\
Internet Engineering Task Force                                  H. Chen
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                                   N. So
Expires: September 14, 2012                                 Verizon Inc.
                                                                  A. Liu
                                                                Ericsson
                                                             O. Komolafe
                                                           Cisco Systems
                                                                  L. Liu
                                                       KDDI R&D Lab Inc.
                                                          March 13, 2012


       Extensions to RSVP-TE for P2MP LSP Egress Local Protection
             draft-chen-mpls-p2mp-egress-protection-05.txt

Abstract

   This document describes extensions to Resource Reservation Protocol -
   Traffic Engineering (RSVP-TE) for locally protecting egress nodes of
   a Traffic Engineered (TE) point-to-multipoint (P2MP) Label Switched
   Path (LSP) in a Multi-Protocol Label Switching (MPLS) and Generalized
   MPLS (GMPLS) network.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  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 September 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



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   (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.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
   4.  Mechanism  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  An Example of Egress Local Protection  . . . . . . . . . .  4
     4.2.  Set up of Backup sub LSP . . . . . . . . . . . . . . . . .  5
     4.3.  Forwarding State for Backup sub LSP(s) . . . . . . . . . .  6
     4.4.  Detection of Egress Node Failure . . . . . . . . . . . . .  6
   5.  Egress Local Protection with FRR . . . . . . . . . . . . . . .  7
   6.  Representation of a Backup Sub LSP . . . . . . . . . . . . . .  7
     6.1.  EGRESS_BACKUP_SUB_LSP Object . . . . . . . . . . . . . . .  7
       6.1.1.  EGRESS_BACKUP_SUB_LSP IPv4 Object  . . . . . . . . . .  8
       6.1.2.  EGRESS_BACKUP_SUB_LSP IPv6 Object  . . . . . . . . . .  8
     6.2.  EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object  . . . . . .  9
   7.  Path Message . . . . . . . . . . . . . . . . . . . . . . . . .  9
     7.1.  Format of Path Message . . . . . . . . . . . . . . . . . .  9
     7.2.  Processing of Path Message . . . . . . . . . . . . . . . . 10
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   9.  Acknowledgement  . . . . . . . . . . . . . . . . . . . . . . . 11
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 11
     10.2. Informative References . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12

















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1.  Introduction

   RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels"
   describes two methods for protecting P2P LSP tunnels or paths at
   local repair points.  The first method is a one-to-one protection
   method, where a detour backup P2P LSP for each protected P2P LSP is
   created at each potential point of local repair, which is an
   intermediate node between the ingress node and the egress node of the
   protected LSP.  The second method is a facility bypass backup
   protection method, where a bypass backup P2P LSP tunnel is created
   using MPLS label stacking to protect a potential failure point for a
   set of P2P LSP tunnels.  The bypass backup tunnel can protect a set
   of P2P LSPs having similar backup constraints.

   RFC 4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to
   use the one-to-one protection method and facility bypass backup
   protection method to protect a link or intermediate node failure on
   the path of a P2MP LSP.  However, there is no mention of locally
   protecting any egress node failure in a protected P2MP LSP.

   An existing method for protecting the egress nodes of a P2MP LSP sets
   up a backup P2MP LSP from a backup ingress node to the backup egress
   nodes, where each egress node is paired with a backup egress node and
   protected by the backup egress node.  The backup P2MP LSP carries the
   same traffic as the P2MP LSP at the same time.  A traffic receiver
   from the P2MP LSP is normally connected to an egress node and its
   paired backup egress node.  It receives the traffic from the egress
   node in normal situations.

   The receiver selects the egress or backup egrss node for receiving
   the traffic according to the route to the source through RPF.  In a
   normal situation, it selects the egress node.  When the egress node
   fails, it selects the backup egress for receiving the traffic since
   the route to the source through the egress node is gone and the route
   to the source through the backup egress node is active.

   The main disadvantage of this method is that double network resources
   such as double bandwidths are used for protecting the egress nodes
   since the backup P2MP LSP consumes the same amount of network
   resource as the primary P2MP LSP.  The impact on network efficiency
   can be significant in case of large P2MP deployments.

   This document proposes a new method to locally protect the egress
   nodes of a P2MP LSP, which is called Egress Local Protection.  It
   specifies the mechanism and extensions to RSVP-TE for locally
   protecting an egress node of a Traffic Engineered (TE) point-to-
   multipoint (P2MP) Label Switched Path through using a backup P2MP sub
   LSP.  The new method overcomes the disadvantages described above.



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   The same extensions and mechanism can also be used to protect the
   egress node of a TE P2P LSP.


2.  Terminology

   This document uses terminologies defined in RFC 2205, RFC 3031, RFC
   3209, RFC 3473, RFC 4090, RFC 4461, and RFC 4875.


3.  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.


4.  Mechanism

   This section briefly describes a solution that locally protects an
   egress node of a P2MP LSP through using a backup P2MP sub LSP.  We
   first show an example, and then present different parts of the
   solution, which includes the creation of the backup sub LSP, the
   forwarding state for the backup sub LSP, and the detection of a
   failure in the egress node.

4.1.  An Example of Egress Local Protection

   Figure 1 below illustrates an example of using backup sub LSPs to
   locally protect egress nodes of a P2MP LSP.  The P2MP LSP is from
   ingress node R1 to three egress nodes: L1, L2 and L3.  It is
   represented by double lines in the figure.

   La, Lb and Lc are the designated backup egress nodes for the egress
   nodes L1, L2 and L3 of the P2MP LSP respectively.  In order to
   distinguish an egress node (e.g., L1 in the figure) and a backup
   egress node (e.g., La in the figure), an egress node is called a
   primary egress node in the follwing description.

   The backup sub LSP used to protect the primary egress node L1 is from
   its previous hop node R3 to the backup egress node La.  The backup
   sub LSP used to protect the primary egress node L2 is from its
   previous hop node R5 to the backup egress node Lb.  The backup sub
   LSP used to protect the primary egress node L3 is from its previous
   hop node R5 to the backup egress node Lc via the intermediate node
   Rc.

   During normal operation, the traffic transported by the P2MP LSP is



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   forwarded through R3 to L1, then delivered to its destination CE1.
   When the failure of L1 is detected, R3 forwards the traffic to the
   backup egress node La, which then delivers the traffic to its
   destination CE1.  The time for switching the traffic after L1 fails
   is within tens of milliseconds.

   L1's failure CAN be detected by a BFD session between L1 and R3.

                         [R2]=====[R3]=====[L1]----[CE1]
                        //           \            /
                       //             \          /
                      //               \___[La]_/
                     //
                    //
                   //
                  //
              +---[R1]====[R4]====[R5]=====[L2]----[CE2]
              |                   |\\ \           /
              |                   | \\ \         /
         [S]--|                   |  \\ \__[Lb]_/
              |                   |   \\
              |                   |    \\
                                  |     \\
                                  |      \\
                                  |       \\
                                  |        [L3]----[CE3]
                                  |               /
                                  |              /
                                [Rc]_______[Lc]_/


           Figure 1: P2MP sub LSP for Locally Protecting Egress

4.2.  Set up of Backup sub LSP

   A backup egress node is designated for a primary egress node of a
   LSP.  The previous hop node of the primary egress node sets up a
   backup sub LSP from itself to the backup egress node after receiving
   the information about the backup egress node.

   The previous hop node sets up the backup sub LSP, creates and
   maintains its state in the same way as of setting up a source to leaf
   (S2L) sub LSP from the signalling's point of view.  It constructs and
   sends a RSVP-TE PATH message along the path for the backup sub LSP,
   receives and processes a RSVP-TE RESV message that responses to the
   PATH message.





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4.3.  Forwarding State for Backup sub LSP(s)

   The forwarding state for the backup sub LSP is different from that
   for a P2MP S2L sub LSP.  After receiving the RSVP-TE RESV message for
   the backup sub LSP, the previous hop node creates a forwarding entry
   with an inactive state or flag called inactive forwarding entry.
   This inactive forwarding entry is not used to forward any data
   traffic during normal operations.  It SHALL only be used after the
   failure of the primary egress node.

   Upon detection of the primary egress node failure, the state or flag
   of the forwarding entry for the backup sub LSP is set to be active.
   Thus, the previous hop node of the primary egress node will forward
   the traffic to the backup egress node through the backup sub LSP,
   which then send the traffic to its destination.

4.4.  Detection of Egress Node Failure

   The previous hop node of the primary egress node SHALL detect four
   types of failures described below:

   o  The failure of the primary egress node (e.g.  L1 in Figure 1)

   o  The failure of the link between the primary egress node and its
      previous hop node (e.g. the link between R3 and L1 in Figure 1)

   o  The failure of the destination node for the primary egress node
      (e.g.  CE1 in Figure 1)

   o  The failure of the link between the primary egress node and its
      destination node (e.g. the failure of the link between L1 and CE1
      in Figure 1).

   Failure of the primary egress node and the link between itself and
   its previous hop node CAN be detected through a BFD session between
   itself and its previous hop node in MPLS networks.

   In the GMPLS networks where the control plane and data plane are
   physically separated, the detection and localization of failures in
   the physical layer can be achieved by introducing the link management
   protocol (LMP) or assisting by performance monitoring devices.

   Failure of the destination node and the link between the primary
   egress node and the destination node CAN be detected by a BFD session
   between the previous hop node and the destination node.

   Upon detecting any above mentioned failures, the previous hop node
   imports the traffic from the LSP into the backup sub LSP.  The



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   traffic is then delivered to its destination through the backup
   egress node.


5.  Egress Local Protection with FRR

   RFC4875 "Extensions to RSVP-TE for P2MP TE LSPs" describes how to use
   RFC 4090 "Fast Reroute Extensions to RSVP-TE for LSP Tunnels" (FFR
   for short) to locally protect failures in a link or intermediate node
   of a P2MP LSP.  However, there is not any standard that locally
   protects the egresses of the P2MP LSP.  The egress local protection
   mechanism proposed in this document fills this gap.  Thus, through
   using the egress local protection and the FRR, we can locally protect
   the egress nodes, all the links and the intermediate nodes of a P2MP
   LSP.  The traffic switchover time is within tens of milliseconds
   whenever any of the egresses, the links and the intermediate nodes of
   the P2MP LSP fails.

   All the egress nodes of the P2MP LSP can be locally protected through
   using the egress local protection.  All the links and the
   intermediate nodes of the LSP can be locally protected by using the
   FRR.  Note that the methods for locally protecting all the links and
   the intermediate nodes of a P2MP LSP are out of scope of this
   document.


6.  Representation of a Backup Sub LSP

   A backup sub LSP exists within the context of a P2MP LSP in a way
   similar to a S2L sub LSP.  It is identified by the P2MP LSP ID,
   Tunnel ID, and Extended Tunnel ID in the SESSION object, the tunnel
   sender address and LSP ID in the SENDER_TEMPLATE object, and the
   backup sub LSP destination address in the EGRESS_BACKUP_SUB_LSP
   object (to be defined in the section below).

   An EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object (EB-SERO) is used to
   optionally specify the explicit route of a backup sub LSP that is
   from a previous hop node to a backup egress node.  The EB-SERO is
   defined in the following section.

6.1.  EGRESS_BACKUP_SUB_LSP Object

   An EGRESS_BACKUP_SUB_LSP object identifies a particular backup sub
   LSP belonging to the LSP.







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6.1.1.  EGRESS_BACKUP_SUB_LSP IPv4 Object

   The class of the EGRESS_BACKUP_SUB_LSP IPv4 object is the same as
   that of the S2L_SUB_LSP IPv4 object defined in RFC 4875.  The C-Type
   of the object is a new number 3, or may be another number assigned by
   Internet Assigned Numbers Authority (IANA).

    EGRESS_BACKUP_SUB_LSP Class = 50,
    EGRESS_BACKUP_SUB_LSP_IPv4 C-Type = 3

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Egress Backup Sub LSP IPv4 destination address        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Egress IPv4 address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Egress Backup Sub LSP IPv4 destination address
       IPv4 address of the backup sub LSP destination is the backup
       egress node.
    Egress IPv4 address
       IPv4 address of the egress node

6.1.2.  EGRESS_BACKUP_SUB_LSP IPv6 Object

   The class of the EGRESS_BACKUP_SUB_LSP IPv6 object is the same as
   that of the S2L_SUB_LSP IPv6 object defined in RFC 4875.  The C-Type
   of the object is a new number 4, or may be another number assigned by
   Internet Assigned Numbers Authority (IANA).




















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    EGRESS_BACKUP_SUB_LSP Class = 50,
    EGRESS_BACKUP_SUB_LSP_IPv6 C-Type = 4

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Egress Backup Sub LSP IPv6 destination address        |
       |                         (16 bytes)                            |
       |                         ....                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Egress IPv6 address                       |
       |                         (16 bytes)                            |
       |                         ....                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Egress Backup Sub LSP IPv6 destination address
       IPv6 address of the backup sub LSP destination is the backup
       egress node.
    Egress IPv6 address
       IPv6 address of the egress node

6.2.  EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE Object

   The format of an EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE (EB-SERO)
   object is defined as identical to that of the ERO.  The class of the
   EB-SERO is the same as that of the SERO defined in RFC 4873.  The EB-
   SERO uses a new C-Type 3, or may use another number assigned by
   Internet Assigned Numbers Authority (IANA).  The formats of sub-
   objects in an EB-SERO are identical to those of sub-objects in an ERO
   defined in RFC 3209.


7.  Path Message

   This section describes extensions to the Path message defined in RFC
   4875.  The Path message is enhanced to transport the information
   about a backup egress node to the previous hop node of a primary
   egress node of a P2MP LSP through including an egress backup sub LSP
   descriptor list.

7.1.  Format of Path Message

   The format of the enhanced Path message is illustrated below.







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      <Path Message> ::=  <Common Header> [ <INTEGRITY> ]
                          [ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ...]
                          [ <MESSAGE_ID> ]
                          <SESSION> <RSVP_HOP>
                          <TIME_VALUES>
                          [ <EXPLICIT_ROUTE> ]
                          <LABEL_REQUEST>
                          [ <PROTECTION> ]
                          [ <LABEL_SET> ... ]
                          [ <SESSION_ATTRIBUTE> ]
                          [ <NOTIFY_REQUEST> ]
                          [ <ADMIN_STATUS> ]
                          [ <POLICY_DATA> ... ]
                          <sender descriptor>
                          [<S2L sub-LSP descriptor list>]
                          [<egress backup sub LSP descriptor list>]


   The format of the egress backup sub LSP descriptor list in the
   enhanced Path message is defined as follows.

      <egress backup sub LSP descriptor list> ::=
                          <egress backup sub LSP descriptor>
                          [ <egress backup sub LSP descriptor list> ]

      <egress backup sub LSP descriptor> ::=
                          <EGRESS_BACKUP_SUB_LSP>
                          [ <EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE> ]


7.2.  Processing of Path Message

   The ingress node of a LSP initiates a Path message with an egress
   backup sub LSP descriptor list for protecting primary egress nodes of
   the LSP.  In order to protect a primary egress node of the LSP, the
   ingress node MUST add an EGRESS_BACKUP_SUB_LSP object into the list.
   The object contains the information about the backup egress node to
   be used to protect the failure of the primary egress node.  An
   EGRESS_BACKUP_SECONDARY_EXPLICIT_ROUTE object (EB-SERO), which
   describes an explicit path to the backup egress node, SHALL follow
   the EGRESS_BACKUP_SUB_LSP.

   If the previous hop node of the primary egress node receives the Path
   message with an egress backup sub LSP descriptor list, it generates a
   new Path message based on the information in the
   EGRESS_BACKUP_SUB_LSP (and according to EB-SERO if it exists)
   containing the backup egress node.




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   The format of this new Path message is the same as that of the Path
   message defined in RFC 4875.  This new Path message is used to signal
   the segment of a special S2L sub-LSP from the previous hop node to
   the backup egress node.  The new Path message is sent to the next-hop
   node along the path for the backup sub LSP.

   If an intermediate node receives the Path message with an egress
   backup sub LSP descriptor list.  Then it MUST put the
   EGRESS_BACKUP_SUB_LSP (according to EB-SERO if exists) containing a
   backup egress into a Path message to be sent towards the backup
   egress.  This SHALL be done for each EGRESS_BACKUP_SUB_LSP containing
   a backup egress node in the list.

   When a primary egress node of the LSP receives the Path message with
   an egress backup sub LSP descriptor list, it SHOULD ignore the egress
   backup sub LSP descriptor list and generate a PathErr message.


8.  IANA Considerations

   TBD


9.  Acknowledgement

   The authors would like to thank Richard Li, Rob Rennison, Neil
   Harrison, Kannan Sampath, Yimin Shen, Ronhazli Adam and Quintin Zhao
   for their valuable comments and suggestions on this draft.


10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3692]  Narten, T., "Assigning Experimental and Testing Numbers
              Considered Useful", BCP 82, RFC 3692, January 2004.

   [RFC2205]  Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
              Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
              Functional Specification", RFC 2205, September 1997.

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031, January 2001.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,



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              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.

   [RFC3473]  Berger, L., "Generalized Multi-Protocol Label Switching
              (GMPLS) Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC4090]  Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
              Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
              May 2005.

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

   [P2MP FRR]
              Le Roux, J., Aggarwal, R., Vasseur, J., and M. Vigoureux,
              "P2MP MPLS-TE Fast Reroute with P2MP Bypass Tunnels",
              draft-leroux-mpls-p2mp-te-bypass , March 1997.

10.2.  Informative References

   [RFC4461]  Yasukawa, S., "Signaling Requirements for Point-to-
              Multipoint Traffic-Engineered MPLS Label Switched Paths
              (LSPs)", RFC 4461, April 2006.


Authors' Addresses

   Huaimo Chen
   Huawei Technologies
   Boston, MA
   USA

   Email: Huaimochen@huawei.com


   Ning So
   Verizon Inc.
   2400 North Glenville Drive
   Richardson, TX  75082
   USA

   Email: Ning.So@verizonbusiness.com






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   Autumn Liu
   Ericsson
   CA
   USA

   Email: autumn.liu@ericsson.com


   Olufemi Komolafe
   Cisco Systems
   96 Commercial Street
   Edinburgh,   EH6 6LX
   United Kingdom

   Email: femi@cisco.com


   Lei Liu
   KDDI R&D Lab Inc.
   2-1-15
   Ohara Fujimino-shi, Saitama
   Japan

   Email: le-liu@kddilabs.jp



























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