Internet DRAFT - draft-bocci-mpls-tp-gach-gal

draft-bocci-mpls-tp-gach-gal



MPLS Working Group                                        M. Vigoureux 
Internet Draft                                               M. Bocci 
Updates: 3032, 4385                                     Alcatel-Lucent 
Intended status: Standard Track                                       
Expires: April 2009                                        G. Swallow 
                                                              D. Ward 
                                                   Cisco Systems, Inc. 
                                                                      
                                                          R. Aggarwal 
                                                      Juniper Networks 
 
                                                      October 24, 2008 
 
 
                                      
                      MPLS Generic Associated Channel  
                      draft-bocci-mpls-tp-gach-gal-00 


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Copyright Notice 

   Copyright (C) The IETF Trust (2008). 

Abstract 
 
 
 
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   This document generalises the applicability of the pseudowire 
   Associated Channel Header (ACH), enabling the realization of a 
   control channel associated to MPLS Label Switched Paths (LSP), MPLS 
   pseudowires (PW) and MPLS Sections. In order to identify the presence 
   of this G-ACH, this document also assigns of one of the reserved MPLS 
   label values to the 'Generic Alert Label (GAL)', to be used as a 
   label based exception mechanism. 

Conventions used in this document 

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 
   document are to be interpreted as described in RFC 2119 [1]. 

Table of Contents 

   1. Introduction................................................3 
      1.1. Contributing Authors....................................4 
      1.2. Objectives.............................................4 
      1.3. Scope..................................................4 
      1.4. Terminology............................................5 
   2. Generic Associated Channel...................................5 
      2.1. Allocation of Channel Types.............................6 
   3. Generalised Exception Mechanism..............................6 
      3.1. Relationship with Existing MPLS OAM Alert Mechanisms.....6 
      3.2. GAL Applicability and Usage.............................7 
         3.2.1. GAL Processing.....................................7 
            3.2.1.1. MPLS Section..................................7 
            3.2.1.2. Label Switched Paths..........................8 
            3.2.1.3. Tandem Connection Monitoring Entity...........9 
      3.3. Relationship with RFC 3429.............................10 
   4. Compatibility..............................................10 
   5. Congestion Considerations...................................10 
   6. Security Considerations.....................................11 
   7. IANA Considerations........................................11 
   8. Acknowledgments............................................12 
   9. References.................................................12 
      9.1. Normative References...................................12 
      9.2. Informative References.................................13 
   Authors' Addresses............................................14 
   Contributing Authors' Addresses................................14 
   Intellectual Property Statement................................15 
   Disclaimer of Validity........................................15 
    



 
 
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1. Introduction 

   There is a need for Operations, Administration and Maintenance (OAM) 
   mechanisms that   can be used for edge-to-edge (i.e. between 
   originating and terminating LSRs or T-PEs) and segment fault 
   detection (e.g. between any two LSRs or T-PEs/S-PEs along the path of 
   an LSP or PW or an MPLS section [17]), diagnostics, maintenance and 
   other functions for a Pseudowire and an LSP. Some of these functions 
   can be supported using tools such as VCCV [8], BFD [9], or LSP-Ping 
   [6]. However, a requirement has been indicated to extend these 
   toolsets, in particular where MPLS networks are used for packet 
   transport services and network operations [16]. These include 
   performance monitoring, automatic protection switching, and support 
   for management and signaling communication channels. These tools must 
   be applicable to, and function in essentially the same manner (from 
   an operational point of view) on both MPLS PWs and MPLS LSPs. They 
   must also operate in-band on the PW or LSP such that they do not 
   depend on PSN routing, user data traffic or ultimately on control 
   plane functions. 

   Virtual Circuit Connectivity Verification (VCCV) can use an 
   associated channel to provide a control channel between a PW's 
   ingress and egress points over which OAM and other control messages 
   can be exchanged. In this document, we propose a generic associated 
   channel header (G-ACH) to enable the same control channel mechanism 
   be used for MPLS Sections, LSPs and PWs. The associated channel 
   header (ACH) specified in RFC 4385 [11] is used with additional code 
   points to support additional MPLS OAM functions. 

   Generalizing the ACH mechanism to MPLS LSPs and MPLS Sections also 
   requires a method to identify that a packet contains a G-ACH followed 
   by a non-service payload. This document therefore also defines a 
   label based exception mechanism (the Generic Alert Label, or GAL) 
   that serves to inform an LSR that a packet that it receives on an LSP 
   or section belongs to an associated channel. 

   RFC 4379 [6] and BFD for MPLS LSPs [9] have defined alert mechanisms 
   that enable a MPLS LSR to identify and process MPLS OAM packets when 
   the OAM packets are encapsulated in an IP header.  These alert 
   mechanisms are based on TTL expiration and/or use an IP destination 
   address in the range 127/8. These mechanisms are the default 
   mechanisms for identifying MPLS OAM packets when the OAM packets are 
   encapsulated in an IP header. However it may not always be possible 
   to use these mechanisms in some MPLS applications, (e.g. MPLS-TP 
   [17]) particularly when IP based demultiplexing cannot be used. This 
   document proposes an OPTIONAL mechanism that is RECOMMENDED for 

 
 
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   identifying and demultiplexing MPLS OAM packets when IP based 
   mechanisms such as [6] and [9] are not available. 

   The G-ACH and GAL mechanisms are defined to work together. 

   Note that, in this document, OAM functions and packets should be 
   understood in the broad sense, that is, as a set of FCAPS mechanisms 
   that also include Automatic Protection Switching (APS), Signalling 
   Control Channel (SCC) and Management Control Channel (MCC). 

   Note that the GAL and G-ACH are applicable to MPLS in general. Their 
   applicability to specific applications is outside the scope of this 
   document. For example, the applicability of the GAL and G-ACH to 
   MPLS-TP is described in [17] and [18]. 

    

1.1. Contributing Authors 

   The editors gratefully acknowledge the following additional 
   contributors: Stewart Bryant, Italo Busi, Marc Lasserre, Lieven 
   Levrau, and Lou Berger. 

1.2. Objectives 

   This document proposes a mechanism to provide for the extended OAM 
   needs of emerging applications for MPLS. It creates a generic OAM 
   identification mechanism that may be applied to all MPLS LSPs, while 
   maintaining compatibility with the PW associated channel header (ACH) 
   [11].  It also normalizes the use of the ACH for PWs in a transport 
   context. 

    

1.3. Scope 

   This document defines the encapsulation header for LSP, MPLS Section 
   and PW associated channel messages.  

   It does not define how associated channel capabilities are signaled 
   or negotiated between LSRs or PEs, the operation of various OAM 
   functions, or the messages transmitted on the associated channel.  

   This document does not deprecate existing MPLS and PW OAM mechanisms.  



 
 
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1.4. Terminology 

   G-ACH:  Generic Associated Channel Header 

   GAL: Generic Alert Label 

2. Generic Associated Channel 

   VCCV [8] defines three Control Channel Types that may be used to 
   multiplex OAM messages onto a PW: CC Type 1 uses an associated 
   channel header and is referred to as "In-band VCCV"; CC Type 2 uses 
   the router alert label to indicate VCCV packets and is referred to as 
   "Out of Band VCCV"; CC Type 3 uses the TTL to force the packet to be 
   processed by the targeted routers control plane and is referred to as 
   "MPLS PW Label with TTL == 1".  

   The use of the CC Type 1, currently limited to MPLS PWs, is extended 
   to apply to MPLS LSPs as well as to MPLS Sections. This associated 
   channel header is called the Generic Associated Channel Header (G-
   ACH). 

    

   The CC Type 1 channel header is depicted in figure below: 

     0                   1                   2                   3 
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |0 0 0 1|Version|   Reserved    |         Channel Type          | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
               Figure 1 : Generic Associated Channel Header 

   In the above figure, the first nibble is set to 0001b to indicate a 
   channel associated with a PW, a LSP or a Section. The Version and 
   Reserved fields are set to 0, as specified in RFC 4385 [11]. 

   Note that VCCV also includes mechanisms for negotiating the control 
   channel and connectivity verification (i.e. OAM functions) types 
   between PEs. These mechanisms need to be extended when a Generalised 
   associated channel is used for e.g. MPLS LSP OAM. This will most 
   likely require extensions to label distribution protocols and is 
   outside the scope of this document. 




 
 
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2.1. Allocation of Channel Types 

   Values for the Channel Type field, currently used for VCCV, are 
   specified in RFC 4446 [12]. 

   The functionality of any additional channel types will be defined in 
   another document. Each associated channel protocol solution document 
   must specify the value to use for any additional channel types.  

    

3. Generalised Exception Mechanism 

   The above mechanism enables the multiplexing of various OAM packets 
   onto a PW, LSP or section and provides information on the type of OAM 
   function being performed. In the case of a PW, the use of a control 
   word is negotiated at the time of the PW establishment. However, in 
   the case of an MPLS LSP or section, there is a need to notify an LSR 
   of the presence of an associated channel packet i.e. LSPs and 
   sections require a mechanism to differentiate specific packets (e.g. 
   OAM) from others, such as normal user-plane ones. This document 
   proposes that a label be used and calls this special label the 
   'Generic Alert Label (GAL)'. One of the reserved label values defined 
   in RFC 3032 [3] is assigned for this purpose. The value of the label 
   is to be allocated by IANA; this document suggests the value 13. 

   The GAL provides a generalised exception mechanism to: 

   o Differentiate specific packets (e.g. OAM) from others, such as 
      normal user-plane ones, 

   o Indicate that the Generic Associated Channel Header (G-ACH) 
      appears immediately after the bottom of the label stack. 

   The 'Generic Alert Label (GAL)' MUST only be used where both of these 
   purposes are applicable.  

3.1. Relationship with Existing MPLS OAM Alert Mechanisms 

   RFC 4379 [6] and BFD for MPLS LSPs [9] have defined alert mechanisms 
   that enable a MPLS LSR to identify and process MPLS OAM packets when 
   the OAM packets are encapsulated in an IP header. These alert 
   mechanisms are based on TTL expiration and/or use an IP destination 
   address in the range 127/8. 



 
 
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   These alert mechanisms SHOULD preferably be used in non MPLS-TP 
   environments. The mechanism defined in this document MAY also be 
   used. 

3.2. GAL Applicability and Usage 

   The 'Generic Alert Label (GAL)' MUST only be used with Label Switched 
   Paths (LSPs), with their associated Tandem Connection Monitoring 
   Entities (see [18] for definitions of TCMEs) and with MPLS Sections. 
   An MPLS Section is a network segment between two LSRs that are 
   immediately adjacent at the MPLS layer. 

   The GAL applies to both P2P and P2MP LSPs, unless otherwise stated. 

   In MPLS-TP, the GAL MUST always be at the bottom of the label stack 
   (i.e. S bit set to 1). However, in other MPLS environments, this 
   document places no restrictions on where the GAL may appear within 
   the label stack. 

   The G-ACH MUST be used for PWs when OAM functions that cannot be 
   demultiplexed using the IP mechanisms described in section 1. The 
   PWE3 control word MUST be present in the encapsulation of user 
   packets when the G-ACH is used to demultiplex OAM on a PW. 

   The GAL MUST NOT appear in the label stack when transporting normal 
   user-plane packets. Furthermore, the GAL MUST only appear once in the 
   label stack for OAM packets of a given layer. 

3.2.1. GAL Processing 

   The Traffic Class (TC) field (formerly known as the EXP field) of the 
   label stack entry containing the GAL follows the definition and 
   processing rules specified and referenced in [10]. 

   The Time-To-Live (TTL) field of the label stack entry that contains 
   the GAL follows the definition and processing rules specified in [4]. 

3.2.1.1. MPLS Section 

   The following figure (Figure 2) depicts two MPLS LSRs immediately 
   adjacent at the MPLS layer. 

                          +---+             +---+ 
                          | A |-------------| Z | 
                          +---+             +---+ 
    
                Figure 2 : MPLS-TP OAM over a MPLS Section 
 
 
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   With regards to the MPLS Section, both LERs contain Maintenance End 
   Points (see [18] for definitions of MEPs). 

   The following figure (Figure 3) depicts the format of a labelled OAM 
   packet on an associated channel when used for MPLS Section OAM. 

      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 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                  GAL                  |  TC |S|       TTL     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                          Generic-ACH                          | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                                                               . 
     .                       MPLS-TP OAM packet                      . 
     .                                                               | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
        Figure 3 : Labelled MPLS-TP OAM packet for MPLS Section OAM 

   To send an MPLS-TP OAM packet on an associated channel of the MPLS 
   Section, the head-end LSR (A) of the MPLS Section generates a OAM 
   packet with a G-ACH to which it pushes a GAL. 

   o The TTL field of the GAL SHOULD be set to 1. 

   o The S bit of the GAL MUST be set to 1. 

   The OAM packet, the G-ACH and the GAL SHOULD NOT be modified towards 
   the tail-end LSR (Z). Upon reception of the labelled packet, the 
   tail-end LSR (Z), after having checked the GAL fields, SHOULD pass 
   the whole packet to the appropriate processing entity. 

3.2.1.2. Label Switched Paths 

   The following figure (Figure 4) depicts four LSRs. A LSP is 
   established from A to D and switched in B and C. 

        +---+             +---+             +---+             +---+ 
        | A |-------------| B |-------------| C |-------------| D | 
        +---+             +---+             +---+             +---+ 
    
                     Figure 4 : MPLS-TP OAM over a LSP 

   LERs A and D contain Maintenance End Points (MEPs) with respect to 
   this LSP. Furthermore, LSRs B and C could also contain Maintenance 

 
 
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   Intermediate Points (MIPs) (see [18] for definitions of MEPs and 
   MIPs). 

   The following figure (Figure 5) depicts the format of a labelled 
   MPLS-TP OAM packet when used for LSP OAM. 

      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 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |               LSP Label               |  TC |S|       TTL     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                  GAL                  |  TC |S|       TTL     | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                          Generic-ACH                          | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                                                               . 
     .                       MPLS-TP OAM packet                      . 
     .                                                               | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
             Figure 5 : Labelled MPLS-TP OAM packet for LSP OAM 

   Note that it is possible that the LSP MAY also be tunnelled in 
   another LSP (e.g. if an MPLS Tunnel exists between B and C), and as 
   such other labels MAY be present above it in the label stack. 

   To send an MPLS-TP OAM packet on the LSP, the head-end LSR (A) 
   generates a MPLS-TP OAM packet with a G-ACH on which it first pushes 
   a GAL followed by the LSP label. 

   o The TTL field of the GAL SHOULD be set to 1. 

   o The S bit of the GAL SHOULD be set to 1, in MPLS-TP. 

   The MPLS-TP OAM packet, the G-ACH or the GAL SHOULD NOT be modified 
   towards the targeted destination. Upon reception of the labelled 
   packet, the targeted destination, after having checked both the LSP 
   label and GAL fields, SHOULD pass the whole packet to the appropriate 
   processing entity. 

3.2.1.3. Tandem Connection Monitoring Entity 

   Tandem Connection Monitoring will be specified in a separate 
   document. 



 
 
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3.3. Relationship with RFC 3429 

   RFC 3429 [15] describes the assignment of one of the reserved label 
   values, defined in RFC 3032 [3], to the 'OAM Alert Label' that is 
   used by user-plane MPLS OAM functions for the identification of MPLS 
   OAM packets. The value of 14 is used for that purpose. 

   Both this document and RFC 3429 therefore describe the assignment of 
   reserved label values for similar purposes. The rationale for the 
   assignment of a new reserved label can be summarized as follows: 

   o Unlike the mechanisms described and referenced in RFC 3429, MPLS-
      TP OAM packet payloads will not reside immediately after the GAL 
      but instead behind the G-ACH, which itself resides immediately 
      after the bottom of the label stack when the GAL is present. This 
      ensures that OAM using the generic associated channel complies 
      with RFC 4928 [7]. 

   o The set of OAM functions potentially operated in the context of 
      the generic associated channel is wider than the set of OAM 
      functions referenced in RFC 3429. 

   o It has been reported that there are existing implementations and 
      running deployments using the 'OAM Alert Label' as described in 
      RFC 3429. It is therefore not possible to modify the 'OAM Alert 
      Label' allocation, purpose or usage. Nevertheless, it is 
      RECOMMENDED by this document that no further OAM extensions based 
      on 'OAM Alert Label' (Label 14) usage be specified or developed. 

    

4. Compatibility 

   An LER, LSR or PE MUST discard received G-ACH packets if it is not G-
   ACH capable, it is not capable of processing packets on the indicated 
   G-ACH channel, or it has not, through means outside the scope of this 
   document, indicated to the sending LSR, LER or PE that it will 
   process G-ACH packets received on the indicated channel. The LER, LSR 
   or PE MAY increment an error counter and MAY also optionally issue a 
   system and/or SNMP notification. 

5. Congestion Considerations 

   The congestion considerations detailed in RFC 5085 [8] apply. Further 
   generic associated channel-specific congestion considerations will be 
   detailed in a future revision of this document. 

 
 
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6. Security Considerations 

   The security considerations detailed in RFC 5085 [1], the MPLS 
   architecture [2], the PWE3 architecture [5] and the MPLS-TP framework 
   [17]apply.  

7. IANA Considerations 

   This document requests that IANA allocates a Label value, to the 
   'Generalised-ACH Label (GAL)', from the pool of reserved labels, and 
   suggests this value to be 13. 

   Channel Types for the Generic Associated Channel are allocated from 
   the IANA PW Associated Channel Type registry [12]. The PW Associated 
   Channel Type registry is currently allocated based on the IETF 
   consensus process, described in [13]. This allocation process was 
   chosen based on the consensus reached in the PWE3 working group that 
   pseudowire associated channel mechanisms should be reviewed by the 
   IETF and only those that are consistent with the PWE3 architecture 
   and requirements should be allocated a code point. 

   However, a requirement has emerged (see [16]) to allow for 
   optimizations or extensions to OAM and other control protocols 
   running in an associated channel to be experimented with without 
   resorting to the IETF standards process, by supporting experimental 
   code points [14]. This would prevent code points used for such 
   functions from being used from the range allocated through the IETF 
   standards and thus protects an installed base of equipment from 
   potential inadvertent overloading of code points. In order to 
   support this requirement, this document requests that the code-point 
   allocation scheme for the PW Associated Channel Type be changed as 
   follows: 

   0 - 32751 : IETF Consensus 

   32752 - 32767 : Experimental 

   Code points in the experimental range MUST be used according to the 
   guidelines of RFC 3692 [14]. Experimental OAM functions MUST be 
   disabled by default. The channel type value used for a given 
   experimental OAM function MUST be configurable, and care MUST be 
   taken to ensure that different OAM functions that are not 
   interoperable are configured to use different channel type values. 


 
 
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8. Acknowledgments 

   The authors would like to thank all members of the teams (the Joint 
   Working Team, the MPLS Interoperability Design Team in IETF and the 
   T-MPLS Ad Hoc Group in ITU-T) involved in the definition and 
   specification of MPLS Transport Profile. 

9. References 

9.1. Normative References 

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement 
         Levels", BCP 14, RFC 2119, March 1997 

   [2]  Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol Label 
         Switching Architecture", RFC 3031, January 2001 

   [3]  Rosen, E., et al., "MPLS Label Stack Encoding", RFC 3032, 
         January 2001 

   [4]  Agarwal, P., Akyol, B., "Time To Live (TTL) Processing in 
         Multi-Protocol Label Switching (MPLS) Networks", RFC 3443, 
         January 2003 

   [5]  Bryant, S., Pate, P., "Pseudo Wire Emulation Edge-to-Edge 
         (PWE3) Architecture", RFC 3985, March 2005 

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

   [7]  Swallow, G., Bryant, S., Andersson, L., "Avoiding Equal Cost 
         Multipath Treatment in MPLS Networks", BCP 128, RFC 4928, June 
         2007 

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

   [9]  Aggarwal, R., Kompella, K., Swallow, G., Nadeau, T., "BFD For 
         MPLS LSPs", draft-ietf-bfd-mpls-07, June 2008 

   [10] Andersson, L., ""EXP field" renamed to "CoS Field"", draft-
         ietf-mpls-cosfield-def-02, June 2008 

   [11] Bryant, S., et al., "Pseudowire Emulation Edge-to-Edge (PWE3) 
         Control Word for Use over an MPLS PSN", RFC 4385, February 2006 

 
 
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   [12] Martini, L., "IANA Allocations for Pseudowire Edge to Edge 
         Emulation (PWE3)", RFC 4446, April 2006 

   [13] Narten, T., Alvestrand, H., " Guidelines for Writing an IANA 
         Considerations Section in RFCs", RFC 2434, October 1998 

   [14] Narten, T., "Assigning Experimental and Testing Numbers 
         Considered Useful", RFC 3692, January 2004 

    

9.2. Informative References 

   [15] Ohta, H., "Assignment of the 'OAM Alert Label' for 
         Multiprotocol Label Switching Architecture (MPLS) Operation and 
         Maintenance (OAM) Functions", RFC 3429, November 2002 

   [16] Vigoureux, M., Betts, M., Ward, D., "Requirements for OAM in 
         MPLS Transport Networks", draft-vigoureux-mpls-tp-oam-
         requirements-00, July 2008 

   [17] Bryant, S., Bocci, M., Lasserre, M., "A Framework for MPLS in 
         Transport Networks", draft-blb-mpls-tp-framework-00.txt, July 
         2008 

   [18] Busi, I., Niven-Jenkins B., "MPLS-TP OAM Framework and 
         Overview", draft-busi-mpls-tp-oam-framework-00, October 2008 



















 
 
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Authors' Addresses 

   Martin Vigoureux (Editor) 
   Alcatel-Lucent 
    
   Email: martin.vigoureux@alcatel-lucent.com 
    

   Matthew Bocci (Editor) 
   Alcatel-Lucent 
    
   Email: matthew.bocci@alcatel-lucent.com 
    

   David Ward (Editor) 
   Cisco Systems, Inc. 
    
   Email: dward@cisco.com 
    

   George Swallow (Editor) 
   Cisco Systems, Inc. 
    
   Email: swallow@cisco.com 
    

   Rahul Aggarwal (Editor) 
   Juniper Networks 
    
   Email: rahul@juniper.net 
    

Contributing Authors' Addresses 

   Stewart Bryant 
   Cisco Systems, Inc. 
    
   Email: stbryant@cisco.com 
    

   Italo Busi 
   Alcatel-Lucent 
    
   Email: italo.busi@alcatel-lucent.it 
    
 
 
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   Marc Lasserre 
   Alcatel-Lucent 
    
   Email: mlasserre@alcatel-lucent.com 
    

   Lieven Levrau 
   Alcatel-Lucent 
    
   Email: llevrau@alcatel-lucent.com 
    

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Copyright Statement 

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Acknowledgment 

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