PWE3 Working Group G. Liu Internet-Draft J. Yu Intended status: Informational ZTE Corporation Expires: June 15, 2013 December 12, 2012 p2mp pw protection for MPLS-TP network draft-liu-pwe3-mpls-tp-p2mp-pw-protection-02 Abstract The requirements of MPLS-TP in RFC 5654 include a requirement(R63) that requires MPLS-TP MUST be possible to provide protection for MPLS-TP data plane without any IP forwarding capability and control plane.If applying 1:1 protection for the p2mp traffic in rfc6718 , it must have a return path to coordinate the switch state to select the same path to receive and send the traffic packet.As there exists the above problem statement,This document describes a kind of protection solution to recovery and protect the p2mp traffic under the failure condition. This document is a product of a joint Internet Task Force(IETF) / International Telecommunications Union Telecommunications Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. 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 June 15, 2013. Liu & Yu Expires June 15, 2013 [Page 1] Internet-Draft p2mp pw protection for mpls-tp network December 2012 Copyright Notice Copyright (c) 2012 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 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. Problem statement . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . . 3 3. protection solution . . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . . 8 7.2. Informative References . . . . . . . . . . . . . . . . . . 8 7.3. URL References . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Liu & Yu Expires June 15, 2013 [Page 2] Internet-Draft p2mp pw protection for mpls-tp network December 2012 1. Problem statement According to MPLS-TP requirement(RFC 5654), It requires that MPLS-TP data plane is independent of control plane and IP forwarding capability. So it means that MPLS-TP data plane can still work without control plane and any IP forwarding capability.It must be essential for unidiretional path including p2p or p2mp path to set up a return path between any leaf node and root node . So it costs more configuration and maintenece . While this document describes a kind of protection solution for p2mp traffic without return path, IP forwarding capability and control plane. 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. OAM: Operations, Administration, Maintenance LSP: Label Switched Path. PW: Pseudowire P2MP:Point to Multi-Point P2P:Point to Point PSC:Protection Switching Coordination CE:Customer Equipment LER:Label Edge Router LSR:Label Switch Router IP: Interenet Protocol MPLS-TP:Multi-Protocol Label Switching Transport Profile ME: Maintenance Entity MEP:MEG End Point CE: Customer Equipment Liu & Yu Expires June 15, 2013 [Page 3] Internet-Draft p2mp pw protection for mpls-tp network December 2012 3. protection solution This section will describe a protection solution for p2mp pw path,which uses one leaf node as protector node of another leaf node.The two leaf nodes protect each other.in addtion, In order to be easy to access to CE node, It should set up backup node to directly access to CE node. If the backup node is still a leaf node of the p2mp pw path , the protector node and the backup node are the same node. in addtion, A bidirectional p2p pw should be configurated between the protected node, the backup node and the protector node .Just as the following figure 1: ___ ___ ___ */LSR\ ********* /LER\********** /CE1\ * \ A / \_1_/ + \___/ __ * - - + + /LER\* . _+_ + /LER\+ \_O_/* . \_2_/+ * . + + * ___ _+_ + ___ * /LSR\ /LER\ + /CE3\ * \ B / ********** \_3_/*********** \___/ - - ***** working pw +++++ protection pw Figure 1 LER0 is the root node of a p2mp pw, LER1 and LER3 are leaf nodes of the p2mp pw. LER2 is backup node for LER1 and LER3. When protected node LER1 or LER3 has the failure, its backup node LER2 will replace a protected node LER1 or LER3 to transmit the protected p2mp traffic packet to CE1 or CE3. If CE1 or CE3 detects a failure on its working access link(*), it will select protection access link(+) to receive the traffic.Just as the following figure 2,. Liu & Yu Expires June 15, 2013 [Page 4] Internet-Draft p2mp pw protection for mpls-tp network December 2012 ___ ___ ___ */LSR\ ********* /LER\****X***** /CE1\ * \ A / \_1_/ + \___/ __ * - - X + /LER\* . _+_ + /LER\+ \_O_/* . \_2_/+ * . + + * ___ _+_ + ___ * /LSR\ /LER\ + /CE3\ * \ B / ********** \_3_/*********** \___/ - - ***** working pw +++++ protection pw X failure Figure 2 If LER1 has a failure, CE1 and LER2 MUST detect the failure by OAM or other checking mechanism. Then LER2 will notify its protector node LER3 of the failure by pw status message[1]. When LER3 receives the failure status message, it will begin to duplicate the traffic packet of the p2mp pw to transmit to LER2 by pre-configured p2p protection pw. Then LER2 sends the traffic packet of the p2mp pw to CE1 by the protection access link(LER2-CE1).At the same time, When CE1 detects the failure on its working access link(LER1-CE1), it must switch to receive the traffic packet from its protection access link(LER2-CE1). If only a failure is detected on the working access link, such as access link(LER1-CE1) in the following figure 3: Liu & Yu Expires June 15, 2013 [Page 5] Internet-Draft p2mp pw protection for mpls-tp network December 2012 ___ ___ ___ */LSR\ ********* /LER\****X***** /CE1\ * \ A / \_1_/ + \___/ __ * - - + + /LER\* . _+_ + /LER\+ \_O_/* . \_2_/+ * . + + * ___ _+_ + ___ * /LSR\ /LER\ + /CE3\ * \ B / ********** \_3_/*********** \___/ - - ***** working pw +++++ protection pw X failure Figure 3 when CE1 and LER1 detect a failure on the working access link(LER1- CE1), LER1 firstly notify its backup node LER2 of the egress AC failure by pw status message[1]. Then LER1 will send the protected traffic packet to LER2 by protection p2p pw between LER1 and LER2. LER2 will transmit the traffic packet to CE1 by its protection access link(LER2-CE1). At the same time, CE1 will switch to receive the traffic packet from its protection access link(LER2-CE1). When a leaf node detects a failure on its working pw , it will notify the failure of its backup node or protector node by pw status message[1]. So that its backup node will transmit the protected traffic packet to the protected node.For example, The following figure 4 describes the protection scenario. Liu & Yu Expires June 15, 2013 [Page 6] Internet-Draft p2mp pw protection for mpls-tp network December 2012 ___ ___ ___ */LSR\ *****X**** /LER\********* /CE1\ * \ A / \_1_/ + \___/ __ * - - + + /LER\* . _+_ + /LER\+ \_O_/* . \_2_/+ * . + + * ___ _+_ + ___ * /LSR\ /LER\ + /CE3\ * \ B / ********** \_3_/*********** \___/ - - ***** working pw +++++ protection pw X failure Figure 4 When a failure happens on the branch working pw path(LER0-LSRA-LER1), the protected node LER1 will detect the failure and notify the failure of its backup node LER2 and protector node LER3. Then LER2 and LER3 receive the failure message from LER1 ,LER3 will duplicate the traffic packet of the p2mp pw to send it to the backup node LER2 firstly. Then LER2 continue to transmit the traffic packet to the protected node LER1. CE1 will still receive the traffic packet on its working access link(LER1-CE1) 4. Security Considerations TBD 5. IANA Considerations TBD. 6. Acknowledgments TBD . 7. References Liu & Yu Expires June 15, 2013 [Page 7] Internet-Draft p2mp pw protection for mpls-tp network December 2012 7.1. Normative References [RFC 5654] IETF, "IETF RFC5654(MPLS-TP requirement)", September 2009. [RFC 5921] IETF, "IETF RFC5654(MPLS-TP framework)", July 2010. [RFC 6478] IETF, "IETF RFC6478(Pseudowire Status for Static Pseudowires)", May 2012. [RFC 6718] IETF, "IETF RFC6718(Pseudowire Redundancy)", August 2012. 7.2. Informative References [draft-ietf-pwe3-redundancy-bit-08] Praveen Muley, Mustapha Aissaoui, "Pseudowire Preferential Forwarding Status Bit", September 2012. 7.3. URL References [MPLS-TP-22] IETF - ITU-T Joint Working Team, "", 2008, . Authors' Addresses Guoman Liu ZTE Corporation No.50, Ruanjian Road, Yuhuatai District Nanjing 210012 P.R.China Phone: +86 025 88014227 Email: liu.guoman@zte.com.cn Liu & Yu Expires June 15, 2013 [Page 8] Internet-Draft p2mp pw protection for mpls-tp network December 2012 Jinghai Yu ZTE Corporation No.50, Ruanjian Road, Yuhuatai District Nanjing 45241 P.R China Phone: +86 025 88014226 Email: yu.jinghai@zte.com.cn Liu & Yu Expires June 15, 2013 [Page 9]