Network Working Group A. Takacs Internet-Draft Ericsson Intended status: Standards Track D. Fedyk Expires: June 26, 2009 Nortel H. Jia Huawei December 23, 2008 OAM Configuration Framework and Requirements for GMPLS RSVP-TE draft-ietf-ccamp-oam-configuration-fwk-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 June 26, 2009. Copyright Notice Copyright (c) 2008 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. Takacs, et al. Expires June 26, 2009 [Page 1] Internet-Draft OAM Configuration Framework December 2008 Abstract OAM functions are essential to ensure that the desired service level of traffic engineered connections are met. In certain technologies OAM entities are inherently established once the connection is set up. However other technologies, especially OAM for packet switched networks, require an extra configuration step after connection establishment to setup OAM entities. This document specifies extensions to RSVP-TE to support the establishment and configuration of OAM entities along with LSP signalling. Takacs, et al. Expires June 26, 2009 [Page 2] Internet-Draft OAM Configuration Framework December 2008 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 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. GMPLS RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . 9 3.1. Operation overview . . . . . . . . . . . . . . . . . . . . 9 3.2. OAM entities desired -- LSP Attributes flag . . . . . . . 10 3.3. OAM Configuration TLV . . . . . . . . . . . . . . . . . . 11 3.4. Monitoring Disabled - Admin_Status bit . . . . . . . . . . 11 3.5. OAM configuration errors . . . . . . . . . . . . . . . . . 12 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 Appendix A. Discussion on alternatives . . . . . . . . . . . . . 16 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Takacs, et al. Expires June 26, 2009 [Page 3] Internet-Draft OAM Configuration Framework December 2008 1. Introduction Operations and Management (OAM) functions are essential to ensure that the desired service level of traffic engineered connections are met. OAM functions ease network operation by reducing complexity, enhance network survivability, verify network performance, and in turn reduce operational costs. In certain technologies OAM entities are inherently established once the connection is set up. However other technologies, especially OAM for packet switched networks, require an extra configuration step after connection establishment to setup OAM entities. In some situations the use of OAM functions, like those of Fault- (FM) and Performance Management (PM), may be optional confirming to actual network management policies. Hence the network operator must be able to choose which kind of OAM functions to apply to specific connections and with what parameters the selected OAM functions should be configured and operated. To achieve this objective OAM entities and specific functions must be selectively configurable. The GMPLS control plane consists of a set of protocols: OSPF-TE, RSVP-TE and LMP. which are used to reduce manual configuration and improve management efficiency. RSVP-TE is used to setup and configure end-to-end connections. A new useful application of RSVP-TE is OAM configuration and control for transport networks. When RSVP-TE is used for LSP establishment it is desirable to bind OAM setup to connection establishment signalling to avoid two separate management/configuration steps (connection setup followed by OAM configuration) which increases delay, processing and more importantly may be prune to misconfiguration errors. The mechansim described in this document provides an additional option for bootstrapping OAM that is not intended to replace or deprecate the use of other OAM bootstrapping techniques such as LSP Ping [RFC4379]. The procedures specified in this document are intended only for use in environments where RSVP-TE signaling is already in use to set up the LSPs that are to be monitored using OAM. This document describes requirements on OAM configuration and control via RSVP-TE, and specifies extensions to the RSVP-TE protocol providing a framework to configure and control OAM entities along with capability to carry technology specific information. Extensions can be grouped into generic elements that are applicable to any OAM solution and technology specific elements that provide additional configuration parameters only needed for a specific OAM technology. This document specifies the technology agnostic elements that alone Takacs, et al. Expires June 26, 2009 [Page 4] Internet-Draft OAM Configuration Framework December 2008 can be used to establish OAM entities in the case no technology specific information is needed, and specifies the way additional technology specific OAM parameters are provided. Takacs, et al. Expires June 26, 2009 [Page 5] Internet-Draft OAM Configuration Framework December 2008 2. Requirements MPLS OAM requirements are described in [RFC4377]. It provides requirements to create consistent OAM functionality for MPLS networks. GMPLS OAM requirements are described in [GMPLS-OAM]. The GMPLS OAM requirements are based on the MPLS OAM requirements [RFC4377], in addition it also considers the existing OAM techniques in non-packet networks. The following list is an excerpt of MPLS OAM requirements documented in [RFC4377]. Only a few requirements are discussed that bear a direct relevance to the discussion set forth in this document. o It is desired to support the automation of LSP defect detection. It is especially important in cases where large numbers of LSPs might be tested. o In particular some LSPs may require automated ingress-LSR to egress-LSR testing functionality, while others may not. o Mechanisms are required to coordinate network responses to defects. Such mechanisms may include alarm suppression, translating defect signals at technology boundaries, and synchronising defect detection times by setting appropriately bounded detection timeframes. MPLS-TP defines a profile of MPLS targeted at transport applications [MPLS-TP-FWK]. This profile specifies the specific MPLS characteristics and extensions required to meet transport requirements, including providing additional OAM, survivability and other maintenance functions not currently supported by MPLS. Specific OAM requirements for MPLS-TP are specified in [MPLS-TP-OAM-REQ]. MPLS-TP poses requirements on the control plane to configure and control OAM entities. o The use of OAM functions SHOULD be optional for the operator. A network operator SHOULD be able to choose which OAM functions to use and which Maintenance Entity to apply them to. o The MPLS-TP control pane MUST support the configuration and modification of OAM maintenance points as well as the activation/ deactivation of OAM when the transport path is established or modified. OAM functions SHOULD be configurable as part of connectivity (LSP or PW) management. Ethernet Connectivity Fault Management (CFM) defines an adjunct connectivity monitoring OAM flow to check the liveliness of Ethernet networks [IEEE-CFM]. With PBB-TE [IEEE-PBBTE] Ethernet networks will Takacs, et al. Expires June 26, 2009 [Page 6] Internet-Draft OAM Configuration Framework December 2008 support explicitly-routed Ethernet connections. CFM can be used to track the liveliness of PBB-TE connections and detect data plane failures. In IETF the GMPLS controlled Ethernet Label Switching (GELS) [GELS-Framework] work is extending the GMPLS control plane to support the establishment of point-to-point PBB-TE data plane connections. Without control plane support separate management commands would be needed to configure and start CFM. GMPLS based OAM configuration and control should be general to be applicable to a wide range of data plane technologies and OAM solution. There are three typical data plane technologies used for transport application, which are wavelength based such as WSON, TDM based such as SDH/SONET, packet based such as MPLS-TP [MPLS-TP-FWK] and Ethernet PBB-TE [IEEE-PBBTE]. In all these data planes, the operator MUST be able to configure and control the following OAM functions. o It MUST be possible to explicitly request the setup of OAM entities for the signalled LSP and provide specific information for the setup if this is required by the technology. o When periodic messages are used for liveliness check (continuity check) of LSPs it MUST be possible to set the frequency of messages allowing proper configuration for fulfilling the requirements of the service and/or meeting the detection time boundaries posed by possible congruent connectivity check operations of higher layer applications. For a network operator to be able to balance the trade-off in fast failure detection and overhead it is beneficial to configure the frequency of continuity check messages on a per LSP basis. o Control of alarms is important to avoid false alarm indications and reporting to the management system. It MUST be possible to enable/disable alarms generated by OAM functions. In some cases selective alarm control may be desirable when, for instance, the operator is only concerned about critical alarms thus the non- service affecting alarms should be inhibited. o Performance Monitoring (PM) is continuously collecting information about specific characteristics of the connection. It MUST be possible to configure PM functions, e.g., set monitoring intervals and thresholds for PM initiated alarms. For consistent measurement of Service Level Agreements (SLAs) it may be required that measurement points agree on a common probing rate to avoid measurement problems. o The extensions must allow the operator to use only a minimal set of OAM configuration and control features if the data plane Takacs, et al. Expires June 26, 2009 [Page 7] Internet-Draft OAM Configuration Framework December 2008 technology, the OAM solution or network management policy allows. The extensions must be reusable as much as reasonably possible. That is generic OAM parameters and data plane or OAM technology specific parameters must be separated. Takacs, et al. Expires June 26, 2009 [Page 8] Internet-Draft OAM Configuration Framework December 2008 3. GMPLS RSVP-TE Extensions 3.1. Operation overview Two types of Maintenance Poits (MPs) are distinguished: Maintenance End Points (MEPs) and Maintenance Intermediate Points (MIPs). MEPs are located at the ends of an LSP and are capable of initiating and terminating OAM packets for Fault Management (FM) and Performance Monitoring (PM). MIPs on the other hand are located at transit nodes of an LSP and are capable of reacting to some OAM packets but otherwise do not initiate packets. Maintenance Entity (ME) refers to an association of MEPs and MIPs that are provisioned to monitor an LSP. The ME association is achieved by configuring MPs of an ME with the same unique ME ID. Each MEP must have unique identification (MEP ID) within the ME. When an LSP is signalled forwarding association is established between endpoints and transit nodes via label bindings. This association creates a context for the OAM entities monitoring the LSP. On top of this association OAM entities may be configured with an ME ID and MEP IDs. The ME ID may be used to detect misconfiguration errors and leacking OAM traffic. Within the ME the MEP ID can be used to demultiplex and identify the originating MEP of OAM packets. Since MIPs do not originate OAM packets no specific configuration is required for them. In addition to the ME and MEP identification parameters pro-active OAM functions (e.g., Continuity Check (CC), Performance Monitoring) may have specific parameters requiring configuration as well. In particular, the frequency of periodic CC packets and the measurement interval for loss and delay measurements may need to be configured. MEP +-------------+ |OAM Functions| | FM | PM | +------+------+ | MEP ID | +-------------+ | ME ID | +-------------+ +-------------+ | LSP | +-------------+ In some cases all the above parameters may be either derived form some exiting information or pre-configured default values can be Takacs, et al. Expires June 26, 2009 [Page 9] Internet-Draft OAM Configuration Framework December 2008 used. In the simplest case the control plane needs to provide information whether or not a ME with MPs need to be setup for the signalled LSP. If OAM entities are created signalling must provide means to activate/deactivate OAM message flows and associated alarms. ME and MEP IDs as well as configuration of OAM functions are technology specific, i.e., vary depending on the data plane technology and the chosen OAM solution. In addition for any given data plane technology a set of OAM solutions may be applicable. The OAM configuration framework allows selecting a specific OAM solution to be used for the signalled LSP and provides technology specific TLVs to carry further detailed configuration information. 3.2. OAM entities desired -- LSP Attributes flag In RSVP-TE the Flags field of the SESSION_ATTRIBUTE object is used to indicate options and attributes of the LSP. The Flags field has 8 bits and hence is limited to differentiate only 8 options. [RFC4420] defines a new object for RSVP-TE messages to allow the signalling of arbitrary attribute parameters making RSVP-TE easily extensible to support new applications. Furthermore, [RFC4420] allows options and attributes that do not need to be acted on by all Label Switched Routers (LSRs) along the path of the LSP. In particular, these options and attributes may apply only to key LSRs on the path such as the ingress LSR and egress LSR. Options and attributes can be signalled transparently, and only examined at those points that need to act on them. The LSP_ATTRIBUTES object and the LSP_REQUIRED_ATTRIBUTES objects are defined in [RFC4420] to provide means to signal LSP attributes and options in the form of TLVs. Options and attributes signalled in the LSP_ATTRIBUTES object can be passed transparently through LSRs not supporting a particular option or attribute, while the contents of the LSP_REQUIRED_ATTRIBUTES object must be examined and processed by each LSR. One TLV is defined in [RFC4420]: the Attributes Flags TLV. A new bit (10 IANA to assign): "OAM entities desired" is allocated in the LSP Attributes Flags TLV. If the "OAM entities desired" bit is set it is indicating that the establishment of OAM entities are required at the endpoints of the signalled LSP. If the establishment of OAM entities is not supported an error must be generated: "OAM Problem/OAM establishment not supported". If the "OAM entities desired" bit is set and additional parameters are needed to configure the OAM entities an OAM Configuration TLV may be included in the LSP_ATTRIBUTES object. Takacs, et al. Expires June 26, 2009 [Page 10] Internet-Draft OAM Configuration Framework December 2008 3.3. OAM Configuration TLV This TLV specifies which OAM technology/method should be used for the LSP. The OAM Configuration TLV is carried in the LSP_ATTRIBUTES object in Path messages. 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 (2) (IANA) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OAM Type | OAM Function | Reserved (set to all 0s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: indicates a new type: the OAM Configuration TLV (2) (IANA to assign). OAM Type: specifies the technology specify OAM method. If the requested OAM method is not supported an error must be generated: "OAM Problem/Unsupported OAM Type". This document defines no types. The receiving node based on the OAM Type will check if a corresponding technology specific OAM configuration TLV is included. OAM Function Flags: specifies proactive OAM functions (e.g., connectivity monitoring, loss and delay measurement) that should be established and configured. If the selected OAM Function(s) is(are) not supported an error must be generated: "OAM Problem/Unsupported OAM Function". This document defines the following flags. OAM Function Flag Description --------------------- --------------------------- 0 Connectivity Monitoring 1-7 Reserved 3.4. Monitoring Disabled - Admin_Status bit Administrative Status Information is carried in the ADMIN_STATUS Object. The Administrative Status Information is described in [RFC3471], the ADMIN_STATUS Object is specified for RSVP-TE in [RFC3473]. One bit is allocated for the administrative control of OAM Takacs, et al. Expires June 26, 2009 [Page 11] Internet-Draft OAM Configuration Framework December 2008 monitoring. In addition to the Reflect (R) bit, 7 bits are currently occupied (assigned by IANA or temporarily blocked by work in progress Internet drafts). As the 24th bit (IANA to assign) this draft introduces the Monitoring Disabled (M) bit. When this bit is set the monitoring and OAM triggered alarms of the LSP are disabled (e.g., no continuity check messages are sent). 3.5. OAM configuration errors To handle OAM configuration errors a new Error Code (IANA to assign) "OAM Problem" is introduced. To refer to specific problems a set of Error Values is defined. If a node does not support the establishment of OAM entities via RSVP-TE signalling it must use the error value (IANA to assign): "OAM establishment not supported" in the PathErr message. If a node does not support a specific OAM technology/solution it must use the error value (IANA to assign): "Unsupported OAM Type" in the PathErr message. If a node does not support a specific OAM Function it must use the error value (IANA to assign): "Unsupported OAM Function" in the PathErr message. Takacs, et al. Expires June 26, 2009 [Page 12] Internet-Draft OAM Configuration Framework December 2008 4. IANA Considerations One bit (Monitoring Disabled (M)) needs to be allocated in the ADMIN_STATUS Object. One bit ("OAM entities desired") needs to be allocated in the LSP Attributes Flag Registry. This document specifies one new TLVs to be carried in the LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES objects in Path messages: OAM Configuration TLV. One new Error Code: "OAM Problem" and three new values: "OAM establishment not supported", "Unsupported OAM Type" and "Unsupported OAM Function" needs to be assigned. Takacs, et al. Expires June 26, 2009 [Page 13] Internet-Draft OAM Configuration Framework December 2008 5. Security Considerations The signalling of OAM related parameters and the automatic establishment of OAM entities introduces additional security considerations to those discussed in [RFC3473]. In particular, a network element could be overloaded, if an attacker would request liveliness monitoring, with frequent periodic messages, for a high number of LSPs, targeting a single network element. Security aspects will be covered in more detailed in subsequent versions of this document. Takacs, et al. Expires June 26, 2009 [Page 14] Internet-Draft OAM Configuration Framework December 2008 6. Acknowledgements The authors would like to thank Francesco Fondelli, Adrian Farrel, Loa Andersson, Eric Gray and Dimitri Papadimitriou for their useful comments. Takacs, et al. Expires June 26, 2009 [Page 15] Internet-Draft OAM Configuration Framework December 2008 Appendix A. Discussion on alternatives This appendix summarises the discussions after IETF-71 about the way OAM configuration information should be carried in RSVP-TE. The first question is how the requirement for OAM establishment is signalled and how the operation of OAM is controlled. There is a straightforward way to achieve these using existing objects and fields: o Use one or more OAM flags in the LSP Attributes Flag TLV within the LSP_ATTRIBUTES/LSP_REQUIRED_ATTRIBUTES object to signal that OAM entities for the LSP need to be established. If for any reason this cannot be done a notification is sent or an error is raised. o Once the LSP with the desired OAM entities is established OAM operation may be controlled using one or more flags in the ADMIN_STATUS object. For instance, the generation of connectivity monitoring messages can be disabled/enabled by setting/clearing a flag in the ADMIN_STATUS object. However, there are two alternatives when it comes to signalling the actual configuration parameters of OAM entities. o Extension of the LSP_ATTRIBUTES object with new TLVs. o Definition of a new RSVP-TE object to carry OAM information. In the first case, a new OAM configuration TLV is defined in the LSP_ATTRIBUTES object. This TLV would provide the detailed information needed for LSPs with a set OAM flag in the LSP Attributes Flag TLV. The rationale for this approach is that in addition to setting flags the LSP_ATTRIBUTES object may carry complementary information for all or some of the flags set. Furthermore, as top level RSVP-TE objects may become scarce resources, it seems to be beneficial not to allocate new RSVP-TE objects for the purpose of providing detailed information for new LSP Attribute Flags. Currently there is only one TLV, the Attributes Flag TLV, defined in the LSP_ATTRIBUTES object. Defining a new TLV associated with one of the flags would make a precedence and possibly be a guideline for similar future extensions. The other alternative would be to allocate a dedicated object for OAM configuration information. The rationale for this is that the complex information that may be required for OAM configuration would unnecessarily add complexity to LSP_ATTRIBUTES/ LSP_REQUIRED_ATTRIBUTES objects and their processing mechanisms. Takacs, et al. Expires June 26, 2009 [Page 16] Internet-Draft OAM Configuration Framework December 2008 Furthermore, traditionally RSVP uses dedicated objects (*_SPECs) to carry configuration information of data plane entities, thus a new object like an "OAM_SPEC" may be a better fit to existing protocol elements. The authors of this document favour the first alternative (adding new TLVs to LSP_ATTRIBTES/LSP_REQUIRED_ATTRIBUTES. However, which alternative to select for standardisation is up for the working group to decide. In any case, the information to be carried would be the same or very similar for both alternatives. Takacs, et al. Expires June 26, 2009 [Page 17] Internet-Draft OAM Configuration Framework December 2008 7. References [GELS-Framework] "GMPLS Ethernet Label Switching Architecture and Framework", Internet Draft, work in progress. [GMPLS-OAM] "OAM Requirements for Generalized Multi-Protocol Label Switching (GMPLS) Networks", Internet Draft, work in progress. [IEEE-CFM] "IEEE 802.1ag, Draft Standard for Connectivity Fault Management", work in progress. [IEEE-PBBTE] "IEEE 802.1Qay Draft Standard for Provider Backbone Bridging Traffic Engineering", work in progress. [MPLS-TP-FWK] "A Framework for MPLS in Transport Networks", Internet Draft, work in progress. [MPLS-TP-OAM-REQ] "Requirements for OAM in MPLS Transport Networks", Internet Draft, work in progress. [RFC3469] "Framework for Multi-Protocol Label Switching (MPLS)-based Recovery", RFC 3469, February 2003. [RFC3471] "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC4377] "Operations and Management (OAM) Requirements for Multi- Protocol Label Switched (MPLS) Networks", RFC 4377, February 2006. [RFC4420] "Encoding of Attributes for Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Establishment Using Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 4420, February 2006. Takacs, et al. Expires June 26, 2009 [Page 18] Internet-Draft OAM Configuration Framework December 2008 Authors' Addresses Attila Takacs Ericsson Laborc u. 1. Budapest, 1037 Hungary Email: attila.takacs@ericsson.com Don Fedyk Nortel 600 Technology Park Drive Billerica, MA 01821 USA Email: dwfedyk@nortel.com He Jia Huawei Email: hejia@huawei.com Takacs, et al. 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