Network Working Group Z. Cui Internet-Draft R. Winter Intended status: Standards Track NEC Expires: January 5, 2015 H. Shah Ciena S. Aldrin Huawei Technologies M. Daikoku KDDI July 4, 2014 Use Cases and Requirements for MPLS-TP multi-failure protection draft-cui-mpls-tp-mfp-use-case-and-requirements-02 Abstract The basic survivability technique has been defined in Multiprotocol Label Switching Transport Profile (MPLS-TP) network [RFC6378]. That protocol however is limited to 1+1 and 1:1 protection, not designed to handle multi-failure protection. This document introduces some use cases and requirements for multi- failure protection functionality. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on January 5, 2015. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. Cui, et al. Expires January 5, 2015 [Page 1] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Document scope . . . . . . . . . . . . . . . . . . . . . 3 1.2. Requirements notation . . . . . . . . . . . . . . . . . . 3 2. m:n protection architecture . . . . . . . . . . . . . . . . . 3 3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Increase service availability . . . . . . . . . . . . . . 4 3.2. Reduce the backup costs . . . . . . . . . . . . . . . . . 5 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Today's packet optical transport networks are able to concentrate large volumes of traffic onto a relatively small number of nodes and links. As a result, the failure of a single network element can potentially interrupt a large amount of traffic. For this reason, ensuring survivability through fault-tolerant network design is an important network design objective. The basic survivability technique has been defined in MPLS-TP network [RFC6378]. That protocol however is limited to 1+1 and 1:1 protection, not designed to handle multi-failure protection. The case of multi-failure condition is very rare, but not unheard of. For example, when a working path was closed by network operator for construction work, the network service will become a hazardous condition. During this time, if another failure (e.g. a human-error or network entities failure) is occurred on the protection path, than the operator can't meet service level agreements (SLA). A network must be able to handle multiple failures even that are a rare case, because especially some high-priority services such as emergency telephone calls request to network service provider Cui, et al. Expires January 5, 2015 [Page 2] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 guarantee their service connections in a timely manner in any situation. On the other hand, many network operators have a very limited budget for improving network survivability. This requires a design approach, which takes budget limitations into consideration. To increase the service availability and to reduce the backup network costs, we propose extend the 1+1 and 1:1 protection protocol to support the m:n architecture type. 1.1. Document scope This document describes the use cases and requirements for multi- failure protection in MPLS-TP networks without the use of control plane protocols. Existing solutions based on control plane such as GMPLS may be able to restore user traffic when multiple failures occur. Some networks however do not use full control plane operation for reasons such as service provider preferences, certain limitations or the requirement for fast service restoration (faster than achievable with control plane mechanisms). These networks are the focus of this document which defines a set of requirements for multi- failure protection not based on control plane support. 1.2. Requirements notation 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. m:n protection architecture The following Figure 1 shows a protection domain with n working paths and m protection paths. when a working path is determined to impaired, its normal traffic must be assigned to a protection path if a protection path is available. To reduce the backup network costs, m protection paths are sharing backup resource for n working paths, where m <= n typically. The bandwidth of each protection paths should be allocated enough to protect any of the n working paths. Cui, et al. Expires January 5, 2015 [Page 3] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 +-----+ +-----+ | |=============================| | |LER-A| Working Path #1 |LER-Z| | | | | | |=============================| | | | .... | | | | | | | |=============================| | | | Working Path #n | | | | | | | | | | | | | | | |*****************************| | | | Protection Path #1 | | | | | | | |*****************************| | | | .... | | | | | | | |*****************************| | | | Protection Path #m | | | | | | +-----+ +-----+ |--------Protection Domain--------| Figure 1: m:n ptorection domain 3. Use cases 3.1. Increase service availability With technological advancement of mobile services or data center services, dependencies and business impact of network services have been increased phenomenally. End-users expectations of service availability also are increasing, which is driving service providers enhance their network's availability. Network availability must be maintained especially for high-priority services such as emergency telephone calls, even during natural disasters and other catastrophic events such as earthquake or tsunami. Existing 1+1 or 1:n protection however is limited to cover single failure and no sufficient to maintain disaster recovery. The m:n protection can increase service availability because it take multiple protection paths to ensuring high-priority services continue to operate on the 2nd, 3rd or Nth alternate backup, at least one of m protection paths is a available. Cui, et al. Expires January 5, 2015 [Page 4] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 3.2. Reduce the backup costs Network costs driven by high traffic growth rates are rising steadily, but revenues are no increased in direct proportion to traffic growth rates. This requires a design approach, which takes budget limitations into consideration. Existing protection schemes such as 1+1 protection meet the sub 50 ms performance requirement but only protect against a single failure and are too costly. The m:n protection is a useful solution, that can reduce the backup costs because m dedicated protection paths are sharing backup paths for n working paths, where m =< n typically. The shared Mesh Protection (SMP) also can reduce the backup costs as described in [I-D.ietf-mpls-smp-requirements]. SMP however is based the 1:1 protection and does not able to care that the multiple failures are occurred on both working and protection paths. However, combine use of SMP and a set of m:1 protections to make a m:n protection likely, may be better able to recovers the multiple failures. 4. Requirements Some recovery requirements are defined [RFC5654]. That however is limited to cover single failure and is not able to care that the multiple failures. This Section 4 extends the requirements to support the multiple failures scenarios. MPLS-TP MUST support m:n protection with the following requirements: R1 The m:n protection MUST protects against multiple failures that are simultaneously-detected on both of working path and protection path or more than one multiple working paths. R2 Some priority schemes MUST be provided, because the backup resources are shared by multiple working paths dynamically. R3 TBD 5. Security Considerations TBD Cui, et al. Expires January 5, 2015 [Page 5] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 6. IANA Considerations TBD 7. Normative References [I-D.ietf-mpls-smp-requirements] Weingarten, Y., Aldrin, S., Pan, P., Ryoo, J., and G. Mirsky, "Requirements for MPLS-TP Shared Mesh Protection", draft-ietf-mpls-smp-requirements-06 (work in progress), June 2014. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4427] Mannie, E. and D. Papadimitriou, "Recovery (Protection and Restoration) Terminology for Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4427, March 2006. [RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654, September 2009. [RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear Protection", RFC 6378, October 2011. Authors' Addresses Zhenlong Cui NEC Email: c-sai@bx.jp.nec.com Rolf Winter NEC Email: Rolf.Winter@neclab.eu Himanshu Shah Ciena Email: hshah@ciena.com Cui, et al. Expires January 5, 2015 [Page 6] Internet-DraUse Cases and Requirements for MPLS-TP multi-fail July 2014 Sam Aldrin Huawei Technologies Email: aldrin.ietf@gmail.com Masahiro Daikoku KDDI Email: ms-daikoku@kddi.com Cui, et al. 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