Network Working Group N. McGill Internet-Draft C. Pignataro Updates: 3931 (if approved) Cisco Systems Intended status: Standards Track November 19, 2008 Expires: May 23, 2009 L2TPv3 Extended Circuit Status Values draft-ietf-l2tpext-circuit-status-extensions-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 Internet-Draft will expire on May 23, 2009. Abstract This document defines additional Layer 2 Tunneling Protocol Version 3 (L2TPv3) bit values to be used within the "Circuit Status" Attribute Value Pair (AVP) to communicate more granular error states for Access Circuits and Pseudowires. It also deprecates the use of the New bit in the "Circuit Status" AVP, updating RFC3931. McGill & Pignataro Expires May 23, 2009 [Page 1] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Specification of Requirements . . . . . . . . . . . . . . 3 2. L2TPv3 Extended Circuit Status Values . . . . . . . . . . . . 3 3. Circuit Status Usage and Clarifications . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 11 McGill & Pignataro Expires May 23, 2009 [Page 2] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 1. Introduction Currently the L2TPv3 Circuit Status AVP [RFC3931] is able to convey the UP/DOWN status of an access circuit. However, a finer granularity is often useful to determine the direction of the fault as has been added for MPLS-based pseudowires and used in the pseudowire control protocol using LDP, see Section 3.5 of [RFC4446] and Section 5.4.2 of [RFC4447]. Additionally, it is useful (in redundancy scenarios) to be able to indicate if a pseudowire is in a standby state, where it is fully established but is not switching data. Again, such functionality is available for MPLS-based pseudowires using LDP, see [I-D.ietf-pwe3-redundancy-bit]. This document provides extended circuit status bit values for L2TPv3 and adds them in a manner such that it is backwards compatible with the current Circuit Status AVP. These new bits are applicable to all pseudowires types that use the Circuit Status AVP. 1.1. Specification of Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. L2TPv3 Extended Circuit Status Values The Circuit Status AVP (ICRQ, ICRP, ICCN, OCRQ, OCRP, OCCN, SLI), Attribute Type 71, indicates the initial status of or a status change in the circuit to which the session is bound. The Attribute Value field for this AVP currently defined in [RFC3931] has the following format: 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved |N|A| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Bit Bit-Value Name ---------------------------------------------------------------- (A) 15 0x0001 Active (N) 14 0x0002 New As currently defined in [RFC3931], the two bits have the following McGill & Pignataro Expires May 23, 2009 [Page 3] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 meanings: o The A (Active) bit indicates whether the circuit is up/active/ ready (1) or down/inactive/not-ready (0). o The N (New) bit indicates whether the circuit status indication is for a new circuit (1) or an existing circuit (0). This document updates the semantics of the A and N bits as follows: The A (Active) bit indicates whether the local pseudowire endpoint (both local attachment circuit and local PSN-facing pseudowire) has no faults present and is up/active/ready (1) or has faults present and is down/inactive/not-ready (0). The N (New) bit indicates if the notification is for a new circuit (1) or an existing circuit (0), and is provided to emulate (Frame Relay) NNI signaling between PEs. It MAY be used to convey that a circuit has been re-provisioned or newly provisioned at the PE, which can already be inferred from the L2TP control message type. It is therefore uncertain as to what use the receiving PE can make of this bit, although it MAY include logging. This document deprecates this bit as it is of little or no use, hence this bit SHOULD be ignored on receipt and is OPTIONAL to send. For reference, see Section 3.4 of [RFC4591] which does not specify any additional usage beyond the setting of in the ICRQ, ICRP (and OCRQ, OCRP) and clearing in all other control messages. This document also extends this bitmap of values to allow for finer granularity of local pseudowire (i.e., access circuit or PSN-facing endpoint) status reporting. The Attribute Value field for the Circuit Status AVP including the new values has the following format: McGill & Pignataro Expires May 23, 2009 [Page 4] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved |S|E|I|T|R|0|A| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Bit Bit-Value Name ----------------------------------------------------------------- (A) 15 0x0001 Active: Pseudowire has no faults (N) 14 0x0002 New [use deprecated] (R) 13 0x0004 Local Attachment Circuit (ingress) Receive Fault (T) 12 0x0008 Local Attachment Circuit (egress) Transmit Fault (I) 11 0x0010 Local PSN-facing PW (ingress) Receive Fault (E) 10 0x0020 Local PSN-facing PW (egress) Transmit Fault (S) 9 0x0040 Pseudowire is in Standby mode The new bits values have the following meanings: (R), Local Attachment Circuit (ingress) Receive Fault Fault Here | | | +----------------------+ +----------------------+ | Rx| LCCE |Egress | Peer LCCE | --X-->| |-------->| | | L2TPv3 | [PSN] | L2TPv3 | Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit | <-----| |<--------| | +----------------------+ +----------------------+ An alarm or fault has occurred at the local attachment circuit such that it is unable to receive traffic. It can still transmit traffic. McGill & Pignataro Expires May 23, 2009 [Page 5] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 (T), Local Attachment Circuit (egress) Transmit Fault +----------------------+ +----------------------+ Rx| LCCE |Egress | Peer LCCE | ----->| |-------->| | | L2TPv3 | [PSN] | L2TPv3 | Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit | <--X--| |<--------| | | +----------------------+ +----------------------+ | | Fault Here A fault has occurred at the local attachment circuit such that it is unable to transmit traffic. It can still receive traffic. (I), Local PSN-facing PW (ingress) Receive Fault +----------------------+ +----------------------+ Rx| LCCE |Egress | Peer LCCE | ----->| |-------->| | | L2TPv3 | [PSN] | L2TPv3 | Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit | <-----| |<---X----| | +----------------------+ | +----------------------+ | | Fault Here A fault has occurred in the receive direction between the local endpoint and the remote L2TP endpoint. Note that a fault at the session level would not necessarily trigger an L2TP control connection timeout. The means of detecting this fault are outside the scope of this document; as an example, detection may be via PW Type-specific means, BFD, or other methods. McGill & Pignataro Expires May 23, 2009 [Page 6] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 (E), Local PSN-facing PW (egress) Transmit Fault Fault Here | | +----------------------+ | +----------------------+ Rx| LCCE |Egress| | Peer LCCE | ----->| |------X->| | | L2TPv3 | [PSN] | L2TPv3 | Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit | <-----| |<--------| | +----------------------+ +----------------------+ A fault has occurred in the transmit direction between the local endpoint and the remote L2TP endpoint. Note that a fault at the session level would not necessarily trigger an L2TP control connection timeout. The means of detecting this fault are outside the scope of this document; as an example, detection may be via PW Type-specific means, BFD, or other methods. (S), Pseudowire is in Standby mode Standby | | +----------------------+ | +----------------------+ Rx| LCCE |Egress | Peer LCCE | ----->| |---X---->| | | L2TPv3 | [PSN] | L2TPv3 | Tx| Circuit Pseudowire |Ingress | Pseudowire Circuit | <-----| |<--X-----| | +----------------------+ | +----------------------+ | | Standby The pseudowire has been placed into a standby mode which means that although it was signaled and is operational, it is NOT switching traffic. Any received traffic SHOULD be dropped. Traffic MUST NOT be transmitted. 3. Circuit Status Usage and Clarifications The following are clarifications regarding the usage of the Circuit Status AVP bits: McGill & Pignataro Expires May 23, 2009 [Page 7] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 o The (R), (T), (I) and (E) bits are collectively referred to as "fault status bits". o [RFC3931] defined the (A) bit as pertaining to local access circuit state only. This draft redefines it as meaning that "no faults are present on the local pseudowire endpoint." o If multiple faults occur, all the fault status bits corresponding to each fault MUST be set (i.e., they MUST be bitwise-OR-d together). o The (A) bit MUST NOT be set until all fault status bits are cleared. This behavior allows an endpoint to be backwards compatible with a remote endpoint that does not understand these new status bits. o If any of the fault status bits are set, then the (A) bit MUST be cleared. That is, the fault status bits (R, T, I, E) are a more granular definition of (A), such that OR-ing the bits provides an inverted (A). o If (A) is clear and the fault status bits (R, T, I, E) are clear, it means that there is no extended circuit status. That is, the circuit is down/inactive/not-ready (from the (A) bit), without a more granular (extended) indication. o The (S) bit can be set in conjunction with any other bit, including (A). A pseudowire endpoint in Standby (S bit set) can be up/active/ready (A bit set) or experiencing a fault (A bit cleared and (R, T, I, E) bit(s) set). o Leaving standby mode is indicated by the clearing of the (S) bit. o The usage of the (N) bit has been deprecated. 4. Security Considerations No additional security considerations exist with extending this attribute. 5. IANA Considerations The Circuit Status Bits number space reachable at [IANA.l2tp-parameters] is managed by IANA as per [RFC3931]. Five new bits (bits 9 through 13) and one updated bit (bit 14) are requested to be assigned as follows: McGill & Pignataro Expires May 23, 2009 [Page 8] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 Circuit Status Bits - per [RFC3931] ------------------- Bit 9 - S (Standby) bit Bit 10 - E (Local PSN-facing PW (egress) Tx Fault) bit Bit 11 - I (Local PSN-facing PW (ingress) Rx Fault) bit Bit 12 - T (Local AC (egress) Tx Fault) bit Bit 13 - R (Local AC (ingress) Rx Fault) bit Bit 14 - N (New) bit [use deprecated] 6. Acknowledgements The authors wish to thank Muhammad Yousuf, Mark Townsley, George Wilkie, and Prashant Jhingran for comments received. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. 7.2. Informative References [I-D.ietf-pwe3-redundancy-bit] Muley, P., Bocci, M., and L. Martini, "Preferential Forwarding Status bit definition", draft-ietf-pwe3-redundancy-bit-01 (work in progress), September 2008. [IANA.l2tp-parameters] Internet Assigned Numbers Authority, "Layer Two Tunneling Protocol "L2TP"", December 2007, . [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", BCP 116, RFC 4446, April 2006. [RFC4447] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, April 2006. [RFC4591] Townsley, M., Wilkie, G., Booth, S., Bryant, S., and J. McGill & Pignataro Expires May 23, 2009 [Page 9] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 Lau, "Frame Relay over Layer 2 Tunneling Protocol Version 3 (L2TPv3)", RFC 4591, August 2006. Authors' Addresses Neil McGill Cisco Systems 7025-4 Kit Creek Rd PO Box 14987 Research Triangle Park, NC 27709 USA Email: nmcgill@cisco.com Carlos Pignataro Cisco Systems 7200-12 Kit Creek Road PO Box 14987 Research Triangle Park, NC 27709 USA Email: cpignata@cisco.com McGill & Pignataro Expires May 23, 2009 [Page 10] Internet-Draft L2TPv3 Extended Circuit Status Values November 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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