APN Scope and Gap Analysis
draft-peng-apn-scope-gap-analysis-02

Document Type Active Internet-Draft (individual)
Authors Shuping Peng  , Zhenbin Li  , Gyan Mishra 
Last updated 2021-05-24
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Network Working Group                                            S. Peng
Internet-Draft                                                     Z. Li
Intended status: Informational                       Huawei Technologies
Expires: November 26, 2021                                     G. Mishra
                                                            Verizon Inc.
                                                            May 25, 2021

                       APN Scope and Gap Analysis
                  draft-peng-apn-scope-gap-analysis-02

Abstract

   The APN work in IETF is focused on developing a framework and set of
   mechanisms to derive, convey and use an attribute to allow for the
   implementation of fine-grain user group-level and application group-
   level requirements at the network layer.  APN aims to apply various
   policies in different nodes along a network path onto a traffic flow
   altogether, for example, at the headend to steer into corresponding
   path, at the midpoint to collect corresponding performance
   measurement data, and at the service function to execute particular
   policies.  Currently there is still no way to realize this composite
   network service provisioning along the path very efficiently.  This
   document further clarifies the scope of the APN work and describes
   the solution gap analysis.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 26, 2021.

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Copyright Notice

   Copyright (c) 2021 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminologies . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  APN Framework and Scope . . . . . . . . . . . . . . . . . . .   3
   4.  Example Use Case and Existing Issues  . . . . . . . . . . . .   4
   5.  Basic Solution and Benefits . . . . . . . . . . . . . . . . .   5
   6.  Solution Gap Analysis . . . . . . . . . . . . . . . . . . . .   7
     6.1.  IPv6/MPLS Flow Label  . . . . . . . . . . . . . . . . . .   7
     6.2.  SFC ServiceID . . . . . . . . . . . . . . . . . . . . . .   7
     6.3.  IOAM Flow ID  . . . . . . . . . . . . . . . . . . . . . .   8
     6.4.  Binding SID . . . . . . . . . . . . . . . . . . . . . . .   9
     6.5.  FlowSpec Label  . . . . . . . . . . . . . . . . . . . . .   9
     6.6.  Group Policy ID . . . . . . . . . . . . . . . . . . . . .   9
     6.7.  Summary . . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  Informative References  . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Application-aware Networking (APN) is introduced in
   [I-D.li-apn-framework] and [I-D.li-apn-problem-statement-usecases].
   APN conveys an attribute along with data packets into network and
   make the network aware of fine-grain user group-level and application
   group-level requirements.

   Such an attribute is acquired, constructed in a structured value, and
   then encapsulated in the packets.  Such structured value is treated
   as an opaque object in the network, to which the network operator
   applies policies in various nodes/service functions along the path
   and provide corresponding services.

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   This structured attribute can be encapsulated in various data plane
   adopted within a Network Operator controlled limited domain, e.g.
   MPLS, VXLAN, SR/SRv6 and other tunnel technologies, which waits to be
   further specified.

   With APN, it becomes possible to apply various policies in different
   nodes along a network path onto a traffic flow altogether in a more
   efficient way, e.g., at the headend to steer into corresponding path,
   at the midpoint to collect corresponding performance measurement
   data, and at the service function to execute particular policies.
   Currently there is still no way to realize this composite network
   service provisioning along the path very efficiently.  It may be
   possible to stack those various policies in a list of TLVs at the
   headend.  However, this approach would introduce great complexities
   and impose big challenges on the hardware processing and forwarding.

   The example use-case presented in this draft further expands on the
   rationale for such an attribute and how it can be derived and used in
   that specific context.

   This document further clarifies the scope of the APN work and
   describes the solution gap analysis.

2.  Terminologies

   APN: Application-aware Networking

   CPE: Customer Premises Equipment

   DPI: Deep Packet Inspection

   OS: Operating System

3.  APN Framework and Scope

   The APN framework is introduced in [I-D.li-apn-framework], as shown
   in the Figure 1.

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   +-----+                                                    +-----+
   |App x|-\                                                /-|App x|
   +-----+ |  +-----+   +-----------------------+   +-----+ | +-----+
            \-|APN- |   |   Application-aware   |   |APN- |-/
              |     |---|        Network        |---|     |
            /-|Edge |   |  Service Provisioning |   |Edge |-\
   +-----+ |  +-----+   +-----------------------+   +-----+ | +-----+
   |App y|-/     |                                     |    \-|App y|
   +-----+       |<--- Network Operator Controlled --->|      +-----+
                             Limited Domain

                    Figure 1. APN Framework and Scope

   APN works within a limited trusted domain.  Typically, an APN domain
   is defined as a Network Operator controlled limited domain (see
   Figure 1), in which MPLS, VXLAN, SR/SRv6 and other tunnel
   technologies are adopted to provide network services.

   With APN, the attribute is acquired based on the existing information
   in the packet header such as 5-tuple and QinQ (S-VLAN and C-VLAN) at
   the edge devices of the APN domain, added to the data packets along
   with the tunnel encapsulation, and delivered to the network, wherein,
   according to this attribute, corresponding network services are
   provisioned.  When the packets leave the APN domain, the attribute
   will be removed together with the tunnel encapsulation header.

4.  Example Use Case and Existing Issues

   To be more specific and more concrete, here we use SD-WAN as an
   example use case to further expand on the rationale for such
   attribute and how it can be derived and used in that specific
   context.

   In the case of SD-WAN, an enterprise obtains WAN services from an SD-
   WAN provider so that its employees have access to the applications in
   the Cloud, and then the SD-WAN provider may buy WAN lines from a
   Network Operator.  The enterprise may know what applications will use
   the SD-WAN services, but it will only provide the 5 tuples (i.e.
   source IP address, source port, destination IP address, destination
   port, transport protocol) of those applications to the SD-WAN
   provider.  So, the SD-WAN provider does not know what applications it
   is serving, and will only provide 5 tuples to the Network Operator
   and the service performance requirements for steering their
   customer's traffic.  In this way, the Network Operator does not know
   anything else about the traffic except the 5 tuples and requirements.
   Nowadays, SD-WAN is usually using 5-tuple to steer the traffic into

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   corresponding WAN lines across the Network Operator's network
   [SD-WAN].

   However, there are two main issues in the current SD-WAN deployments.

   1) It is complicated to resolve the 5 tuples.  Even worse, as the
   traffic is encrypted, it becomes impossible to obtain any transport
   layer information.  Moreover, in the IPv6 data plane, with the
   extension headers being added before the upper layer, in some
   implementations it becomes very difficult and even impossible to
   obtain transport layer information because that information is so
   deep in the packet.  So, there is no 5 tuples anymore, and maybe only
   2 tuples are available.

   2) Currently there is still no way to apply various policies in
   different nodes along the network path onto a traffic flow
   altogether, that is, at the headend to steer into corresponding path,
   at the midpoint to collect corresponding performance measurement
   data, and at the service function to execute particular policies.  It
   may be possible to stack those various policies in a list of TLVs at
   the headend.  However, this approach would introduce great
   complexities and impose big challenges on the hardware processing and
   forwarding.

5.  Basic Solution and Benefits

   With APN, at the edge node, i.e. CPE, of the SD-WAN (see Figure 2),
   the 5-tuple, plus information related to user or application group-
   level requirements is constructed into a structured value, called as
   APN attribute.  This attribute is only meaningful for the network
   operators to apply various policies in different nodes/service
   functions, which can be enforced from the Controllers.

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                           +-----------------+
                 +---------|SD-WAN Controller|---------+
                 |         +--------|--------+         |
                 |                  |                  |
                 |          +-------|-------+          |
                 |          |SDN  Controller|          |
                 |          +-------|-------+          |
   +-----+       |                  |                  |      +-----+
   |App x|-\     |                  |                  |    /-|App x|
   +-----+ |  +--|--+   +-----------|-----------+   +--|--+ | +-----+
            \-|     |   |   Application-aware   |   |     |-/
              |CPE 1|---|        Network        |---|CPE 2|
            /-|     |   |  Service Provisioning |   |     |-\
   +-----+ |  +-----+   +-----------------------+   +-----+ | +-----+
   |App y|-/     |                                     |    \-|App y|
   +-----+       |<--- Network Operator Controlled --->|      +-----+
                             Limited Domain

                    Figure 2. SD-WAN using the APN Framework

   With such an attribute in the network, we can easily solve the two
   issues above-mentioned.  For example, when the packet is sent from
   the CPE1 and the attribute is added along with the tunnel
   encapsulation, then it is not necessary to resolve the 5-tuple and
   perform the deep inspection in every node along the path.  This
   attribute is encapsulated in the network layer and can be easily read
   by the routers and service functions.  If the tunnel is based on the
   IPv6 data plane, for example, such an attribute can be encapsulated
   in an option of IPv6 hop-by-hop options header.

   Since this attribute is taken as an object to the network, the
   network operators will simply place the policies in the nodes/service
   functions where this indicated traffic will go through, and the
   corresponding node/service function will just apply policies for this
   object.  This can be easily done by utilizing this attribute, which
   is not possible with any current existing mechanism.

   Such attribute will also bring other benefits, for example,

   o  Improve the forwarding performance since it will only use 1 field
      in the IP layer instead of resolving 5 tuples, which will also
      improve the scalability.

   o  Very flexible policy enforcement in various nodes and service
      functions along the network path.

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   Furthermore, with such attribute, more new services could be enabled,
   for example,

   o  Even more fine-granularity performance measurement could be
      achieved and the granularity to be monitored and visualized can be
      controllable, which is able to relieve the processing pressure on
      the controller when it is facing the massive monitoring data.

   o  The policy execution on the service function can be based only on
      this value and not based on 5-tuple, which can eliminate the need
      of deep packet inspection.

   o  The underlay performance guarantee could be achieved for SD-WAN
      overlay services, such as explicit traffic engineering path
      satisfying SLA and selective visualized accurate performance
      measurement.

6.  Solution Gap Analysis

   There are already some solutions specified in IETF, which use
   identifier to perform traffic steering and service provisioning.
   However, The existing solutions are specific to a particular scenario
   or data plane.  None of them is the same as APN and able to achieve
   the same effects.

6.1.  IPv6/MPLS Flow Label

   [RFC6437] specifies the IPv6 flow label which enables the IPv6 flow
   classification.  However, the IPv6 flow label is mainly used for
   Equal Cost Multipath Routing (ECMP) and Link Aggregation [RFC6438].

   Similarly, [RFC6391] describes a method of adding an additional Label
   Stack Entry (LSE) at the bottom of the stack in order to facilitate
   the load balancing of the flows within a pseudowire (PW) over the
   available ECMPs.  A similar design for general MPLS use has also been
   proposed in [RFC6790] using the concept of Entropy Label.

6.2.  SFC ServiceID

   Subscriber Identifier and Performance Policy Identifier are specified
   in [I-D.ietf-sfc-serviceid-header].  These identifiers are carried
   only in the Network Service Header (NSH) [RFC8300] Context Header, as
   shown in Figure 3, while the APN attribute can be carried in various
   data plane encapsulations.

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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Metadata Class       |      Type     |U|    Length   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                      Subscriber Identifier                    ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Metadata Class       |      Type     |U|    Length   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      ~                     Performance Policy Identifier             ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 3. Subscriber Identifier and Performance Policy Identifier

   In this draft [I-D.ietf-sfc-serviceid-header], the Subscriber
   Identifier carries an opaque local identifier that is assigned to a
   subscriber by a network operator, and the Performance Policy
   Identifier represents an opaque value pointing to specific
   performance policy to be enforced.  In this way, in order to apply
   various policies in different nodes along the network path onto a
   traffic flow altogether, e.g., at the headend to steer into
   corresponding path, at the midpoint to collect corresponding
   performance measurement data, and at the service function to execute
   particular policies, those various policies would have to be stacked
   in a list of TLVs at the headend, introducing great complexities and
   big challenges on the hardware processing and forwarding.

   The APN attribute is treated as an opaque object in the network, to
   which the network operator applies policies in various nodes/service
   functions along the path and provide corresponding services.

6.3.  IOAM Flow ID

   A 32-bit Flow ID is specified in [I-D.ietf-ippm-ioam-direct-export],
   which is used to correlate the exported data of the same flow from
   multiple nodes and from multiple packets, while the APN attribute can
   serve more various purposes.

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6.4.  Binding SID

   The Binding SID (BSID) [RFC8402] is bound to an SR Policy,
   instantiation of which may involve a list of SIDs.  Any packets
   received with an active segment equal to BSID are steered onto the
   bound SR Policy.  A BSID may be either a local or a global SID.
   While the APN attribute is not bound to SR only, and it can be
   carried in various data plane encapsulations.

6.5.  FlowSpec Label

   The flow specification (FlowSpec) [RFC5575] is actually an n-tuple
   consisting of several matching criteria that can be applied to IP
   traffic, which include elements such as source and destination
   address prefixes, IP protocol, and transport protocol port numbers.
   In BGP VPN/MPLS networks, BGP FlowSpec can be extended to identify
   and change (push/swap/pop) the label(s) for traffic that matches a
   particular FlowSpec rule in [I-D.ietf-idr-flowspec-mpls-match] and
   [I-D.ietf-idr-bgp-flowspec-label].  In
   [I-D.liang-idr-bgp-flowspec-route], BGP is used to distribute the
   FlowSpec rule bound with label(s).  While the APN attribute is not
   bound to MPLS only, and it can be carried in various data plane
   encapsulations.

6.6.  Group Policy ID

   The capabilities of the VXLAN-GPE protocol can be extended by
   defining next protocol "shim" headers that are used to implement new
   data plane functions.  For example, Group Policy ID is carried in the
   Group-Based Policy (GBP) Shim header [I-D.lemon-vxlan-lisp-gpe-gbp].
   GENEVE has similar ability as VXLAN-GPE to carry metadata.

6.7.  Summary

   As driven by ever-emerging new 5G services, fine-granularity service
   provisioning becomes urgent.  The existing solutions are either
   specific to a particular scenario or data plane.  While APN aims to
   define a generalized attribute used for fine-granularity service
   provisioning, and can be carried in various data plane
   encapsulations.

7.  IANA Considerations

   There are no IANA considerations in this document.

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8.  Acknowledgements

   The authors would like to acknowledge Martin Vigoureux, Alvaro
   Retana, Barry Leiba, Stefano Previdi, Adrian Farrel, and Daniel King
   for their valuable review and comments.

9.  Informative References

   [I-D.brockners-ippm-ioam-vxlan-gpe]
              Brockners, F., Bhandari, S., Govindan, V. P., Pignataro,
              C., Gredler, H., Leddy, J., Youell, S., Mizrahi, T., Kfir,
              A., Gafni, B., Lapukhov, P., and M. Spiegel, "VXLAN-GPE
              Encapsulation for In-situ OAM Data", draft-brockners-ippm-
              ioam-vxlan-gpe-03 (work in progress), November 2019.

   [I-D.ietf-idr-bgp-flowspec-label]
              Liang, Q., Hares, S., You, J., Raszuk, R., and D. Ma,
              "Carrying Label Information for BGP FlowSpec", draft-ietf-
              idr-bgp-flowspec-label-01 (work in progress), December
              2016.

   [I-D.ietf-idr-flowspec-mpls-match]
              Yong, L., Hares, S., Liang, Q., and J. You, "BGP Flow
              Specification Filter for MPLS Label", draft-ietf-idr-
              flowspec-mpls-match-01 (work in progress), December 2016.

   [I-D.ietf-ippm-ioam-direct-export]
              Song, H., Gafni, B., Zhou, T., Li, Z., Brockners, F.,
              Bhandari, S., Sivakolundu, R., and T. Mizrahi, "In-situ
              OAM Direct Exporting", draft-ietf-ippm-ioam-direct-
              export-03 (work in progress), February 2021.

   [I-D.ietf-sfc-serviceid-header]
              Sarikaya, B., Hugo, D. V., and M. Boucadair, "Subscriber
              and Performance Policy Identifier Context Headers in the
              Network Service Header (NSH)", draft-ietf-sfc-serviceid-
              header-14 (work in progress), December 2020.

   [I-D.lemon-vxlan-lisp-gpe-gbp]
              Lemon, J., Maino, F., Smith, M., and A. Isaac, "Group
              Policy Encoding with VXLAN-GPE and LISP-GPE", draft-lemon-
              vxlan-lisp-gpe-gbp-02 (work in progress), April 2019.

   [I-D.li-6man-app-aware-ipv6-network]
              Li, Z., Peng, S., Li, C., Xie, C., Voyer, D., Li, X., Liu,
              P., Cao, C., and K. Ebisawa, "Application-aware IPv6
              Networking (APN6) Encapsulation", draft-li-6man-app-aware-
              ipv6-network-03 (work in progress), February 2021.

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   [I-D.li-apn-framework]
              Li, Z., Peng, S., Voyer, D., Li, C., Liu, P., Cao, C.,
              Ebisawa, K., Previdi, S., and J. N. Guichard,
              "Application-aware Networking (APN) Framework", draft-li-
              apn-framework-02 (work in progress), February 2021.

   [I-D.li-apn-problem-statement-usecases]
              Li, Z., Peng, S., Voyer, D., Xie, C., Liu, P., Qin, Z.,
              Ebisawa, K., Previdi, S., and J. N. Guichard, "Problem
              Statement and Use Cases of Application-aware Networking
              (APN)", draft-li-apn-problem-statement-usecases-01 (work
              in progress), September 2020.

   [I-D.liang-idr-bgp-flowspec-route]
              Liang, Q. and J. You, "BGP FlowSpec based Multi-
              dimensional Route Distribution", draft-liang-idr-bgp-
              flowspec-route-00 (work in progress), October 2014.

   [I-D.peng-apn-security-privacy-consideration]
              Peng, S., Li, Z., Voyer, D., Li, C., Liu, P., and C. Cao,
              "APN Security and Privacy Considerations", draft-peng-apn-
              security-privacy-consideration-00 (work in progress),
              September 2020.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5575]  Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
              <https://www.rfc-editor.org/info/rfc5575>.

   [RFC6391]  Bryant, S., Ed., Filsfils, C., Drafz, U., Kompella, V.,
              Regan, J., and S. Amante, "Flow-Aware Transport of
              Pseudowires over an MPLS Packet Switched Network",
              RFC 6391, DOI 10.17487/RFC6391, November 2011,
              <https://www.rfc-editor.org/info/rfc6391>.

   [RFC6437]  Amante, S., Carpenter, B., Jiang, S., and J. Rajahalme,
              "IPv6 Flow Label Specification", RFC 6437,
              DOI 10.17487/RFC6437, November 2011,
              <https://www.rfc-editor.org/info/rfc6437>.

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   [RFC6438]  Carpenter, B. and S. Amante, "Using the IPv6 Flow Label
              for Equal Cost Multipath Routing and Link Aggregation in
              Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011,
              <https://www.rfc-editor.org/info/rfc6438>.

   [RFC6790]  Kompella, K., Drake, J., Amante, S., Henderickx, W., and
              L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
              RFC 6790, DOI 10.17487/RFC6790, November 2012,
              <https://www.rfc-editor.org/info/rfc6790>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [SD-WAN]   MEF 70.1 Draft (R1), available at https://www.mef.net/wp-
              content/uploads/2020/08/MEF-70-1-Draft-R1.pdf/, "SD-WAN
              Service Attributes and Service Framework", August 2020.

Authors' Addresses

   Shuping Peng
   Huawei Technologies
   Beijing
   China

   Email: pengshuping@huawei.com

   Zhenbin Li
   Huawei Technologies
   Beijing
   China

   Email: lizhenbin@huawei.com

   Gyan Mishra
   Verizon Inc.
   USA

   Email: gyan.s.mishra@verizon.com

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