Network Working Group J. Dong Internet-Draft M. Chen Intended status: Standards Track Huawei Technologies Expires: April 24, 2014 G. Mirsky Ericsson October 21, 2013 LDP Extensions for Lock Instruct and Loopback of Pseudowire in MPLS Transport Profile draft-dong-pwe3-mpls-tp-li-lb-05 Abstract This document specifies extensions to the Label Distribution Protocol (LDP) to support provisioning of lock instruct (LI) and loopback (LB) mechanism for MPLS Transport Profile (MPLS-TP) pseudowires (PWs). Requirements Language 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 [RFC2119]. 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 April 24, 2014. Copyright Notice Copyright (c) 2013 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 Dong, et al. Expires April 24, 2014 [Page 1] Internet-Draft LDP Extensions for PW LI&LB October 2013 (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 2. LDP Extensions . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Extensions to MPLS-TP PW OAM Administration TLV . . . . . 3 2.2. Extensions to PW Status TLV . . . . . . . . . . . . . . . 3 3. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Lock Instruct . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Loopback . . . . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction The requirements for Lock Instruct (LI) and Loopback (LB) are specified in [RFC5860], and the framework of LI and LB is specified in [RFC6371]. [RFC6435] defines management plane based LI and LB mechanisms, and an LI OAM message can be used for additional lock coordination between the Maintenance Entity Group End Points (MEPs). Management plane based LI and LB are suitable for scenarios where dynamic control plane is not available. When a dynamic control plane is used for establishing MPLS-TP pseudowires (PWs), it's natural to use and extend the control plane protocol for the provisioning of LI and LB functions. Unlike other OAM mechanisms, LI and LB would modify the forwarding plane of a PW, thus without the involvement of control plane this may result in inconsistency between control plane and data plane. Besides, with control plane based mechanism, it does not need to rely on the TTL expiration to make the OAM requests reach particular Maintenance Entity Group Intermediate Point (MIP) or MEP. There are some existing control plane based OAM provisioning mechanisms for MPLS-TP PWs. For example, [I-D.ietf-pwe3-oam-config] specifies the LDP extensions for the configuration of proactive OAM functions for MPLS-TP PWs when control plane is used. Dong, et al. Expires April 24, 2014 [Page 2] Internet-Draft LDP Extensions for PW LI&LB October 2013 This document defines mechanisms similar to [I-D.ietf-pwe3-oam-config] to implement LI and LB functions for MPLS- TP PWs when MPLS-TP control plane is used. The mechanisms defined in this document are complementary to [RFC6435]. 2. LDP Extensions 2.1. Extensions to MPLS-TP PW OAM Administration TLV Two new flags (Lock bit and Loopback bit) are defined in MPLS-TP PW OAM Administration TLV [I-D.ietf-pwe3-oam-config]. The format of the extended MPLS-TP PW OAM Administration TLV is as below: 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| Type (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |I|A|K|B| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Lock (K): When this bit is set, it indicates that the T-PE needs to enable "Lock" function for this PW. Loopback (B): When this bit is set, it indicates that the target node of this message SHOULD enable loopback function for this PW. 2.2. Extensions to PW Status TLV Two new Status bits are defined in PW Status TLV: Bit Mask Description ==================================================================== TBD1 Pseudowire in Lock Mode [this document] TBD2 Pseudowire in Loopback Mode [this document] 3. Operations The control plane based LI and LB functions are applicable to both Single-Segment Pseudowire (SS-PW) [RFC3985] [RFC4447] and Multi- Segment Pseudowire (MS-PW) [RFC5659] [RFC6073]. 3.1. Lock Instruct Dong, et al. Expires April 24, 2014 [Page 3] Internet-Draft LDP Extensions for PW LI&LB October 2013 When a PE/T-PE intends to put a PW into lock mode, it MUST send a Mapping message with the Lock (K) bit in the MPLS-TP PW OAM Administration TLV set. For SS-PW, when the Mapping message arrives at the remote PE, the receiving PE SHOULD try to take the PW out of service. If the receiving PE locks the PW successfully, it SHOULD send a Notification message with PW status "Pseudowire in Lock Mode". Otherwise, it SHOULD send a Notification message with the LDP Status code set to "PW Lock Failure". For MS-PW, when the Mapping message arrives at a downstream S-PE, the receiving S-PE SHOULD forward this Mapping message with the K bit unchanged towards the remote T-PE. When the Mapping message arrives at the remote T-PE, the receiving T-PE node SHOULD try to take the PW out of service. If the receiving T-PE locks the PW successfully, it SHOULD send a Notification message with PW status "Pseudowire in Lock Mode" to the upstream S-PE. Otherwise, it SHOULD send a Notification message with the LDP Status code set to "PW Lock Failure". On receipt of the Notification message, the S-PEs would know whether the MS-PW is in lock mode or not, and the S-PEs SHOULD forward the Notification message back to the Source T-PE. When the PE/T-PE intends to take the PW out of the lock mode, it MUST send a Mapping message with the Lock (K) bit in the MPLS-TP PW OAM Administration TLV cleared. The receiving PE/T-PE SHOULD try to unlock the PW. If the PW is unlocked successfully, the receiving PE/ T-PE SHOULD send a Notification message with PW status bit "Pseudowire in Lock Mode" cleared. Otherwise, it SHOULD send a Notification message with the LDP Status code set to "PW Unlock Failure". 3.2. Loopback When a PE/T-PE intends to put the remote PE/T-PE of a PW into loopback mode, it MUST send a Mapping message with both the Lock (K) bit and Loopback (B) bit in the MPLS-TP PW OAM Administration TLV set. When a T-PE intends to put a particular S-PE of the MS-PW into loopback mode, it MUST send a Mapping message with both the Lock (K) bit and Loopback (B) bit set, and an Explicit Route Hop TLV(ER-Hop TLV) [I-D.ietf-pwe3-mspw-er] identifying the Target S-PE node MUST be carried in the Mapping message. The L flag in the ER-Hop TLV SHOULD be cleared. To ensure that the ER-Hop TLV identifies a single node as the Target S-PE, The PreLen field in the IPv4 prefix ER-Hop TLV SHOULD be set to 32, the PreLen field in the IPv6 prefix ER-Hop TLV SHOULD be set to 128, and the PreLen field in the L2 PW Address ER- Hop TLV SHOULD be set to 96. Information of the S-PE node may be collected using the SP-PE TLVs [RFC6073]. Dong, et al. Expires April 24, 2014 [Page 4] Internet-Draft LDP Extensions for PW LI&LB October 2013 When the Mapping message arrives at the remote PE/T-PE, the receiving PE SHOULD try to put the PW in loopback mode. If the receiver node puts the PW into loopback mode successfully, it SHOULD send a Notification message with PW status "Pseudowire in Loopback Mode". Otherwise, it SHOULD send a Notification message with the LDP Status code set to "PW Enter Loopback Failure". When a Mapping message with an ER-Hop TLV arrives an S-PE, the S-PE SHOULD check the ER-Hop TLV to see if it is the target S-PE of the message. If not, the S-PE SHOULD forward the message with the K and B bit unchanged to the next hop S-PE. When the Mapping message arrives at the target S-PE, the S-PE SHOULD parse the MPLS-TP PW OAM Administration TLV and try to put the PW into loopback mode. If the S-PE puts the PW into loopback mode successfully, it SHOULD send a Notification message with PW status set to "Pseudowire in Loopback Mode". An SP-PE TLV [RFC6073] identifying the S-PE in loopback mode SHOULD also be carried in the Notification message. If the S-PE fails to put the PW into loopback mode, it SHOULD send a Notification message with the LDP Status code set to "PW Enter Loopback Failure". An SP-PE TLV identifying this S-PE SHOULD also be carried in the Notification message. When the PE/T-PE intends to take the remote PE/T-PE out of the loopback mode, it MUST send a Mapping message with the Lock (K) bit set and Loopback (B) bit cleared. When the T-PE intends to take a particular S-PE out of loopback mode, the message MUST also carry an ER-Hop TLV to identify the target S-PE. If the PW is taken out of loopback mode successfully on the receiving PE/T-PE/S-PE, it SHOULD send a Notification message with PW status bit "Pseudowire in Loopback Mode" cleared. Otherwise, it SHOULD send a Notification message with the LDP Status code set to "PW Exit Loopback Failure". For the S-PE case, An SP-PE TLV identifying this S-PE node SHOULD also be carried in the Notification message. 4. IANA Considerations Two bits "Lock" (K) and "Loopback" (B) as defined in section 2.1 need to be allocated in the MPLS-TP PW OAM Administration TLV. Two new PW Status bits as defined in section 2.2 need to be allocated by IANA in the "Pseudowire Status Codes" registry. Four new LDP status codes need to be assigned by IANA in the LDP "Status Code Name Space" registry: Range/Value E Description TBA 0 PW Lock Failure TBA 0 PW Unlock Failure Dong, et al. Expires April 24, 2014 [Page 5] Internet-Draft LDP Extensions for PW LI&LB October 2013 TBA 0 PW Enter Loopback Failure TBA 0 PW Exit Loopback Failure 5. Security Considerations This document introduces no new security considerations over [RFC5036], [RFC4447] and [RFC6073]. 6. References 6.1. Normative References [I-D.ietf-pwe3-mspw-er] Dutta, P., Bocci, M., and L. Martini, "Explicit Path Routing for Dynamic Multi-Segment Pseudowires", draft- ietf-pwe3-mspw-er-02 (work in progress), December 2012. [I-D.ietf-pwe3-oam-config] Zhang, F., Bo, W., and E. Bellagamba, "Label Distribution Protocol Extensions for Proactive Operations, Administration and Maintenance Configuration of Dynamic MPLS Transport Profile PseudoWire", draft-ietf-pwe3-oam- config-01 (work in progress), August 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3985] Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to- Edge (PWE3) Architecture", RFC 3985, March 2005. [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. [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. [RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi- Segment Pseudowire Emulation Edge-to-Edge", RFC 5659, October 2009. [RFC5860] Vigoureux, M., Ward, D., and M. Betts, "Requirements for Operations, Administration, and Maintenance (OAM) in MPLS Transport Networks", RFC 5860, May 2010. [RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M. Aissaoui, "Segmented Pseudowire", RFC 6073, January 2011. Dong, et al. Expires April 24, 2014 [Page 6] Internet-Draft LDP Extensions for PW LI&LB October 2013 [RFC6371] Busi, I. and D. Allan, "Operations, Administration, and Maintenance Framework for MPLS-Based Transport Networks", RFC 6371, September 2011. 6.2. Informative References [RFC6435] Boutros, S., Sivabalan, S., Aggarwal, R., Vigoureux, M., and X. Dai, "MPLS Transport Profile Lock Instruct and Loopback Functions", RFC 6435, November 2011. Authors' Addresses Jie Dong Huawei Technologies Huawei Building, No.156 Beiqing Rd. Beijing 100095 China Email: jie.dong@huawei.com Mach(Guoyi) Chen Huawei Technologies Huawei Building, No.156 Beiqing Rd. Beijing 100095 China Email: mach.chen@huawei.com Greg Mirsky Ericsson Email: gregory.mirsky@ericsson.com Dong, et al. Expires April 24, 2014 [Page 7]