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Network Working Group                                       B. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Informational                                    B. Liu
Expires: January 1, 2018                    Huawei Technologies Co., Ltd
                                                           June 30, 2017


  Technical Objective Formats for the Autonomic Network Infrastructure
                draft-carpenter-anima-ani-objectives-02

Abstract

   This document defines the formats of several technical objectives for
   the Generic Autonomic Signaling Protocol (GRASP) used 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 January 1, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Objectives for Secure Bootstrap . . . . . . . . . . . . . . .   3
     2.1.  Additional value for GRASP message syntax . . . . . . . .   3
     2.2.  Discovered Sychronization Objective for the Join
           Registrar . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.3.  Flooded Objective for Join Proxy  . . . . . . . . . . . .   4
   3.  Objective for Autonomic Control Plane . . . . . . . . . . . .   5
   4.  Objective for Stable Connectivity of Network OAM  . . . . . .   6
   5.  Flood Frequency . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Change log [RFC Editor: Please remove] . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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 support infrastructure
   components of the Autonomic Network Infrastructure (ANI) outlined in
   the ANIMA reference model [I-D.ietf-anima-reference-model].

   Note: This draft is posted to allow systematic discussion of the
   various objectives in a consistent way.  It is possible 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 with GRASP to form the ANI:

      Secure Bootstrap.

      Autonomic Control Plane (ACP).

      Stable Connectivity of Network OAM.

   The following sections define GRASP objectives for each of these
   cases.  They are described in an informal object notation and
   formally using CBOR data definition language (CDDL)




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   [I-D.greevenbosch-appsawg-cbor-cddl].  Undefined CDDL terms are
   defined in [I-D.ietf-anima-grasp].

2.  Objectives for Secure Bootstrap

   Three ANI components are involved in the Bootstrapping Remote Secure
   Key Infrastructures (BRSKI) process described in
   [I-D.ietf-anima-bootstrapping-keyinfra]: the Join Registrar, the Join
   Proxy, and the Pledge (a node joining the domain).  In the present
   document we only consider interactions between autonomic nodes
   involved in BRSKI; non-autonomic nodes are expected to use different
   methods not involving 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.  Between the proxy and the pledge,
   therefore, only one GRASP message type is used - flooding - to avoid
   giving away any unnecessary information.  The proxy and pledge have a
   link-local connection between them.  Mutual discovery and bootstrap
   can happen without any prior provisioning of helper information by an
   external mechanism.  Instead, link-local multicast with GRASP is
   used.  This will minimize exposure to eavesdroppers and malicious
   nodes.  On the other hand, there may be multiple physical hops
   between the proxy and the registrar.  Therefore, two different GRASP
   objectives are required: one that is used over an existing secure
   network (typically the ACP) between the registrar and the proxy, and
   another that is used over an insecure link-local hop between the
   proxy and the pledge.  Furher security aspects are discussed in
   [I-D.ietf-anima-bootstrapping-keyinfra] and [I-D.ietf-anima-grasp].

2.1.  Additional value for GRASP message syntax

   This document extends the syntax of the GRASP protocol
   [I-D.ietf-anima-grasp] by adding an additional value for the
   "transport-proto" element:

     transport-proto /= IPPROTO_IP
     IPPROTO_IP = 41

   This value indicates IP-in-IP encapsulation.

2.2.  Discovered Sychronization Objective for the Join Registrar

   The Join Proxy discovers a Join Registrar by using the
   "AN_join_registrar" GRASP objective.  It must only be used when GRASP
   is running securely, typically because the Join Proxy is in a node
   that has already joined the ACP.  The value of the objective will




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   indicate the BRSKI methods supported by the registrar and the
   corresponding locators for BRSKI traffic.

   First, the pledge performs GRASP discovery.  If multiple responses
   occur, it chooses one by an implementation-defined method.  Then the
   pledge initiates GRASP synchronization to obtain the BRSKI methods
   supported by the discovered registrar.  Alternatively, if
   implemented, GRASP rapid mode could be used to combine the two
   operations.

   An example of the objective is informally:

   ["AN_join_registrar", SYNCH-FLAG, 6, [["BRSKI-TCP", [O_IPv6_LOCATOR,
   fd45:1345::6789, 6, 443]]]

   The formal CDDL definition is:

     registrar-objective = ["AN_join_registrar", objective-flags,
                            loop-count, [*[method, locator-option]]]

     objective-flags = ; as in the GRASP specification
     loop-count =      ; as in the GRASP specification
     locator-option =  ; as in the GRASP specification
     method = "BRSKI-TCP" / "BRSKI-UDP" / "BRSKI-IPIP"
                       ; name of the BRSKI method supported


   The objective-flags field is set to indicate synchronization.

   The loop-count is set to a suitable value to limit the scope of
   discovery.  A suggested default value is 6.

   The Join Proxy, upon receiving this objective, will select one or
   more of the methods for announcement to Pledges.  It will store the
   provided locator for each method for subsequent BRSKI operations.
   Note that this locator is distinct from the locator for the Join
   Registrar's ASA, which is used only for GRASP operations.

2.3.  Flooded Objective for Join Proxy

   A Join Proxy announces itself to potential pledges by use of the
   "AN_join_proxy" objective.  This is a synchronization objective
   intended only 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:




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   ["AN_join_proxy", SYNCH-FLAG, 1, "BRSKI-TCP"]

   The formal CDDL definition is:

     proxy-objective = ["AN_join_proxy", objective-flags, loop-count,
                        method]

     objective-flags = ; as in the GRASP specification
     loop-count = 1    ; limit to link-local operation
     method = "BRSKI-TCP" / "BRSKI-UDP" / "BRSKI-IPIP"

   The objective-flags field is set to indicate synchronization.

   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.  A Join Proxy that supports more than one
   method will flood multiple versions of the "AN_join_proxy" objective.

   Thus, a proxy that floods this objective with the value "BRSKI-IPIP"
   will attach a locator option such as the following to it:

   [O_IPv6_LOCATOR, ipv6-address, IPPROTO_IP, nil]

   where 'ipv6-address' is the link-local address of the proxy.
   Similarly, locators for "BRSKI-TCP" and "BRSKI-UDP" would be:

   [O_IPv6_LOCATOR, ipv6-address, IPPROTO_TCP, port]

   [O_IPv6_LOCATOR, ipv6-address, IPPROTO_UDP, port]

   By this mechanism, a proxy may announce one or more connection
   methods to all pledges, each with an associated link-local address,
   protocol number and port number.

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.  As for the Join Proxy, a
   flooding mechanism, in which each node announces itself and it
   security methods to its neighbors, is used.

   Thus each autonomic node runs an ASA that supports the corresponding
   objective.  This ASA runs permanently, as long as the node is capable




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   of being part of the ACP, in order to discover or detect new ACP
   neighbors or to remove failed neighbors.

   A node announces itself to potential ACP peers by use of the "AN_ACP"
   objective.  This is a synchronization objective 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_ACP", SYNCH-FLAG, 1, ["IKEv2","TLS"]

   The formal CDDL definition is:

     acp-objective = ["AN_ACP", objective-flags, loop-count, method]

     objective-flags = ; as in the GRASP specification
     loop-count = 1    ; limit to link-local operation
     method = text     ; name of the connection method supported

   The objective-flags field is set to indicate synchronization.

   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", "GRE-IKEv2", "TLS" and "dTLS".  A node that supports more
   than one method may flood multiple versions of the "AN_ACP"
   objective, each accompanied by its own locator.

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

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 requires a 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.




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   An example of the objective is informally:

   ["AN_NOC", NEG-FLAG, 6, [TBD]]

   The formal CDDL definition is:

     noc-objective = ["AN_NOC", objective-flags, loop-count, [TBD]]

     objective-flags = ; as in the GRASP specification
     TBD = any ; node information to be defined

   The objective-flags field is set to indicate negotiation.

   Dry run mode must not be used.

   The loop-count is set to a suitable value to limit the scope of
   discovery.  A suggested default value is 6.

   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 the value TBD.  If
   successfully received, the NOC ASA must reply 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.  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).

6.  Security Considerations

   General security issues for GRASP are covered in
   [I-D.ietf-anima-grasp].  The objectives "AN_join_proxy" and "AN_ACP"
   must be implemented using a DULL instance of GRASP.  Specific issues
   not mentioned above are discussed in the referenced drafts for each
   use case.




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7.  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_join_registrar
         AN_join_proxy
         AN_ACP
         AN_NOC

8.  Acknowledgements

   Valuable comments were made by Toerless Eckert, Max Pritikin, and
   Michael Richardson.

9.  References

9.1.  Normative References

   [I-D.greevenbosch-appsawg-cbor-cddl]
              Birkholz, H., Vigano, C., and C. Bormann, "CBOR data
              definition language (CDDL): a notational convention to
              express CBOR data structures", draft-greevenbosch-appsawg-
              cbor-cddl-10 (work in progress), March 2017.

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-13 (work in progress), June 2017.

9.2.  Informative References

   [I-D.ietf-anima-autonomic-control-plane]
              Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
              Control Plane", draft-ietf-anima-autonomic-control-
              plane-06 (work in progress), March 2017.

   [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-06 (work in progress), May 2017.

   [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-03 (work in progress), March 2017.



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   [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-02 (work in progress), February
              2017.

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

   draft-carpenter-anima-ani-objectives-02, 2017-06-30:

   Limited scope to initial ANI components

   Updated details and removed alternatives

   draft-carpenter-anima-ani-objectives-01, 2017-02-13:

   Added prefix management case

   Updated objectives for BRSKI

   Editorial corrections

   draft-carpenter-anima-ani-objectives-00, 2016-11-15:

   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
   Q22, Huawei Campus
   No.156 Beiqing Road
   Hai-Dian District, Beijing  100095
   P.R. China

   Email: leo.liubing@huawei.com





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