--- 1/draft-cui-mpls-tp-mfp-use-case-and-requirements-06.txt 2016-01-10 08:15:09.822776997 -0800 +++ 2/draft-cui-mpls-tp-mfp-use-case-and-requirements-07.txt 2016-01-10 08:15:09.846777576 -0800 @@ -1,24 +1,24 @@ Network Working Group Z. Cui Internet-Draft R. Winter Intended status: Informational NEC -Expires: July 9, 2016 H. Shah +Expires: July 13, 2016 H. Shah Ciena S. Aldrin Huawei Technologies M. Daikoku KDDI - January 6, 2016 + January 10, 2016 Use Cases and Requirements for MPLS-TP multi-failure protection - draft-cui-mpls-tp-mfp-use-case-and-requirements-06 + draft-cui-mpls-tp-mfp-use-case-and-requirements-07 Abstract For the Multiprotocol Label Switching Transport Profile (MPLS-TP) linear protection capable of 1+1 and 1:1 protection has already been defined. That linear protection mechanism has not been designed for handling multiple, simultaneously occuring failures, i.e. multiple failures that affect the working and the protection entity during the same time period. In these situations currently defined protection mechanisms would fail. @@ -35,21 +35,21 @@ 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 July 9, 2016. + This Internet-Draft will expire on July 13, 2016. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. 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 @@ -78,25 +78,25 @@ 1. Introduction Today's packet optical transport networks 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 careful network design and appropriate technical means is important. - In MPLS-TP networks, a basic survivability technique is available as - specified in [RFC6378], [RFC7271] and [RFC7324]. That protocol - however is limited to 1+1 and 1:1 protection and not designed to - handle multiple failures that affect both the working and protection - entity at the same time. + In MPLS-TP networks, a basic end-to-end linear protection + survivability technique is available as specified in [RFC6378], + [RFC7271] and [RFC7324]. That protocol however is limited to 1+1 and + 1:1 protection and not designed to handle multiple failures that + affect both the working and protection entity at the same time. There are various scenarios where multi-failure protection is an important requirement for network survivability. E.g for disaster recovery, after catastrophic events such as earthquakes or tsunamis. During the period after such events, network availability is crucial, in particular for high-priority services such as emergency telephone calls. Existing 1+1 or 1:n protection however is limited to cover single failures which has proven as not sufficient during past events. @@ -234,23 +234,25 @@ entity is configured while the system is in operation. Additional protection entities are configured by either a control plane protocol or static configuration using a management system directly after failure detection and/or notification of either the working entity or the protection entities. In case a management system is used, there is no need for a standardized solution. 3.2. m:n (m, n > 1, n >= m > 1) protection - In order to reduce the cost of protection entities, in the m:n - scenario, m dedicated protection transport entities are sharing - protection resources for n working transport entities. + Because m:n protecion introduces additional protection entities + compared to 1:1 protection, an additional cost has to be paid. In + order to reduce the cost of these additional protection entities, in + the m:n scenario, m dedicated protection transport entities are + sharing protection resources for n working transport entities. The bandwidth of each protection entity should be allocated in such a way that it may be possible to protect any of the n working entities in case at least one of the m protection entities is available. When a working entity is determined to be impaired, its traffic first must be assigned to an available protection transport entity followed by a transition from the working to the assigned protection entity at both Node A and Node Z of the protected domain. It is noted that when more than m working entities are impaired, only m working entities can be protected.