Criteria for Evaluating Network Access Server Protocols (RFC3169)
Original Publication Date: 2001-Sep-01
Included in the Prior Art Database: 2019-Feb-13
Internet Society Requests For Comment (RFCs)
M. Beadles: AUTHOR [+1]
This document defines requirements for protocols used by Network Access Servers (NAS). This memo provides information for the Internet community.
Network Working Group M. Beadles Request for Comments: 3169 SmartPipes, Inc. Category: Informational D. Mitton Nortel Networks September 2001
Criteria for Evaluating Network Access Server Protocols
Status of this Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2001). All Rights Reserved.
This document defines requirements for protocols used by Network Access Servers (NAS).
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 [KEYWORDS].
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 Management 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 requirements, may be found in [NAS-MODEL].
3. 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]
Beadles & Mitton Informational [Page 1]
RFC 3169 Criteria for Evaluating NAS Protocols September 2001
carried over a telephony protocol. Second are broadband pseudo- telephony access protocols, 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.
4. 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 protocol 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 protocol requirements imposed by virtue of the device being a NAS.
5. AAA Protocol Requirements
5.1. General protocol characteristic...