CCAMP Working Group E. Bellagamba, Ed. Internet-Draft L. Andersson, Ed. Intended status: Experimental Ericsson Expires: January 3, 2010 P. Skoldstrom Acreo July 2, 2009 RSVP-TE Extensions for MPLS-TP OAM Configuration draft-bellagamba-ccamp-rsvp-te-mpls-tp-oam-ext-00 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 3, 2010. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document defines a method for the configuration of the Bellagamba, et al. Expires January 3, 2010 [Page 1] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 Bidirectional Forwarding Detection (BFD) OAM mechanism through RSVP-TE Control Plane. The procedures described are experimental and are intended to be possibly updated with other proposed OAM tools and BFD future extensions. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3 1.2. Contributing Authors . . . . . . . . . . . . . . . . . . . 3 1.3. Background . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview of BFD OAM operation . . . . . . . . . . . . . . . . . 4 3. RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Operation overview . . . . . . . . . . . . . . . . . . . . 4 3.2. OAM Configuration TLV . . . . . . . . . . . . . . . . . . . 6 3.3. BFD OAM Configuration TLV . . . . . . . . . . . . . . . . . 6 3.4. Local Discriminator Sub-TLV . . . . . . . . . . . . . . . . 7 3.5. Required TX interval . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . . 9 6.2. Informative References . . . . . . . . . . . . . . . . . . 9 Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Bellagamba, et al. Expires January 3, 2010 [Page 2] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 1. Introduction This document defines a method for the configuration of the Bidirectional Forwarding Detection (BFD) OAM mechanism through GMPLS Control Plane. The procedures described are experimental and are intended to be possibly updated with other proposed OAM tools and BFD future extensions. The document intent is both disseminating experimental results carried out within Ericsson Research and provide an initial input for further Control Plane extension in CCAMP IETF group. 1.1. 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]. 1.2. Contributing Authors The editors gratefully acknowledge the contributions of Benoit C Tremblay, Andras Kern, Attila Takacs and David Jocha. 1.3. Background MPLSTransport Profile (MPLS-TP), describes a profile of MPLS that enables operational models typical in transport networks, while providing additional OAM, survivability and other maintenance functions not currently supported by MPLS. [MPLS-TP-OAM-REQ] defines the requirements by which the OAM functionality of MPLS-TP should abide. The requirements listed may be met by one or more OAM Protocols. Bidirectional Forwarding Detection, as described in [BFD], defines a protocol that provides low-overhead, short-duration detection of failures in the path between two forwarding engines, including the interfaces, data link(s), and to the extent possible the forwarding engines themselves. BFD can be used to track the liveliness of MPLS-TP point-to-point and p2mp connections and detect data plane failures. This version of the draft is focused on unidirectional and bidirectional p2p connection. There are no OAM mechanisms designated to operate in conjunction with MPLS-TP yet. BFD meets several of the requirements listed so far in [MPLS-TP-OAM-REQ] and can be a good candidate for Continuity Check in Bellagamba, et al. Expires January 3, 2010 [Page 3] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 MPLS-TP. Other proposed OAM tools and BFD future extensions will be possibly taken into account in this document during the next releases. RSVP-TE control plane [RFC3471] has been chosen to support the establishment of MPLS-TP LSPs. 2. Overview of BFD OAM operation BFD is a simple hello protocol that in many respects is similar to the detection components of well-known routing protocols. A pair of systems transmit BFD packets periodically over each path between the two systems, and if a system stops receiving BFD packets for long enough, some component in that particular bidirectional path to the neighboring system is assumed to have failed. Systems may also negotiate to not send periodic BFD packets in order to reduce overhead. A path is only declared to be operational when two-way communication has been established between systems, though this does not preclude the use of unidirectional links. Section 3 in [BFD] states that a separate BFD session is created for each communications path and data protocol in use between two systems. Each system estimates how quickly it can send and receive BFD packets in order to come to an agreement with its neighbor about how rapidly detection of failure will take place. These estimates can be modified in real time in order to adapt to unusual situations. This design also allows for fast systems on a shared medium with a slow system to be able to more rapidly detect failures between the fast systems while allowing the slow system to participate to the best of its ability. The ability of each system to control the BFD packet transmission rate in both directions provides a mechanism for congestion control, particularly when BFD is used across multiple network hops. 3. RSVP-TE Extensions 3.1. Operation overview A BFD session may be established for a FEC associated with a MPLS LSP. In case of: Bellagamba, et al. Expires January 3, 2010 [Page 4] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 o PHP o when the egress LSR distributes an explicit null label to the penultimate hop router o next-hop label allocation the BFD control packet received by the egress LSR does not contain sufficient information to associate it with a BFD session. Hence the demultiplexing MUST be done using the remote discriminator field in the received BFD control packet. The exchange of BFD discriminators for this purpose can be achieved with LSP Ping as described in [LSP Ping]. However, LSP Ping presents some drawbacks such as high computational complexity and the dependency to the IP protocol, as described in [MPLS-TP OAM Analysis]. Such dependency should be avoided in a MPLS-TP context, since MPLS-TP can not count on IP as forwarding mechanism in the data plane. Below, we define some simple additions that can be done in GMPLS RSVP-TE in order to carry out a BFD session setup at the same time as the setup of the LSP related to the BFD session. With the terms "ingress LSR" and "egress LSR" we will not refer to any direction in the forwarding plane, but only to the LSR triggering the LSP setup (ingress LSR) and the one triggering the response to it (egress LSR). During the LSP signaling, the Control Plane instance in the ingress and the egress LSR announces the BFD OAM Configuration TLV (inside the LSP_ATTRIBUTES object carried by the Path and Resv message respectively), which includes the "Local Discriminator" sub-TLV. During the BFD session the ingress LSR will use as "MyDiscriminator" the value announced in the "Local Discriminator"(Path message) and as "YourDiscriminator" the value received in the "Local Discriminator" (Resv message). Moreover, in the BFD protocol, the time values used to determine BFD packet transmission intervals and the session Detection Time are continuously negotiated by the BFD protocol itself, and thus may be changed at any time. The negotiation and time values are independent in each direction for each session, as described in [BFD] section 6.8.2. It is introduced the possibility of advertising the initial time values, together with the Discriminator values, during the control plane session setup. The Control Plane instance in the ingress LSR Bellagamba, et al. Expires January 3, 2010 [Page 5] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 will advertise its timing requirements in the Path messages. It will be signaled a single value for both directions in asynchronous and echo mode. The egress LSR will acknowledge them or reply with an error message. 3.2. OAM Configuration TLV This TLV is specified in [OAM-CONF-FWK] and is used to select which OAM technology/method should be used for the LSP. In this document a new OAM Type: BFD OAM is defined. +----------+--------------+ | OAM Type | Description | +----------+--------------+ | 0 | Reserved | | 1 | Ethernet OAM | | 2 | BFD | | 2-256 | Reserved | +----------+--------------+ The receiving node when the BFD OAM Type is requested should look for the corresponding technology specific BFD OAM configuration TLV. 3.3. BFD OAM Configuration TLV The BFD OAM Configuration TLV (depicted below) is defined for BFD OAM specific configuration parameters. The BFD OAM Configuration TLV is carried in the LSP_ATTRIBUTES object both in Path and Resv messages. This new TLV accommodates generic BFD OAM information and carries sub-TLVs. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (4) (IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Vers.|R| Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: indicates a new type, the BFD OAM Configuration TLV (4) (IANA to define). Bellagamba, et al. Expires January 3, 2010 [Page 6] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 Length: indicates the total length including sub-TLVs. Version: identifies the BFD protocol version. If a node does not support a specific BFD version an error must be generated: "OAM Problem/Unsupported OAM Version " R Flag: Role Flag. If set, the receiving node is required to act with an Active Role as described in [BFD], section 6.1. When the BFD OAM Configuration TLV is carried in the Resv message, the flag it not taken into consideration by the receiving node. 3.4. Local Discriminator Sub-TLV The Local Discriminator sub-TLV is depicted 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (1) (IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Local Discriminator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: indicates a new type, the Local Discriminator sub TLV (1) (IANA to define). Length: indicates the total length of the TLV including padding. Local Discriminator: A unique, nonzero discriminator value generated by the transmitting system and referring to itself, used to demultiplex multiple BFD sessions between the same pair of systems. This Discriminator will be signaled both by the ingress LSR and the egress LSR in the Path and Resv message respectively. 3.5. Required TX interval The Required TX interval sub-TLV is depicted below. Bellagamba, et al. Expires January 3, 2010 [Page 7] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (3) (IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Required Asynchronous TX interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Required Echo TX Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Detect. Mult | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: indicates a new type, the Required TX interval sub TLV (3) (IANA to define). Length: indicates the total length of the TLV including padding. Required Asynchronous TX interval: the interval, in microseconds, that the local system would like to have when both transmitting and receiving BFD Control packets, less any jitter applied. The value zero is reserved. If the receiving system can not support this value it will return an error. Required Echo TX Interval: the minimum interval, in microseconds, between received BFD Echo packets that this system is capable of supporting, less any jitter applied by the sender as described in [BFD], section 6.8.9. This value is also an indication for the receiving system of the minimum interval between transmitted BFD Echo packets. If this value is zero, the transmitting system does not support the receipt of BFD Echo packets. If the receiving system can not support this value it will return an error. Detect Mult: detection time multiplier. The transmit interval, multiplied by this value, provides the Detection Time for the transmitting and receiving system in Asynchronous mode. 4. IANA Considerations This document specifies a new BFD OAM Configuration TLV to be carried in the OAM Configuration TLV in LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES objects in Path messages. 5. Security Considerations This document does not introduce any new security considerations. Bellagamba, et al. Expires January 3, 2010 [Page 8] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 6. References 6.1. Normative References [BFD] Katz, D. and D. Ward, "Bidirectional Forwarding Detection", 2009, . [MPLS-TP-OAM-REQ] Vigoureux, M., Ward, D., and M. Betts, "Requirements for OAM in MPLS Transport Networks", 2009, . [OAM-CONF-FWK] Takacs, A., Fedyk, D., and J. van He, "OAM Configuration Framework for GMPLS RSVP-TE", 2009, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. 6.2. Informative References [LSP Ping] Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", 2006, . [MPLS-TP OAM Analysis] Sprecher, N., Nadeau, T., van Helvoort, H., and Weingarten, "MPLS-TP OAM Analysis", 2006, . Appendix A. Additional Stuff This becomes an Appendix. Bellagamba, et al. Expires January 3, 2010 [Page 9] Internet-Draft RSVP-TE Ext for MPLS-TP OAM Config July 2009 Authors' Addresses Elisa Bellagamba (editor) Ericsson Farogatan 6 Stockholm, 164 40 Sweden Phone: +46 761440785 Email: elisa.bellagamba@ericsson.com Loa Andersson (editor) Ericsson Farogatan 6 Stockholm, 164 40 Sweden Phone: Email: loa.andersson@ericsson.com Pontus Skoldstrom Acreo Stockholm, 164 40 Sweden Phone: Email: pontus.skoldstrom@acreo.com Bellagamba, et al. Expires January 3, 2010 [Page 10]