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Versions: (draft-takacs-ccamp-oam-configuration-fwk) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 RFC 7260

Network Working Group                                          A. Takacs
Internet-Draft                                                  Ericsson
Intended status: Standards Track                                D. Fedyk
Expires: July 14, 2012                                    Alcatel-Lucent
                                                                   J. He
                                                                  Huawei
                                                        January 11, 2012


             GMPLS RSVP-TE extensions for OAM Configuration
               draft-ietf-ccamp-oam-configuration-fwk-07

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.




























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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 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 July 14, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.














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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  RSVP-TE based OAM Configuration  . . . . . . . . . . . . . . .  9
     3.1.  Establishment of OAM Entities and Functions  . . . . . . .  9
     3.2.  Adjustment of OAM Parameters . . . . . . . . . . . . . . . 11
     3.3.  Deleting OAM Entities  . . . . . . . . . . . . . . . . . . 11
   4.  RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . . . . 13
     4.1.  LSP Attributes Flags . . . . . . . . . . . . . . . . . . . 13
     4.2.  OAM Configuration TLV  . . . . . . . . . . . . . . . . . . 14
       4.2.1.  OAM Function Flags Sub-TLV . . . . . . . . . . . . . . 15
       4.2.2.  Technology Specific sub-TLVs . . . . . . . . . . . . . 16
     4.3.  Administrative Status Information  . . . . . . . . . . . . 16
     4.4.  Handling OAM Configuration Errors  . . . . . . . . . . . . 16
     4.5.  Considerations on Point-to-Multipoint OAM Configuration  . 17
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 19
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 22
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24




























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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 Ethernet Provider
   Backbone Bridging -- Traffic Engineering (PBB-TE) and MPLS.  In most
   of these technologies there are Operations, Administration and
   Maintenance (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



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   to any OAM solution and technology specific elements that provide
   additional configuration parameters, which are 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.






























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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
   [RFC5921].  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 [RFC5654] [RFC5860].  MPLS-TP poses
   requirements on the control plane to configure and control OAM
   entities:

   o  From [RFC5860]: OAM functions MUST operate and be configurable
      even in the absence of a control plane.  Conversely, it SHOULD be
      possible to configure as well as enable/disable the capability to
      operate OAM functions as part of connectivity management, and it
      SHOULD also be possible to configure as well as enable/disable the
      capability to operate OAM functions after connectivity has been
      established.

   o  From [RFC5654]: 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 or
      transport service is established or modified.

   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



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   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) (see [RFC5828] and [RFC6060]) work extended the GMPLS control
   plane to support the establishment of 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
   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 [RFC5921] 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 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) measurement points must use common probing rate
      to avoid measurement errors.

   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



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      specific parameters must be separated.


















































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3.  RSVP-TE based OAM Configuration

   In general, two types of Maintenance Points (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 from
   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 should 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 can be signaled and established without OAM configuration



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   first, and OAM entities can be added later with a subsequent re-
   signaling of the LSP.  Alternatively, the LSP can 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 the 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,
   the OAM source function 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 are already 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



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   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



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   "OAM Alarms Enabled" 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.



























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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 (IANA to assign): "OAM MEP entities desired" is allocated in
   the LSP Attributes Flags TLV to be used in the LSP_ATTRIBUTES object.
   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 need to be configured, an OAM Configuration TLV MAY be
   included in the LSP_ATTRIBUTES Object.

   One bit (IANA to assign): "OAM MIP entities desired" is allocated in
   the LSP Attributes Flags TLV to be used in the LSP_ATTRIBUTES or
   LSP_REQUIRED_ATTRIBUES objects.  This bit can only be set if the "OAM
   MEP entities desired" bit is set in.  If the "OAM MIP entities
   desired" bit is set in the LSP_ATTRIBUTES Flags TLV in the
   LSP_REQUIRED_ATTRIBUTES Object, 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".





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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
   configuration information.  The OAM Configuration TLV MAY be carried
   in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object in Path and
   Resv messages.  When carried in the LSP_REQUIRED_ATTRIBUTES object it
   is indicating that intermediate nodes MUST recognize and eventually
   react on the OAM configuration onformation.


    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 (IANA)         |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    OAM Type   |                 Reserved                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                           sub-TLVs                            ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: indicates a new type: the OAM Configuration TLV (3) (IANA to
   assign).

   OAM Type: specifies the technology specific OAM method.  When carried
   in the LSP_REQUIRED_ATTRIBUTES Object, if the requested OAM method is
   not supported at a given node an error MUST be generated: "OAM
   Problem/Unsupported OAM Type".  When carried in the LSP_ATTRIBUTES
   Object, intermediate nodes not supporting the OAM Type pass the
   object forward unchanged as specified in [RFC5420] only Label Edge
   Nodes MUST generate the error if the OAM Type is not supported.


       OAM Type             Description
     ------------      --------------------
        0-255                Reserved

   This document defines no types.  IANA is requested 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".  IANA is requested to
   maintain the sub-TLV space in the new "RSVP-TE OAM Configuration



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   Registry".

   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.  Only when that is set MAY an "OAM
   Configuration TLV" 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".

4.2.1.  OAM Function Flags Sub-TLV

   As the first sub-TLV the "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                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   OAM Function Flags is bitmap with extensible length based on the
   Lenght field of the TLV.  Bits are numbered from left to right.  IANA
   is requested to maintain the OAM Function Flags in the new "RSVP-TE
   OAM Configuration Registry".  This document defines the following
   flags.












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     OAM Function Flag bit#      Description
     ---------------------  ---------------------------
             0              Continuity Check (CC)
             1              Connectivity Verification (CV)
             2              Fault Monitoring Signal (FMS)
             3              Performance Monitoring/Loss (PM/Loss)
             4              Performance Monitoring/Delay (PM/Delay)
             5              Performance Monitoring/Throughput Measurement
                            (PM/Throughput)

4.2.2.  Technology Specific sub-TLVs

   One technology specific sub-TLV MAY 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, when
   used, MUST be carried within the OAM Configuration TLV.  IANA is
   requested to maintain the sub-TLV space in the new "RSVP-TE OAM
   Configuration Registry".

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.  Two bits (IANA to assign) are allocated by this draft:
   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



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   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.

4.5.  Considerations on Point-to-Multipoint OAM Configuration

   RSVP-TE extensions for the establishment of point-to-multipoint
   (P2MP) LSPs are specified in [RFC4875].  A P2MP LSP is comprised of
   multiple source-to-leaf (S2L) sub-LSPs.  These S2L sub-LSPs are set
   up between the ingress and egress LSRs and are appropriately combined
   by the branch LSRs using RSVP semantics to result in a P2MP TE LSP.
   One Path message may signal one or multiple S2L sub-LSPs for a single
   P2MP LSP.  Hence the S2L sub-LSPs belonging to a P2MP LSP can be
   signaled using one Path message or split across multiple Path
   messages.

   P2MP OAM mechanisms are very specific to the data plane technology,
   hence in this document we only highlight basic operations for P2MP
   OAM configuration.  We consider only the configuration of the root to
   leaves OAM flows of P2MP LSPs and as such aspects of any return path
   are outside the scope of our discussions.  We also limit our
   consideration to cases where all leaves must successfully establish
   OAM entities in order a P2MP OAM is successfully established.  In any
   case, the discussion set forth below provides only guidelines for
   P2MP OAM configuration, details SHOULD be specified in technology
   specific documents.

   The root node may select if it uses a single Path message or multiple
   Path messages to setup the whole P2MP tree.  In the case when
   multiple Path messages are used the root node is responsible also to
   keep the OAM Configuration information consistent in each of the sent
   Path messages, i.e., the same information MUST be included in all
   Path messages used to construct the multicast tree.  Each branching
   node will propagate the Path message downstream on each of the
   branches, when constructing a Path message the OAM Configuration
   information MUST be copied unchanged from the received Path message,
   including the related ADMIN_STATUS bits, LSP Attribute Flags and the
   OAM Configuration TLV.  The latter two also imply that the



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   LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES Object MUST be copied for
   the upstream Path message to the subsequent downstream Path messages.

   Leaves MUST create and configure OAM sink functions according to the
   parameters received in the Path message, for P2MP OAM configuration
   there is no possibility for parameter negotiation on a per leaf
   basis.  This is due to the fact that the only OAM source function,
   residing in the root of the tree, can only operate with a single
   configuration which must be obeyed by all leaves.  If a leaf cannot
   accept the OAM parameters it MUST use the RRO Attributes sub-object
   [RFC5420] to notify the root of the problem.  In particular, if the
   OAM configuration was successful the leaf would set the "OAM MEP
   entities desired" flag in the RRO Attributes sub-object in the Resv
   message, while, if due to any reason, OAM entities could not be
   established the Resv message should be sent with the "OAM MEP
   entities desired" bit cleared in the RRO Attributes sub-object.
   Branching nodes should collect and merge the received RROs according
   to the procedures described in [RFC4875].  This way, the root when
   receiving the Resv message (or messages if multiple Path messages
   were used to setup the tree) will have a clear information on which
   of the leaves could the OAM sink functions be established.  If all
   leaves established OAM entities successfully, the root can enable the
   OAM message flow.  On the other hand, if at some leaves the
   establishment was unsuccessful additional actions will be needed
   before the OAM message flow can be enabled.  Such action could be to
   setup two independent P2MP LSPs.  One with OAM Configuration
   information towards leaves which successfully setup OAM.  This can be
   done by prunning the leaves which failed to setup OAM of the
   previously signalled P2MP LSP.  The other P2MP LSP could be
   constructed for leaves without OAM entities.  What exact procedures
   are needed are technology specific and SHOULD be described in
   technology specific documents.



















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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.

   IANA is requested to open a new registry: "RSVP-TE OAM Configuration
   Registry" that maintains the "OAM Type" code points, an associated
   sub-TLV space, and the allocations of "OAM Function Flags" within the
   OAM Configuration TLV.






























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6.  Security Considerations

   The signaling of OAM related parameters and the automatic
   establishment of OAM entities based on RSVP-TE messages adds a new
   aspect to the security considerations discussed in [RFC3473].  In
   particular, a network element could be overloaded, if a remote
   attacker could request liveliness monitoring, with frequent periodic
   messages, for a high number of LSPs, targeting a single network
   element.  Such an attack can efficiently be prevented when mechanisms
   for message integrity and node authentication are deployed.  Since
   the OAM configuratiuon extensions rely on the hop-by-hop exchange of
   exiting RSVP-TE messages, procedures specified for RSVP message
   security in [RFC2747] can be used to mitigate possible attacks.

   For a more comprehensive discussion on GMPLS security please see the
   Security Framework for MPLS and GMPLS Networks [RFC5920].
   Cryptography can be used to protect against many attacks described in
   [RFC5920].

































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7.  Acknowledgements

   The authors would like to thank Francesco Fondelli, Adrian Farrel,
   Loa Andersson, Eric Gray and Dimitri Papadimitriou for their useful
   comments.














































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8.  References

8.1.  Normative References

   [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.

   [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.

8.2.  Informative References

   [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.

   [RFC2747]  "RSVP Cryptographic Authentication", RFC 2747,
              January 2000.

   [RFC3469]  "Framework for Multi-Protocol Label Switching (MPLS)-based
              Recovery", RFC 3469, February 2003.

   [RFC4377]  "Operations and Management (OAM) Requirements for Multi-
              Protocol Label Switched (MPLS) Networks", RFC 4377,
              February 2006.

   [RFC4379]  "Detecting Multi-Protocol Label Switched (MPLS) Data Plane
              Failures", RFC 4379, February 2006.

   [RFC4875]  "Extensions to Resource Reservation Protocol - Traffic
              Engineering (RSVP-TE) for Point-to-Multipoint TE Label
              Switched Paths (LSPs)", RFC 4875, May 2007.

   [RFC5654]  "Requirements of an MPLS Transport Profile", RFC 5654,
              September 2009.

   [RFC5828]  "GMPLS Ethernet Label Switching Architecture and
              Framework", RFC 5828, March 2010.



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   [RFC5860]  "Requirements for OAM in MPLS Transport Networks",
              RFC 5860, May 2010.

   [RFC5920]  "Security Framework for MPLS and GMPLS Networks",
              RFC 5920, July 2010.

   [RFC5921]  "A Framework for MPLS in Transport Networks", RFC 5921,
              July 2010.

   [RFC6060]  "Generalized Multiprotocol Label Switching (GMPLS) Control
              of Ethernet Provider Backbone Traffic Engineering
              (PBB-TE)", RFC 6060.







































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Authors' Addresses

   Attila Takacs
   Ericsson
   Konyves Kalman krt. 11.
   Budapest,   1097
   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



























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