Network Working Group A. Takacs Internet-Draft Ericsson Intended status: Standards Track D. Fedyk Expires: August 1, 2010 Alcatel-Lucent J. He Huawei January 28, 2010 OAM Configuration Framework and Requirements for GMPLS RSVP-TE draft-ietf-ccamp-oam-configuration-fwk-03 Abstract OAM is an integral part of transport connections, hence it is required that OAM functions are activated/deactivated in sync with connection commissioning/decommissioning; avoiding spurious alarms and ensuring consistent operation. In certain technologies OAM entities are inherently established once the connection is set up, while other technologies require extra configuration to establish and configure OAM entities. This document specifies extensions to RSVP-TE to support the establishment and configuration of OAM entities along with LSP signaling. Takacs, et al. Expires August 1, 2010 [Page 1] Internet-Draft GMPLS OAM Configuration Framework January 2010 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 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 August 1, 2010. Copyright Notice Copyright (c) 2010 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 BSD License. Takacs, et al. Expires August 1, 2010 [Page 2] Internet-Draft GMPLS OAM Configuration Framework January 2010 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. GMPLS based OAM Configuration . . . . . . . . . . . . . . . . 8 3.1. Establishment of OAM Entities and Functions . . . . . . . 8 3.2. Adjustment of OAM Parameters . . . . . . . . . . . . . . . 10 3.3. Deleting OAM Entities . . . . . . . . . . . . . . . . . . 10 4. RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . . . . 12 4.1. LSP Attributes Flags . . . . . . . . . . . . . . . . . . . 12 4.2. OAM Configuration TLV . . . . . . . . . . . . . . . . . . 12 4.2.1. OAM Function Flags Sub-TLV . . . . . . . . . . . . . . 14 4.2.2. Technology Specific sub-TLVs . . . . . . . . . . . . . 14 4.3. Administrative Status Information . . . . . . . . . . . . 14 4.4. Handling OAM Configuration Errors . . . . . . . . . . . . 15 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 Appendix A. Discussion on Alternatives . . . . . . . . . . . . . 19 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22 Takacs, et al. Expires August 1, 2010 [Page 3] Internet-Draft GMPLS OAM Configuration Framework January 2010 1. Introduction GMPLS is designed as an out-of-band control plane supporting dynamic connection provisioning for any suitable data plane technology; including spatial switching (e.g., incoming port or fiber to outgoing port or fiber), wavelength-division multiplexing (e.g., DWDM), time- division multiplexing (e.g., SONET/SDH, G.709), and lately Ethernet Provider Backbone Bridging -- Traffic Engineering (PBB-TE) and MPLS Transport Profile (MPLS-TP). In most of these technologies there are Operations and Management (OAM) functions employed to monitor the health and performance of the connections and to trigger data plane (DP) recovery mechanisms. Similarly to connections, OAM functions follow general principles but also have some technology specific characteristics. OAM is an integral part of transport connections, hence it is required that OAM functions are activated/deactivated in sync with connection commissioning/decommissioning; avoiding spurious alarms and ensuring consistent operation. In certain technologies OAM entities are inherently established once the connection is set up, while other technologies require extra configuration to establish and configure 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. In general, it is required that the management plane and control plane connection establishment mechanisms are synchronized with OAM establishment and activation. In particular, if the GMPLS control plane is employed it is desirable to bind OAM setup and configuration to connection establishment signaling 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. Once OAM entities are setup and configured, pro-active as well as on-demand OAM functions can be activated via the management plane. On the other hand, it should be possible to activate/deactivate pro-active OAM functions via the GMPLS control plane as well. 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 the capability to carry technology specific information. Extensions can be grouped into generic elements that are applicable Takacs, et al. Expires August 1, 2010 [Page 4] Internet-Draft GMPLS OAM Configuration Framework January 2010 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, which alone can be used to establish and control OAM entities in the case no technology specific information is needed, and specifies the way additional technology specific OAM parameters are provided. This document addresses end-to-end OAM configuration, that is, the setup of OAM entities bound to an end-to-end LSP, and configuration and control of OAM functions running end-to-end in the LSP. Configuration of OAM entities for LSP segments and tandem connections are out of the scope of this document. The mechanisms described in this document provide an additional option for bootstrapping OAM that is not intended to replace or deprecate the use of other technology specific OAM bootstrapping techniques; e.g., LSP Ping [RFC4379] for MPLS networks. 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. Takacs, et al. Expires August 1, 2010 [Page 5] Internet-Draft GMPLS OAM Configuration Framework January 2010 2. Requirements MPLS OAM requirements are described in [RFC4377], which provides requirements to create consistent OAM functionality for MPLS 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 synchronizing 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 plane 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. GMPLS based OAM configuration and control should be general to be applicable to a wide range of data plane technologies and OAM solutions. 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 Takacs, et al. Expires August 1, 2010 [Page 6] Internet-Draft GMPLS OAM Configuration Framework January 2010 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 signaled LSP and provide specific information for the setup if this is required by the technology. 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 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 Pro-active Performance Monitoring (PM) functions are continuously collecting information about specific characteristics of the connection. 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 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 August 1, 2010 [Page 7] Internet-Draft GMPLS OAM Configuration Framework January 2010 3. GMPLS based OAM Configuration In general, two types of Maintenance Poits (MPs) can be distinguished: Maintenance End Points (MEPs) and Maintenance Intermediate Points (MIPs). MEPs reside at the ends of an LSP and are capable of initiating and terminating OAM messages 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 messages but otherwise do not initiate messages. 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 to belong to the same ME. When an LSP is signaled, 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 to unambigously identify MPs and MEs. In addition to MP and ME 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. In some cases all the above parameters may be either derived form some exiting information or pre-configured default values can be used. In the simplest case the control plane needs to provide information whether or not OAM entities need to be setup for the signaled LSP. If OAM entities are created signaling must provide means to activate/deactivate OAM message flows and associated alarms. OAM identifiers as well as the 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 signaled LSP and provides technology specific TLVs to carry further detailed configuration information. 3.1. Establishment of OAM Entities and Functions In order to avoid spurious alarms OAM functions must be setup and enabled in the appropriate order. When using the GMPLS control plane, establishment and enabling of OAM functions must be bound to RSVP-TE message exchanges. An LSP may be signaled and established without OAM configuration Takacs, et al. Expires August 1, 2010 [Page 8] Internet-Draft GMPLS OAM Configuration Framework January 2010 first, and OAM entities may be added later with a subsequent re- signaling of the LSP. Alternatively, the LSP may be setup with OAM entities right with the first signaling of the LSP. The below procedures apply to both cases. Before the initiator first sends a Path messages with OAM Configuration information, it MUST establish and configure the corresponding OAM entities locally, however OAM source functions MUST NOT start sending any OAM messages. In the case of bidirectional connections, the initiator node MUST setup the OAM sink function to be prepared to receive OAM messages but MUST suppress any OAM alarms (e.g., due to missing or unidentified OAM messages). The Path message MUST be sent with the "OAM Alarms Enabled" ADMIN_STATUS flag cleared, i.e, data plane OAM alarms are suppressed. When the Path message arrives at the receiver, the remote end MUST establish and configure OAM entities according to the OAM information provided in Path message. If this is not possible a PathErr SHOULD be sent and neither the OAM entities nor the LSP SHOULD be established. If OAM entities are established successfully, the OAM sink function MUST be prepared to receive OAM messages but MUST not generate any OAM alarms (e.g., due to missing or unidentified OAM messages). In the case of bidirectional connections, an OAM source function MUST be setup and, according to the requested configuration, it MUST start sending OAM messages. Then a Resv message is sent back, including the OAM Configuration TLV that corresponds to the actually established and configured OAM entities and functions. Depending on the OAM technology, some elements of the OAM Configuration TLV MAY be updated/changed; i.e., if the remote end is not supporting a certain OAM configuration it may suggest an alternative setting, which may or may not be accepted by the initiator of the Path message. If it is accepted, the initiator will reconfigure its OAM functions according to the information received in the Resv message. If the alternate setting is not acceptable a ResvErr may be sent tearing down the LSP. Details of this operation are technology specific and should be described in accompanying technology specific documents. When the initiating side receives the Resv message it completes any pending OAM configuration and enables the OAM source function to send OAM messages. After this round, OAM entities are established and configured for the LSP and OAM messages MAY already be exchanged. OAM alarms can now be enabled. The initiator, while still keeping OAM alarms disabled sends a Path message with "OAM Alarms Enabled" ADMIN_STATUS flag set. The receiving node enables the OAM alarms after processing the Path message. The initiator enables OAM alarms after it receives the Resv Takacs, et al. Expires August 1, 2010 [Page 9] Internet-Draft GMPLS OAM Configuration Framework January 2010 message. Data plane OAM is now fully functional. 3.2. Adjustment of OAM Parameters There may be a need to change the parameters of an already established and configured OAM function during the lifetime of the LSP. To do so the LSP needs to be re-signaled with the updated parameters. OAM parameters influence the content and timing of OAM messages and identify the way OAM defects and alarms are derived and generated. Hence, to avoid spurious alarms, it is important that both sides, OAM sink and source, are updated in a synchronized way. First, the alarms of the OAM sink function should be suppressed and only then should expected OAM parameters be adjusted. Subsequently, the parameters of the OAM source function can be updated. Finally, the alarms of the OAM sink side can be enabled again. In accordance with the above operation, the LSP MUST first be re- signaled with "OAM Alarms Enabled" ADMIN_STATUS flag cleared and including the updated OAM Configuration TLV corresponding to the new parameter settings. The initiator MUST keep its OAM sink and source functions running unmodified, but it MUST suppress OAM alarms after the updated Path message is sent. The receiver MUST first disable all OAM alarms, then update the OAM paramaters according to the information in the Path message and reply with a Resv message acknowledging the changes by including the OAM Configuration TLV. Note that the receiving side has the possibility to adjust the requested OAM configuration parameters and reply with and updated OAM Configuration TLV in the Resv message, reflecting the actually configured values. However, in order to avoid an extensive negotiation phase, in the case of adjusting already configured OAM functions, the receiving side SHOULD NOT update the parameters requested in the Path message to an extent that would provide lower performance than what has been configured previously. The initiator MUST only update its OAM sink and source functions after it received the Resv message. After this Path/Resv message exchange (in both unidirectional and bidirectional LSP cases) the OAM parameters are updated and OAM is running according the new parameter settings. However OAM alarms are still disabled. A subsequent Path/ Resv message exchange with "OAM Alarms Enabled" ADMIN_STATUS flag set is needed to enable OAM alarms again. 3.3. Deleting OAM Entities In some cases it may be useful to remove some or all OAM entities and functions from an LSP without actually tearing down the connection. To avoid any spurious alarm, first the LSP SHOULD be re-signaled with Takacs, et al. Expires August 1, 2010 [Page 10] Internet-Draft GMPLS OAM Configuration Framework January 2010 "OAM Alarms" ADMIN_STATUS flag cleared but unchanged OAM configuration. Subsequently, the LSP is re-signaled with "OAM MEP Entities desired" and "OAM MIP Entities desired" LSP ATTRIBUTES flags cleared, and without the OAM Configuration TLV, this MUST result in the deletion of all OAM entities associated with the LSP. All control and data plane resources in use by the OAM entities and functions SHOULD be freed up. Alternatively, if only some OAM functions need to be removed, the LSP is re-signalled with the updated OAM Configuration TLV. Changes between the contents of the previously signalled OAM Configuration TLV and the currently received TLV represent which functions SHOULD be removed/added. First, OAM source functions SHOULD be deleted and only after that SHOULD the associated OAM sink functions be removed, this will ensure that OAM messages do not leak outside the LSP. To this end the initiator, before sending the Path message, SHOULD remove the OAM source, hence terminating the OAM message flow associated to the downstream direction. In the case of a bidirectional connection, it SHOULD leave in place the OAM sink functions associated to the upstream direction. The remote end, after receiving the Path message, SHOULD remove all associated OAM entities and functions and reply with a Resv message without an OAM Configuration TLV. The initiator completely removes OAM entities and functions after the Resv message arrived. Takacs, et al. Expires August 1, 2010 [Page 11] Internet-Draft GMPLS OAM Configuration Framework January 2010 4. RSVP-TE Extensions 4.1. LSP Attributes Flags 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. [RFC5420] defines new objects for RSVP-TE messages to allow the signaling of arbitrary attribute parameters making RSVP-TE easily extensible to support new applications. Furthermore, [RFC5420] 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 signaled transparently, and only examined at those points that need to act on them. The LSP_ATTRIBUTES and the LSP_REQUIRED_ATTRIBUTES objects are defined in [RFC5420] to provide means to signal LSP attributes and options in the form of TLVs. Options and attributes signaled 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 [RFC5420]: the Attributes Flags TLV. One bit (10 IANA to assign): "OAM MEP entities desired" is allocated in the LSP Attributes Flags TLV. If the "OAM MEP entities desired" bit is set it is indicating that the establishment of OAM MEP entities are required at the endpoints of the signaled LSP. If the establishment of MEPs is not supported an error must be generated: "OAM Problem/MEP establishment not supported". If the "OAM MEP entities desired" bit is set and additional parameters are needed to be configured the OAM entities an OAM Configuration TLV may be included in the LSP_ATTRIBUTES object. One bit (11 IANA to assign): "OAM MIP entities desired" is allocated in the LSP Attributes Flags TLV. This bit can only be set if the "OAM MEP entities desired" bit is set. If the "OAM MIP entities desired" bit is set in the LSP_ATTRIBUTES Flags TLV, it is indicating that the establishment of OAM MIP entities is required at every transit node of the signalled LSP. If the establishment of a MIP is not supported an error must be generated: "OAM Problem/MIP establishment not supported". 4.2. OAM Configuration TLV This TLV provides information about which OAM technology/method should be used and carries sub-TLVs for any additional OAM Takacs, et al. Expires August 1, 2010 [Page 12] Internet-Draft GMPLS OAM Configuration Framework January 2010 configuration information. The OAM Configuration TLV may be carried in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object in Path and Resv 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ sub-TLVs ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: indicates a new type: the OAM Configuration TLV (2) (IANA to assign). OAM Type: specifies the technology specific OAM method. If the requested OAM method is not supported an error must be generated: "OAM Problem/Unsupported OAM Type". OAM Type Description ------------ -------------------- 0-255 Reserved This document defines no types. IANA is requests to maintain the values in a new "RSVP-TE OAM Configuration Registry". The receiving node based on the OAM Type will check if a corresponding technology specific OAM configuration sub-TLV is included. If the included technology specific OAM configuration sub- TLV is different than what is specified in the OAM Type an error must be generated: "OAM Problem/OAM Type Mismatch". Note that there is a hierarchical dependency in between the OAM configuration elements. First, the "OAM MEP (and MIP) entities desired" flag needs to be set. When it is set an "OAM Configuration TLV" may be included in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES Object. When this TLV is present, based on the "OAM Type" field, it may carry a technology specific OAM configuration sub-TLV. If this hierarchy is broken (e.g., "OAM MEP entities desired" flag is not set but an OAM Configuration TLV is present) an error must be generated: "OAM Problem/Configuration Error". Takacs, et al. Expires August 1, 2010 [Page 13] Internet-Draft GMPLS OAM Configuration Framework January 2010 4.2.1. OAM Function Flags Sub-TLV As the first sub-TLV one "OAM Function Flags sub-TLV" MUST be always included in the "OAM Configuration TLV". "OAM Function Flags" specifies which pro-active OAM functions (e.g., connectivity monitoring, loss and delay measurement) and which fault management signals MUST be established and configured. If the selected OAM Function(s) is(are) not supported, an error must be generated: "OAM Problem/Unsupported OAM Function". 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ OAM Function Flags ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This document defines the following flags. OAM Function Flag Description --------------------- --------------------------- 0 Continuity Check (CC) 1 Connectivity Verification (CV) 2 Performance Monitoring/Loss (PM/Loss) 3 Performance Monitoring/Delay (PM/Delay) 4.2.2. Technology Specific sub-TLVs One technology specific sub-TLV SHOULD be defined for each "OAM Type". This sub-TLV MUST contain any further OAM configuration information for that specific "OAM Type". The technology specific sub-TLV may be carried within the OAM Configuration TLV. 4.3. Administrative Status Information 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]. Two bits are allocated for the administrative control of OAM monitoring. In addition to the Reflect (R) bit, 7 bits are currently occupied (assigned by IANA or temporarily blocked by work in progress Takacs, et al. Expires August 1, 2010 [Page 14] Internet-Draft GMPLS OAM Configuration Framework January 2010 Internet drafts). As the 24th and 25th bits (IANA to assign) this draft introduces the "OAM Flows Enabled" (M) and "OAM Alarms Enabled" (O) bits. When the "OAM Flows Enabled" bit is set, OAM packets are sent if it is cleared no OAM packets are emitted. When the "OAM Alarms Enabled" bit is set OAM triggered alarms are enabled and associated consequent actions are executed including the notification of the management system. When this bit is cleared, alarms are suppressed and no action is executed and the management system is not notified. 4.4. Handling 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 MEP or MIP entities it must use the error value (IANA to assign): "MEP establishment not supported" or "MIP establishment not supported" respectively 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 different technology specific OAM configuration TLV is included than what was specified in the OAM Type an error must be generated with error value: "OAM Type Mismatch" in the PathErr message. There is a hierarchy in between the OAM configuration elements. If this hierarchy is broken the error value: "Configuration Error" must be used in the PathErr message. If a node does not support a specific OAM Function it must use the error value: "Unsupported OAM Function" in the PathErr message. Takacs, et al. Expires August 1, 2010 [Page 15] Internet-Draft GMPLS OAM Configuration Framework January 2010 5. IANA Considerations Two bits ("OAM Alarms Enabled" (O) and "OAM Flows Enabled" (M)) needs to be allocated in the ADMIN_STATUS Object. Two bits ("OAM MEP entities desired" and "OAM MIP entities desired") needs to be allocated in the LSP Attributes Flags Registry. This document specifies one new TLV to be carried in the LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES objects in Path and Resv messages: OAM Configuration TLV. One new Error Code: "OAM Problem" and a set of new values: "MEP establishment not supported", "MIP establishment not supported", "Unsupported OAM Type", "Configuration Error" and "Unsupported OAM Function" needs to be assigned. The IANA is requested to open a new registry: "RSVP-TE OAM Configuration Registry" that maintains the "OAM Type" code points and the allocations of "OAM Function Flags" within the OAM Configuration TLV. Takacs, et al. Expires August 1, 2010 [Page 16] Internet-Draft GMPLS OAM Configuration Framework January 2010 6. Security Considerations The signaling 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 August 1, 2010 [Page 17] Internet-Draft GMPLS OAM Configuration Framework January 2010 7. 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 August 1, 2010 [Page 18] Internet-Draft GMPLS OAM Configuration Framework January 2010 Appendix A. Discussion on Alternatives This appendix summarizes 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 signaled 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 signaling 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 August 1, 2010 [Page 19] Internet-Draft GMPLS OAM Configuration Framework January 2010 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 favor the first alternative (adding new TLVs to LSP_ATTRIBTES/LSP_REQUIRED_ATTRIBUTES. However, which alternative to select for standardization 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 August 1, 2010 [Page 20] Internet-Draft GMPLS OAM Configuration Framework January 2010 8. 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. [RFC5420] "Encoding of Attributes for Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Establishment Using Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 5420, February 2009. Takacs, et al. Expires August 1, 2010 [Page 21] Internet-Draft GMPLS OAM Configuration Framework January 2010 Authors' Addresses Attila Takacs Ericsson Laborc u. 1. Budapest, 1037 Hungary Email: attila.takacs@ericsson.com Don Fedyk Alcatel-Lucent Groton, MA 01450 USA Email: donald.fedyk@alcatel-lucent.com Jia He Huawei Email: hejia@huawei.com Takacs, et al. Expires August 1, 2010 [Page 22]