One document matched: draft-sprecher-mpls-tp-oam-primer-00.txt




Network Working Group                                        N. Sprecher
Internet-Draft                                    Nokia Siemens Networks
Intended status: Informational                             E. Bellagamba
Expires: January 5, 2011                                        Ericsson
                                                           Y. Weingarten
                                                  Nokia Siemens Networks
                                                            July 4, 2010


                           MPLS-TP OAM Primer
                draft-sprecher-mpls-tp-oam-primer-00.txt

Abstract

   This document provides basic information on the existing MPLS
   Operations, Administration, and Maintenance (OAM) toolset and
   analyzes these tools relative to the set of requirements for OAM for
   the Transport Profile of MPLS(MPLS-TP) as defined in [MPLS-TP OAM
   Reqs].  On this basis the document tries to highlight features that
   need to be extended in order to deliver the higher-quality OAM
   required for transport applications.

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 January 5, 2011.

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



Sprecher, et al.         Expires January 5, 2011                [Page 1]

Internet-Draft               MPLS OAM Primer                   July 2010


   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.


































Sprecher, et al.         Expires January 5, 2011                [Page 2]

Internet-Draft               MPLS OAM Primer                   July 2010


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2.  Organization of the document . . . . . . . . . . . . . . .  4
     1.3.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.4.  Contributing Authors . . . . . . . . . . . . . . . . . . .  5
   2.  Pre-existing OAM tools . . . . . . . . . . . . . . . . . . . .  5
     2.1.  LSP Ping . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  MPLS BFD . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.3.  PW VCCV  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     2.4.  IETF Performance Measurement . . . . . . . . . . . . . . .  8
   3.  MPLS-TP OAM Functionality  . . . . . . . . . . . . . . . . . . 10
     3.1.  Basic OAM functionality  . . . . . . . . . . . . . . . . . 10
     3.2.  Fault detection functionality  . . . . . . . . . . . . . . 10
       3.2.1.  Continuity Check and Connectivity Verification . . . . 11
       3.2.2.  Remote Defect Indication . . . . . . . . . . . . . . . 11
       3.2.3.  Route Tracing  . . . . . . . . . . . . . . . . . . . . 11
       3.2.4.  Alarm Reporting  . . . . . . . . . . . . . . . . . . . 11
       3.2.5.  Client Failure Indication  . . . . . . . . . . . . . . 12
     3.3.  Performance Measurement Functionality  . . . . . . . . . . 12
       3.3.1.  Packet Loss Measurement  . . . . . . . . . . . . . . . 12
       3.3.2.  Packet Delay Measurement . . . . . . . . . . . . . . . 12
   4.  Enhancing the existing toolset for MPLS-TP . . . . . . . . . . 13
     4.1.  Gap Analysis . . . . . . . . . . . . . . . . . . . . . . . 13
       4.1.1.  OAM Infrastructure . . . . . . . . . . . . . . . . . . 13
     4.2.  BFD enhancements . . . . . . . . . . . . . . . . . . . . . 13
     4.3.  LSP Ping enhancements  . . . . . . . . . . . . . . . . . . 13
     4.4.  Performance Measurement enhancements . . . . . . . . . . . 13
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   8.  Informative References . . . . . . . . . . . . . . . . . . . . 14
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16

















Sprecher, et al.         Expires January 5, 2011                [Page 3]

Internet-Draft               MPLS OAM Primer                   July 2010


1.  Introduction

1.1.  Scope

   OAM (Operations, Administration, and Maintenance) plays a significant
   role in carrier networks, providing methods for fault management and
   performance monitoring in both the transport and the service layers
   in order to improve their ability to support services with guaranteed
   and strict Service Level Agreements (SLAs) while reducing their
   operational costs.

   [MPLS-TP Reqs] in general, and [MPLS-TP OAM Reqs] in particular
   define a set of requirements for OAM functionality in MPLS-Transport
   Profile (MPLS-TP) for MPLS-TP Label Switched Paths (LSPs) (network
   infrastructure), Pseudowires (PWs) (services), and MPLS-TP Sections.

   The purpose of this document is to evaluate whether existing OAM
   tools defined for MPLS can be used to meet the requirements, identify
   possible extensions to the tools to comply with the requirements.
   The existing tools that are evaluated include LSP Ping (defined in
   [LSP Ping]), MPLS Bi-directional Forwarding Detection (BFD) (defined
   in [BASE BFD]), Virtual Circuit Connectivity Verification (VCCV)
   (defined in [PW VCCV] and [VCCV BFD]), and IETF performance
   measurement tools defined in [RFC4656] and [RFC5357].

1.2.  Organization of the document

   Section 2 provides an overview of the existing MPLS/IETF tools.

   Section 3 highlights the requirements for enhanced OAM functionality
   for the transport environment.

   Section 4 identifies the enhancements to the existing OAM tools that
   are needed to address the additional requirements.

















Sprecher, et al.         Expires January 5, 2011                [Page 4]

Internet-Draft               MPLS OAM Primer                   July 2010


1.3.  Acronyms

   This draft uses the following acronyms:

   AC      Attachment Circuit
   ACH     Associated Channel Header
   BFD     Bidirectional Forwarding Detection
   CC-V    Continuity Check and Connectivity Verification
   FEC     Forwarding Equivalence Class
   G-ACH   Generic Associated Channel Header
   LDP     Label Distribution Protocol
   LSP     Label Switched Path
   MPLS-TP Transport Profile for MPLS
   OAM     Operations, Administration, and Maintenance
   OWAMP   One Way Active Measurement Protocol
   PDU     Packet Data Unit
   PW      Pseudowire
   RDI     Remote Defect Indication
   SLA     Service Level Agreement
   TLV     Type, Length, Value
   TTL     Time-to-live
   TWAMP   Two Way Active Measurement Protocol
   VCCV    Virtual Circuit Connectivity Verification

1.4.  Contributing Authors

   Yaakov Stein (Rad), Annamaria Fulignoli (Ericsson), Italo Busi
   (Alcatel Lucent)


2.  Pre-existing OAM tools

2.1.  LSP Ping

   LSP Ping is a variation of ICMP Ping and traceroute [ICMP] adapted to
   the needs of MPLS LSP.  Forwarding, of the LSP Ping packets, is based
   upon the LSP Label and label stack, in order to guarantee that the
   echo messages are switched in-band (i.e. over the same data route) of
   the LSP.  However, it should be noted that the messages are
   transmitted using IP/UDP encapsulation and IP addresses in the 127/8
   (loopback) range.  The use of the loopback range guarantees that the
   LSP Ping messages will be terminated, by a loss of connectivity or
   inability to continue on the path, without being transmitted beyond
   the LSP.  For a bi-directional LSP (either associated or co-routed)
   the return message of the LSP Ping could be sent on the return LSP.
   For unidirectional LSPs and in some case for bi-directional LSPs, the
   return message may be sent using IP forwarding to the IP address of
   the LSP ingress node.



Sprecher, et al.         Expires January 5, 2011                [Page 5]

Internet-Draft               MPLS OAM Primer                   July 2010


   LSP Ping extends the basic ICMP Ping operation (of data-plane
   connectivity and continuity check) with functionality to verify data-
   plane vs. control-plane consistency for a Forwarding Equivalence
   Class (FEC) and also Maximum Transmission Unit (MTU) problems.  The
   traceroute functionality may be used to isolate and localize the MPLS
   faults, using the Time-to-live (TTL) indicator to incrementally
   identify the sub-path of the LSP that is successfully traversed
   before the faulty link or node.

   As mentioned above, LSP Ping requires the presence of the MPLS
   control plane when verifying the consistency of the data-plane
   against the control-plane.  However, LSP Ping is not dependent on the
   MPLS control-plane for its operation, i.e. even though the
   propagation of the LSP label may be performed over the control-plane
   via the Label Distribution Protocol (LDP).

   It should be noted that LSP Ping does support unique identification
   of the LSP within an addressing domain.  The identification is
   checked using the full FEC identification.  LSP Ping is easily
   extensible to include additional information needed to support new
   functionality, by use of Type-Length-Value (TLV) constructs.

   LSP Ping can be activated both in on-demand and pro-active
   (asynchronous) modes, as defined in [MPLS-TP OAM Reqs].

   [P2MP LSP Ping] clarifies the applicability of LSP Ping to MPLS P2MP
   LSPs, and extends the techniques and mechanisms of LSP Ping to the
   MPLS P2MP environment.

   [MPLS LSP Ping] extends LSP Ping to operate over MPLS tunnels or for
   a stitched LSP.

   As pointed out above, TTL exhaust is the method used to terminate
   flows at intermediate LSRs.  This is used as part of the traceroute
   of a path and to locate a problem that was discovered previously.

   Some of the drawbacks identified with LSP Ping include - LSP Ping is
   considered to be computational intensive as pointed out in [MPLS
   BFD].  The applicability for a pro-active mode of operation is
   analyzed in the sections below.  Use of the loopback address range
   (to protect against leakage outside the LSP) assumes that all of the
   intermediate nodes support some IP functionality.  Note that ECMP is
   not supported in MPLS-TP, therefore its implication on OAM
   capabilities is not analyzed in this document.







Sprecher, et al.         Expires January 5, 2011                [Page 6]

Internet-Draft               MPLS OAM Primer                   July 2010


2.2.  MPLS BFD

   BFD (Bidirectional Forwarding Detection) [BASE BFD] is a mechanism
   that is defined for fast fault detection for point-to-point
   connections.  BFD defines a simple packet that may be transmitted
   over any protocol, dependent on the application that is employing the
   mechanism.  BFD is dependent upon creation of a session that is
   agreed upon by both ends of the link (which may be a single link,
   LSP, etc.) that is being checked.  The session is assigned a separate
   identifier by each end of the path being monitored.  This session
   identifier is by nature only unique within the context of node that
   assigned it.  As part of the session creation, the end-points
   negotiate an agreed transmission rate for the BFD packets.  BFD
   supports an echo function to check the continuity, and verify the
   reachability of the desired destination.  BFD does not support
   neither a discovery mechanism nor a traceroute capability for fault
   localization, these must be provided by use of other mechanisms.  The
   BFD packets support authentication between the routers being checked.

   BFD can be used in pro-active (asynchronous) and on-demand modes, as
   defined in [MPLS-TP OAM Reqs], of operation.

   [MPLS BFD] defines the use of BFD for P2P LSP end-points and is used
   to verify data-plane continuity.  It uses a simple hello protocol
   which can be easily implemented in hardware.  The end-points of the
   LSP exchange hello packets at negotiated regular intervals and an
   end-point is declared down when expected hello packets do not show
   up.  Failures in each direction can be monitored independently using
   the same BFD session.  The use of the BFD echo function and on-demand
   activation are outside the scope of the MPLS BFD specification.

   The BFD session mechanism requires an additional (external) mechanism
   to bootstrap and bind the session to a particular LSP or FEC.  LSP
   Ping is designated by [MPLS BFD] as the bootstrap mechanism for the
   BFD session in an MPLS environment.  The implication is that the
   session establishment BFD messages for MPLS are transmitted using a
   IP/UDP encapsulation.

   In order to be able to identify certain extreme cases of mis-
   connectivity, it is necessary that each managed connection have its
   own unique identifiers.  BFD uses Discriminator values to identify
   the connection being verified, at both ends of the path.  These
   discriminator values are set by each end-node to be unique only in
   the context of that node.  This limited scope of uniqueness would not
   identify a misconnection of crossing paths that could assign the same
   discriminators to the different sessions.





Sprecher, et al.         Expires January 5, 2011                [Page 7]

Internet-Draft               MPLS OAM Primer                   July 2010


2.3.  PW VCCV

   [PW VCCV] provides end-to-end fault detection and diagnostics for PWs
   (regardless of the underlying tunneling technology).  The VCCV
   switching function provides a control channel associated with each PW
   (based on the PW Associated Channel Header (ACH) which is defined in
   [PW ACH]), and allows sending OAM packets in-band with PW data (using
   CC Type 1: In-band VCCV)

   VCCV currently supports the following OAM mechanisms: ICMP Ping, LSP
   Ping, and BFD.  ICMP and LSP Ping are IP encapsulated before being
   sent over the PW ACH.  BFD for VCCV supports two modes of
   encapsulation - either IP/UDP encapsulated (with IP/UDP header) or
   PW-ACH encapsulated (with no IP/UDP header) and provides support to
   signal the AC status.  The use of the VCCV control channel provides
   the context, based on the MPLS-PW label, required to bind and
   bootstrap the BFD session to a particular pseudo wire (FEC),
   eliminating the need to exchange Discriminator values.

   VCCV consists of two components: (1) signaled component to
   communicate VCCV capabilities as part of VC label, and (2) switching
   component to cause the PW payload to be treated as a control packet.

   VCCV is not directly dependent upon the presence of a control plane.
   The VCCV capability negotiation may be performed as part of the PW
   signaling when LDP is used.  In case of manual configuration of the
   PW, it is the responsibility of the operator to set consistent
   options at both ends.

2.4.  IETF Performance Measurement

   OWAMP (One-Way Active Measurement Protocol) [RFC4656] enables
   measurement of unidirectional characteristics of IP networks, such as
   packet loss and one-way delay.  For its proper operation OWAMP
   requires accurate time of day setting at its end points.

   TWAMP (Two-Way Active Measurement Protocol) [RFC5357] is a similar
   protocol that enables measurement of two-way (round trip)
   characteristics.  TWAMP does not require accurate time of day, and,
   furthermore, allows the use of a simple session reflector, making it
   an attractive alternative to OWAMP.

   Both OWAMP and TWAMP consist of inter-related control and test
   protocols, although "TWAMP Light" eliminates the need for the control
   protocol.

   OWAMP and TWAMP control protocols run over TCP, while the test
   protocols run over UDP.  The purpose of the control protocols is to



Sprecher, et al.         Expires January 5, 2011                [Page 8]

Internet-Draft               MPLS OAM Primer                   July 2010


   initiate, start, and stop test sessions, and for OWAMP to fetch
   results.  The test protocols introduce test packets (which contain
   sequence numbers and timestamps) along the IP path under test
   according to a schedule, and record statistics of packet arrival.
   Multiple sessions may be simultaneously defined, each with a session
   identifier, and defining the number of packets to be sent, the amount
   of padding to be added (and thus the packet size), the start time,
   and the send schedule (which can be either a constant time between
   test packets or exponentially distributed pseudo-random).  Statistics
   recorded conform to the relevant IPPM RFCs.

   OWAMP defines the following logical roles: Session-Sender, Session-
   Receiver, Server, Control-Client, and Fetch-Client.  The Session-
   Sender originates test traffic that is received by the Session-
   receiver.  The Server configures and manages the session, as well as
   returning the results.  The Control-Client initiates requests for
   test sessions, triggers their start, and may trigger their
   termination.  The Fetch-Client requests the results of a completed
   session.  Multiple roles may be combined in a single host - for
   example, one host may play the roles of Control-Client, Fetch-Client,
   and Session-Sender, and a second playing the roles of Server and
   Session-Receiver.

   In a typical OWAMP session the Control-Client establishes a TCP
   connection to port 861 of the Server, which responds with a server
   greeting message indicating supported security/integrity modes.  The
   Control-Client responds with the chosen communications mode and the
   Server accepts the modes.  The Control-Client then requests and fully
   describes a test session to which the Server responds with its
   acceptance and supporting information.  More than one test session
   may be requested with additional messages.  The Control-Client then
   starts a test session and the Server acknowledges.  The Session-
   Sender then sends test packets with pseudorandom padding to the
   Session-Receiver until the session is complete or until the Control-
   Client stops the session.  Once finished, the Fetch-Client sends a
   fetch request to the server, which responds with an acknowledgement
   and immediately thereafter the result data.

   TWAMP defines the following logical roles: session-sender, session-
   reflector, server, and control-client.  These are similar to the
   OWAMP roles, except that the Session-Reflector does not collect any
   packet information, and there is no need for a Fetch-Client.

   In a typical TWAMP session the Control-Client establishes a TCP
   connection to port 862 of the Server, and mode is negotiated as in
   OWAMP.  The Control-Client then requests sessions and starts them.
   The Session-Sender sends test packets with pseudorandom padding to
   the Session-Reflector which returns them with insertion of



Sprecher, et al.         Expires January 5, 2011                [Page 9]

Internet-Draft               MPLS OAM Primer                   July 2010


   timestamps.

   OWAMP and TWAMP test traffic is designed with security in mind.  Test
   packets are hard to detect because they are simply UDP streams
   between negotiated port numbers, with potentially nothing static in
   the packets.  OWAMP and TWAMP also include optional authentication
   and encryption for both control and test packets.


3.  MPLS-TP OAM Functionality

   The following sections discuss the required OAM functionality as
   required by [MPLS-TP OAM Reqs].

3.1.  Basic OAM functionality

   [MPLS-TP OAM Reqs] includes a set of basic requirements for all OAM
   tools to be used for MPLS-TP transport paths.  This includes the
   following:

   o  [MPLS-TP OAM Reqs] requires that the MPLS-TP OAM must be able to
      support both an IP based and non-IP based environment.  If the
      network is IP based, i.e.  IP routing and forwarding are
      available, then the MPLS-TP OAM toolset should rely on the IP
      routing and forwarding capabilities.  On the other hand, in
      environments where IP functionality is not available, the OAM
      tools must still be able to operate without dependence on IP
      forwarding and routing.

   o  [MPLS-TP OAM Reqs] requires that all OAM protocols support
      identification information, at least in the form of IP addressing
      structure and be extensible to support additional identification
      schemes.

   o  It is also required that OAM packets and the user traffic are
      congruent (i.e.  OAM packets are transmitted in-band) and there is
      a need to differentiate OAM packets from user-plane ones.
      Inherent in this requirement is the principle that MPLS-TP OAM be
      independent of any existing control-plane, although it should not
      preclude use of the control-plane functionality.

   In addition, the requirements for specific OAM functions will be
   highlighted in the following sub-sections.

3.2.  Fault detection functionality

   MPLS supports tools that provide basic fault detection functionality
   for different forms of paths, as outlined in section 2 of this



Sprecher, et al.         Expires January 5, 2011               [Page 10]

Internet-Draft               MPLS OAM Primer                   July 2010


   document.  These tools provide the basic functionality for an MPLS
   environment.  The transport environment requires certain additional
   functionality that is outlined in the following subsections.

3.2.1.  Continuity Check and Connectivity Verification

   Continuity Check and Connectivity Verification (CC-V) are OAM
   operations generally used in tandem, and compliment each other.
   These functions are generally run proactively, but may also be used
   on-demand, either due to bandwidth considerations or for diagnoses of
   a specific condition.  Proactively [MPLS-TP OAM Reqs] states that the
   function should allow the MEPs to monitor the liveness and
   connectivity of a transport path.  In on-demand mode, this function
   should support monitoring between the MEPs and, in addition, between
   a MEP and MIP.

   The [MPLS-TP OAM Frwk] highlights the need for the CC-V messages to
   include unique identification of the MEG that is being monitored and
   the MEP that originated the message.  The function, both proactively
   and in on-demand mode, need to be transmitted at regular rates pre-
   configured by the operator.

3.2.2.  Remote Defect Indication

   Remote Defect Indication (RDI) is used proactively by a path end-
   point to report to its peer end-point that a defect is detected on a
   bi-directional connection between them.  [MPLS-TP OAM Reqs] points
   out that this function may be applied to a unidirectional LSP only if
   there a return path exists.  [MPLS-TP OAM Frwk] points out that this
   function is associated with the proactive CC-V function.

3.2.3.  Route Tracing

   [MPLS-TP OAM Reqs] defines that there is a need for functionality
   that would allow a path end-point to identify the intermediate and
   end-points of the path.  This function would be used in on-demand
   mode.  Normally, this path will be used for bidirectional PW, LSP,
   and sections, however, unidirectional paths may be supported only if
   a return path exists.

3.2.4.  Alarm Reporting

   Alarm Reporting is a function used by an intermediate point of a
   path, that becomes aware of a fault on the path, to report to the
   end-points of the path.  [MPLS-TP OAM Frwk] states that this may
   occur as a result of a defect condition discovered at a server sub-
   layer.  This generates an Alarm Indication Signal (AIS) that
   continues until the fault is cleared.  The consequent action of this



Sprecher, et al.         Expires January 5, 2011               [Page 11]

Internet-Draft               MPLS OAM Primer                   July 2010


   function is detailed in [MPLS-TP OAM Frwk].

3.2.5.  Client Failure Indication

   Client Failure Indication (CFI) is defined in [MPLS-TP OAM Reqs] to
   allow the propagation information from one edge of the network to the
   other.  The information concerns a defect to a client, in the case
   that the client does not support alarm notification.

3.3.  Performance Measurement Functionality

   The current performance measurement tools defined in the IETF,
   outlined in Section 2 of this document, do not directly address MPLS
   paths.  In addition, when extending MPLS to address the needs of the
   transport community there is a need to support enhanced performance
   measurement functionality, as detailed in the following sub-sections.

3.3.1.  Packet Loss Measurement

   Packet Loss Measurement is a function that is used to verify the
   quality of the service.  This function indicates the ratio of packets
   that are not delivered out of all packets that are transmitted by the
   path source.

   There are two possible ways of determining this measurement -

   o  Using OAM packets, it is possible to compute the statistics based
      on a series of OAM packets.  This, however, has the disadvantage
      of being artificial, and may not be representative since part of
      the packet loss may be dependent upon packet sizes.

   o  Sending delimiting messages for the start and end of a measurement
      period during which the source and sink of the path count the
      packets transmitted and received.  After the end delimiter, the
      ratio would be calculated by the path OAM entity.

3.3.2.  Packet Delay Measurement

   Packet Delay Measurement is a function that is used to measure one-
   way or two-way delay of a packet transmission between a pair of the
   end-points of a path (PW, LSP, or Section).  Where:

   o  One-way packet delay is the time elapsed from the start of
      transmission of the first bit of the packet by a source node until
      the reception of the last bit of that packet by the destination
      node.





Sprecher, et al.         Expires January 5, 2011               [Page 12]

Internet-Draft               MPLS OAM Primer                   July 2010


   o  Two-way packet delay is the time elapsed from the start of
      transmission of the first bit of the packet by a source node until
      the reception of the last bit of the loop-backed packet by the
      same source node, when the loopback is performed at the packet's
      destination node.

   Similarly to the packet loss measurement this could be performed in
   one of two ways -

   o  Using OAM packets - checking delay (either one-way or two-way) in
      transmission of OAM packets.  May not fully reflect delay of
      larger packets, however, gives feedback on general service level.

   o  Using delimited periods of transmission - may be too intrusive on
      the client traffic.


4.  Enhancing the existing toolset for MPLS-TP

4.1.  Gap Analysis

4.1.1.  OAM Infrastructure

   Creating these extensions/mechanisms would fulfill the following
   architectural requirements, mentioned above:

   o  Independence of IP forwarding and routing, when needed.

   o  OAM packets should be transmitted in-band.

   o  Support a single OAM technology for LSP, PW, and Sections.

   In addition, the following additional requirements can be satisfied:

   o  Provide the ability to carry other types of communications (e.g.,
      APS, Management Control Channel (MCC), Signaling Control Channel
      (SCC)), by defining new types of communication channels for PWs,
      Sections, and LSPs.

   o  The design of the OAM mechanisms for MPLS-TP MUST allow the
      ability to support vendor specific and experimental OAM functions.

4.2.  BFD enhancements

4.3.  LSP Ping enhancements

4.4.  Performance Measurement enhancements




Sprecher, et al.         Expires January 5, 2011               [Page 13]

Internet-Draft               MPLS OAM Primer                   July 2010


5.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.


6.  Security Considerations

   This document does not by itself raise any particular security
   considerations.


7.  Acknowledgements

   The authors wish to acknowledge the encouragement of the MPLS WG
   chairs and the area directors in directing this work.


8.  Informative References

   [RFC 2119]
              Bradner, S., "Internet Control Message Protocol", BCP 14,
              RFC 2119, March 1997.

   [ICMP]     Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, Sept 1981.

   [LSP Ping]
              Kompella, K. and G. Swallow, "Detecting Multi-Protocol
              Label Switched (MPLS) Data Plane Failures", RFC 4379,
              February 2006.

   [PW ACH]   Bryant, S., Swallow, G., Martini, L., and D. McPherson,
              "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
              Use over an MPLS PSN", RFC 4385, February 2006.

   [PW VCCV]  Nadeau, T. and C. Pignataro, "Pseudowire Virtual Circuit
              Connectivity Verification (VCCV): A Control Channel for
              Pseudowires", RFC 5085, December 2007.

   [BASE BFD]
              Katz, D. and D. Ward, "Bidirectional Forwarding
              Detection", ID draft-ietf-bfd-base-09.txt, February 2009.

   [MPLS BFD]
              Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,



Sprecher, et al.         Expires January 5, 2011               [Page 14]

Internet-Draft               MPLS OAM Primer                   July 2010


              "BFD For MPLS LSPs", ID draft-ietf-bfd-mpls-07.txt,
              June 2008.

   [VCCV BFD]
              Nadeau, T. and C. Pignataro, "Bidirectional Forwarding
              Detection (BFD) for the Pseudowire Virtual Circuit
              Connectivity Verification (VCCV)",
              ID draft-ietf-pwe3-vccv-bfd-07.txt, February 2008.

   [bfdMultipoint]
              Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              for Multipoint Networks",
              ID draft-katz-ward-bfd-multipoint-02.txt, February 2009.

   [P2MP LSP Ping]
              Nadeau, T. and A. Farrel, "Detecting Data Plane Failures
              in Point-to-Multipoint Multiprotocol Label Switching
              (MPLS) - Extensions to LSP Ping",
              ID draft-ietf-mpls-p2mp-lsp-ping-06.txt, June 2008.

   [MPLS LSP Ping]
              Bahadur, N. and K. Kompella, "Mechanism for performing
              LSP-Ping over MPLS tunnels",
              ID draft-ietf-mpls-lsp-ping-enhanced-dsmap-00, June 2008.

   [RFC4656]  Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
              Zekauskas, "A One-way Active Measurement Protocol",
              RFC 4656, September 2006.

   [RFC5357]  Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
              Babiarz, "A Two-Way Active Measurement Protocol",
              RFC 5357, Oct 2008.

   [MPLS-TP OAM Reqs]
              Vigoureux, M., Betts, M., and D. Ward, "Requirements for
              OAM in MPLS Transport Networks",
              ID draft-ietf-mpls-tp-oam-requirements-01, April 2009.

   [MPLS-TP OAM Frwk]
              Busi, I. and B. Niven-Jenkins, "MPLS-TP OAM Framework and
              Overview", ID draft-ietf-mpls-tp-oam-requirements-01,
              March 2009.

   [MPLS-TP Reqs]
              Niven-Jenkins, B., Nadeau, T., and C. Pignataro,
              "Requirements for the Trasport Profile of MPLS",
              ID draft-ietf-mpls-tp-requirements-06, April 2009.




Sprecher, et al.         Expires January 5, 2011               [Page 15]

Internet-Draft               MPLS OAM Primer                   July 2010


   [MPLS G-ACH]
              Bocci, M., Bryant, S., and M. Vigoureux, "MPLS Generic
              Associated Channel", RFC 5586, June 2009.

   [MPLS-TP ACH TLV]
              Boutros, S., Bryant, S., Sivabalan, S., Swallow, G., and
              D. Ward, "Definition of ACH TLV Structure",
              ID draft-ietf-mpls-tp-ach-tlv-00, June 2009.

   [RFC3813]  Srinivasan, C., Viswanathan, A., and T. Nadeau,
              "Multiprotocol Label Switching (MPLS) Label Switching
              Router (LSR) Management Information Base (MIB)", RFC 3813,
              June 2004.

   [Y.1731]   International Telecommunications Union - Standardization,
              "OAM functions and mechanisms for Ethernet based
              networks", ITU Y.1731, May 2006.


Authors' Addresses

   Nurit Sprecher
   Nokia Siemens Networks
   3 Hanagar St. Neve Ne'eman B
   Hod Hasharon,   45241
   Israel

   Email: nurit.sprecher@nsn.com


   Elisa Bellagamba
   Ericsson
   6 Farogatan St
   Stockholm,   164 40
   Sweden

   Phone: +46 761440785
   Email: elisa.bellagamba@ericsson.com













Sprecher, et al.         Expires January 5, 2011               [Page 16]

Internet-Draft               MPLS OAM Primer                   July 2010


   Yaacov Weingarten
   Nokia Siemens Networks
   3 Hanagar St. Neve Ne'eman B
   Hod Hasharon,   45241
   Israel

   Phone: +972-9-775 1827
   Email: yaacov.weingarten@nsn.com











































Sprecher, et al.         Expires January 5, 2011               [Page 17]



PAFTECH AB 2003-20262026-04-24 03:26:20