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Network Working Group                                       B. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Informational                                    B. Liu
Expires: May 22, 2017                       Huawei Technologies Co., Ltd
                                                       November 18, 2016


     Technical Objectives for the Autonomic Network Infrastructure
                draft-carpenter-anima-ani-objectives-00

Abstract

   This document defines several technical objectives for the Generic
   Autonomic Signaling Protocol (GRASP) for use by components of the
   Autonomic Networking Infrastructure outlined in the ANIMA reference
   model.

Status of This Memo

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   This Internet-Draft will expire on May 22, 2017.

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   Copyright (c) 2016 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Objectives for Secure Bootstrap . . . . . . . . . . . . . . .   3
     2.1.  Flooding Alternative for Proxy  . . . . . . . . . . . . .   4
     2.2.  Negotiation Alternative for Proxy . . . . . . . . . . . .   4
   3.  Objective for Autonomic Control Plane . . . . . . . . . . . .   5
     3.1.  Flooding Alternative  . . . . . . . . . . . . . . . . . .   5
     3.2.  Negotiation Alternative . . . . . . . . . . . . . . . . .   6
   4.  Objective for Stable Connectivity of Network OAM  . . . . . .   7
   5.  Objectives for Intent Distribution  . . . . . . . . . . . . .   7
   6.  Objective for Prefix Management . . . . . . . . . . . . . . .   8
   7.  Flood Frequency . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     11.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Appendix A.  Change log [RFC Editor: Please remove] . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   This document defines several technical objectives for use with for
   the Generic Autonomic Signaling Protocol (GRASP)
   [I-D.ietf-anima-grasp].  They are intended for use by corresponding
   Autonomic Service Agents (ASAs) that realise infrastructure
   components of the Autonomic Network Infrastructure (ANI) outlined in
   the ANIMA reference model [I-D.ietf-anima-reference-model].  Also
   other early use cases are in scope.

   Note: This draft is posted to allow systematic discussion of the
   various objectives in a consistent way.  It is quite probable that
   rather than this being published as an RFC, the various objective
   definitions will be incorporated directly in the relevant
   specifications.

   The reference model identifies several infrastructure components that
   will fit together to form the ANI, and early use cases for ANIMA are
   also considered:

      Secure Bootstrap.

      Autonomic Control Plane (ACP).

      Stable Connectivity of Network OAM.




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      Intent Distribution.

      Prefix Management

   The following sections define GRASP objectives for each of these
   cases.  They are described an informal object notation and formally
   using CBOR data definition language (CDDL)
   [I-D.greevenbosch-appsawg-cbor-cddl].  Undefined CDDL terms are
   defined in [I-D.ietf-anima-grasp].

2.  Objectives for Secure Bootstrap

   Three components are involved in the Bootstrapping Remote Secure Key
   Infrastructures (BRSKI) process described in
   [I-D.ietf-anima-bootstrapping-keyinfra]: the Registrar, the Join
   Assistant (or Proxy), and the Joining Node (or Pledge).  The proxy
   and the pledge are attached to the same link-layer and use link-local
   communications only, to minimize exposure to eavesdroppers and
   malicious nodes.  There may be multiple hops between the proxy and
   the registrar.  Therefore, two different GRASP objectives are
   required: one that is used over an existing secure network between
   the registrar and the proxy, and another that is used over an
   insecure link-local hop between the proxy and the pledge.  The
   security aspects and the corresponding limited instances of GRASP are
   discussed in [I-D.ietf-anima-bootstrapping-keyinfra] and
   [I-D.ietf-anima-grasp].

   Note that since secure bootstrap takes place, by definition, on an
   incompletely secure network, the use of any protocol needs to be kept
   as simple and limited as possible.  Therefore, only one GRASP message
   type is used - flooding - to avoid giving away any unnecessary
   information by any node involved.

   A registrar announces itself to potential proxies by use of the
   "AN_registrar" objective.  This is a synchronization objective
   primarily intended to be flooded throughout the network using the
   GRASP Flood Synchronization (M_FLOOD) message.  In accordance with
   the design of the Flood message, a locator consisting of a specific
   IP address, IP protocol number and port number will be distributed
   with the flooded objective.  An example of the objective is
   informally:

   ["AN_registrar", F_SYNCH, loop_count, [7, "BRSKI-TLS"]]

   The formal CDDL definition is

   registrar-objective = ["AN_registrar", F_SYNCH, loop-count, [radius,
   method]]



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   radius = uint ; loop-count at the source node
   method = text ; name of the BRSKI method supported

   The 'radius' parameter allows a proxy that receives this message to
   determine its distance in hops from the registrar, by subtracting the
   received 'loop-count' from 'radius'.

   The 'method' parameter indicates the specific BRSKI method available
   at the given locator.  The initial possible values are "BRSKI-TLS"
   and "BRSKI-COAP".  A registrar that supports more than one method
   will flood multiple versions of the "AN_registrar" objective.

2.1.  Flooding Alternative for Proxy

   A proxy announces itself to potential pledges by use of the
   "AN_proxy" objective.  This is a synchronization objective primarily
   intended to be flooded on a single link using the GRASP Flood
   Synchronization (M_FLOOD) message.  In accordance with the design of
   the Flood message, a locator consisting of a specific link-local IP
   address, IP protocol number and port number will be distributed with
   the flooded objective.  An example of the objective is informally:

   ["AN_proxy", F_SYNCH, 1, "BRSKI-TLS"]

   The formal CDDL definition is

   proxy-objective = ["AN_proxy", F_SYNCH, 1, method]
   method = text ; name of the BRSKI method supported

   The loop-count is fixed at 1 since this is a link-local operation.

   The 'method' parameter indicates the specific BRSKI method available
   at the given locator.  The initial possible values are "BRSKI-TLS"
   and "BRSKI-COAP".  A proxy that supports more than one method will
   flood multiple versions of the "AN_proxy" objective.

2.2.  Negotiation Alternative for Proxy

   This alternative to "AN_proxy" uses additional features of GRASP.  It
   requires additional complexity in the pledge, and requires the pledge
   to announce its existence to any on-link eavesdroppers via a
   Discovery message.  It is therefore not recommended on security
   grounds, but is defined here for completeness.

   A pledge discovers a local proxy and negotiates a BRSKI method with
   it by use of the "AN_join" objective.  First, the pledge performs
   GRASP discovery, with the loop-count set to 1 and limited to link-
   local addresses.  If multiple responses occur, it chooses one by an



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   implementation-defined method.  Then the pledge initiates GRASP
   negotiation to choose a mutually acceptable BRSKI method.

   An example of the objective is informally:

   ["AN_join", F_NEG, 6, ["BRSKI-COAP","BRSKI-TLS"]]

   The formal CDDL definition is

   join-objective = ["AN_join", F_NEG, loop-count, [*method]]
   method = text ; name of the BRSKI method supported

   The parties will negotiate until one side proposes a single BRSKI
   method and the other side accepts.  In the simplest case of immediate
   acceptance, there will only be two messages (Request Negotiate and
   End Negotiate).  The locator (IP address, IP protocol number, port
   number) used for the negotiation will be available for the subsequent
   BRSKI operations, if required.

   Note that in the Discovery message, the loop count will be set to 1
   to limit discovery to the local link.  In the negotiation stage, the
   loop count will serve its normal purpose (limiting the negotiation to
   6 steps in the above example).

3.  Objective for Autonomic Control Plane

   The Autonomic Control Plane (ACP)
   [I-D.ietf-anima-autonomic-control-plane] constructs itself without
   outside intervention.  To achieve this, each node needs to identify
   its link-local neighbors on all interfaces, and agree on a secure
   connection method with each of them.  There are at least two possible
   approaches for this: a flooding mechanism, in which each node
   announces itself and it security methods to its neighbors, or a
   discovery and negotiation mechanism, in which each node actively
   discovers its neighbors.  For the moment this draft describes both
   methods.

   For either method, each node runs an ASA that supports the
   corresponding objective.  This ASA runs permanently, in order to
   discover or detect new ACP neighbors or to remove failed neighbors.

3.1.  Flooding Alternative

   A node announces itself to potential ACP peers by use of the "AN_ACP"
   objective.  This is a synchronization objective primarily intended to
   be flooded on a single link using the GRASP Flood Synchronization
   (M_FLOOD) message.  In accordance with the design of the Flood
   message, a locator consisting of a specific link-local IP address, IP



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   protocol number and port number will be distributed with the flooded
   objective.  An example of the objective is informally:

   ["AN_ACP", F_SYNCH, 1, "IKEv2"]

   The formal CDDL definition is

   acp-objective = ["AN_ACP", F_SYNCH, 1, method]
   method = text ; name of the connection method supported

   The loop-count is fixed at 1 since this is a link-local operation.

   The 'method' parameter indicates the specific connection method
   available at the given locator.  The initial possible values are
   "IKEv2" and "TLS".  A node that supports more than one method will
   flood multiple versions of the "AN_ACP" objective.

   Note that a node serving both as an ACP node and BRSKI proxy may
   choose to distribute the "AN_ACP" objectives and "AN_proxy"
   objectives in the same message, since GRASP allows multiple
   objectives in one Flood message.

3.2.  Negotiation Alternative

   Each node discovers its neighbours and negotiates a connection method
   with each one by use of the "AN_ACP" objective.  First, the node
   performs GRASP discovery, with the loop-count set to 1 and limited to
   link-local addresses.  It records each response that it receives
   within the chosen discovery timeout.  Then the pledge initiates GRASP
   negotiation with each newly discovered peer in turn to choose a
   mutually acceptable connection method.

   An example of the objective is informally:

   ["AN_ACP", F_NEG, 6, ["IKEv2","TLS"]]

   The formal CDDL definition is

   acp-objective = ["AN_ACP", F_NEG, loop-count, [*method]]
   method = text ; name of the connection method supported

   The parties will negotiate until one side proposes a single
   connection method and the other side accepts.  In the simplest case
   of immediate acceptance, there will only be two messages (Request
   Negotiate and End Negotiate).  The locator (IP address, IP protocol
   number, port number) used for the negotiation will be available for
   the subsequent operations, if required.




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   Note that in the Discovery message, the loop count will be set to 1
   to limit discovery to the local link.  In the negotiation stage, the
   loop count will serve its normal purpose (limiting the negotiation to
   6 steps in the above example).

4.  Objective for Stable Connectivity of Network OAM

   For OAM purposes [I-D.ietf-anima-stable-connectivity], a special-
   purpose ASA, which we will call the NOC ASA, mediates connectivity
   between NOC systems performing OAM operations and autonomic nodes
   that can be reached securely via the ACP.  This is requires s
   discovery operation, which could be handled in two ways: the NOC ASA
   discovers all nodes, or each node discovers the NOC ASA.  The latter
   seems much more practical.  However, the NOC will need to know
   something about each target node, so the corresponding objective is
   defined as a negotiation objective to allow for this.

   An example of the objective is informally:

   ["AN_NOC", F_NEG, 6, [TBD]]

   The formal CDDL definition is

   noc-objective = ["AN_NOC", F_NEG, loop-count, [TBD]]
   TBD = any ; node information to be defined

   When a node joins the ACP, one of its initial actions must be to
   perform GRASP discovery for "AN_NOC" and then to send a Request
   Negotiate message to the NOC ASA supplying TBD.  If successfully
   received, the NOC ASA must rely with an End Negotiate message.  From
   then on, any OAM communication between the NOC and the node in
   question will proceed over the ACP using the information TBD.

5.  Objectives for Intent Distribution

   The format and semantics of Intent are not yet defined, although some
   aspects are discussed in [I-D.du-anima-an-intent].  Here we assume
   that Intent is supplied to the whole network as a single file and
   that the file is obtained by each node that needs it via a specific
   Uniform Resource Identifier, typically a URL.  We also assume that
   Intent, within a given autonomic domain, is qualified by a
   monotonically increasing version number, so that nodes can determine
   if their current copy of Intent is out of date.  (A timestamp is not
   used for this purpose, since it would depend on all nodes having
   consistent clocks.)

   Thus, a source of Intent announces itself to all nodes by use of the
   "AN_intent" objective.  This is a synchronization objective primarily



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   intended to be flooded using the GRASP Flood Synchronization
   (M_FLOOD) message.  An example of the objective is informally:

   ["AN_intent", F_SYNCH, loop_count, [12345, "https://noc.example.com/
   Intent/"]

   The formal CDDL definition is

   intent-objective = ["AN_Intent", F_SYNCH, loop-count, [version-
   number,uri]]
   version-number = uint
   uri = text ; URI conforming to RFC 3986

   A node that needs to obtain or update Intent will use the latest
   received version of this objective to check if the version number has
   increased, and will use the given URI to obtain the current Intent if
   necessary.

6.  Objective for Prefix Management

   TBD

7.  Flood Frequency

   Any ASA that floods one of the above objectives should do so at a
   carefully chosen frequency.  Recipient nodes may be starting up,
   reconnecting, or waking up from sleep, so floods need to be refreshed
   periodically.  On the other hand, excessive flooding will consume
   bandwidth, CPU and battery capacity throughout the network, and might
   even resemble a DoS attack.  A general guideline is to flood an
   objective once immediately after its value is initialised or changed,
   and then repeat the flood at intervals of at least 30 seconds.
   Additionally, the flooding interval should be slightly jittered to
   avoid synchronicity with other floods.  Finally, the value of a
   flooded objective should change as rarely as possible (on a timescale
   of at least minutes, not seconds).

8.  Security Considerations

   General security issues for GRASP are covered in
   [I-D.ietf-anima-grasp].  Specific issues that are not mentioned above
   are discussed in the referenced drafts for BRSKI, ACP, stable
   connectivity and Intent.








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9.  IANA Considerations

   IANA is requested to add the following entries to the GRASP Objective
   Names Table registry created by [I-D.ietf-anima-grasp]:
   AN_registrar
   AN_proxy
   AN_ACP
   AN_NOC
   AN_intent

10.  Acknowledgements

   TBD.

11.  References

11.1.  Normative References

   [I-D.greevenbosch-appsawg-cbor-cddl]
              Vigano, C. and H. Birkholz, "CBOR data definition language
              (CDDL): a notational convention to express CBOR data
              structures", draft-greevenbosch-appsawg-cbor-cddl-09 (work
              in progress), September 2016.

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-08 (work in progress), October 2016.

11.2.  Informative References

   [I-D.du-anima-an-intent]
              Du, Z., Jiang, S., Nobre, J., Ciavaglia, L., and M.
              Behringer, "ANIMA Intent Policy and Format", draft-du-
              anima-an-intent-04 (work in progress), July 2016.

   [I-D.ietf-anima-autonomic-control-plane]
              Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
              Control Plane", draft-ietf-anima-autonomic-control-
              plane-04 (work in progress), October 2016.

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
              S., and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
              keyinfra-04 (work in progress), October 2016.





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   [I-D.ietf-anima-reference-model]
              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              Pierre, P., Liu, B., Nobre, J., and J. Strassner, "A
              Reference Model for Autonomic Networking", draft-ietf-
              anima-reference-model-02 (work in progress), July 2016.

   [I-D.ietf-anima-stable-connectivity]
              Eckert, T. and M. Behringer, "Using Autonomic Control
              Plane for Stable Connectivity of Network OAM", draft-ietf-
              anima-stable-connectivity-01 (work in progress), July
              2016.

Appendix A.  Change log [RFC Editor: Please remove]

   draft-carpenter-anima-ani-objectives-00, 2018-11-15:

   Initial version

Authors' Addresses

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

   Email: brian.e.carpenter@gmail.com


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

   Email: leo.liubing@huawei.com













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