A Method for Transmitting PPP Over Ethernet (PPPoE)
RFC 2516
Document | Type |
RFC - Informational
(February 1999; Errata)
Was draft-carrel-info-pppoe (individual)
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Authors | David Carrel , Jeff Evarts , Kurt Lidl , Louis Mamakos , Dan Simone , Ross Wheeler | ||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2516 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group L. Mamakos Request for Comments: 2516 K. Lidl Category: Informational J. Evarts UUNET Technologies, Inc. D. Carrel D. Simone RedBack Networks, Inc. R. Wheeler RouterWare, Inc. February 1999 A Method for Transmitting PPP Over Ethernet (PPPoE) Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Abstract The Point-to-Point Protocol (PPP) [1] provides a standard method for transporting multi-protocol datagrams over point-to-point links. This document describes how to build PPP sessions and encapsulate PPP packets over Ethernet. Applicability This specification is intended to provide the facilities which are defined for PPP, such as the Link Control Protocol, Network-layer Control Protocols, authentication, and more. These capabilities require a point-to-point relationship between the peers, and are not designed for the multi-point relationships which are available in Ethernet and other multi-access environments. This specification can be used by multiple hosts on a shared, Ethernet to open PPP sessions to multiple destinations via one or more bridging modems. It is intended to be used with broadband remote access technologies that provide a bridged Ethernet topology, when access providers wish to maintain the session abstraction associated with PPP. Mamakos, et. al. Informational [Page 1] RFC 2516 Transmitting PPP Over Ethernet February 1999 This document describes the PPP Over Ethernet encapsulation that is being deployed by RedBack Networks, RouterWare, UUNET and others. 1. Introduction Modern access technologies are faced with several conflicting goals. It is desirable to connect multiple hosts at a remote site through the same customer premise access device. It is also a goal to provide access control and billing functionality in a manner similar to dial-up services using PPP. In many access technologies, the most cost effective method to attach multiple hosts to the customer premise access device, is via Ethernet. In addition, it is desirable to keep the cost of this device as low as possible while requiring little or no configuration. PPP over Ethernet (PPPoE) provides the ability to connect a network of hosts over a simple bridging access device to a remote Access Concentrator. With this model, each host utilizes it's own PPP stack and the user is presented with a familiar user interface. Access control, billing and type of service can be done on a per-user, rather than a per-site, basis. To provide a point-to-point connection over Ethernet, each PPP session must learn the Ethernet address of the remote peer, as well as establish a unique session identifier. PPPoE includes a discovery protocol that provides this. 2. Conventions The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this document, are to be interpreted as described in [2]. 3. Protocol Overview PPPoE has two distinct stages. There is a Discovery stage and a PPP Session stage. When a Host wishes to initiate a PPPoE session, it must first perform Discovery to identify the Ethernet MAC address of the peer and establish a PPPoE SESSION_ID. While PPP defines a peer-to-peer relationship, Discovery is inherently a client-server relationship. In the Discovery process, a Host (the client) discovers an Access Concentrator (the server). Based on the network topology, there may be more than one Access Concentrator that the Host can communicate with. The Discovery stage allows the Host to discover all Access Concentrators and then select one. When Discovery completes successfully, both the Host and the selected Access Concentrator have the information they will use to build their point-to-point connection over Ethernet. Mamakos, et. al. Informational [Page 2] RFC 2516 Transmitting PPP Over Ethernet February 1999 The Discovery stage remains stateless until a PPP session is established. Once a PPP session is established, both the Host andShow full document text