INTERNET DRAFT Pat R. Calhoun Category: Informational Erik Guttman Title: draft-calhoun-diameter-impl-guide-00.txt Sun Microsystems, Inc. Date: December 1999 Allan C. Rubens Tut Systems, Inc. Haseeb Akhtar Nortel Networks William Bulley Merit Network, Inc. Jeff Haag Cisco Systems DIAMETER Implementation Guidelines 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 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. 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. Copyright (C) The Internet Society 1999. All Rights Reserved. Calhoun et al. expires May 2000 [Page 1] INTERNET DRAFT December 1999 Abstract The DIAMETER protocol is used for Authentication, Authorization and Accounting (AAA) for Mobile-IP and NASREQ. This document contains implementation guidelines that may be useful to DIAMETER protocol developers. Table of Contents 1.0 Introduction 2.0 Base Protocol 2.1 Acknowledgment Timeouts 2.1.1 Calculating Adaptive Acknowledgment Timeout 2.1.2 Flow Control: Adjusting for Timeout 2.2 Examples of sequence numbering 2.2.1 Lock-step tunnel establishment 2.2.2 Multiple messages acknowledged 2.2.3 Lost message with retransmission 2.3 Backward Compatibility with RADIUS 2.4 Delayed Acknowledgement Optimization 2.5 Device-Reboot-Ind Message Flow 2.6 Device-Watchdog-Ind Message Flow 2.7 Message-Reject-Ind Message Flow 2.8 Peer Fail-Over and Load Balancing 3.0 NASREQ Extension 3.1 EAP Retransmission and Timer 3.2 Example of an EAP OTP Authentication 3.2.1 Successful Authentication 3.2.2 NAS Initiated EAP Authentication 3.2.3 Server-Initiated Authentication 3.2.4 Example of failed EAP Authentication 3.2.5 Example of DIAMETER Server not supporting EAP 3.2.6 Example of DIAMETER Proxy not supporting EAP 3.2.7 Example of PPP Client not supporting EAP 4.0 References 5.0 Acknowledgements 5.0 Author's Addresses 6.0 Full Copyright Statement Calhoun et al. expires May 2000 [Page 2] INTERNET DRAFT December 1999 1.0 Introduction The DIAMETER protocol is used for Authentication, Authorization and Accounting (AAA) for Mobile-IP and NASREQ. This document contains implementation guidelines that may be useful to DIAMETER protocol developers. This specification contains implementation guidelines for both the DIAMETER base protocol [2] and the NASREQ extension [3]. 2.0 Base Protocol This section contains implementation guidelines for the DIAMETER Base protocol [2]. 2.1 Acknowledgment Timeouts DIAMETER uses sliding windows and timeouts to provide flow-control across the underlying medium and to perform efficient data buffering to keep two DIAMETER peers' receive window full without causing receive buffer overflow. DIAMETER requires that a timeout be used to recover from dropped messages. When the timeout for a peer expires, the previously transmitted message with Ns value equal to the highest in-sequence value of Nr received from the peer is retransmitted. The receiving peer does not advance its value for the receive sequence number state, Sr, until it receives a message with Ns equal to its current value of Sr. This rule assures that all subsequent acknowledgements to this peer will contain an Nr value equal to the Ns value of the first missing message until a message with the missing Ns value is received. The exact implementation of the acknowledgment timeout is vendor- specific. It is suggested that an adaptive timeout be implemented with back-off for flow control. The timeout mechanism proposed here has the following properties: Independent timeouts for each peer. A device will have to maintain and calculate timeouts for every active peer. An administrator-adjustable maximum timeout, MaxTimeOut, unique to each device. An adaptive timeout mechanism that compensates for changing throughput. To reduce message processing overhead, vendors may Calhoun et al. expires May 2000 [Page 3] INTERNET DRAFT December 1999 choose not to recompute the adaptive timeout for every received acknowledgment. The result of this overhead reduction is that the timeout will not respond as quickly to rapid network changes. Timer back-off on timeout to reduce congestion. The backed-off timer value is limited by the configurable maximum timeout value. Timer back-off is done every time an acknowledgment timeout occurs. In general, this mechanism has the desirable behavior of quickly backing off upon a timeout and of slowly decreasing the timeout value as messages are delivered without errors. 2.1.1 Calculating Adaptive Acknowledgment Timeout We must decide how much time to allow for acknowledgments to return. If the timeout is set too high, we may wait an unnecessarily long time for dropped messages. If the timeout is too short, we may time out just before the acknowledgment arrives. The acknowledgment timeout should also be reasonable and responsive to changing network conditions. The suggested adaptive algorithm detailed below is based on the TCP 1989 implementation and is explained in Richard Steven's book TCP/IP Illustrated, Volume 1 (page 300). 'n' means this iteration of the calculation, and 'n-1' refers to values from the last calculation. DIFF[n] = SAMPLE[n] - RTT[n-1] DEV[n] = DEV[n-1] + (beta * (|DIFF[n]| - DEV[n-1])) RTT[n] = RTT[n-1] + (alpha * DIFF[n]) ATO[n] = MIN (RTT[n] + (chi * DEV[n]), MaxTimeOut) DIFF represents the error between the last estimated round-trip time and the measured time. DIFF is calculated on each iteration. DEV is the estimated mean deviation. This approximates the standard deviation. DEV is calculated on each iteration and stored for use in the next iteration. Initially, it is set to 0. RTT is the estimated round-trip time of an average message. RTT is calculated on each iteration and stored for use in the next iteration. Initially, it is set to PPD. ATO is the adaptive timeout for the next transmitted message. ATO is calculated on each iteration. Its value is limited, by the MIN function, to be a maximum of the configure MaxTimeOut value. Calhoun et al. expires May 2000 [Page 4] INTERNET DRAFT December 1999 Alpha is the gain for the round trip estimate error and is typically 1/8 (0.125). Beta is the gain for the deviation and is typically 1/4 (0.250). Chi is the gain for the timeout and is typically set to 4. To eliminate division operations for fractional gain elements, the entire set of equations can be scaled. With the suggested gain constants, they should be scaled by 8 to eliminate all division. To simplify calculations, all gain values are kept to powers of two so that shift operations can be used in place of multiplication or division. The above calculations are carried out each time an acknowledgment is received for a message that was not retransmitted (no timeout occurred). 2.1.2 Flow Control: Adjusting for Timeout This section describes how the calculation of ATO is modified in the case where a timeout does occur. When a timeout occurs, the timeout value should be adjusted rapidly upward. To compensate for shifting internetwork time delays, a strategy must be employed to increase the timeout when it expires. A simple formula called Karn's Algorithm is used in TCP implementations and may be used in implementing the back-off timers for the DIAMETER peers. Notice that in addition to increasing the timeout, we also shrink the size of the window as described in the next section. Karn's timer back-off algorithm, as used in TCP, is: NewTIMEOUT = delta * TIMEOUT Adapted to our timeout calculations, for an interval in which a timeout occurs, the new timeout interval ATO is calculated as: RTT[n] = delta * RTT[n-1] DEV[n] = DEV[n-1] ATO[n] = MIN (RTT[n] + (chi * DEV[n]), MaxTimeOut) In this modified calculation of ATO, only the two values that contribute to ATO and that are stored for the next iteration are calculated. RTT is scaled by delta, and DEV is unmodified. DIFF is not carried forward and is not used in this scenario. A value of 2 for Delta, the timeout gain factor for RTT, is suggested. Calhoun et al. expires May 2000 [Page 5] INTERNET DRAFT December 1999 2.2 Examples of sequence numbering This appendix uses several common scenarios to illustrate how sequence number state progresses and is interpreted. 2.2.1 Lock-step session establishment In this example, a DIAMETER host establishes communication with a peer, with the exchange involving each side alternating in the sending of messages. This example is contrived, in that the final acknowledgement typically would be included in the Device-Watchdog- Ind message. DIAMETER Host A DIAMETER Host B -> Device-Reboot-Ind Nr: 0, Ns: 0 (ZLB) <- Nr: 1, Ns: 0 -> Device-Watchdog-Ind Nr: 0, Ns: 1 (delay) (ZLB) <- Nr: 2, Ns: 0 2.2.2 Multiple messages acknowledged This example shows a flow of messages from DIAMETER Host B to Host A, with Host A having no traffic of its own. Host A is waiting 1/4 of its timeout interval, and then acknowledging all messages seen since the last interval. Calhoun et al. expires May 2000 [Page 6] INTERNET DRAFT December 1999 DIAMETER Host A DIAMETER Host B (previous message flow precedes this) -> (ZLB) Nr: 7000, Ns: 1000 (non-ZLB) <- Nr: 1000, Ns: 7000 (non-ZLB) <- Nr: 1000, Ns: 7001 (non-ZLB) <- Nr: 1000, Ns: 7002 (Host A's timer indicates it should acknowledge pending traffic) -> (ZLB) Nr: 7003, Ns: 1000 2.2.3 Lost message with retransmission Host A attempts to communicate with Host B. The Device-Reboot-Ind sent from B to A is lost and must be retransmitted by Host B. Calhoun et al. expires May 2000 [Page 7] INTERNET DRAFT December 1999 DIAMETER Host A DIAMETER Host B -> Device-Reboot-Ind Nr: 0, Ns: 0 (message lost) Device-Reboot-Ind <- Nr: 1, Ns: 0 (pause; Host A's timer started first, so fires first) -> Device-Reboot-Ind Nr: 0, Ns: 0 (Host B realizes it has already seen this message) (Host B might use this as a cue to retransmit, as in this example) Device-Reboot-Ind <- Nr: 1, Ns: 0 -> Device-Watchdog-Ind Nr: 1, Ns: 1 (delay) (ZLB) <- Nr: 2, Ns: 1 2.3 Backward Compatibility with RADIUS The DIAMETER protocol was designed with RADIUS [1] compatibility in mind. A DIAMETER node MAY listen for incoming RADIUS and DIAMETER packets on the same UDP port. The first octet in the message would indicate whether the message is of type RADIUS or DIAMETER. The RADIUS protocol defines a one octet attribute space, and the DIAMETER protocol reserves the first 255 attribute identifiers to be the same as those defined in RADIUS. This allows DIAMETER servers to easily perform protocol conversion, since an additional dictionary lookup would not be necessary in order to map a RADIUS attribute to a DIAMETER AVP. By re-using the RADIUS attribute space, a DIAMETER server could easily read a typical RADIUS user profile without any additional conversions. This reduces the need to create duplicate user profiles for both protocols, and also does not require any database conversion while reading the profiles. Calhoun et al. expires May 2000 [Page 8] INTERNET DRAFT December 1999 2.4 Delayed Acknowledgement Optimization This optimization will potentially reduce the amount of traffic sent between DIAMETER peers. This optimization affects when acknowledgments are sent, as presented in Section 3.1 of [2]. If a peer does not have a message queued to transmit at the time a non-ZLB message is received then it should delay a short time before sending a ZLB message containing the latest values of Sr and Ss, as described above. This short delay is to allow for the possible arrival of a message to be transmitted back to its peer, thus avoiding the need to issue a ZLB. The suggested value for this time delay is 1/4 the receiving peer's value of Round-Trip-Time (RTT - see Appendix A), if it computes RTT, or a maximum of 1/2 of its fixed acknowledgment timeout interval otherwise. This timeout should provide a reasonable opportunity for the receiving peer to obtain a payload message destined for its peer, upon which the ACK of the received message MAY be piggybacked. Note that if a peer's window is full, it MAY advertise an older Nr value if it is not ready to accept new messages. This delay value should be treated as a suggested maximum; an implementation could make this delay quite small without adversely affecting the protocol. The default time delay is 2 seconds. To provide for better throughput, the receiving peer should skip this delay entirely and send a ZLB message immediately in the case where its receive window is filled and it has no queued data to send for this connection or it can't send queued data because the transmit window is closed. 2.5 Device-Reboot-Ind Message Flow The following figure depicts a sample flow of Device-Reboot-Ind between three DIAMETER peers, one being a proxy or broker server. In this example DIA1 initiates the bootstrap sequence with DIA2, and later DIA3 initiates the bootstrap sequence with DIA2. After some time DIA1 needs to reboot and informs DIA2. The details of each message is provided below. Calhoun et al. expires May 2000 [Page 9] INTERNET DRAFT December 1999 +-------+ +-------+ +-------+ | DIA1 | | PROXY | | DIA3 | | | | DIA2 | | | +-------+ +-------+ +-------+ | | | |DRI (ns=0, nr=0) | | | Rebooted | | | version 1, | | | extensions 1, 4 | | (a) |------------------->| | |DRI (ns=0, nr=1) | | | Rebooted | | | version 1, | | | extension 1 | | (b) |<-------------------| | |ZLB (ns=0, nr=1) | | (c) |------------------->| | | . |DRI (ns=0, nr=0) | | . | Rebooted | | | version 1, | | | extensions 1, 2 | (d) | |<------------------| | |DRI (ns=0, nr=1) | | | Rebooted | | | version 1, | | | extension 1 | (e) | |------------------>| | |ZLB (ns=0, nr=1) | (f) | |<------------------| |DRI (ns=x, nr=y) | . | | Upcoming Reboot | . | (g) |------------------->| | | . | | | . | | |DRI (ns=0, nr=0) | | | Rebooted | | | version 1, | | | extensions 1, 4 | | (h) |------------------->| | | | | Figure 1: Sample DRI Message Flow in a Proxy Environment (a) DIA1 sends a DRI message to DIA2 indicating that its version is one (1) and that its supported extensions are 1 (Roamops) and 4 (Mobile-IP). (b) DIA2 sends a DRI message to DIA1 indicating that its version is one (1) and that its supported extension is 1 (Roamops). Calhoun et al. expires May 2000 [Page 10] INTERNET DRAFT December 1999 This message also includes a piggy-backed acknowledgement of (a). (c) DIA1 sends an acknowledgement of (b) (d) DIA3 sends a DRI message to DIA2 indicating that its version is one (1) and that its supported extensions are 1 (Roamops) and 2 (Secure Proxy). (e) DIA2 sends a DRI message to DIA3 indicating that its version is one (1) and that its supported extension is 1 (Roamops). This message also includes a piggy-backed acknowledgement of (d). (f) DIA3 sends an acknowledgement of (e) (g) after some time DIA1 sends an indication to DIA2 that it is about to reboot. All messages destined to the domain for which DIA1 is responsible for should be redirected to an alternate DIAMETER Server. (h) Once the reboot is complete, DIA sends the DRI, which causes steps (a) through (c) to be repeated. 2.6 Device-Watchdog-Ind Message Flow The following figure provides an example of how the Device-Watchdog- Ind message is used in a proxy environment. The details of each message is provided below. Calhoun et al. expires May 2000 [Page 11] INTERNET DRAFT December 1999 +-------+ +-------+ +-------+ | DIA1 | | PROXY | | DIA3 | | | | DIA2 | | | +-------+ +-------+ +-------+ | | | |CMD-X (ns=23, nr=40)| | (a) |------------------->| | |ZLB (ns=40, nr=24) | | (b) |<-------------------| | | . | | | . | | | |CMD-Y (ns=12, nr=20)| (c) | |------------------->| | |ZLB (ns=20, nr=13) | (d) | |<-------------------| |WDI (ns=24, nr=40) | . | (e) |------------------->| . | |ZLB (ns=40, nr=25) | | (f) |<-------------------| | | |WDI (ns=21, nr=13) | (g) | |<-------------------| | |ZLB (ns=13, nr=22) | (h) | |------------------->| | | | Figure 2: Sample WDI Message in a Proxy Environment (a) DIA1 issues a message to DIA2 (b) DIA2 acknowledges the receipt of (a) (c) DIA2 issues a message to DIA3 (d) DIA3 acknowledges the receipt of (c) (e) After some time of inactivity, DIA1 issues a WDI to DIA2 (f) DIA2 acknowledges the receipt of (e) (g) After some period of inactivity, DIA3 issues a WDI to DIA2 (h) DIA2 acknowledges the receipt of (g) 2.7 Message-Reject-Ind Message Flow The following figure show sample flows of MRI command between two DIAMETER peers. In this example DIA1 and DIA2 servers generates error messages. The details of the messages are provided below. Calhoun et al. expires May 2000 [Page 12] INTERNET DRAFT December 1999 +-------+ +-------+ | DIA1 | | DIA2 | +-------+ +-------+ | | |Unknown command | (a) |------------------------------------>| |MRI, err=DIAMETER_COMMAND_UNSUPPORTED| (b) |<------------------------------------| | . | | . | |Unknown AVP | (c) |<------------------------------------| |MRI, err=DIAMETER_AVP_UNSUPPORTED | (d) |------------------------------------>| | . | | . | |Bad value in a valid AVP | (e) |------------------------------------>| |MRI, err=DIAMETER_INVALID_AVP_VALUE | (f) |<------------------------------------| Figure 3: Sample MRI Message Flow (a) DIA2 receives an unknown command from DIA1. (b) DIA2 recognizes that it received an unknown command and hence sends an MRI with the Result-Code AVP set to DIAMETER_COMMAND_UNSUPPORTED and the Command-Code AVP encapsulated within the Failed-AVP AVP. (c) DIA1 receives an unknown AVP in a message sent by DIA2. (d) DIA1 recognizes that it received an unknown AVP and returns an MRI with the Result-Code AVP set to DIAMETER_AVP_UNSUPPORTED and the offending AVP encapsulated within a Failed-AVP AVP. (e) DIA2 receives a bad parameter within a otherwise valid AVP from DIA1. (f) As soon as it discovers that it has received a bad parameter, it returns an MRI message to DIA1 with the Result-Code AVP set to DIAMETER_INVALID_AVP_VALUE and the offending AVP encapsulated within a Failed-AVP AVP. 2.8 Peer Fail-Over and Load Balancing Although not a function of the DIAMETER protocol, in some networks it is desirable to ensure resilient service by providing alternate Calhoun et al. expires May 2000 [Page 13] INTERNET DRAFT December 1999 peers, should communication with a peer fail. Figure 4 provides an example of such a network, where the client communicates with one of two servers providing proxying services. The proxy servers, in turn, communicate with one of two servers in the home domain. +--------+ | DIAM | | Primary| +--------+ | Home | | DIAM +---------+ Server +----+ | Primary| +--------+ | +--------+ | Proxy | +--------+ | | +--------+ Server +---------+ DIAM | | | DIAM | +--------+ |Alternat| | | Client | +--------+ | Home | | | +--------+ DIAM +---------+ Server | | +--------+ |Alternat| +--------+ | | Proxy | | | Server +-----------------------+ +--------+ Figure 4: Redundant DIAMETER Servers Each node in the network MUST know a priori about its communicating peers, and each peer MAY have a relative priority, forcing all traffic to be sent through a preferred server, if it is available. When a node detects that a communicating peer is no longer available, it MUST attempt to redirect all traffic (including the packets in the retransmission queue destined for the former peer) to the new peer. It is possible that an alternate path not exist, such would be the case if the DIAMETER Client was no longer reachable. In this case, the DIAMETER proxy servers SHOULD drop all responses directed to the client, and MUST respond to all requests directed to the client with an appropriate Result Code. An implementation MAY also make use of the multiple peer arrangement described above to balance the load between a set of peers. A clever implementation MAY also redirect traffic to an alternate peer when it detects that its primary communicating peer's window is full. 3.0 NASREQ Extension This section contains implementation guidelines for the NASREQ DIAMETER Extension [3]. 3.1 EAP Retransmission and Timers Calhoun et al. expires May 2000 [Page 14] INTERNET DRAFT December 1999 As noted in [4], the EAP authenticator (NAS) is responsible for retransmission of packets between the authenticating peer and the NAS. Thus if an EAP packet is lost in transit between the authenticating peer and the NAS (or vice versa), the NAS will retransmit. As defined in the base protocol [2], a DIAMETER node is responsible to retransmit all packets with its peer. Note that it may be necessary to adjust authentication timeouts in certain cases. For example, when a token card is used additional time may be required to allow the user to find the card and enter the token. Since the NAS will typically not have knowledge of the required parameters, these need to be provided by the DIAMETER server. This can be accomplished by inclusion of the Idle-Timeout in the DIAMETER-EAP-Answer message. 3.2 Example of an EAP OTP Authentication This section provides sample messages exchanges between an Authenticating Peer, which is typically a dial-up PPP client, a NAS and a DIAMETER server. The protocol used between the Dial-up PPP client and the NAS is EAP over PPP as defined in [4]. The protocol between the NAS and the DIAMETER Server is EAP encapsulated within DIAMETER, as described in this specification. For all PPP packets, the messages are formatted as: [LCP Packet Type] [EAP Packet Type]/[EAP Payload] For all DIAMETER packets, the messages are formatted as: [DIAMETER Command Code]/[EAP Packet Type]/[EAP Payload] In the example provided below, the PPP client attempts to authenticate using a One-Time-Password [5] encapsulated within EAP [4]. 3.2.1 Successful Authentication The example below shows the conversation between the authenticating peer, NAS, and server, for the case of a One Time Password (OTP) authentication. OTP is used only for illustrative purposes; other authentication protocols could also have been used, although they would show somewhat different behavior. Calhoun et al. expires May 2000 [Page 15] INTERNET DRAFT December 1999 Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP ACK-EAP auth -> DIAMETER- EAP-Request/ EAP-Payload/Start -> <- DIAMETER- EAP-Answer/ EAP- Payload/Identity <- PPP EAP-Request/ Identity PPP EAP-Response/ Identity (MyID) -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ (MyID) -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP- Request OTP/OTP Challenge <- PPP EAP-Request/ OTP/OTP Challenge PPP EAP-Response/ OTP, OTPpw -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ OTP, OTPpw -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP- Success (other AVPs) <- PPP EAP-Success PPP Authentication Phase complete, NCP Phase starts Calhoun et al. expires May 2000 [Page 16] INTERNET DRAFT December 1999 3.2.2: NAS Initiated EAP Authentication In the case where the NAS sends the authenticating peer an EAP- Request/Identity packet without first sending an EAP-Start packet to the DIAMETER server, the conversation would appear as follows: Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP ACK-EAP auth -> <- PPP EAP-Request/ Identity PPP EAP-Response/ Identity (MyID) -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ (MyID) -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP-Request OTP/OTP Challenge <- PPP EAP-Request/ OTP/OTP Challenge PPP EAP-Response/ OTP, OTPpw -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ OTP, OTPpw -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP-Success (other AVPs) <- PPP EAP-Success PPP Authentication Phase complete, NCP Phase starts 3.2.3: Server-Initiated Authentication Calhoun et al. expires May 2000 [Page 17] INTERNET DRAFT December 1999 As described in [6], when a server has successfully authenticated and authorized a user, it may include a timeout period to the authorization. The server can later initiate an unsolicited re- authentication request to the user, through the NAS. This method has the advantage of reducing the number of round trips required for re- authentication/authorization. Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- DIAMETER-EAP-Ind/ EAP-Payload/EAP-Request OTP/OTP Challenge <- PPP EAP-Request/ OTP/OTP Challenge PPP EAP-Response/ OTP, OTPpw -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ OTP, OTPpw -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP-Success (other AVPs) <- PPP EAP-Success 3.2.4: Example of failed EAP Authentication In the case where the client fails EAP authentication, the conversation would appear as follows: Calhoun et al. expires May 2000 [Page 18] INTERNET DRAFT December 1999 Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP ACK-EAP auth -> DIAMETER- EAP-Request/ EAP-Payload/Start -> <- DIAMETER- EAP-Answer/ EAP-Payload/Identity <- PPP EAP-Request/ Identity PPP EAP-Response/ Identity (MyID) -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ (MyID) -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP-Request OTP/OTP Challenge <- PPP EAP-Request/ OTP/OTP Challenge PPP EAP-Response/ OTP, OTPpw -> DIAMETER- EAP-Request/ EAP-Payload/ EAP-Response/ OTP, OTPpw -> <- DIAMETER- EAP-Answer/ EAP-Payload/EAP-Failure <- PPP EAP-Failure <- LCP Terminate 3.2.5: Example of DIAMETER Server not supporting EAP In the case that the DIAMETER server or proxy does not support EAP extensions the conversation would appear as follows: Calhoun et al. expires May 2000 [Page 19] INTERNET DRAFT December 1999 Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP ACK-EAP auth -> DIAMETER EAP-Request/ EAP-Payload/Start -> <- DIAMETER Command-Unrecognized <- PPP LCP Request-CHAP auth PPP LCP ACK-CHAP auth -> <- PPP CHAP Challenge PPP CHAP Response -> DIAMETER AA-Request-> <- DIAMETER AA-Answer <- PPP LCP CHAP-Success PPP Authentication Phase complete, NCP Phase starts 3.2.6: Example of DIAMETER Proxy not supporting EAP In the case where the local DIAMETER Server does support the EAP extensions but the remote DIAMETER Server does not, the conversation would appear as follows: Calhoun et al. expires May 2000 [Page 20] INTERNET DRAFT December 1999 Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP ACK-EAP auth -> DIAMETER- EAP-Request/ EAP-Payload/Start -> <- DIAMETER- EAP-Answer/ EAP-Payload/Identity <- PPP EAP-Request/ Identity PPP EAP-Response/ Identity (MyID) -> DIAMETER- EAP-Request/ EAP-Payload/EAP-Response/ (MyID) -> <- DIAMETER- EAP-Answer (proxied from remote DIAMETER Server) <- PPP LCP Request-CHAP auth PPP LCP ACK-CHAP auth -> <- PPP CHAP Challenge PPP CHAP Response -> DIAMETER AA-Request-> <- DIAMETER AA-Answer (proxied from remote DIAMETER Server) <- PPP LCP CHAP-Success PPP Authentication Phase complete, NCP Phase starts 3.2.7: Example of PPP Client not supporting EAP In the case where the authenticating peer does not support EAP, but Calhoun et al. expires May 2000 [Page 21] INTERNET DRAFT December 1999 where EAP is required for that user, the conversation would appear as follows: Authenticating Peer NAS DIAMETER Server ------------------- --- --------------- <- PPP LCP Request-EAP auth PPP LCP NAK-EAP auth -> <- PPP LCP Request-EAP auth PPP LCP NAK-EAP auth -> <- PPP LCP Request-CHAP auth PPP LCP ACK-CHAP auth -> <- PPP CHAP Challenge PPP CHAP Response -> DIAMETER- AA-Request/ User-Name, CHAP-Password -> <- DIAMETER- EAP-Answer/ EAP-Payload <- LCP Terminate Req 4.0 References [1] Rigney, et alia, "RADIUS", RFC-2138, April 1997 [2] P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, "DIAMETER Base Protocol", draft-calhoun-diameter-11.txt (work in progress), December 1999. [3] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "DIAMETER NASREQ Extension", draft-calhoun-diameter-nasreq-00.txt (work in progress), December 1999. [4] L. J. Blunk, J. R. Vollbrecht, "PPP Extensible Authentication Protocol (EAP)." RFC 2284, March 1998. [5] N Haller, C. Metz, P. Nesset, M. Straw, "A One-Time Password (OTP) System", RFC 2289, February 1998. [6] G. Zorn, P. Calhoun, "Limiting Fraud in Roaming", draft-ietf- roamops-fraud-limit-00.txt (work in progress), May 1999. Calhoun et al. expires May 2000 [Page 22] INTERNET DRAFT December 1999 5.0 Acknowledgements The authors would like to thank Nenad Trifunovic, Tony Johansson and Pankaj Patel for their participation in the Document Reading Party. The authors would also like to acknowledge the following people for their contribution in the development of the DIAMETER protocol: Bernard Aboba, Jari Arkko, William Bulley, Daniel C. Fox, Lol Grant, Ignacio Goyret, Nancy Greene, Peter Heitman, Paul Krumviede, Fergal Ladley, Ryan Moats, Victor Muslin, Kenneth Peirce, Sumit Vakil, John R. Vollbrecht and Jeff Weisberg and Glen Zorn. 6.0 Author's Addresses Questions about this memo can be directed to: Pat R. Calhoun Network and Security Research Center, Sun Laboratories 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 Allan C. Rubens Tut Systems, Inc. 220 E. Huron, Suite 260 Ann Arbor, MI 48104 USA Phone: 1-734-995-1697 E-Mail: arubens@tutsys.com Haseeb Akhtar Wireless Technology Labs Nortel Networks 2221 Lakeside Blvd. Richardson, TX 75082-4399 USA Phone: 1-972-684-8850 Calhoun et al. expires May 2000 [Page 23] INTERNET DRAFT December 1999 E-Mail: haseeb@nortelnetworks.com Erik Guttman Network and Security Research Center, Sun Laboratories Sun Microsystems, Inc. 15 Network Circle Menlo Park, California, 94025 USA Phone: 49-7263-911-701 E-mail: erik.guttman@germany.sun.com William Bulley Merit Network, Inc. Building One, Suite 2000 4251 Plymouth Road Ann Arbor, Michigan 48105-2785 USA Phone: 1-734-764-9993 Fax: 1-734-647-3185 E-mail: web@merit.edu Jeff Haag Cisco Systems 7025 Kit Creek Road PO Box 14987 Research Triangle Park, NC 27709 Phone: 1-919-392-2353 E-Mail: haag@cisco.com 7.0 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 Calhoun et al. expires May 2000 [Page 24] INTERNET DRAFT December 1999 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." Calhoun et al. expires May 2000 [Page 25]