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Versions: 00 01 02 draft-ietf-anima-prefix-management

ANIMA WG                                                   S. Jiang, Ed.
Internet-Draft                                                     Z. Du
Intended status: Informational              Huawei Technologies Co., Ltd
Expires: April 20, 2016                                     B. Carpenter
                                                       Univ. of Auckland
                                                                  Q. Sun
                                                           China Telecom
                                                        October 18, 2015


          Autonomic Prefix Management in Large-scale Networks
                 draft-jiang-anima-prefix-management-02

Abstract

   This document describes an autonomic solution for prefix management
   in large-scale networks.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 April 20, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   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




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Intended User and Administrator Experience  . . . . . . .   3
     2.2.  Analysis of Parameters and Information Involved . . . . .   3
       2.2.1.  Parameters each device can decide for itself  . . . .   4
       2.2.2.  Information needed from policy intent . . . . . . . .   4
       2.2.3.  Comparison with current solutions . . . . . . . . . .   5
     2.3.  Interaction with other devices  . . . . . . . . . . . . .   5
       2.3.1.  Information needed from other devices . . . . . . . .   5
       2.3.2.  Monitoring, diagnostics and reporting . . . . . . . .   6
   3.  Autonomic Prefix Management Solution  . . . . . . . . . . . .   6
     3.1.  Behaviors to discover prefix providing device . . . . . .   6
     3.2.  Behaviors on prefix providing device  . . . . . . . . . .   6
     3.3.  Prefix Requests Behaviors . . . . . . . . . . . . . . . .   7
     3.4.  Prefix log  . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  Autonomic Prefix Management Options . . . . . . . . . . . . .   8
     4.1.  Prefix Objective option . . . . . . . . . . . . . . . . .   8
   5.  Prefix Management Intent  . . . . . . . . . . . . . . . . . .   8
     5.1.  Example of Prefix Management Intent . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   9.  Change log [RFC Editor: Please remove]  . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   This document proposes an autonomic solution for prefix management in
   large-scale networks.  The background to Autonomic Network (AN) is
   described in [RFC7575] and [RFC7576].  A generic autonomic signaling
   protocol (GRASP) is proposed by [I-D.ietf-anima-grasp], which would
   be used by the proposed autonomic prefix management solution.

   This document is dedicated to how to make IPv6 prefix management in
   pure IPv6 large-scale networks as autonomic as possible.  This
   document for now is only considering service provider (ISP) networks.
   Although there are similarities with large enterprise networks, the
   requirements are a little different for the two use cases.

   Note in draft: This version is preliminary.  In particular, many
   design details may be subject to change until the anima
   specifications become agreed.



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2.  Problem Statement

   The autonomic networking use case considered here is autonomic IP
   address management in large-scale networks.

   Although DHCPv6 Prefix Delegation [RFC3633] has supported automated
   delegation of IPv6 prefixes, prefix management is still largely
   depending on human planning.  In other words, there is no basic
   information or policy to support autonomic decisions on the prefix
   length that each router should request or be delegated, according to
   its role in the network.  Roles could be locally defined or could be
   generic (edge router, interior router, etc.).  Furthermore, the
   current IPv6 prefix management by humans is rigid and static after
   initial planning.

   The problem to be solved by AN is how to dynamically and
   autonomically manage IPv6 address space in large-scale networks, so
   that IPv6 addresses can be used efficiently.  The AN approach
   discussed in this document is based on the assumption that there is a
   generic discovery and negotiation protocol that enables direct
   negotiation between intelligent IP routers.  [I-D.ietf-anima-grasp]
   is one of the attempts at such a protocol.

2.1.  Intended User and Administrator Experience

   The intended experience is, for the administrator(s) of a large-scale
   network, that the management of IPv6 address space can be run with
   minimum efforts, for both the network and network device initiation
   stage and during running time.  In the ideal scenario, the
   administrator(s) only have to configure a single IPv6 prefix for the
   whole network and the initial prefix length for each device role.

   The actual address usage needs to be logged for potential offline
   management operations including audit and security incident tracing.

2.2.  Analysis of Parameters and Information Involved

   For specific purposes of address management, a few parameters are
   involved on each device (some of them can be pre-configured before
   they are connected).  They include:

   o  Identity of this device.  It can be verified by the certification
      authority (CA) that is maintained by the network administrator(s).

   o  Identity of a trust anchor which is certification authority (CA)
      that is maintained by the network administrator(s).

   o  Role of this device.



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   o  An IPv6 prefix length for this device.

   o  An IPv6 prefix that is assigned to this device and its downstream
      devices.

   A few parameters are involved in the network as a whole.  They are:

   o  Identity of a trust anchor which is a certification authority (CA)
      that is maintained by the network administrator(s).

   o  Total IPv6 address space.  It is one (or several) IPv6 prefix(es).

   o  The initial prefix length for each device role.

2.2.1.  Parameters each device can decide for itself

   This section identifies those of the above parameters that do not
   need external information in order for the devices concerned to set
   them to a reasonable value after bootstrap or after a network
   disruption.  There are few of these:

   o  Role of this device.

   o  Default IPv6 prefix length for this device.

   o  Identity of this device.

   The device may be shipped from the manufacture with pre-configured
   role and default prefix length.

2.2.2.  Information needed from policy intent

   This section identifies those parameters that need external
   information about policy intent in order for the devices concerned to
   set them to a non-default value.

   o  Non-default value for the IPv6 prefix length for this device.
      This needs to be decided based on the role of this device.

   o  The initial prefix length for each device role.

   o  Identity of a trust anchor.

   o  Whether to allow the device request more address space.

   o  The policy when to request more address space, for example, the
      address usage reaches a certain limit or percentage.




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2.2.3.  Comparison with current solutions

   This section briefly compares the above use case with current
   solutions.  Currently, the address management is still largely
   depending on human planning.  It is rigid and static after initial
   planning.  The address requests will fail if the configured address
   space is used up.

   Some functions, for autonomic and dynamic address management, may be
   achievable by extending the existing protocols, for example,
   extending DHCPv6-PD to request IPv6 address according to the device
   role.  However, defining uniform device roles may not be a practical
   task.  Some functions are not suitable to be achieved by any existing
   protocols.

   However, using a generic autonomic discovery and negotiation protocol
   instead of specific solutions has the advantage that additional
   parameters can be included in the autonomic solution without creating
   new mechanisms.  This is the principal argument for a generic
   approach.

2.3.  Interaction with other devices

2.3.1.  Information needed from other devices

   This section identifies those of the above parameters that need
   external information from neighbor devices (including the upstream
   devices).  In many cases, two-way dialogue with neighbor devices is
   needed to set or optimize them.

   o  Identity of a trust anchor.

   o  The device will need to discover a device, from which it can
      acquire IPv6 address space.

   o  The initial prefix length for each device role, particularly for
      its own downstream devices.

   o  The default value of the IPv6 prefix length may be overridden by a
      non-default value.

   o  The device will need to request and acquire IPv6 prefix that is
      assigned to this device and its downstream devices.

   o  The device may respond to prefix delegation request from its
      downstream devices.





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   o  The device may require to be assigned more IPv6 address space, if
      it used up its assigned IPv6 address space.

2.3.2.  Monitoring, diagnostics and reporting

   This section discusses what role devices should play in monitoring,
   fault diagnosis, and reporting.

   o  The actual address assignments need to be logged for the potential
      offline management operations.

   o  In general, the usage situation of address space should be
      reported to the network administrators, in an abstract way, for
      example, statistics or visualized report.

   o  A forecast of address exhaustion should be reported.

3.  Autonomic Prefix Management Solution

   This section introduces an autonomic prefix management solution.  It
   extends the generic discovery and negotiation protocol defined by
   [I-D.ietf-anima-grasp].  The relevant options are defined in
   Section 4.

3.1.  Behaviors to discover prefix providing device

   A device should decide the length of request prefix by the intent-
   based mechanism, described in Section 5.  If it used up its current
   address resource, it could request more, which is not necessary to be
   on the same scale as its initial resource.

   A prefix requesting device that needs new or more address space
   should firstly discover peer devices that may be able to provide
   extra address space.  The device should send out a GRASP Discovery
   message that contains a Prefix Objective option Section 4.1, in which
   the device also indicates whether it supports the DHCPv6 Prefix
   Delegation (PD) [RFC3633] function and the length of requested
   prefix.

3.2.  Behaviors on prefix providing device

   A peer device receiving a Discovery message with a Prefix Objective
   option, if it is able to provide such a prefix, should respond with a
   GRASP Response message.  The Response message also carries a Prefix
   Objective option, which also indicate whether the peer device
   supports the PD function and the available prefix length matching the
   request.  If the peer device does not have enough resource, it may
   silently drop the Discovery message or return a GRASP Response



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   message, which contains a longer prefix length (smaller address
   space) that it can provide.  A divert option may also be added into
   the GRASP Response message.  This divert option indicates another
   device that may provide the prefix.  The diverted device is typically
   an upstream gateway router, but it could in theory be any device that
   might have unused prefix space.

   A gateway router in a hierarchical network topology is normally
   responsible to provide prefixes for routers within its subnet.  In
   the case that it does not have enough resource for the downstream
   requesting router, it should return a GRASP Response message, which
   contains a longer prefix length (smaller address space) that this
   gateway router may provide.  In this case too, a divert option may be
   added into the GRASP Response message.  The diverted device is
   typically another upstream gateway router.

   A resource shortage may cause the gateway router to request more
   resource from its upstream device.  This would be another independent
   GND discovery and negotiation process.  During the processing time,
   the gateway router should send a Confirm-waiting Message to the
   initial requesting router.  When the new resource becomes available,
   the gateway router responds with a GRASP Response message with the
   prefix length matching the request.

   The algorithm to choose which prefixes to assign on the prefix
   providing devices is an implementation choice out of document scope.

3.3.  Prefix Requests Behaviors

   Upon receiving the GRASP Response message that indicates the
   requesting prefix length is accepted, the requesting device may
   request the prefix using DHCPv6 PD, if both itself and the response
   device support PD.

   Upon receiving the GRASP Response message that indicates the
   requesting prefix length is not possible, but a longer prefix length
   is available, the requesting device may request the longer prefix
   using DHCPv6 PD, if both itself and the response device support PD.

   If the GRASP Response message carries a divert option, the requesting
   device may sent an unicast GRASP Discovery message to the diverted
   device to find out whether that device can provide the requested
   length prefix.

   [Author's note: undecided whether we should support prefix delegation
   using the GRASP protocol.  This would have some partial overlap with
   DHCPv6 PD.  But it seems more consistent as a solution.]




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3.4.  Prefix log

   Within the autonomic prefix management, all the prefix assignment is
   done by devices without human intervention.  It is even more
   important to record all the prefix assignment history.  However, the
   logging and reporting process is out of document scope.

4.  Autonomic Prefix Management Options

   This section defines the GRASP options that are used to support
   autonomic prefix management.

4.1.  Prefix Objective option

   The Prefix Objective option carries the PD support flag and the
   prefix length.  The format of the Prefix Objective option is
   described as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Prefix_Obj_Option        |         option-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |PD_Support_Flag| Prefix_Length |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code    Prefix_Obj_Option (TBA1).

   option-len     2, length of option content in octets.

   PD_Support_Flag Indicates whether the message sender supports
                  DHCPv6 Prefix Delegation function, 1 for support,
                  0 for no support, as client or server accordingly.
                  This flag must not be set to any other values.

   Prefix_Length  Indicate the prefix length that the message sender
                  requests or is willing to provide.

5.  Prefix Management Intent

   With in a single administrative domain, the network operator could
   manage all their devices with role set.  If so, there is possibility
   to configure/manage the prefix length for every device in a simple
   way.

   The network operator could only manage the default prefix length for
   each type of role.  A prefix management intent, which contains all
   mapping information of device roles and their default prefix lengths,



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   should be flooded in the network, through the Autonomic Control Plane
   (ACP) [I-D.ietf-anima-autonomic-control-plane].  The intent flooding
   mechanism is out of document scope.

   Upon receiving the prefix management intent, every device can decide
   its default prefix length by matching its own role.

5.1.  Example of Prefix Management Intent

   The prefix management intent in this document is used to carry
   mapping information of device roles and their default prefix lengths
   in an autonomic domain.  For example, an IPRAN operator wants to
   configure the prefix length of RNC Site Gateway (RSG) as 34, the
   prefix length of Aggregation Site Gateway (ASG) as 44, and the prefix
   length of Cell Site Gateway (CSG) as 56.  She/he may input the
   following intent into the autonomic network:

   {"autonomic_intent":
   [
      {"model_version": "1.0"},
      {"intent_type": "Network management"},
      {"autonomic_domain": "Customer_X_intranet"},
      {"intent_name": "Prefix management"},
      {"intent_version": 73},
      {"Timestamp": "20150606 00:00:00"},
      {"Lifetime": "Permanent"},
      {"signature": "XXXXXXXXXXXXXXXXXXX"},
      {"content":
      [
         {"role": [{"role_name": "RSG"},
            {"role_characteristic":
               [{"prefix_length": "34"}]}
            ]},
         {"role": [{"role_name": "ASG"},
            {"role_characteristic":
               [{"prefix_length": "44"}]}
            ]},
         {"role": [{"role_name": "CSG"},
            {"role_characteristic":
               [{"prefix_length": "56"}]}
            ]}
      ]
      }
   ]
   }






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6.  Security Considerations

   Relevant security issues are discussed in [I-D.ietf-anima-grasp].
   The security mechanism in this document is established on a Public
   Key Infrastructure (PKI) system [RFC3647] that is maintained by the
   network administrator(s).

   It is RECOMMENDED that DHCPv6 PD, if used, should be operated using
   DHCPv6 authentication or Secure DHCPv6.

7.  IANA Considerations

   This document defines one new GRASP option.  The IANA is requested to
   assign a value for this option from the GRASP Option Codes table of
   the GRASP Parameters registry as defined by [I-D.ietf-anima-grasp]
   (if approved).

   o  The Prefix Objective option (TBA1), described in Section 4.1.

8.  Acknowledgements

   Valuable comments were received from Michael Behringer and Chongfeng
   Xie.

   This document was produced using the xml2rfc tool [RFC2629].

9.  Change log [RFC Editor: Please remove]

   draft-jiang-anima-prefix-management-00: original version, 2014-10-25.

   draft-jiang-anima-prefix-management-01: add intent example and
   coauthor Zongpeng Du, 2015-05-04.

   draft-jiang-anima-prefix-management-02: update references and the
   format of the prefix management intent, 2015-10-14.

10.  References

   [I-D.ietf-anima-autonomic-control-plane]
              Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An
              Autonomic Control Plane", draft-ietf-anima-autonomic-
              control-plane-01 (work in progress), October 2015.

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-01 (work in progress), October 2015.




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   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              DOI 10.17487/RFC2629, June 1999,
              <http://www.rfc-editor.org/info/rfc2629>.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              DOI 10.17487/RFC3633, December 2003,
              <http://www.rfc-editor.org/info/rfc3633>.

   [RFC3647]  Chokhani, S., Ford, W., Sabett, R., Merrill, C., and S.
              Wu, "Internet X.509 Public Key Infrastructure Certificate
              Policy and Certification Practices Framework", RFC 3647,
              DOI 10.17487/RFC3647, November 2003,
              <http://www.rfc-editor.org/info/rfc3647>.

   [RFC7575]  Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking: Definitions and Design Goals", RFC 7575,
              DOI 10.17487/RFC7575, June 2015,
              <http://www.rfc-editor.org/info/rfc7575>.

   [RFC7576]  Jiang, S., Carpenter, B., and M. Behringer, "General Gap
              Analysis for Autonomic Networking", RFC 7576,
              DOI 10.17487/RFC7576, June 2015,
              <http://www.rfc-editor.org/info/rfc7576>.

Authors' Addresses

   Sheng Jiang (editor)
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   Email: jiangsheng@huawei.com


   Zongpeng Du
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   Email: duzongpeng@huawei.com







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   Brian Carpenter
   Department of Computer Science
   University of Auckland
   PB 92019
   Auckland  1142
   New Zealand

   Email: brian.e.carpenter@gmail.com


   Qiong Sun
   China Telecom
   No.118, Xizhimennei Street
   Beijing  100035
   P. R. China

   Email: sunqiong@ctbri.com.cn


































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