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Versions: (draft-bocci-mpls-tp-gach-gal) 00 01 02 03 04 05 06 RFC 5586

MPLS Working Group                                        M. Vigoureux
Internet Draft                                               M. Bocci
Updates: 3032, 4385                                     Alcatel-Lucent
Intended status: Standard Track
Expires: May 2009                                          G. Swallow
                                                              D. Ward
                                                   Cisco Systems, Inc.

                                                          R. Aggarwal
                                                      Juniper Networks

                                                     November 27, 2008



                      MPLS Generic Associated Channel
                      draft-ietf-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-ietf-mpls-tp-framework-00.txt,
         November 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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   The IETF invites any interested party to bring to its attention any
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Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.




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Internet-Draft              G-ACH and GAL                November 2008


Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
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Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




































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