[Docs] [txt|pdf|xml] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 draft-ietf-anima-grasp

Network Working Group                                       B. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Standards Track                                  B. Liu
Expires: July 10, 2015                      Huawei Technologies Co., Ltd
                                                         January 6, 2015


 A Generic Discovery and Negotiation Protocol for Autonomic Networking
                 draft-carpenter-anima-gdn-protocol-01

Abstract

   This document establishes requirements for a protocol that enables
   intelligent devices to dynamically discover peer devices, to
   synchronize state with them, and to negotiate mutual configurations
   with them.  The document then defines a general protocol for
   discovery, synchronization and negotiation, while the technical
   objectives for specific scenarios are to be described in separate
   documents.  An Appendix briefly discusses existing protocols as
   possible alternatives.

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
   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 July 10, 2015.

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



Carpenter & Liu           Expires July 10, 2015                 [Page 1]


Internet-Draft                GDN Protocol                  January 2015


   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.  Requirement Analysis of Discovery, Synchronization and
       Negotiation . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements for Discovery  . . . . . . . . . . . . . . .   4
     2.2.  Requirements for Synchronization and Negotiation
           Capability  . . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Specific Technical Requirements . . . . . . . . . . . . .   6
   3.  GDNP Protocol Overview  . . . . . . . . . . . . . . . . . . .   7
     3.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   7
     3.2.  High-Level Design Choices . . . . . . . . . . . . . . . .   9
     3.3.  GDNP Protocol Basic Properties and Mechanisms . . . . . .  12
       3.3.1.  Discovery Mechanism and Procedures  . . . . . . . . .  12
       3.3.2.  Certificate-based Security Mechanism  . . . . . . . .  14
       3.3.3.  Negotiation Procedures  . . . . . . . . . . . . . . .  17
       3.3.4.  Synchronization Procedure . . . . . . . . . . . . . .  18
     3.4.  GDNP Constants  . . . . . . . . . . . . . . . . . . . . .  19
     3.5.  Device Identifier and Certificate Tag . . . . . . . . . .  19
     3.6.  Session Identifier (Session ID) . . . . . . . . . . . . .  20
     3.7.  GDNP Messages . . . . . . . . . . . . . . . . . . . . . .  20
       3.7.1.  GDNP Message Format . . . . . . . . . . . . . . . . .  20
       3.7.2.  Discovery Message . . . . . . . . . . . . . . . . . .  21
       3.7.3.  Response Message  . . . . . . . . . . . . . . . . . .  21
       3.7.4.  Request Message . . . . . . . . . . . . . . . . . . .  22
       3.7.5.  Negotiation Message . . . . . . . . . . . . . . . . .  22
       3.7.6.  Negotiation-ending Message  . . . . . . . . . . . . .  22
       3.7.7.  Confirm-waiting Message . . . . . . . . . . . . . . .  22
     3.8.  GDNP General Options  . . . . . . . . . . . . . . . . . .  23
       3.8.1.  Format of GDNP Options  . . . . . . . . . . . . . . .  23
       3.8.2.  Divert Option . . . . . . . . . . . . . . . . . . . .  23
       3.8.3.  Accept Option . . . . . . . . . . . . . . . . . . . .  24
       3.8.4.  Decline Option  . . . . . . . . . . . . . . . . . . .  24
       3.8.5.  Waiting Time Option . . . . . . . . . . . . . . . . .  25
       3.8.6.  Certificate Option  . . . . . . . . . . . . . . . . .  26
       3.8.7.  Signature Option  . . . . . . . . . . . . . . . . . .  26
       3.8.8.  Locator Options . . . . . . . . . . . . . . . . . . .  27
     3.9.  Discovery Objective Option  . . . . . . . . . . . . . . .  29
     3.10. Negotiation and Synchronization Objective Options and
           Considerations  . . . . . . . . . . . . . . . . . . . . .  29
       3.10.1.  Organizing of GDNP Options . . . . . . . . . . . . .  30
       3.10.2.  Vendor Specific Options  . . . . . . . . . . . . . .  30
       3.10.3.  Experimental Options . . . . . . . . . . . . . . . .  31



Carpenter & Liu           Expires July 10, 2015                 [Page 2]


Internet-Draft                GDN Protocol                  January 2015


     3.11. Items for Future Work . . . . . . . . . . . . . . . . . .  31
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  33
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  36
   7.  Change log [RFC Editor: Please remove]  . . . . . . . . . . .  36
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  37
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  37
   Appendix A.  Capability Analysis of Current Protocols . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   The success of the Internet has made IP-based networks bigger and
   more complicated.  Large-scale ISP and enterprise networks have
   become more and more problematic for human based management.  Also,
   operational costs are growing quickly.  Consequently, there are
   increased requirements for autonomic behavior in the networks.
   General aspects of autonomic networks are discussed in
   [I-D.irtf-nmrg-autonomic-network-definitions] and
   [I-D.irtf-nmrg-an-gap-analysis].  In order to fulfil autonomy,
   devices that embody autonomic service agents need to be able to
   discover each other, to synchronize state with each other, and to
   negotiate parameters and resources directly with each other.  There
   is no restriction on the type of parameters and resources concerned,
   which include very basic information needed for addressing and
   routing, as well as anything else that might be configured in a
   conventional network.

   Following this Introduction, Section 2 describes the requirements for
   network device discovery, synchronization and negotiation.
   Negotiation is an iterative process, requiring multiple message
   exchanges forming a closed loop between the negotiating devices.
   State synchronization, when needed, can be effected as a special case
   of negotiation.  Section 3.2 describes a behavior model for a
   protocol intended to support discovery, synchronization and
   negotiation.  The design of Generic Discovery and Negotiation
   Protocol (GDNP) in Section 3 of this document is mainly based on this
   behavior model.  The relevant capabilities of various existing
   protocols are reviewed in Appendix A.

   The proposed discovery mechanism is oriented towards synchronization
   and negotiation objectives.  It is based on a neighbor discovery
   process, but also supports diversion to off-link peers.  Although
   many negotiations will occur between horizontally distributed peers,
   many target scenarios are hierarchical networks, which is the
   predominant structure of current large-scale networks.  However, when
   a device starts up with no pre-configuration, it has no knowledge of



Carpenter & Liu           Expires July 10, 2015                 [Page 3]


Internet-Draft                GDN Protocol                  January 2015


   a hierarchical superior.  The protocol itself is capable of being
   used in a small and/or flat network structure such as a small office
   or home network as well as a professionally managed network.
   Therefore, the discovery mechanism needs to be able to bootstrap
   itself without making any prior assumptions about network structure.

   Because GDNP can be used to perform a decision process among
   distributed devices or between networks, it adopts a tight
   certificate-based security mechanism, which needs a Public Key
   Infrastructure (PKI) [RFC5280] system.  The PKI may be managed by an
   operator or be autonomic.

   It is understood that in realistic deployments, not all devices will
   support GDNP.  Such mixed scenarios are not discussed in this
   specification.

2.  Requirement Analysis of Discovery, Synchronization and Negotiation

   This section discusses the requirements for discovery, negotiation
   and synchronization capabilities.

2.1.  Requirements for Discovery

   In an autonomic network we must assume that when a device starts up
   it has no information about any peer devices.  In some cases, when a
   new user session starts up, the device concerned may again lack
   information about relevant peer devices.  It might be necessary to
   set up resources on multiple other devices, coordinated and matched
   to each other so that there is no wasted resource.  Security settings
   might also need updating to allow for the new device or user.
   Therefore a basic requirement is that there must be a mechanism by
   which a device can separately discover peer devices for each of the
   technical objectives that it needs to manage or configure.  Some
   objectives may only be significant on the local link, but others may
   be significant across the routed network and require off-link
   operations.  Thus, the relevant peer devices might be immediate
   neighbors on the same layer 2 link or they might be more distant and
   only accessible via layer 3.  The mechanism must therefore support
   both on-link discovery and off-link discovery of peers that support
   specific technical objectives.

   The relevant peer devices may be different for different technical
   objectives.  Therefore discovery needs to be repeated as often as
   necessary to find peers capable of acting as counterparts for each
   objective that a discovery initiator needs to handle.  In many
   scenarios, the discovery process may be followed by a synchronization
   or negotiation process.  Therefore, a discovery objective may be




Carpenter & Liu           Expires July 10, 2015                 [Page 4]


Internet-Draft                GDN Protocol                  January 2015


   associated with one or more synchronization or negotiation
   objectives.

   When a device first starts up, it has no knowledge of the network
   structure.  Therefore the discovery process must be able to support
   any network scenario, assuming only that the device concerned is
   bootstrapped from factory condition.

   In some networks, as mentioned above, there will be some hierarchical
   structure, at least for certain synchronization or negotiation
   objectives.  A special case of discovery is that each device must be
   able to discover its hierarchical superior for each such objective
   that it is capable of handling.  This is part of the more general
   requirement to discover off-link devices.

   During initialisation, a device must be able to discover the
   appropriate trust anchor, i.e. the appropriate PKI authority.
   Logically, this is just a specific case of discovery.  However, it
   might be a special case requiring its own solution.  In any case, the
   trust anchor must be discovered before the security environment is
   completely established.  This question requires further study and is
   the subject of [I-D.pritikin-anima-bootstrapping-keyinfra].  In
   addition, depending on the type of network involved, discovery of
   other central functions might be needed, such as the Network
   Operations Center (NOC) [I-D.eckert-anima-stable-connectivity].

2.2.  Requirements for Synchronization and Negotiation Capability

   We start by considering routing protocols, the closest approximation
   to autonomic networking in widespread use.  Routing protocols use a
   largely autonomic model based on distributed devices that communicate
   iteratively with each other.  However, routing is mainly based on
   one-way information synchronization (in either direction), rather
   than on bi-directional negotiation.  The focus is reachability, so
   current routing protocols only consider simple link status, i.e., up
   or down.  More information, such as latency, congestion, capacity,
   and particularly unused capacity, would be helpful to get better path
   selection and utilization rate.  Also, autonomic networks need to be
   able to manage many more dimensions, such as security settings, power
   saving, load balancing, etc.  A basic requirement for the protocol is
   therefore the ability to represent, discover, synchronize and
   negotiate almost any kind of network parameter.

   Human intervention in complex situations is costly and error-prone.
   Therefore, synchronization or negotiation of parameters without human
   intervention is desirable whenever the coordination of multiple
   devices can improve overall network performance.  It follows that a




Carpenter & Liu           Expires July 10, 2015                 [Page 5]


Internet-Draft                GDN Protocol                  January 2015


   requirement for the protocol is to be capable of being installed in
   any device that would otherwise need human intervention.

   Human intervention in large networks is often replaced by use of a
   top-down network management system (NMS).  It therefore follows that
   a requirement for the protocol is to be capable of being installed in
   any device that would otherwise be managed by an NMS, and that it can
   co-exist with an NMS.

   Since the goal is to minimize human intervention, it is necessary
   that the network can in effect "think ahead" before changing its
   parameters.  In other words there must be a possibility of
   forecasting the effect of a change.  Stated differently, the protocol
   must be capable of supporting a "dry run" of a changed configuration
   before actually installing the change.

   Status information and traffic metrics need to be shared between
   nodes for dynamic adjustment of resources and for monitoring
   purposes.  While this might be achieved by existing protocols when
   they are available, the new protocol needs to be able to support
   parameter exchange, including mutual synchronization, even when no
   negotiation as such is required.

   Recovery from faults and identification of faulty devices should be
   as automatic as possible.  The protocol needs to be capable of
   detecting unexpected events such a negotiation counterpart failing,
   so that all devices concerned can initiate a recovery process.

   The protocol needs to be able to deal with a wide variety of
   technical objectives, covering any type of network parameter.
   Therefore the protocol will need either an explicit information model
   describing its messages, or at least a flexible and extensible
   message format.  One design consideration is whether to adopt an
   existing information model or to design a new one.  Another
   consideration is whether to be able to carry some or all of the
   message formats used by existing configuration protocols.

2.3.  Specific Technical Requirements

   To be a generic platform, the protocol should be IP version
   independent.  In other words, it should be able to run over IPv6 and
   IPv4.  Its messages and general options should be neutral with
   respect to the IP version.  However, some functions, such as
   multicasting or broadcasting on a link, might need to be IP version
   dependent.  In case of doubt, IPv6 should be preferred.

   The protocol must be able to access off-link counterparts, i.e., must
   not be restricted to link-local operation.



Carpenter & Liu           Expires July 10, 2015                 [Page 6]


Internet-Draft                GDN Protocol                  January 2015


   The negotiation process must be guaranteed to terminate (with success
   or failure) and if necessary it must contain tie-breaking rules for
   each technical objective that requires them.

   Dependencies: In order to decide a configuration on a given device,
   the device may need information from neighbors.  This can be
   established through the negotiation procedure, or through
   synchronization if that is sufficient.  However, a given item in a
   neighbor may depend on other information from its own neighbors,
   which may need another negotiation or synchronization procedure to
   obtain or decide.  Therefore, there are potential dependencies among
   negotiation or synchronization procedures.  Thus, there need to be
   clear boundaries and convergence mechanisms for these negotiation
   dependencies.  Also some mechanisms are needed to avoid loop
   dependencies.

   Policy constraints: There must be provision for general policy intent
   rules to be applied by all devices in the network (e.g., security
   rules, prefix length, resource sharing rules).  However, policy
   intent distribution might not use the negotiation protocol itself.

   Management monitoring, alerts and intervention: Devices should be
   able to report to a monitoring system.  Some events must be able to
   generate operator alerts and some provision for emergency
   intervention must be possible (e.g.  to freeze synchronization or
   negotiation in a mis-behaving device).  These features may not use
   the negotiation protocol itself.

   The protocol needs to be fully secure against forged messages and
   man-in-the middle attacks, and as secure as reasonably possible
   against denial of service attacks.  It needs to be capable of
   encryption in order to resist unwanted monitoring, although this
   capability may not be required in all deployments.

3.  GDNP Protocol Overview

3.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119] when they appear in ALL CAPS.  When these words are not in
   ALL CAPS (such as "should" or "Should"), they have their usual
   English meanings, and are not to be interpreted as [RFC2119] key
   words.

   The following terms are used throughout this document:




Carpenter & Liu           Expires July 10, 2015                 [Page 7]


Internet-Draft                GDN Protocol                  January 2015


   o  Discovery: a process by which a device discovers peer devices
      according to a specific discovery objective.  The discovery
      results may be different according to the different discovery
      objectives.  The discovered peer devices may later be used as
      negotiation counterparts or as sources of synchronization data.

   o  Negotiation: a process by which two (or more) devices interact
      iteratively to agree on parameter settings that best satisfy the
      objectives of one or more devices.

   o  State Synchronization: a process by which two (or more) devices
      interact to agree on the current state of parameter values stored
      in each device.  This is a special case of negotiation in which
      information is exchanged but the devices do not request their
      peers to change parameter settings.  All other definitions apply
      to both negotiation and synchronization.

   o  Discovery Objective: a specific network functionality, network
      element role or type of autonomic service agent (TBD) which the
      discovery initiator intends to discover.  One device may support
      multiple discovery objectives.  A discovery objective may be in
      one-to-one correspondence with a synchronization objective or a
      negotiation objective, or it may correspond to a certain group of
      such objectives.

   o  Discovery Initiator: a device that spontaneously starts discovery
      by sending a discovery message referring to a specific discovery
      objective.

   o  Discovery Responder: a peer device which responds to the discovery
      objective initiated by the discovery initiator.

   o  Synchronization Objective: specific technical content, which needs
      to be synchronized among a number of devices.  It is naturally
      based on a specific service or function or action.  It could be a
      logical, numeric, or string value or a more complex data
      structure.

   o  Synchronization Initiator: a device that spontaneously starts
      synchronization by sending a request message referring to a
      specific synchronization objective.

   o  Synchronization Responder: a peer device which responds with the
      value of a synchronization objective.

   o  Negotiation Objective: specific technical content, which needs to
      be decided in coordination with another network device.  It is
      naturally based on a specific service or function or action.  It



Carpenter & Liu           Expires July 10, 2015                 [Page 8]


Internet-Draft                GDN Protocol                  January 2015


      could be a logical, numeric, or string value or a more complex
      data structure.

   o  Negotiation Initiator: a device that spontaneously starts
      negotiation by sending a request message referring to a specific
      negotiation objective.

   o  Negotiation Counterpart: a peer device with which the Negotiation
      Initiator negotiates a specific negotiation objective.

   o  Device Identifier: a public key, which identifies the device in
      GDNP messages.  It is assumed that its associated private key is
      maintained in the device only.

   o  Device Certificate: A certificate for a single device, also the
      identifier of the device, further described in Section 3.5.

   o  Device Certificate Tag: a tag, which is bound to the device
      identifier.  It is used to present a Device Certificate in short
      form.

3.2.  High-Level Design Choices

   This section describes a behavior model and some considerations for
   designing a generic discovery, synchronization and negotiation
   protocol, which can act as a platform for different technical
   objectives.

   NOTE: This protocol is described here in a stand-alone fashion as a
   proof of concept.  An elementary version has been prototyped by
   Huawei and the Beijing University of Posts and Telecommunications.
   However, this is not yet a definitive proposal for IETF adoption.  In
   particular, adaptation and extension of one of the protocols
   discussed in Appendix A might be an option.  Also, the security model
   outlined below would in practice be part of a general security
   mechanism in an autonomic control plane
   [I-D.behringer-anima-autonomic-control-plane].  This whole
   specification is subject to change as a result.

   o  A generic platform

      The protocol is designed as a generic platform, which is
      independent from the synchronization or negotiation contents.  It
      takes care of the general intercommunication between counterparts.
      The technical contents will vary according to the various
      synchronization or negotiation objectives and the different pairs
      of counterparts.




Carpenter & Liu           Expires July 10, 2015                 [Page 9]


Internet-Draft                GDN Protocol                  January 2015


   o  Security infrastructure and trust relationship

      Because this negotiation protocol may directly cause changes to
      device configurations and bring significant impacts to a running
      network, this protocol is based on a restrictive security
      infrastructure, allowing it to be trusted and monitored so that
      every device in this negotiation system behaves well and remains
      well protected.

      On the other hand, a limited negotiation model might be deployed
      based on a limited trust relationship.  For example, between two
      administrative domains, devices might also exchange limited
      information and negotiate some particular configurations based on
      a limited conventional or contractual trust relationship.


   o  Discovery, synchronization and negotiation designed together

      The discovery method and the synchronization and negotiation
      methods are designed in the same way and can be combined when this
      is useful.  These processes can also be performed independently
      when appropriate.


   o  A uniform pattern for technical contents

      The synchronization and negotiation contents are defined according
      to a uniform pattern.  They could be carried either in TLV (Type,
      Length and Value) format or in payloads described by a flexible
      language.  The initial protocol design uses the TLV approach.  The
      format is extensible for unknown future requirements.


   o  A conservative model for synchronization

      Synchronization across a number of nodes is not a new problem and
      the Trickle model that is already known to be effective and
      efficient is adopted.


   o  A simple initiator/responder model for negotiation

      Multi-party negotiations are too complicated to be modeled and
      there might be too many dependencies among the parties to converge
      efficiently.  A simple initiator/responder model is more feasible
      and can complete multiple-party negotiations by indirect steps.





Carpenter & Liu           Expires July 10, 2015                [Page 10]


Internet-Draft                GDN Protocol                  January 2015


   o  Organizing of synchronization or negotiation content

      Naturally, the technical content will be organized according to
      the relevant function or service.  The content from different
      functions or services is kept independent from each other.  They
      are not combined into a single option or single session because
      these contents may be negotiated or synchronized with different
      counterparts or may be different in response time.


   o  Self aware network device

      Every network device will be pre-loaded with various functions and
      be aware of its own capabilities, typically decided by the
      hardware, firmware or pre-installed software.  Its exact role may
      depend on the surrounding network behaviors, which may include
      forwarding behaviors, aggregation properties, topology location,
      bandwidth, tunnel or translation properties, etc.  The surrounding
      topology will depend on the network planning.  Following an
      initial discovery phase, the device properties and those of its
      neighbors are the foundation of the synchronization or negotiation
      behavior of a specific device.  A device has no pre-configuration
      for the particular network in which it is installed.


   o  Requests and responses in negotiation procedures

      The initiator can negotiate with its relevant negotiation
      counterpart devices, which may be different according to the
      specific negotiation objective.  It can request relevant
      information from the negotiation counterpart so that it can decide
      its local configuration to give the most coordinated performance.
      It can request the negotiation counterpart to make a matching
      configuration in order to set up a successful communication with
      it.  It can request certain simulation or forecast results by
      sending some dry run conditions.

      Beyond the traditional yes/no answer, the responder can reply with
      a suggested alternative if its answer is 'no'.  This would start a
      bi-directional negotiation ending in a compromise between the two
      devices.


   o  Convergence of negotiation procedures

      To enable convergence, when a responder makes a suggestion of a
      changed condition in a negative reply, it should be as close as
      possible to the original request or previous suggestion.  The



Carpenter & Liu           Expires July 10, 2015                [Page 11]


Internet-Draft                GDN Protocol                  January 2015


      suggested value of the third or later negotiation steps should be
      chosen between the suggested values from the last two negotiation
      steps.  In any case there must be a mechanism to guarantee
      convergence (or failure) in a small number of steps, such as a
      timeout or maximum number of iterations.



      *  End of negotiation

         A limited number of rounds, for example three, or a timeout, is
         needed on each device for each negotiation objective.  It may
         be an implementation choice, a pre-configurable parameter, or a
         network-wide policy intent.  These choices might vary between
         different types of autonomic service agent.  Therefore, the
         definition of each negotiation objective MUST clearly specify
         this, so that the negotiation can always be terminated
         properly.


      *  Failed negotiation

         There must be a well-defined procedure for concluding that a
         negotiation cannot succeed, and if so deciding what happens
         next (deadlock resolution, tie-breaking, or revert to best-
         effort service).  Again, this MUST be specified for individual
         negotiation objectives, as an implementation choice, a pre-
         configurable parameter, or a network-wide policy intent.

3.3.  GDNP Protocol Basic Properties and Mechanisms

3.3.1.  Discovery Mechanism and Procedures

   o  Separated discovery and negotiation mechanisms

         Although discovery and negotiation or synchronization are
         defined together in the GDNP, they are separated mechanisms.
         The discovery process could run independently from the
         negotiation or synchronization process.  Upon receiving a
         discovery (Section 3.7.2) or request (Section 3.7.4) message,
         the recipient device should return a message in which it either
         indicates itself as a discovery responder or diverts the
         initiator towards another more suitable device.

         The discovery objective could be network functionalities, role-
         based network elements or service agents (TBD).  The discovery
         results could be utilized by the negotiation protocol to decide
         which device the initiator will negotiate with.



Carpenter & Liu           Expires July 10, 2015                [Page 12]


Internet-Draft                GDN Protocol                  January 2015


   o  Discovery Procedures

         Discovery starts as on-link operation.  The Divert option can
         tell the discovery initiator to contact an off-link discovery
         objective device.  Every DISCOVERY message is sent by a
         discovery initiator to the ALL_GDNP_NEIGHBOR multicast address
         (Section 3.4).  Every network device that supports the GDNP
         always listens to a well-known transport port to capture the
         discovery messages.

         If the neighbor device supports the requested discovery
         objective, it MAY respond with a Response message
         (Section 3.7.3) with locator option(s).  Otherwise, if the
         neigbor device has cached information about a device that
         supports the requested discovery objective (usually because it
         discovered the same objective before), it SHOULD respond with a
         Response message with a Divert option pointing to the
         appropriate Discovery Responder.

         After a GDNP device successfully discovers a Discovery
         Responder supporting a specific objective, it MUST cache this
         information.  This cache record MAY be used for future
         negotiation or synchronization, and SHOULD be passed on when
         appropriate as a Divert option to another Discovery Initiator.

         A GDNP device with multiple link-layer interfaces (typically a
         router) MUST support discovery on all interfaces.  If it
         receives a DISCOVERY message on a given interface for a
         specific objective that it does not support and for which it
         has not previously discovered a Discovery Responder, it MUST
         relay the query by re-issuing the same DISCOVERY message on its
         other interfaces.  Togther with the caching mechanism, this
         should be sufficient to support most network bootstrapping
         scenarios.

   o  A complete discovery process will start with multicast on the
      local link; a neighbor might divert it to an off-link destination,
      which could be a default higher-level gateway in a hierarchical
      network.  Then discovery would continue with a unicast to that
      gateway; if that gateway is still not the right counterpart, it
      should divert to another device, which is in principle closer to
      the right counterpart.  Finally the right counterpart responds to
      start the negotiation or synchronization process.

   o  Rapid Mode (Discovery/Negotiation binding)

         A Discovery message MAY include one or more Negotiation
         Objective option(s).  This allows a rapid mode of negotiation



Carpenter & Liu           Expires July 10, 2015                [Page 13]


Internet-Draft                GDN Protocol                  January 2015


         described in Section 3.3.3.  A similar mechanism is defined for
         synchronization.

3.3.2.  Certificate-based Security Mechanism

   A certificate-based security mechanism provides security properties
   for GDNP:

   o  the identity of a GDNP message sender can be verified by a
      recipient.

   o  the integrity of a GDNP message can be checked by the recipient of
      the message.

   o  anti-replay protection can be assured by the GDNP message
      recipient.

   The authority of the GDNP message sender depends on a Public Key
   Infrastructure (PKI) system with a Certification Authority (CA),
   which should normally be run by the network operator.  In the case of
   a network with no operator, such as a small office or home network,
   the PKI itself needs to be established by an autonomic process, which
   is out of scope for this specification.

   A Request message MUST carry a Certificate option, defined in
   Section 3.8.6.  The first Negotiation Message, responding to a
   Request message, SHOULD also carry a Certificate option.  Using these
   messages, recipients build their certificate stores, indexed by the
   Device Certificate Tags included in every GDNP message.  This process
   is described in more detail below.

   Every message MUST carry a signature option (Section 3.8.7).

   For now, the authors do not think packet size is a problem.  In this
   GDNP specification, there SHOULD NOT be multiple certificates in a
   single message.  The current most used public keys are 1024/2048
   bits; some may reach 4096.  With overhead included, a single
   certificate is less than 500 bytes.  Messages are expected to be far
   shorter than the normal packet MTU within a modern network.

3.3.2.1.  Support for algorithm agility

   Hash functions are used to provide message integrity checks.  In
   order to provide a means of addressing problems that may emerge in
   the future with existing hash algorithms, as recommended in
   [RFC4270], a mechanism for negotiating the use of more secure hashes
   in the future is provided.




Carpenter & Liu           Expires July 10, 2015                [Page 14]


Internet-Draft                GDN Protocol                  January 2015


   In addition to hash algorithm agility, a mechanism for signature
   algorithm agility is also provided.

   The support for algorithm agility in this document is mainly a
   unilateral notification mechanism from sender to recipient.  If the
   recipient does not support the algorithm used by the sender, it
   cannot authenticate the message.  Senders in a single administrative
   domain are not required to upgrade to a new algorithm simultaneously.

   So far, the algorithm agility is supported by one-way notification,
   rather than negotiation mode.  As defined in Section 3.8.7, the
   sender notifies the recipient what hash/signature algorithms it uses.
   If the responder doesn't know a new algorithm used by the sender, the
   negotiation request would fail.  In order to establish a negotiation
   session, the sender MAY fall back to an older, less preferred
   algorithm.  Certificates and network policy intent SHOULD limit the
   choice of algorithms.

3.3.2.2.  Message validation on reception

   When receiving a GDNP message, a recipient MUST discard the GDNP
   message if the Signature option is absent, or the Certificate option
   is in a Request Message.

   For the Request message and the Response message with a Certification
   Option, the recipient MUST first check the authority of this sender
   following the rules defined in [RFC5280].  After successful authority
   validation, an implementation MUST add the sender's certification
   into the local trust certificate record indexed by the associated
   Device Certificate Tag (Section 3.5).

   The recipient MUST now authenticate the sender by verifying the
   Signature and checking a timestamp, as specified in Section 3.3.2.3.
   The order of two procedures is left as an implementation decision.
   It is RECOMMENDED to check timestamp first, because signature
   verification is much more computationally expensive.

   The signature field verification MUST show that the signature has
   been calculated as specified in Section 3.8.7.  The public key used
   for signature validation is obtained from the certificate either
   carried by the message or found from a local trust certificate record
   by searching the message-carried Device Certificate Tag.

   Only the messages that get through both the signature verifications
   and timestamp check are accepted and continue to be handled for their
   contained GDNP options.  Messages that do not pass the above tests
   MUST be discarded as insecure messages.




Carpenter & Liu           Expires July 10, 2015                [Page 15]


Internet-Draft                GDN Protocol                  January 2015


3.3.2.3.  TimeStamp checking

   Recipients SHOULD be configured with an allowed timestamp Delta
   value, a "fuzz factor" for comparisons, and an allowed clock drift
   parameter.  The recommended default value for the allowed Delta is
   300 seconds (5 minutes); for fuzz factor 1 second; and for clock
   drift, 0.01 second.

   The timestamp is defined in the Signature Option, Section 3.8.7.  To
   facilitate timestamp checking, each recipient SHOULD store the
   following information for each sender:

   o  The receive time of the last received and accepted GDNP message.
      This is called RDlast.

   o  The time stamp in the last received and accepted GDNP message.
      This is called TSlast.

   An accepted GDNP message is any successfully verified (for both
   timestamp check and signature verification) GDNP message from the
   given peer.  It initiates the update of the above variables.
   Recipients MUST then check the Timestamp field as follows:

   o  When a message is received from a new peer (i.e., one that is not
      stored in the cache), the received timestamp, TSnew, is checked,
      and the message is accepted if the timestamp is recent enough to
      the reception time of the packet, RDnew:

         -Delta < (RDnew - TSnew) < +Delta

      The RDnew and TSnew values SHOULD be stored in the cache as RDlast
      and TSlast.

   o  When a message is received from a known peer (i.e., one that
      already has an entry in the cache), the timestamp is checked
      against the previously received GDNP message:

         TSnew + fuzz > TSlast + (RDnew - RDlast) x (1 - drift) - fuzz

      If this inequality does not hold, the recipient SHOULD silently
      discard the message.  If, on the other hand, the inequality holds,
      the recipient SHOULD process the message.

      Moreover, if the above inequality holds and TSnew > TSlast, the
      recipient SHOULD update RDlast and TSlast.  Otherwise, the
      recipient MUST NOT update RDlast or TSlast.





Carpenter & Liu           Expires July 10, 2015                [Page 16]


Internet-Draft                GDN Protocol                  January 2015


   An implementation MAY use some mechanism such as a timestamp cache to
   strengthen resistance to replay attacks.  When there is a very large
   number of nodes on the same link, or when a cache filling attack is
   in progress, it is possible that the cache holding the most recent
   timestamp per sender will become full.  In this case, the node MUST
   remove some entries from the cache or refuse some new requested
   entries.  The specific policy as to which entries are preferred over
   others is left as an implementation decision.

3.3.3.  Negotiation Procedures

   A negotiation initiator sends a negotiation request to counterpart
   devices, which may be different according to different negotiation
   objectives.  It may request relevant information from the negotiation
   counterpart so that it can decide its local configuration to give the
   most coordinated performance.  This would be sufficient in a case
   where the required function is limited to state synchronization.  It
   may additionally request the negotiation counterpart to make a
   matching configuration in order to set up a successful communication
   with it.  It may request a certain simulation or forecast result by
   sending some dry run conditions.  The details, including the
   distinction between dry run and an actual configuration change, will
   be defined separately for each type of negotiation objective.

   If the counterpart can immediately apply the requested configuration,
   it will give an immediate positive (accept) answer.  This will end
   the negotiation phase immediately.  Otherwise, it will negotiate.  It
   will reply with a proposed alternative configuration that it can
   apply (typically, a configuration that uses fewer resources than
   requested by the negotiation initiator).  This will start a bi-
   directional negotiation to reach a compromise between the two network
   devices.

   The negotiation procedure is ended when one of the negotiation peers
   sends a Negotiation Ending message, which contains an accept or
   decline option and does not need a response from the negotiation
   peer.

   A negotiation procedure concerns one objective and one counterpart.
   Both the initiator and the counterpart may take part in simultaneous
   negotiations with various other devices, or in simultaneous
   negotiations about different objectives.  Thus, GDNP is expected to
   be used in a multi-threaded mode.  Certain negotiation objectives may
   have restrictions on multi-threading, for example to avoid over-
   allocating resources.

   Rapid Mode (Discovery/Negotiation linkage)




Carpenter & Liu           Expires July 10, 2015                [Page 17]


Internet-Draft                GDN Protocol                  January 2015


      A Discovery message MAY include one or more Negotiation Objective
      option(s).  In this case the Discovery message also acts as a
      Request message to indicate to the Discovery Responder that it
      could directly reply to the Discovery Initiator with a Negotiation
      message for rapid processing, if the discovery objective could act
      as the corresponding negotiation counterpart.  However, the
      indication is only advisory not prescriptive.

      This rapid mode could reduce the interactions between nodes so
      that a higher efficiency could be achieved.  This rapid
      negotiation function SHOULD be configured off by default and MAY
      be configured on or off by policy intent.

3.3.4.  Synchronization Procedure

   A synchronization initiator sends a synchronization request to
   counterpart devices, which may be different according to different
   synchronization objectives.  The counterpart responds with a Response
   message containing the current value(s) of the requested
   synchronization objective.  No further messages are needed, but
   otherwise the procedure operates as a subset of the negotiation
   procedure.  If no Response message is received, the synchronization
   request MAY be repeated after a suitable timeout.

   A synchronization responder MAY send an unsolicited Response message
   containing a synchronization objective, if and only if the
   specification of this objective permits it.  This MAY be sent as a
   multicast message to the ALL_GDNP_NEIGHBOR multicast address
   (Section 3.4).  In this case the Trickle algorithm [RFC6206] MUST be
   used to avoid excessive multicast traffic.  The parameters Imin, Imax
   and k of the Trickle algorithm will be specified as part of the
   specification of the synchronization objective concerned.

   Rapid Mode (Discovery/Synchronization linkage)

      A Discovery message MAY include one or more Synchronization
      Objective option(s).  In this case the Discovery message also acts
      as a Request message to indicate to the Discovery Responder that
      it could directly reply to the Discovery Initiator with a Response
      message with synchronization data for rapid processing, if the
      discovery target supports the corresponding synchronization
      objective.  However, the indication is only advisory not
      prescriptive.

      This rapid mode could reduce the interactions between nodes so
      that a higher efficiency could be achieved.  This rapid
      synchronization function SHOULD be configured off by default and
      MAY be configured on or off by policy intent.



Carpenter & Liu           Expires July 10, 2015                [Page 18]


Internet-Draft                GDN Protocol                  January 2015


3.4.  GDNP Constants

   o  ALL_GDNP_NEIGHBOR (TBD1)

      A link-local scope multicast address used by a GDNP-enabled device
      to discover GDNP-enabled neighbor (i.e., on-link) devices . All
      devices that support GDNP are members of this multicast group.

      *  IPv6 multicast address: TBD1

      *  IPv4 multicast address: TBD2

   o  GDNP Listen Port (TBD3)

      A UDP port that every GDNP-enabled network device always listens
      to.

3.5.  Device Identifier and Certificate Tag

   A GDNP-enabled Device MUST generate a stable public/private key pair
   before it participates in GDNP.  There MUST NOT be any way of
   accessing the private key via the network or an operator interface.
   The device then uses the public key as its identifier, which is
   cryptographic in nature.  It is a GDNP unique identifier for a GDNP
   participant.

   It then gets a certificate for this public key, signed by a
   Certificate Authority that is trusted by other network devices.  The
   Certificate Authority SHOULD be managed within the local
   administrative domain, to avoid needing to trust a third party.  The
   signed certificate would be used for authentication of the message
   sender.  In a managed network, this certification process could be
   performed at a central location before the device is physically
   installed at its intended location.  In an unmanaged network, this
   process must be autonomic, including the bootstrap phase.

   A 128-bit Device Certifcate Tag, which is generated by taking a
   cryptographic hash over the device certificate, is a short
   presentation for GDNP messages.  It is the index key to find the
   device certificate in a recipient's local trusted certificate record.

   The tag value is formed by taking a SHA-1 hash algorithm [RFC3174]
   over the corresponding device certificate and taking the leftmost 128
   bits of the hash result.







Carpenter & Liu           Expires July 10, 2015                [Page 19]


Internet-Draft                GDN Protocol                  January 2015


3.6.  Session Identifier (Session ID)

   A 24-bit opaque value used to distinguish multiple sessions between
   the same two devices.  A new Session ID MUST be generated for every
   new Discovery or Request message, and for every unsolicited Response
   message.  All follow-up messages in the same discovery,
   synchronization or negotiation procedure, which is initiated by the
   request message, MUST carry the same Session ID.

   The Session ID SHOULD have a very low collision rate locally.  It is
   RECOMMENDED to be generated by a pseudo-random algorithm using a seed
   which is unlikely to be used by any other device in the same network
   [RFC4086].

3.7.  GDNP Messages

   This document defines the following GDNP message format and types.
   Message types not listed here are reserved for future use.  The
   numeric encoding for each message type is shown in parentheses.

3.7.1.  GDNP Message Format

   All GDNP messages share an identical fixed format header and a
   variable format area for options.  Every Message carries the Device
   Certificate Tag of its sender and a Session ID.  Options are
   presented serially in the options field, with no padding between the
   options.  Options are byte-aligned.

   The following diagram illustrates the format of GDNP messages:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | MESSAGE_TYPE  |                Session ID                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                   Device Certificate Tag                      |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Options  (variable length)             |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   MESSAGE_TYPE:  Identifies the GDNP message type. 8-bit.

   Session ID:  Identifies this negotiation session, as defined in
      Section 3.6. 24-bit.



Carpenter & Liu           Expires July 10, 2015                [Page 20]


Internet-Draft                GDN Protocol                  January 2015


   Device Certificate Tag:  Represents the Device Certificate, which
      identifies the negotiation devices, as defined in Section 3.5.
      The Device Certificate Tag is 128 bit, also defined in
      Section 3.5.  It is used as index key to find the device
      certificate.

   Options:  GDNP Options carried in this message.  Options are defined
      starting at Section 3.8.

3.7.2.  Discovery Message

   DISCOVERY (MESSAGE_TYPE = 1):

   A discovery initiator sends a DISCOVERY message to initiate a
   discovery process.

   The discovery initiator sends the DISCOVERY messages to the link-
   local ALL_GDNP_NEIGHBOR multicast address for discovery, and stores
   the discovery results (including responding discovery objectives and
   corresponding unicast addresses or FQDNs).

   A DISCOVERY message MUST include a discovery objective option
   (Section 3.9).

   A DISCOVERY message MAY include one or more negotiation objective
   option(s) (Section 3.10) to indicate to the discovery objective that
   it could directly return to the discovery initiatior with a
   Negotiation message for rapid processing, if the discovery objective
   could act as the corresponding negotiation counterpart, and similarly
   for synchronization.

3.7.3.  Response Message

   RESPONSE (MESSAGE_TYPE = 2):

   A node which receives a DISCOVERY message sends a Response message to
   respond to a discovery.  It MUST contain the same Session ID as the
   DISCOVERY message.  It MAY include a copy of the discovery objective
   from the DISCOVERY message.

   If the responding node supports the discovery objective of the
   discovery, it MUST include at least one kind of locator option
   (Section 3.8.8) to indicate its own location.  A combination of
   multiple kinds of locator options (e.g.  IP address option + FQDN
   option) is also valid.

   If the responding node itself does not support the discovery
   objective, but it knows the locator of the discovery objective, then



Carpenter & Liu           Expires July 10, 2015                [Page 21]


Internet-Draft                GDN Protocol                  January 2015


   it SHOULD respond to the discovery message with a divert option
   (Section 3.8.2) embedding a locator option or a combination of
   multiple kinds of locator options which indicate the locator(s) of
   the discovery objective.

   A node which receives a synchronization request sends a Response
   message with the synchronization data.  A node MAY send an
   unsolicited Response Message with synchronization data and this MAY
   be sent to the link-local ALL_GDNP_NEIGHBOR multicast address.

   If the response contains synchronization data, this will be in the
   form of a GDNP Option for the specific synchronization objective.

3.7.4.  Request Message

   REQUEST (MESSAGE_TYPE = 3):

   A negotiation or synchronization requesting node sends the REQUEST
   message to the unicast address (directly stored or resolved from the
   FQDN) of the negotiation or synchronization counterpart (selected
   from the discovery results).

   A request message MUST include the relevant objective option, with
   the requested value in the case of negotiation.

3.7.5.  Negotiation Message

   NEGOTIATION (MESSAGE_TYPE = 4):

   A negotiation counterpart sends a NEGOTIATION message in response to
   a REQUEST message, a NEGOTIATION message, or a DISCOVERY message in
   Rapid Mode.  A negotiation process MAY include multiple steps.

3.7.6.  Negotiation-ending Message

   NEGOTIATION-ENDING (MESSAGE_TYPE = 5):

   A negotiation counterpart sends an NEGOTIATION-ENDING message to
   close the negotiation.  It MUST contain one, but only one of accept/
   decline option, defined in Section 3.8.3 and Section 3.8.4.  It could
   be sent either by the requesting node or the responding node.

3.7.7.  Confirm-waiting Message

   CONFIRM-WAITING (MESSAGE_TYPE = 6):

   A responding node sends a CONFIRM-WAITING message to indicate the
   requesting node to wait for a further negotiation response.  It might



Carpenter & Liu           Expires July 10, 2015                [Page 22]


Internet-Draft                GDN Protocol                  January 2015


   be that the local process needs more time or that the negotiation
   depends on another triggered negotiation.  This message MUST NOT
   include any other options than the Waiting Time Option
   (Section 3.8.5).

3.8.  GDNP General Options

   This section defines the GDNP general option for the negotiation and
   synchronization protocol signalling.  Option types 10~63 are reserved
   for GDNP general options defined in the future.

3.8.1.  Format of GDNP Options

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          option-code          |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          option-data                          |
   |                      (option-len octets)                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  An unsigned integer identifying the specific option
      type carried in this option.

   Option-len:  An unsigned integer giving the length of the option-data
      field in this option in octets.

   Option-data:  The data for the option; the format of this data
      depends on the definition of the option.

   GDNP options are scoped by using encapsulation.  If an option
   contains other options, the outer Option-len includes the total size
   of the encapsulated options, and the latter apply only to the outer
   option.

3.8.2.  Divert Option

   The divert option is used to redirect a GDNP request to another node,
   which may be more appropriate for the intended negotiation or
   synchronization.  It may redirect to an entity that is known as a
   specific negotiation or synchronization counterpart (on-link or off-
   link) or a default gateway.  The divert option MUST only be
   encapsulated in Response messages.  If found elsewhere, it SHOULD be
   silently ignored.






Carpenter & Liu           Expires July 10, 2015                [Page 23]


Internet-Draft                GDN Protocol                  January 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         OPTION_DIVERT         |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Locator Option(s) of Diversion Device(s)          |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_DIVERT (1).

   Option-len:  The total length of diverted destination sub-option(s)
      in octets.

   Locator Option(s) of Diversion Device(s):  Embedded Locator Option(s)
      (Section 3.8.8) that point to diverted destination device(s).

3.8.3.  Accept Option

   The accept option is used to indicate to the negotiation counterpart
   that the proposed negotiation content is accepted.

   The accept option MUST only be encapsulated in Negotiation-ending
   messages.  If found elsewhere, it SHOULD be silently ignored.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        OPTION_ACCEPT          |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_ACCEPT (2)

   Option-len:  0

3.8.4.  Decline Option

   The decline option is used to indicate to the negotiation counterpart
   the proposed negotiation content is declined and end the negotiation
   process.

   The decline option MUST only be encapsulated in Negotiation-ending
   messages.  If found elsewhere, it SHOULD be silently ignored.








Carpenter & Liu           Expires July 10, 2015                [Page 24]


Internet-Draft                GDN Protocol                  January 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        OPTION_DECLINE         |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_DECLINE (3)

   Option-len:  0

   Notes: there are scenarios where a negotiation counterpart wants to
   decline the proposed negotiation content and continue the negotiation
   process.  For these scenarios, the negotiation counterpart SHOULD use
   a Response message, with either an objective option that contains at
   least one data field with all bits set to 1 to indicate a meaningless
   initial value, or a specific objective option that provides further
   conditions for convergence.

3.8.5.  Waiting Time Option

   The waiting time option is used to indicate that the negotiation
   counterpart needs to wait for a further negotiation response, since
   the processing might need more time than usual or it might depend on
   another triggered negotiation.

   The waiting time option MUST only be encapsulated in Confirm-waiting
   messages.  If found elsewhere, it SHOULD be silently ignored.

   The counterpart SHOULD send a Response message or another Confirm-
   waiting message before the current waiting time expires.  If not, the
   initiator SHOULD abandon or restart the negotiation procedure, to
   avoid an indefinite wait.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       OPTION_WAITING          |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              Time                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_WAITING (4)

   Option-len:  4, in octets

   Time:  Time in milliseconds





Carpenter & Liu           Expires July 10, 2015                [Page 25]


Internet-Draft                GDN Protocol                  January 2015


3.8.6.  Certificate Option

   The Certificate option carries the certificate of the sender.  The
   format of the Certificate option is 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       OPTION Certificate      |           option-len          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     .                    Certificate (variable length)              .
     .                                                               .
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_CERT_PARAMETER (5)

   Option-len:  Length of certificate in octets

   Public key:  A variable-length field containing a certificate

3.8.7.  Signature Option

   The Signature option allows public key-based signatures to be
   attached to a GDNP message.  The Signature option is REQUIRED in
   every GDNP message and could be any place within the GDNP message.
   It protects the entire GDNP header and options.  A TimeStamp has been
   integrated in the Signature Option for anti-replay protection.  The
   format of the Signature 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     OPTION_SIGNATURE          |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           HA-id               |            SA-id              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Timestamp (64-bit)                        |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   .                    Signature (variable length)                .
   .                                                               .
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_SIGNATURE (6)



Carpenter & Liu           Expires July 10, 2015                [Page 26]


Internet-Draft                GDN Protocol                  January 2015


   Option-len:  12 + Length of Signature field in octets.

   HA-id:  Hash Algorithm id.  The hash algorithm is used for computing
      the signature result.  This design is adopted in order to provide
      hash algorithm agility.  The value is from the Hash Algorithm for
      GDNP registry in IANA.  The initial value assigned for SHA-1 is
      0x0001.

   SA-id:  Signature Algorithm id.  The signature algorithm is used for
      computing the signature result.  This design is adopted in order
      to provide signature algorithm agility.  The value is from the
      Signature Algorithm for GDNP registry in IANA.  The initial value
      assigned for RSASSA-PKCS1-v1_5 is 0x0001.

   Timestamp:  The current time of day (NTP-format timestamp [RFC5905]
      in UTC (Coordinated Universal Time), a 64-bit unsigned fixed-point
      number, in seconds relative to 0h on 1 January 1900.).  It can
      reduce the danger of replay attacks.

   Signature:  A variable-length field containing a digital signature.
      The signature value is computed with the hash algorithm and the
      signature algorithm, as described in HA-id and SA-id.  The
      signature constructed by using the sender's private key protects
      the following sequence of octets:

      1.  The GDNP message header.

      2.  All GDNP options including the Signature option (fill the
      signature field with zeroes).

      The signature field MUST be padded, with all 0, to the next 16 bit
      boundary if its size is not an even multiple of 8 bits.  The
      padding length depends on the signature algorithm, which is
      indicated in the SA-id field.

3.8.8.  Locator Options

   These locator options are used to present a device's or interface's
   reachability information.  They are Locator IPv4 Address Option,
   Locator IPv6 Address Option and Locator FQDN (Fully Qualified Domain
   Name) Option.

3.8.8.1.  Locator IPv4 address option








Carpenter & Liu           Expires July 10, 2015                [Page 27]


Internet-Draft                GDN Protocol                  January 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    OPTION_LOCATOR_IPV4ADDR    |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          IPv4-Address                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_LOCATOR_IPV4ADDR (7)

   Option-len:  4, in octets

   IPv4-Address:  The IPv4 address locator of the device/interface

3.8.8.2.  Locator IPv6 address option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   OPTION_LOCATOR_IPV6ADDR     |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                          IPv6-Address                         |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_LOCATOR_IPV6ADDR (8)

   Option-len:  16, in octets

   IPv6-Address:  The IPv6 address locator of the device/interface

   Note: A link-local IPv6 address MUST NOT be used when this option is
   used within the Divert option.

3.8.8.3.  Locator FQDN option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         OPTION_FQDN           |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Fully Qualified Domain Name                 |
   |                       (variable length)                       |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




Carpenter & Liu           Expires July 10, 2015                [Page 28]


Internet-Draft                GDN Protocol                  January 2015


   Option-code:  OPTION_FQDN (9)

   Option-len:  Length of Fully Qualified Domain Name in octets

   Domain-Name:  The Fully Qualified Domain Name of the entity

3.9.  Discovery Objective Option

   The discovery objective option is to express the discovery objectives
   that the initiating node wants to discover and to confirm them in a
   Response message.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         OPTION_DISOBJ         |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Expression of Discovery Objectives (TBD)          |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_DISOBJ (TBD)

   Option-len:  The total length in octets

   Expression of Discovery Objectives (TBD):  This field is to express
      the discovery objectives that the initiating node wants to
      discover.  It might be network functionality, role-based network
      element or service agent.

3.10.  Negotiation and Synchronization Objective Options and
       Considerations

   Negotiation and Synchronization Objective Options MUST be assigned an
   option type greater than 64 in the GDNP option table.

   The Negotiation Objective Options contain negotiation objectives,
   which are various according to different functions/services.  They
   MUST be carried by Discovery, Request or Negotiation Messages only.

   For most scenarios, there SHOULD be initial values in the negotiation
   requests.  Consequently, the Negotiation Objective options SHOULD
   always be completely presented in a Request message,or in a Discovery
   message in rapid mode.  If there is no initial value, the bits in the
   value field SHOULD all be set to 1 to indicate a meaningless value,
   unless this is inappropriate for the specific negotiation objective.





Carpenter & Liu           Expires July 10, 2015                [Page 29]


Internet-Draft                GDN Protocol                  January 2015


   Synchronization Objective Options are similar, but MUST be carried by
   Discovery, Request or Response messages only.  They include value
   fields only in Response messages.

3.10.1.  Organizing of GDNP Options

   Naturally, a negotiation objective, which is based on a specific
   service or function or action, SHOULD be organized as a single GDNP
   option.  It is NOT RECOMMENDED to organize multiple negotiation
   objectives into a single option.

   A negotiation objective may have multiple parameters.  Parameters can
   be categorized into two class: the obligatory ones presented as fixed
   fields; and the optional ones presented in TLV sub-options.  It is
   NOT RECOMMENDED to split parameters in a single objective into
   multiple options, unless they have different response periods.  An
   exception scenario may also be described by split objectives.

3.10.2.  Vendor Specific Options

   Option codes 128~159 have been reserved for vendor specific options.
   Multiple option codes have been assigned because a single vendor
   might use multiple options simultaneously.  These vendor specific
   options are highly likely to have different meanings when used by
   different vendors.  Therefore, they SHOULD NOT be used without an
   explicit human decision and SHOULD NOT be used in unmanaged networks
   such as home networks.

   There is one general requirement that applies to all vendor specific
   options.  They MUST start with a field that uniquely identifies the
   enterprise that defines the option, in the form of a registered 32
   bit Private Enterprise Number (PEN) [I-D.liang-iana-pen].  There is
   no default value for this field.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         OPTION_vendor         |           option-len          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                   Private Enterprise Number                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Option Contents                        |
   .                       (variable length)                       .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-code:  OPTION_vendor (128~159)

   Option-len:  Length of PEN plus option contents in octets



Carpenter & Liu           Expires July 10, 2015                [Page 30]


Internet-Draft                GDN Protocol                  January 2015


3.10.3.  Experimental Options

   Option code 176~191 have been reserved for experimental options.
   Multiple option codes have been assigned because a single experiment
   may use multiple options simultaneously.  These experimental options
   are highly likely to have different meanings when used for different
   experiments.  Therefore, they SHOULD NOT be used without an explicit
   human decision and SHOULD NOT be used in unmanaged networks such as
   home networks.

   These option codes are also RECOMMENDED for use in documentation
   examples.

3.11.  Items for Future Work

   There are various design questions that are worthy of more work in
   the near future, as listed below:

   o  UDP vs TCP: For now, this specification has chosen UDP as message
      transport mechanism.  However, this is not closed yet.  UDP is
      good for short conversations, fitting the discovery and divert
      scenarios well.  However, it may have issues with large packets.
      TCP is good for stable and long sessions, with a little bit of
      time consumption during the session establishment stage.  If
      messages exceed a reasonable MTU, a TCP mode may be necessary.

   o  Message encryption: should GDNP messages be (optionally) encrypted
      as well as signed, to protect against internal eavesdropping or
      monitoring within the network?

   o  DTLS or TLS vs built-in security mechanism.  For now, this
      specification has chosen a PKI based built-in security mechanism
      based on asymmetric cryptography.  However, (D)TLS might be chosen
      as security solution to avoid duplication of effort.  It also
      allows essentially similar security for short messages over UDP
      and longer ones over TCP.  The implementation trade-offs are
      different.  The current approach requires expensive asymmetric
      cryptographic calculations for every message.  (D)TLS has startup
      overheads but cheaper crypto per message.

   o  Should discuss lifetime of discovery cache, and what to do when
      discovery fails (timeout and repeat?).

   o  Timeout for lost Negotiation Ending and other messages to be
      added.






Carpenter & Liu           Expires July 10, 2015                [Page 31]


Internet-Draft                GDN Protocol                  January 2015


   o  We mention convergence mechanisms and say "Also some mechanisms
      are needed to avoid loop dependencies."  These issues need more
      work.

   o  For replay protection, GDNP currently requires every participant
      to have an NTP-synchronized clock.  Is this OK for low-end
      devices, and how does it work during device bootstrapping?  We
      could take the Timestamp out of signature option, to become an
      independent and OPTIONAL (or RECOMMENDED) option.

   o  Would use of MDNS have any impact on the Locator FQDN option?

   o  Need to add a section describing the minimum requirements for the
      specification of an individual discovery, synchronization or
      negotiation objective.  Maybe a formal information model is
      needed.

   o  Is it reasonable to consider that a Discovery Objective is really
      just a set of specific Negotiation and/or Synchronization
      Objectives?  In other words, if a GDNP node supports Negotiation
      and/or Synchronization Objectives A, B and C, then its
      corresponding Discovery Objective is a shorthand for "A+B+C".

   o  Would a DISCOVERY(ANY) mechanism be useful during bootstrapping,
      i.e. used by all GDNP-capable routers to find all their neighbours
      that support any GDNP discovery objective?.

   o  Would it be reasonable to allow an unsolicited Response message
      with Discovery Objective content, to speed up discovery during
      bootstrapping?

   o  Is there a risk that the relaying of discovery messages
      (Section 3.3.1) will lead to loops or multicast storms?  At least
      we should consider throttling discovery relays to a maximum rate.
      Or is there a better method for zeroconf discovery with no
      predefined hierarchy?

   o  Should we consider a distributed or centralised DNS-like approach
      to discovery (after the initial discovery needed for
      bootstrapping)?

   o  Need to discuss automatic recovery mechanism as required by
      Section 2.2 and management monitoring, alerts and intervention in
      general.

   o  The Decline Option (Section 3.8.4) includes a note that a
      counterpart could use a Response message to indicate "Decline but




Carpenter & Liu           Expires July 10, 2015                [Page 32]


Internet-Draft                GDN Protocol                  January 2015


      try again".  That seems strange - why not use a Negotiation
      message for this case?

   o  The Signature Option (Section 3.8.7) states that this option could
      be any place in a message.  Wouldn't it be better to specify a
      position (such as the end)?  That would be much simpler to
      implement.

   o  DoS Attack Protection needs work.

   o  Use case and protocol walkthrough.  A description of how a node
      starts up, performs discovery, and conducts negotiation and
      synchronisation for a sample use case would help readers to
      understand the applicability of this specification.  Maybe it
      should be an artificial use case or maybe a simple real one.
      However, the authors have not yet decided whether to have a
      separate document or have it in this document.

   o  We currently assume that there is only one counterpart for each
      discovery action.  If this is false or one negotiation request
      receives multiple different responses, how does the initiator
      choose between them?  Could it split them into multiple follow-up
      negotiations?

   o  Alternatives to TLV format.  It may be useful to provide a generic
      method of carrying negotiation objectives in a high-level format
      such as YANG or XML schema.  It may also be useful to provide a
      generic method of carrying existing configuration information such
      as DHCP(v6) or IPv6 RA messages.  These features could be provided
      by encapsulating such messages in their own TLVs, but large
      messages would definitely need a TCP mode instead of UDP.

4.  Security Considerations

   It is obvious that a successful attack on negotiation-enabled nodes
   would be extremely harmful, as such nodes might end up with a
   completely undesirable configuration that would also adversely affect
   their peers.  GDNP nodes and messages therefore require full
   protection.

   - Authentication

      A cryptographically authenticated identity for each device is
      needed in an autonomic network.  It is not safe to assume that a
      large network is physically secured against interference or that
      all personnel are trustworthy.  Each autonomic device should be
      capable of proving its identity and authenticating its messages.




Carpenter & Liu           Expires July 10, 2015                [Page 33]


Internet-Draft                GDN Protocol                  January 2015


      GDNP proposes a certificate-based security mechanism to provide
      authentication and data integrity protection.

      The timestamp mechanism provides an anti-replay function.

      Since GDNP is intended to be deployed in a single administrative
      domain operating its own trust anchor and CA, there is no need for
      a trusted public third party.

   - Privacy

      Generally speaking, no personal information is expected to be
      involved in the negotiation protocol, so there should be no direct
      impact on personal privacy.  Nevertheless, traffic flow paths,
      VPNs, etc. may be negotiated, which could be of interest for
      traffic analysis.  Also, carriers generally want to conceal
      details of their network topology and traffic density from
      outsiders.  Therefore, since insider attacks cannot be prevented
      in a large carrier network, the security mechanism for the
      negotiation protocol needs to provide message confidentiality.

   - DoS Attack Protection

      TBD.

5.  IANA Considerations

   Section 3.4 defines the following multicast addresses, which have
   been assigned by IANA for use by GDNP:

   ALL_GDNP_NEIGHBOR multicast address  (IPv6): (TBD1)

   ALL_GDNP_NEIGHBOR multicast address  (IPv4): (TBD2)

   Section 3.4 defines the following UDP port, which has been assigned
   by IANA for use by GDNP:

   GDNP Listen Port:  (TBD3)

   This document defined a new General Discovery and Negotiation
   Protocol.  The IANA is requested to create a new GDNP registry.  The
   IANA is also requested to add two new registry tables to the newly-
   created GDNP registry.  The two tables are the GDNP Messages table
   and GDNP Options table.

   Initial values for these registries are given below.  Future
   assignments are to be made through Standards Action or Specification




Carpenter & Liu           Expires July 10, 2015                [Page 34]


Internet-Draft                GDN Protocol                  January 2015


   Required [RFC5226].  Assignments for each registry consist of a type
   code value, a name and a document where the usage is defined.

   GDNP Messages table.  The values in this table are 16-bit unsigned
   integers.  The following initial values are assigned in Section 3.7
   in this document:

         Type  |          Name               |   RFCs
      ---------+-----------------------------+------------
           0   |Reserved                     | this document
           1   |Discovery                    | this document
           2   |Response                     | this document
           3   |Request Message              | this document
           4   |Negotiation Message          | this document
           5   |Negotiation-end Message      | this document
           6   |Confirm-waiting Message      | this document

   GDNP Options table.  The values in this table are 16-bit unsigned
   integers.  The following initial values are assigned in Section 3.8
   and Section 3.10 in this document:

         Type  |          Name               |   RFCs
      ---------+-----------------------------+------------
           0   |Reserved                     | this document
           1   |Divert Option                | this document
           2   |Accept Option                | this document
           3   |Decline Option               | this document
           4   |Waiting Time Option          | this document
           5   |Certificate Option           | this document
           6   |Signature Option             | this document
           7   |Device IPv4 Address Option   | this document
           8   |Device IPv6 Address Option   | this document
           9   |Device FQDN Option           | this document
        10~63  |Reserved for future GDNP     | this document
               |General Options              |
       128~159 |Vendor Specific Options      | this document
       176~191 |Experimental Options         | this document

   The IANA is also requested to create two new registry tables in the
   GDNP Parameters registry.  The two tables are the Hash Algorithm for
   GDNP table and the Signature Algorithm for GDNP table.

   Initial values for these registries are given below.  Future
   assignments are to be made through Standards Action or Specification
   Required [RFC5226].  Assignments for each registry consist of a name,
   a value and a document where the algorithm is defined.





Carpenter & Liu           Expires July 10, 2015                [Page 35]


Internet-Draft                GDN Protocol                  January 2015


   Hash Algorithm for GDNP.  The values in this table are 16-bit
   unsigned integers.  The following initial values are assigned for
   Hash Algorithm for GDNP in this document:

             Name          |  Value    |  RFCs
      ---------------------+-----------+------------
            Reserved       |   0x0000  | this document
            SHA-1          |   0x0001  | this document
            SHA-256        |   0x0002  | this document

   Signature Algorithm for GDNP.  The values in this table are 16-bit
   unsigned integers.  The following initial values are assigned for
   Signature Algorithm for GDNP in this document:

             Name          |   Value   |  RFCs
      ---------------------+-----------+------------
            Reserved       |   0x0000  | this document
       RSASSA-PKCS1-v1_5   |   0x0001  | this document

6.  Acknowledgements

   A major contribution to the original version of this document was
   made by Sheng Jiang.

   Valuable comments were received from Zhenbin Li, Dimitri
   Papadimitriou, Michael Richardson, Rene Struik, Dacheng Zhang, and
   other participants in the NMRG research group and the ANIMA working
   group.

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

7.  Change log [RFC Editor: Please remove]

   draft-carpenter-anima-discovery-negotiation-protocol-01, restructured
   the logical flow of the document, updated to describe synchronization
   completely, add unsolicited responses, numerous corrections and
   clarifications, expanded future work list, 2015-01-06.

   draft-carpenter-anima-discovery-negotiation-protocol-00, combination
   of draft-jiang-config-negotiation-ps-03 and draft-jiang-config-
   negotiation-protocol-02, 2014-10-08.

8.  References








Carpenter & Liu           Expires July 10, 2015                [Page 36]


Internet-Draft                GDN Protocol                  January 2015


8.1.  Normative References

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

   [RFC3174]  Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1
              (SHA1)", RFC 3174, September 2001.

   [RFC4086]  Eastlake, D., Schiller, J., and S. Crocker, "Randomness
              Requirements for Security", BCP 106, RFC 4086, June 2005.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC6206]  Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko,
              "The Trickle Algorithm", RFC 6206, March 2011.

8.2.  Informative References

   [I-D.behringer-anima-autonomic-control-plane]
              Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An
              Autonomic Control Plane", draft-behringer-anima-autonomic-
              control-plane-00 (work in progress), October 2014.

   [I-D.chaparadza-intarea-igcp]
              Behringer, M., Chaparadza, R., Petre, R., Li, X., and H.
              Mahkonen, "IP based Generic Control Protocol (IGCP)",
              draft-chaparadza-intarea-igcp-00 (work in progress), July
              2011.

   [I-D.eckert-anima-stable-connectivity]
              Eckert, T. and M. Behringer, "Autonomic Network Stable
              Connectivity", draft-eckert-anima-stable-connectivity-00
              (work in progress), October 2014.

   [I-D.ietf-dnssd-requirements]
              Lynn, K., Cheshire, S., Blanchet, M., and D. Migault,
              "Requirements for Scalable DNS-SD/mDNS Extensions", draft-
              ietf-dnssd-requirements-04 (work in progress), October
              2014.

   [I-D.ietf-homenet-hncp]
              Stenberg, M. and S. Barth, "Home Networking Control
              Protocol", draft-ietf-homenet-hncp-02 (work in progress),
              October 2014.




Carpenter & Liu           Expires July 10, 2015                [Page 37]


Internet-Draft                GDN Protocol                  January 2015


   [I-D.ietf-netconf-restconf]
              Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", draft-ietf-netconf-restconf-03 (work in
              progress), October 2014.

   [I-D.irtf-nmrg-an-gap-analysis]
              Jiang, S., Carpenter, B., and M. Behringer, "Gap Analysis
              for Autonomic Networking", draft-irtf-nmrg-an-gap-
              analysis-03 (work in progress), December 2014.

   [I-D.irtf-nmrg-autonomic-network-definitions]
              Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking - Definitions and Design Goals", draft-irtf-
              nmrg-autonomic-network-definitions-05 (work in progress),
              December 2014.

   [I-D.liang-iana-pen]
              Liang, P., Melnikov, A., and D. Conrad, "Private
              Enterprise Number (PEN) practices and Internet Assigned
              Numbers Authority (IANA) registration considerations",
              draft-liang-iana-pen-04 (work in progress), July 2014.

   [I-D.pritikin-anima-bootstrapping-keyinfra]
              Pritikin, M., Behringer, M., and S. Bjarnason,
              "Bootstrapping Key Infrastructures", draft-pritikin-anima-
              bootstrapping-keyinfra-00 (work in progress), November
              2014.

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

   [RFC2608]  Guttman, E., Perkins, C., Veizades, J., and M. Day,
              "Service Location Protocol, Version 2", RFC 2608, June
              1999.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)", RFC
              2865, June 2000.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, December 2001.




Carpenter & Liu           Expires July 10, 2015                [Page 38]


Internet-Draft                GDN Protocol                  January 2015


   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3416]  Presuhn, R., "Version 2 of the Protocol Operations for the
              Simple Network Management Protocol (SNMP)", STD 62, RFC
              3416, December 2002.

   [RFC4270]  Hoffman, P. and B. Schneier, "Attacks on Cryptographic
              Hashes in Internet Protocols", RFC 4270, November 2005.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5905]  Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
              Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, June 2010.

   [RFC5971]  Schulzrinne, H. and R. Hancock, "GIST: General Internet
              Signalling Transport", RFC 5971, October 2010.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

   [RFC6733]  Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
              "Diameter Base Protocol", RFC 6733, October 2012.

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              February 2013.

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, February 2013.

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.

Appendix A.  Capability Analysis of Current Protocols

   This section discusses various existing protocols with properties
   related to the above negotiation and synchronisation requirements.




Carpenter & Liu           Expires July 10, 2015                [Page 39]


Internet-Draft                GDN Protocol                  January 2015


   The purpose is to evaluate whether any existing protocol, or a simple
   combination of existing protocols, can meet those requirements.

   Numerous protocols include some form of discovery, but these all
   appear to be very specific in their applicability.  Service Location
   Protocol (SLP) [RFC2608] provides service discovery for managed
   networks, but requires configuration of its own servers.  DNS-SD
   [RFC6763] combined with mDNS [RFC6762] provides service discovery for
   small networks with a single link layer.
   [I-D.ietf-dnssd-requirements] aims to extend this to larger
   autonomous networks.  However, both SLP and DNS-SD appear to target
   primarily application layer services, not the layer 2 and 3
   objectives relevant to basic network configuration.

   Routing protocols are mainly one-way information announcements.  The
   receiver makes independent decisions based on the received
   information and there is no direct feedback information to the
   announcing peer.  This remains true even though the protocol is used
   in both directions between peer routers; there is state
   synchronization, but no negotiation, and each peer runs its route
   calculations independently.

   Simple Network Management Protocol (SNMP) [RFC3416] uses a command/
   response model not well suited for peer negotiation.  Network
   Configuration Protocol (NETCONF) [RFC6241] uses an RPC model that
   does allow positive or negative responses from the target system, but
   this is still not adequate for negotiation.

   There are various existing protocols that have elementary negotiation
   abilities, such as Dynamic Host Configuration Protocol for IPv6
   (DHCPv6) [RFC3315], Neighbor Discovery (ND) [RFC4861], Port Control
   Protocol (PCP) [RFC6887], Remote Authentication Dial In User Service
   (RADIUS) [RFC2865], Diameter [RFC6733], etc.  Most of them are
   configuration or management protocols.  However, they either provide
   only a simple request/response model in a master/slave context or
   very limited negotiation abilities.

   There are also signalling protocols with an element of negotiation.
   For example Resource ReSerVation Protocol (RSVP) [RFC2205] was
   designed for negotiating quality of service parameters along the path
   of a unicast or multicast flow.  RSVP is a very specialised protocol
   aimed at end-to-end flows.  However, it has some flexibility, having
   been extended for MPLS label distribution [RFC3209].  A more generic
   design is General Internet Signalling Transport (GIST) [RFC5971], but
   it is complex, tries to solve many problems, and is also aimed at
   per-flow signalling across many hops rather than at device-to-device
   signalling.  However, we cannot completely exclude extended RSVP or




Carpenter & Liu           Expires July 10, 2015                [Page 40]


Internet-Draft                GDN Protocol                  January 2015


   GIST as a synchronization and negotiation protocol.  They do not
   appear to be directly useable for peer discovery.

   We now consider two protocols that are works in progress at the time
   of this writing.  Firstly, RESTCONF [I-D.ietf-netconf-restconf] is a
   protocol intended to convey NETCONF information expressed in the YANG
   language via HTTP, including the ability to transit HTML
   intermediaries.  While this is a powerful approach in the context of
   centralised configuration of a complex network, it is not well
   adapted to efficient interactive negotiation between peer devices,
   especially simple ones that are unlikely to include YANG processing
   already.

   Secondly, we consider HomeNet Control Protocol (HNCP)
   [I-D.ietf-homenet-hncp].  This is defined as "a minimalist state
   synchronization protocol for Homenet routers."

   NOTE: HNCP is under revision at the time of this writing, so the
   following comments will soon be out of date.

   Specific features are:

   o  Every participating node has a unique node identifier.

   o  "HNCP is designed to operate between directly connected neighbors
      on a shared link using link-local IPv6 addresses."

   o  Currency of state is maintained by spontaneous link-local
      multicast messages.

   o  HNCP discovers and tracks link-local neighbours.

   o  HNCP messages are encoded as a sequence of TLV objects, sent over
      UDP.

   o  Authentication depends on a signature TLV (assuming public keys
      are associated with node identifiers).

   o  The functionality covered initially includes: site border
      discovery, prefix assignment, DNS namespace discovery, and routing
      protocol selection.

   Clearly HNCP does not completely meet the needs of a general
   negotiation protocol, especially due to its limitation to link-local
   messages and its strict dependency on IPv6, but at the minimum it is
   a very interesting test case for this style of interaction between
   devices without needing a central authority.




Carpenter & Liu           Expires July 10, 2015                [Page 41]


Internet-Draft                GDN Protocol                  January 2015


   A proposal has been made for an IP based Generic Control Protocol
   (IGCP) [I-D.chaparadza-intarea-igcp].  This is aimed at information
   exchange and negotiation but not directly at peer discovery.
   However, it has many points in common with the present work.

   None of the above solutions appears to completely meet the needs of
   discovery, state synchronization and negotiation in the general case.
   Neither is there an obvious combination of protocols that does so.
   Therefore, this document proposes the design of a protocol that does
   meet those needs.  However, this proposal needs to be confronted with
   alternatives such as extension and adaptation of GIST or HNCP, or
   combination with IGCP.

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


















Carpenter & Liu           Expires July 10, 2015                [Page 42]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/