Network Working Group J.He Internet Draft Huawei Technologies Intended status: Standard Track H.Li China Mobile Expires: April 2010 October 26, 2009 Indication of Client Failure in MPLS-TP draft-he-mpls-tp-csf-01.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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." 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Expires April 26, 2010 [Page 1] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 Abstract This document describes a Multi-Protocol Label Switching Transport Profile (MPLS-TP) Operations, Administration and Maintenance (OAM) tool to propagate a client failure indication across an MPLS-TP network in case the propagation of failure status in the client layer is not supported. Table of Contents 1. Introduction................................................2 2. Conventions used in this document...........................3 2.1. Terminology............................................3 3. Mechanisms of CSF...........................................4 3.1. General................................................4 3.2. Transmission of CSF....................................5 3.3. Reception of CSF.......................................5 3.4. Configuration of CSF...................................5 4. Frame format of CSF.........................................5 5. Consequent actions..........................................7 6. Security Considerations.....................................7 7. IANA Considerations.........................................7 8. References..................................................7 8.1. Normative References...................................7 8.2. Informative References.................................8 9. Acknowledgments.............................................8 1. Introduction In transport network OAM functionalities are important and fundamental to ease operational complexity, enhance network availability and meet service performance objectives by efficient and automatic detection, handling, diagnosis and appropriate reporting of defects and performance monitoring. In the case of server layer defects detected in a transport network, normally an AIS/FDI is generated for the downstream client signal as an indication to the downstream network elements that the Client signal is missing due to a server layer defect. According to [MPLS-TP Framework], MPLS-TP clients include PW and network layer clients. Examples of network layer clients include IP, MPLS and MPLS-TP. In cases where the client service to be carried by MPLS-TP networks does not provide mechanisms to propagate its failure information He, et al. Expires April 26, 2010 [Page 2] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 across MPLS-TP networks (e.g. not needed in the original application of the client signal, the signal was originally at the bottom of the layer stack and it was not expected to be transported over a server layer), while such an indication is needed by the downstream, it is necessary that MPLS-TP OAM provides such a tool to help propagate client failure indication to the far end on detection of a failure of the ingress client signal. This document defines a MPLS-TP OAM tool as Client Signal Fail indication (CSF) to propagate client failures and their clearance across a MPLS-TP domain. 2. Conventions used in this document 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 [RFC 2119]. 2.1. Terminology The reader is assumed to be familiar with the terminology in MPLS-TP. The relationship between ITU-T and IETF terminologies on MPLS-TP can be found in [Rosetta stone]. ACH: Associated Channel Header AIS: Alarm Indication Signal CSF: Client Signal Fail indication FDI: Forward Defect Indication LSR: Label Switching Router MEP: Maintenance End Point MIP: Maintenance Intermediate Point OAM: Operations, Administration and Maintenance MPLS-TP: MPLS Transport Profile RDI: Remote Defect Indication He, et al. Expires April 26, 2010 [Page 3] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 3. Mechanisms of CSF 3.1. General Client Signal Fail indication (CSF) provides a function to enable a MEP to propagate a client failure indication to its peer MEP across a MPLS-TP network in case the client service itself does not support propagation of its failure status. Packets with CSF information can be issued by a MEP, upon receiving failure information from its client service. Detection rules for client failure events are client-specific and are therefore outside the scope of this document. +---+ +---+ +---+ +---+ | | | |-->CSF | | | | | A |--X--| B |-----------------| C |------| D | +---+ +---+ +---+ +---+ |<--MPLS-TP domain-->| Figure 1 Use case of CSF Figure 1 depicts a typical connection scenario between two client network elements (Node A and Node D) interconnected through MPLS-TP transport network. Client Node A connects to MPLS-TP Node B and Client Node D connects to MPLS-TP Node C. Node B and C support MPLS- TP MEP function. If a failure is detected between Node A and Node B and is taken as a native client failure condition, the MEP function in Node B will initiate CSF signal and it will be sent to Node C through MPLS-TP network. CSF signal will be extracted at Node C as an indication of client signal failure. Further, this may be mapped back into native client failure indication and regenerated towards client Node D. Node B learns the failure between A and B either by direct detection of signal fail (e.g. loss of signal) or by some fault indications between A and B (e.g. RDI, AIS/FDI). If the connection between Node A and B recovers, Node B may stop sending CSF signals to Node C (implicit failure clearance mechanism) or explicitly send failure clearance indication (e.g. by flags in CSF PDU format) to Node C to help expedite clearance of native client failure conditions. He, et al. Expires April 26, 2010 [Page 4] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 Accordingly, Node C will clear client failure condition when no CSF is received (implicit failure clearance mechanism) or upon receiving explicit failure clearance indication. Consideration of client failure clearance is to be added in the following part in the further version of this document. 3.2. Transmission of CSF Upon learning signal failure condition of its client-layer the MEP can immediately start transmitting periodic packets with CSF information. A MEP continues to transmit periodic packets with CSF information until the client-layer signal failure condition is cleared. The period of CSF generation is client and application specific. For further study. 3.3. Reception of CSF Upon receiving a packet with CSF information a MEP declares a client- layer signal fail condition and forwards this as a signal fail indication to its client-layer. 3.4. Configuration of CSF Specific configuration information required by a MEP to support CSF transmission is the following: CSF transmission period - this is application dependent. For further study PHB - identifies the per-hop behavior of packet with CSF information. A MIP is transparent to packets with CSF information and therefore does not require any information to support CSF functionality. 4. Frame format of CSF Figure 2 depicts the frame format of CSF. CSF PDUs are encapsulated using the ACH, according to [RFC 5586]. He, et al. Expires April 26, 2010 [Page 5] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|0 0 0 0|0 0 0 0 0 0 0 0| MPLS-TP CSF(0xXX) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved 1 | Flags | Reserved 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 Frame format of CSF 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | Res | Type | Period | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 Format of Flags in CSF PDU The first four bytes represent the G-ACH ([RFC 5586]): - first nibble: set to 0001b to indicate a control channel associated with a PW, a LSP or a Section; - G-ACH Version(bits 4 to 7): set to 0, as specified in [RFC 5586] - G-ACH Reserved (bits 8 to 15): set to 0 and ignored on reception, as specified in [RFC 5586]; - G-ACH Channel Type (Bits 16 to 31): value 0xXX identifies the payload as CSF PDU. To be assigned by IANA. - CSF Reserved 1 (Bits 32 to 47): Set to 0; - CSF Reserved 2 (Bits 56 to 63): Set to 0; Figure 3 depicts the format of Flags in CSF PDU - Flag Reserved (Bits 48 to 49): Set to 0; - Type (Bits 50 to 52): Set to the following values to indicate CSF types Value Type 111 Client Signal Fail He, et al. Expires April 26, 2010 [Page 6] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 000 Clearance of Client Signal Fail - Period (Bits 53 to 55): CSF transmission period. For further study 5. Consequent actions To be added in the further version of this document. 6. Security Considerations To be added in a future version of the document 7. IANA Considerations This document requests that IANA allocates a channel type of G-ACH for CSF function to be used in MPLS-TP OAM. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC5586] Vigoureux, M., Bocci, M., Swallow, G., Ward, D., Aggarwal, R., "MPLS Generic Associated Channel", RFC5586, 2009 [ITU-T Recommendation G.7041] "Generic framing procedure (GFP)", ITU- T G.7041, October 2008 [RFC 5654] Niven-Jenkins, B., Brungard, D., Betts, M., "Requirements of an MPLS Transport Profile", RFC 5654, 2009 [MPLS-TP OAM REQ] Vigoureux, M., Ward, D., and Betts, M., "Requirements for OAM in MPLS Transport Networks", draft- ietf-mpls-tp-oam-requirements-02(work in progress), June 2009 [MPLS-TP Framework] Bocci, M., Bryant, S., "A Framework for MPLS in Transport Networks", draft-ietf-mpls-tp-framework-06 (work in progress), October 2009 He, et al. Expires April 26, 2010 [Page 7] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 8.2. Informative References [MPLS-TP OAM Frmk] Busi,I., Niven-Jenkins, B., "MPLS-TP OAM Framework and Overview", draft-ietf-mpls-tp-oam-framework-01(work in progress), July 2009 [Rosetta stone] Van Helvoort, H., Andersson, L., Sprecher, N., "A Thesaurus for the Terminology used in Multiprotocol Label Switching Transport Profile (MPLS-TP) drafts/RFCs and ITU- T's Transport Network Recommendations", draft-ietf-mpls-tp- rosetta-stone-00 (work in progress), June 2009 9. Acknowledgments To be added in a future version of the document This document was prepared using 2-Word-v2.0.template.dot. He, et al. Expires April 26, 2010 [Page 8] Internet-Draft Indication of Client Failure in MPLS-TP October 2009 Authors' Addresses Jia He Huawei Technologies Co., Ltd. Email: hejia@huawei.com Han Li China Mobile Communications Corporation Email: lihan@chinamobile.com He, et al. Expires April 26, 2010 [Page 9]