion in the attribute space, the AAA protocol MUST support a minimum of 64K Attributes (16 bits), each with a minimum length of 64K (16 bits). 8.1.2.1. Attribute Data Types The AAA protocol MUST support simple attribute data types, including integer, enumeration, text string, IP address, and date/time. The AAA protocol MUST also provide some support for complex structured data types. Wherever IP addresses are carried within the AAA protocol, the protocol MUST support both IPv4 and IPv6 [IPV6] addresses. Wherever text information is carried within the AAA protocol, the protocol MUST comply with the IETF Policy on Character Sets and Languages [RFC 2277]. 8.1.2.2. Minimum Set of Attributes At a minimum, the AAA protocol MUST support, or be easily extended to support, the set of attributes supported by RADIUS [RADIUS] and RADIUS Accounting [RADIUS-ACCOUNTING]. If the base AAA protocol does not sup- port this complete set of attributes, then an extension to that protocol MUST be defined which supports this set. Beadles, Mitton Informational [Page 5] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 8.1.2.3. Attribute Extensibility NAS and AAA development is always progressing. In order to prevent the AAA protocol from being a limiting factor in NAS and AAA Server develop- ment, the AAA protocol MUST provide a built-in extensibility mechanism, which MUST include a means for adding new standard attribute extensions. This MUST include a method for registering or requesting extensions through IANA, so that long-term working group involvement is not required to create new attribute types. Ideally, the AAA protocol SHOULD separate specification of the transport from specification of the attributes. The AAA protocol MUST include a means for individual vendors to add value through vendor-specific attributes and SHOULD include support for vendor-specific data types. 8.1.3. Security Requirements 8.1.3.1. Mutual Authentication It is poor security practice for a NAS to communicate with an AAA server that is not trusted, and vice versa. The AAA protocol MUST provide mutual authentication between AAA server and NAS. 8.1.3.2. Shared Secrets At a minimum, the AAA protocol SHOULD support use of a secret shared pairwise between each NAS and AAA server to mutually verify identity. This is intended for small-scale deployments. The protocol MAY provide stronger mutual security techniques. 8.1.3.3. Public Key Security AAA server/NAS identity verification based solely on shared secrets can be difficult to deploy properly at large scale, and it can be tempting for NAS operators to use a single shared secret (that rarely changes) across all NAS's. This can lead to an easy compromise of the secret. Therefore, the AAA protocol MUST also support mutual verification of identity using a public-key infrastructure that supports expiration and Beadles, Mitton Informational [Page 6] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 revocation of keys. 8.1.3.4. Encryption of Attributes Some attributes are more operationally sensitive than others. Also, in a multi-domain scenario, attributes may be inserted by servers from dif- ferent administrative domains. Therefore, the AAA protocol MUST support selective encryption of attributes on an attribute-by-attribute basis, even within the same message. This requirement applies equally to Authentication, Authorization, and Accounting data. 8.2. Authentication and User Security Requirements 8.2.1. Authentication protocol requirements End users who are requesting network access through a NAS will present various types of credentials. It is the purpose of the AAA protocol to transport these credentials between the NAS and the AAA server. 8.2.1.1. Bi-directional Authentication The AAA protocol MUST support transport of credentials from the AAA server to the NAS, between the User and the NAS, and between the NAS and the AAA server. 8.2.1.2. Periodic Re-Authentication The AAA protocol MUST support re-authentication at any time during the course of a session, initiated from either the NAS or the AAA server. This is a requirement of CHAP. [CHAP] 8.2.1.3. Multi-phase Authentication The AAA protocol MUST be able to support multi-phase authentication methods, including but not limited to support for: Beadles, Mitton Informational [Page 7] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 -Text prompting from the NAS to the user -A series of binary challenges and responses of arbitrary length -An authentication failure reason to be transmitted from the NAS to the user -Callback to a pre-determined phone number 8.2.1.4. Extensible Authentication Types Security protocol development is going on constantly as new threats are identified and better cracking methods are developed. Today's secure authentication methods may be proven insecure tomorrow. The AAA proto- col MUST provide some support for addition of new authentication creden- tial types. 8.2.2. Authentication Attribute Requirements In addition to the minimum attribute set, the AAA protocol must support and define attributes that provide the following functions: 8.2.2.1. PPP Authentication protocols Many authentication protocols are defined within the framework of PPP. The AAA protocol MUST be able to act as an intermediary protocol between the authenticatee and the authenticator for the following authentication protocols: -PPP Password Authentication Protocol [PPP] -PPP Challenge Handshake Authentication Protocol [CHAP] -PPP Extensible Authentication Protocol [EAP] 8.2.2.2. User Identification The following are common types of credentials used for user identifica- tion. The AAA protocol MUST be able to carry the following types of identity credentials: Beadles, Mitton Informational [Page 8] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 -A user name in the form of a Network Access Identifier [NAI]. -An Extensible Authentication Protocol [EAP] Identity Request Type packet. -Telephony dialing information such as Dialed Number Identification Service (DNIS) and Caller ID. If a particular type of authentication credential is not needed for a particular user session, the AAA protocol MUST NOT require that dummy credentials be filled in. That is, the AAA protocol MUST support autho- rization by identification or assertion only. 8.2.2.3. Authentication Credentials The following are common types of credentials used for authentication. The AAA protocol MUST be able to carry the following types of authenti- cating credentials at a minimum: -A secret or password. -A response to a challenge presented by the NAS to the user -A one-time password -An X.509 digital certificate [X.509] -A Kerberos v5 ticket [KERBEROS] 8.2.3. Authentication Protocol Security Requirements 8.2.3.1. End-to-End Hiding of Credentials Where passwords are used as authentication credentials, the AAA protocol MUST provide a secure means of hiding the password from intermediates in the AAA conversation. Where challenge/response mechanisms are used, the AAA protocol MUST also prevent against replay attacks. Beadles, Mitton Informational [Page 9] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 8.3. Authorization, Policy, and Resource management 8.3.1. Authorization Protocol Requirements In all cases, the protocol MUST specify that authorization data sent from the NAS to the AAA server is to be regarded as information or "hints", and not directives. The AAA protocol MUST be designed so that the AAA server makes all final authorization decisions and does not depend on a certain state being expected by the NAS. 8.3.1.1. Dynamic Authorization The AAA protocol MUST support dynamic re-authorization at any time dur- ing a user session. This re-authorization may be initiated in either direction. This dynamic re-authorization capability MUST include the capability to request a NAS to disconnect a user on demand. 8.3.1.2. Resource Management Resource management MUST be supported on demand by the NAS or AAA Server at any time during the course of a user session. 8.3.2. Authorization Attribute Requirements 8.3.2.1. Authorization Attribute Requirements - Access Restrictions The AAA protocol serves as a primary means of gathering data used for making Policy decisions for network access. Therefore, the AAA protocol MUST allow network operators to make policy decisions based on the fol- lowing parameters: -Time/day restrictions. The AAA protocol MUST be able to provide an unambiguous time stamp, NAS time zone indication, and date indi- cation to the AAA server in the Authorization information. -Location restrictions: The AAA protocol MUST be able to provide an unambiguous location code that reflects the geographic location Beadles, Mitton Informational [Page 10] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 of the NAS. Note that this is not the same type of thing as either the dialing or dialed station. -Dialing restrictions: The AAA protocol MUST be able to provide accurate dialed and dialing station indications. -Concurrent login limitations: The AAA protocol MUST allow an AAA Server to limit concurrent logins by a particular user or group of users. This mechanism does not need to be explicitly built into the AAA protocol, but the AAA protocol must provide sufficient authorization information for an AAA server to make that determi- nation through an out-of-band mechanism. 8.3.2.2. Authorization Attribute Requirements - Authorization Profiles The AAA protocol is used to enforce policy at the NAS. Essentially, on granting of access, a particular access profile is applied to the user's session. The AAA protocol MUST at a minimum provide a means of applying profiles containing the following types of information: -IP Address assignment: The AAA protocol MUST provide a means of assigning an IPv4 or IPv6 address to an incoming user. -Protocol Filter application: The AAA protocol MUST provide a means of applying IP protocol filters to user sessions. Two dif- ferent methods MUST be supported. First, the AAA protocol MUST provide a means of selecting a proto- col filter by reference to an identifier, with the details of the filter action being specified out of band. The AAA protocol SHOULD define this out-of-band reference mechanism. Second, the AAA protocol MUST provide a means of passing a protocol filter by value. This means explicit passing of pass/block infor- mation by address range, TCP/UDP port number, and IP protocol num- ber at a minimum. -Compulsory Tunneling: The AAA protocol MUST provide a means of directing a NAS to build a tunnel or tunnels to a specified end- point. It MUST support creation of multiple simultaneous tunnels in a specified order. The protocol MUST allow, at a minimum, specification of the tunnel endpoints, tunneling protocol type, underlying tunnel media type, and tunnel authentication credentials (if required by the tunnel type). The AAA protocol MUST support at least the creation of tunnels using the L2TP [L2TP], ESP [ESP], and Beadles, Mitton Informational [Page 11] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 AH [AH] protocols. The protocol MUST provide means of adding new tunnel types as they are standardized. -Routing: The AAA protocol MUST provide a means of assigning a particular static route to an incoming user session. -Expirations/timeouts: The AAA protocol MUST provide a means of communication session expiration information to a NAS. Types of expirations that MUST be supported are: total session time, idle time, total bytes transmitted, and total bytes received. -Quality of Service: The AAA protocol MUST provide a means for supplying Quality of Service parameters to the NAS for individual user sessions. 8.3.2.3. Resource Management Requirements The AAA protocol is a means for network operators to perform management of network resources. The AAA protocol MUST provide a means of collect- ing resource state information, and controlling resource allocation for the following types of network resources. -Network bandwidth usage per session, including multilink sessions. -Access port usage, including concurrent usage and usage pools. -Connect time. -IP Addresses and pools. -Compulsory tunnel limits. 8.3.3. Authorization Protocol Security Requirements 8.3.3.1. Security of Compulsory Tunnel Credentials When an AAA protocol passes credentials that will be used to authenti- cate compulsory tunnels, the AAA protocol MUST provide a means of secur- ing the credentials from end-to-end of the AAA conversation. The AAA protocol MUST also provide protection against replay attacks in this situation. Beadles, Mitton Informational [Page 12] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 8.4. Accounting and Auditing Requirements 8.4.1. Accounting Protocol Requirements 8.4.1.1. Guaranteed Delivery The accounting and auditing functions of the AAA protocol are used for network planning, resource management, policy decisions, and other func- tions that require accurate knowledge of the state of the NAS. NAS operators need to be able to engineer their network usage measurement systems to a predictable level of accuracy. Therefore, an AAA protocol MUST provide a means of guaranteed delivery of accounting information between the NAS and the AAA Server(s). 8.4.1.2. Real Time Accounting NAS operators often require a real time view onto the status of sessions served by a NAS. Therefore, the AAA protocol MUST support real-time delivery of accounting and auditing information. In this context, real time is defined as accounting information delivery beginning within one second of the triggering event. 8.4.1.3. Batch Accounting The AAA protocol SHOULD also support delivery of stored accounting and auditing information in batches (non-real time). 8.4.1.4. Accounting Time Stamps There may be delays associated with the delivery of accounting informa- tion. The NAS operator will desire to know the time an event actually occurred, rather than simply the time when notification of the event was received. Therefore, the AAA protocol MUST carry an unambiguous time stamp associated with each accounting event. This time stamp MUST be unambiguous with regard to time zone. Note that this assumes that the NAS has access to a reliable time source. Beadles, Mitton Informational [Page 13] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 8.4.1.5. Accounting Events At a minimum, the AAA protocol MUST support delivery of accounting information triggered by the following events: -Start of a user session -End of a user session -Expiration of a predetermined repeating time interval during a user session. The AAA protocol MUST provide a means for the AAA server to request that a NAS use a certain interval accounting time. -Dynamic re-authorization during a user session (e.g., new resources being delivered to the user) -Dynamic re-authentication during a user session 8.4.1.6. On-Demand Accounting NAS operators need to maintain an accurate view onto the status of ses- sions served by a NAS, even through failure of an AAA server. There- fore, the AAA protocol MUST support a means of requesting current ses- sion state and accounting from the NAS on demand. 8.4.2. Accounting Attribute Requirements At a minimum, the AAA protocol MUST support delivery of the following types of accounting/auditing data: -All parameters used to authenticate a session. -Details of the authorization profile that was applied to the ses- sion. -The duration of the session. -The cumulative number of bytes sent by the user during the ses- sion. -The cumulative number of bytes received by the user during the session. Beadles, Mitton Informational [Page 14] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 -The cumulative number of packets sent by the user during the ses- sion. -The cumulative number of packets received by the user during the session. -Details of the access protocol used during the session (port type, connect speeds, etc.) 8.4.3. Accounting Protocol Security Requirements 8.4.3.1. Integrity and Confidentiality Note that accounting and auditing data are operationally sensitive information. The AAA protocol MUST provide a means to assure end-to-end integrity of this data. The AAA protocol SHOULD provide a means of assuring the end-to-end confidentiality of this data. 8.4.3.2. Auditibility Network operators use accounting data for network planning, resource management, and other business-critical functions that require confi- dence in the correctness of this data. The AAA protocol SHOULD provide a mechanism to ensure that the source of accounting data cannot easily repudiate this data after transmission. 9. Device Management Protocols This document does not specify any requirements for device management protocols. 10. Acknowledgments Many of the requirements in this document first took form in Glen Zorn's "Yet Another Authentication Protocol (YAAP)" document, for which grate- ful acknowledgment is made. Beadles, Mitton Informational [Page 15] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 11. Security considerations See above for security requirements for the NAS AAA protocol. Where an AAA architecture spans multiple domains of authority, AAA information may need to cross trust boundaries. In this situation, a NAS might operate as a shared device that services multiple administra- tive domains. Network operators are advised take this into considera- tion when deploying NAS's and AAA Servers. 12. IANA Considerations This document does not directly specify any IANA considerations. How- ever, the following recommendations are made: Future development and extension of an AAA protocol will be made much easier if new attributes and values can be requested or registered directly through IANA, rather than through an IETF Standardization pro- cess. The AAA protocol might use enumerated values for some attributes, which enumerate already-defined IANA types (such as protocol number). In these cases, the AAA protocol SHOULD use the IANA assigned numbers as the enu- merated values. 13. References [KEYWORDS] S. Bradner. "Key words for use in RFCs to Indicate Require- ment Levels." RFC 2119, March 1997. [NAS-MODEL] D. Mitton, M. Beadles. "Network Access Server Requirements Next Generation (NASREQNG) NAS Model." draft-ietf-nasreq-nas- model-01.txt, Work in progress. [PPPOE] L. Mamakos, et al. "A Method for Transmitting PPP Over Ethernet (PPPoE)." RFC 2516, February 1999. [L2TP] W. M. Townsley, et al. "Layer Two Tunneling Protocol (L2TP)." RFC 2661, August 1999. Beadles, Mitton Informational [Page 16] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 [PPP] W. Simpson. "The Point-to-Point Protocol (PPP)." RFC 1661, Day- dreamer, July 1994. [TELNET] J. Postel, J. Reynolds. "Telnet Protocol Specification." STD 8, RFC 854, May 1983. [ROUTING-REQUIREMENTS] F. Baker. "Requirements for IP Version 4 Routers." RFC 1812, June 1995. [IPV6] S. Deering, R. Hinden. "Internet Protocol, Version 6 (IPv6) Specification." RFC 2460, December 1998. [RFC 2277] H. Alvestrand. "IETF Policy on Character Sets and Lan- guages." RFC 2277, January 1998. [CHAP] W. Simpson. "PPP Challenge Handshake Authentication Protocol (CHAP)." RFC 1994, August 1996. [EAP] L. Blunk, J. Vollbrecht. "PPP Extensible Authentication Protocol (EAP)." RFC 2284, March 1998. [NAI] B. Aboba, M. Beadles. "The Network Access Identifier." RFC 2486, January 1999. [X.509] ITU-T Recommendation X.509 (1997 E): Information Technology - Open Systems Interconnection - The Directory: Authentication Framework, June 1997. [KERBEROS] J. Kohl, C. Neuman. "The Kerberos Network Authentication Service (V5)." RFC 1510, September 1993. [ESP] S. Kent, R. Atkinson. "IP Encapsulating Security Payload (ESP)." RFC 2406, November 1998. [AH] S. Kent, R. Atkinson. "IP Authentication Header (AH)." RFC 2402, November 1998. [ROAMING-REQUIREMENTS] B. Aboba, G. Zorn. "Criteria for Evaluating Roaming Protocols." RFC 2477, January 1999. [RADIUS] C. Rigney, et al., "Remote Authentication Dial In User Service (RADIUS)" RFC 2138, April 1997 [RADIUS-ACCOUNTING] C. Rigney, "RADIUS Accounting", RFC 2139, April 1997 Beadles, Mitton Informational [Page 17] INTERNET-DRAFT Criteria for NAS Protocols 2 March 2000 14. Author's Addresses Mark Anthony Beadles SmartPipes, Inc. 565 Metro Place South Suite 300 Dublin, OH 43017 Phone: 614-327-8046 EMail: mbeadles@smartpipes.com David Mitton Nortel Networks 8 Federal St Billerica, MA 01821 Phone: 978-288-4570 EMail: dmitton@nortelnetworks.com 15. Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. 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