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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 draft-ietf-anima-grasp-distribution

ANIMA WG                                                          B. Liu
INTERNET-DRAFT                                       Huawei Technologies
Intended Status: Standard Track                                  X. Xiao
Expires: June 14, 2020                                         A. Hecker
                                                MRC, Huawei Technologies
                                                                S. Jiang
                                                     Huawei Technologies
                                                           Z. Despotovic
                                                MRC, Huawei Technologies
                                                       December 12, 2019


            Information Distribution in Autonomic Networking
                 draft-liu-anima-grasp-distribution-13

Abstract

   This document proposes a solution for information distribution in
   autonomic networks. Information distribution is categorized into two
   different modes: 1) instantaneous distribution; 2) publication for
   retrieval. In the former case, the information is sent, propagates
   and is disposed of after reception. In the latter case, information
   needs to be stored in the network.

   The capabilities to distribute information are basic and fundamental
   needs for an autonomous network (cf. ANI [I-D.ietf-anima-reference-
   model]). This document describes typical use cases of information
   distribution in ANI and requirements to ANI, such that rich
   information distribution can be natively supported. The document
   proposes extensions to the autonomic nodes and suggests an
   implementation based on GRASP extensions as a protocol on the wire.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at



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   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3. Requirements of Enriched Information Distribution . . . . . . .  4
   4. Node Behaviors  . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.1 Instant Information Distribution (IID) Sub-module  . . . . .  5
     4.2 Asynchronous Information Distribution (AID) Sub-module . . .  6
     4.3 Summary  . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   5. Extending GRASP for Information Distribution  . . . . . . . . . 10
     5.1 Realizing Instant P2P Transmission . . . . . . . . . . . . . 10
     5.2 Realizing Instant Selective Flooding . . . . . . . . . . . . 11
     5.3 Realizing Subscription as An Event . . . . . . . . . . . . . 11
     5.4 Un_Subscription Objective Option . . . . . . . . . . . . . . 12
     5.5 Publishing Objective Option  . . . . . . . . . . . . . . . . 12
   6. Security Considerations . . . . . . . . . . . . . . . . . . . . 13
   7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1 Normative References . . . . . . . . . . . . . . . . . . . . 13
     8.2 Informative References . . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
   Appendix A. Real-world Use Cases of Information Distribution . . . 15
   Appendix B. Information Distribution Module in ANI . . . . . . . . 18
   Appendix C. Asynchronous Information Distribution Integrated
            with GRASP APIs . . . . . . . . . . . . . . . . . . . . . 18



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1  Introduction

   In an autonomic network, autonomic functions (AFs) running on
   autonomic nodes constantly exchange information, e.g. AF
   control/management signaling or AF data exchange. This document
   discusses the information distribution capability of such exchanges
   between AFs.

   Depending on the number of participants, the information can be
   distributed in in the following scenarios:

      1) Point-to-point (P2P) Communication: information is exchanged
      between parties, i.e. two nodes.

      2) One-to-Many Communication: information exchanges involve an
      information source and multiple receivers.

   The approaches to information distribution can be chiefly categorized
   into two basic modes:

      1) An instantaneous mode (push): a source sends the actual content
      (e.g. control/management signaling, synchronization data and so
      on) to all interested receiver(s) immediately. Generally, some
      preconfiguration is required, as nodes interested in this
      information must be already known to all nodes in the sense that
      any receiving node must be able to decide, to which nodes this
      data is to be sent.

      2) An asynchronous mode (delayed pull): here, a source publishes
      the content in some form in the network, which may later be looked
      for, found and retrieved by some endpoints in the AN. Here,
      depending on the size of the content, either the whole content or
      only its metadata might be published into the AN. In the latter
      case the metadata (e.g. a content descriptor, e.g. a key, and a
      location in the ANI) may be used for the actual retrieval.
      Importantly, the source, i.e. here publisher, needs to be able to
      determine the node, where the information (or its metadata) can be
      stored.

   To avoid repetitive implementations by each AF developer, this
   document opts for a common support for information distribution
   implemented as a basic ANI capability, therefore available to all
   AFs. In fact, GRASP already provides part of the capabilities.

   Regardless, an AF may still define and implement its own information
   distribution capability. Such a capability may then be advertised
   using the common information distribution capability defined in this
   document. Overall, ANI nodes and AFs may decide, which of the



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   information distribution mechanisms they want to use for which type
   of information, according to their own preferences (e.g. semantic
   routing table, etc.)

   This document first analyzes requirements for information
   distribution in autonomic networks (Section 3) and then discuss the
   relevant node behavior (Section 4). After that, the required GRASP
   extensions are formally introduced (Section 5).

2. Terminology

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





































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3. Requirements for Information Distribution in ANI

   The question of information distribution in an autonomic network can
   be discussed through particular use cases or more generally.
   Depending on the situation it can be quite simple or might require
   more complex provisions.

   Indeed, in the simplest case, the information can be sent:
   1) at once (in one packet, in one flow),
   2) straightaway (send-and-forget),
   3) to all nodes.

   Presuming 1), 2) and 3) hold, information distribution in smaller or
   scarce topologies can be implemented using broadcast, i.e.
   unconstrained flooding. For reasons well-understood, this approach
   has its limits in larger and denser networks. In this case, a graph
   can be constructed such that it contains every node exactly once
   (e.g. a spanning tree), still allowing to distribute any information
   to all nodes straightaway. Multicast tree construction protocols
   could be used in this case. There are reasonable use cases for such
   scenarios, as presented in Appendix B.

   A more complex scenario arises, if only 1) and 2) hold, but the
   information only concerns a subset of nodes. Then, some kind of
   selection becomes required, to which nodes the given information
   should be distributed. Here, a further distinction is necessary;
   notably, if the selection of the target nodes is with respect to the
   nature or position of the node, or whether it is with respect to the
   information content. If the first, some knowledge about the node
   types, its topological position, etc (e.g. the routing information
   within ANI) can be used to distinguish nodes accordingly. For
   instance, edge nodes and forwarding nodes can be distinguished in
   this way. If the distribution scope is primarily to be defined by the
   information elements, then a registration / join / subscription or
   label distribution mechanism is unavoidable. This would be the case,
   for instance, if the AFs can be dynamically deployed on nodes, and
   the information is majorily destined to the AFs. Then, depending on
   the current AF deployment, the distribution scope must be adjusted as
   well.

   If only 1) holds, but the information content might be required again
   and again, or might not yet be fully available, then more complex
   mechanisms might be required to store the information within the
   network for later, for further redistribution, and for notification
   of interested nodes. Examples for this include distribution of
   reconfiguration information for different AF instances, which might
   not require an immediate action, but only an eventual update of the
   parameters. Also, in some situations, there could be a significant



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   delay between the occurrence of a new event and the full content
   availability (e.g. if the processing requires a lot of time).

   Finally, none of the three might hold. Then, along with the
   subscription and notification, the actual content might be different
   from its metadata, i.e. some description of the content and,
   possibly, its location. The fetching can then be implemented in
   different, appropriate ways, if necessary as a complex transport
   session.

   In essence, as flooding is usually not an option, and the interest of
   nodes for particular information elements can change over time, ANI
   should support autonomics also for the information distribution.

   This calls for autonomic mechanisms in the ANI, allowing
   participating nodes to 1) advertise or publish 2) look for or
   subscribe to 3) store 4) fetch/retrieve 5) instantaneously push
   information elements.

   In the following cases, situations depicting diverse information
   distribution needs are discussed.

      1) Long Communication Intervals. The actual sending of the
      information is not necessarily instantaneous with some event.
      Advanced AFs may involve into longer jobs/tasks (e.g. database
      lookup, authentication etc.) when processing requests, and might
      not be able to reply immediately. Instead of actively waiting for
      the reply, a better way for an interested AF might be to get
      notified, when the reply is finally available.

      2) Common Interest Distribution. AFs may share interest in common
      information. For example, the network intent will be distributed
      to network nodes enrolled, which is usually one-to-many scenario.
      Intent distribution can also be performed by an instant flooding
      (e.g. via GRASP) to every network node. However, because of
      network dynamics, not every node can be just ready at the moment
      when the network intent is broadcast. Also, a flooding often does
      not cover all network nodes as there is usually a limitation on
      the hop number. In fact, nodes may join in the network
      sequentially. In this situation, an asynchronous communication
      model could be a better choice where every (newly joining) node
      can subscribe the intent information and will get notified if it
      is ready (or updated).

      3) Distributed Coordination. With computing and storage resources
      on autonomic nodes, alive AFs not only consume but also generate
      data information. An example is AFs coordinating with each other
      as distributed schedulers, responding to service requests and



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      distributing tasks. It is critical for those AFs to make correct
      decisions based on local information, which might be asymmetric as
      well. AFs may also need synthetic/aggregated data information
      (e.g. statistic info, like average values of several AFs, etc.) to
      make decisions. In these situations, AFs will need an efficient
      way to form a global view of the network (e.g. about resource
      consumption, bandwidth and statistics). Obviously, purely relying
      on instant communication model is inefficient, while a scalable,
      common, yet distributed data layer, on which AFs can store and
      share information in an asynchronous way, should be a better
      choice.

   Therefore, for ANI, in order to support various communication
   scenarios, an information distribution module is required, and both
   instantaneous and asynchronous communication models should be
   supported. Some real-world use cases are introduced in Appendix A.


4. Node Behaviors

   In this section, how a node should behave in order to support the two
   identified modes of information distribution is discussed. An ANI is
   a distributed system, so the information distribution module must be
   implemented in a distributed way as well.

4.1 Instant Information Distribution (IID) Sub-module

   In this case, An information sender directly specifies the
   information receiver(s). The instant information distribution sub-
   module will be the main element.

 4.1.1 Instant P2P Communication

   IID sub-module performs instant information transmission for ASAs
   running in an ANI. In specific, IID sub-module will have to retrieve
   the address of the information receiver specified by an ASA, then
   deliver the information to the receiver. Such a delivery can be done
   either in a connectionless or a connection-oriented way.

   Current GRASP provides the capability to support instant P2P
   synchronization for ASAs. A P2P synchronization is a use case of P2P
   information transmission. However, as mention in Section 3, there are
   some scenarios where one node needs to transmit some information to
   another node(s). This is different to synchronization because after
   transmitting the information, the local status of the information
   does not have to be the same as the information sent to the receiver.
   This is not directly support by existing GRASP.




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 4.1.2 Instant Flooding Communication

   IID sub-module finishes instant flooding for ASAs in an ANI. Instant
   flooding is for all ASAs in an ANI. An information sender has to
   specify a special destination address of the information and
   broadcast to all interfaces to its neighbors. When another IID sub-
   module receives such a broadcast, after checking its TTL, it further
   broadcast the message to the neighbors. In order to avoid flooding
   storms in an ANI, usually a TTL number is specified, so that after a
   pre-defined limit, the flooding message will not be further broadcast
   again.

   In order to avoid unnecessary flooding, a selective flooding can be
   done where an information sender wants to send information to
   multiple receivers at once. When doing this, sending information
   needs to contain criteria to judge on which interfaces the
   distributed information should and should not be sent. Specifically,
   the criteria contain:

      o  Matching Condition: a set of matching rules such as addresses
      of recipients, node features and so on.

      o  Action: what the node needs to do when the Matching Condition
      is fulfilled. For example, the action could be forwarding or
      discarding the distributed message.

   Sent information must be included in the message distributed from the
   sender. The receiving node reacts by first checking the carried
   Matching Condition in the message to decide who should consume the
   message, which could be either the node itself, some neighbors or
   both. If the node itself is a recipient, Action field is followed; if
   a neighbor is a recipient, the message is sent accordingly.

   An exemplary extension to support selective flooding on GRASP is
   described in Section 5.

4.2 Asynchronous Information Distribution (AID) Sub-module

   In asynchronous information distribution, sender(s) and receiver(s)
   are not immediately specified while they may appear in an
   asynchronous way. Firstly, AID sub-module enables that the
   information can be stored in the network; secondly, AID sub-module
   provides an information publication and subscription (Pub/Sub)
   mechanism for ASAs.

   As sketched in the previous section, in general each node requires
   two modules: 1) Information Storage (IS) module and 2) Event Queue
   (EQ) module in the information distribution module. Details of the



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   two modules are described in the following sections.

 4.2.1 Information Storage

   IS module handles how to save and retrieve information for ASAs
   across the network. The IS module uses a syntax to index information,
   generating the hash index value (e.g. a hash value) of the
   information and mapping the hash index to a certain node in ANI. Note
   that, this mechanism can use existing solutions. Specifically,
   storing information in an ANIMA network will be realized in the
   following steps.

      1) ASA-to-IS Negotiation. An ASA calls the API provided by
      information distribution module (directly supported by IS sub-
      module) to request to store the information somewhere in the
      network. The IS module performs various checks of the request
      (e.g. permitted information size).

      2) Storing Peer Mapping. The information block will be handled by
      the IS module in order to calculate/map to a peer node in the
      network. Since ANIMA network is a peer-to-peer network, a typical
      way is to use distributed hash table (DHT) to map information to a
      unique index identifier. For example, if the size of the
      information is reasonable, the information block itself can be
      hashed, otherwise, some meta-data of the information block can be
      used to generate the mapping.

      3) Storing Peer Negotiation Request. Negotiation request of
      storing the information will be sent from the IS module to the IS
      module on the destination node. The negotiation request contains
      parameters about the information block from the source IS module.
      According to the parameters as well as the local available
      resource, the requested storing peer will send feedback the source
      IS module.

      4) Storing Peer Negotiation Response. Negotiation response from
      the storing peer is sent back to the source IS module. If the
      source IS module gets confirmation that the information can be
      stored, source IS module will prepare to transfer the information
      block; otherwise, a new storing peer must be discovered (i.e.
      going to step 7).

      5) Information Block Transfer. Before sending the information
      block to the storing peer that already accepts the request, the IS
      module of the source node will check if the information block can
      be afforded by one GRASP message. If so, the information block
      will be directly sent by calling a GRASP API. Otherwise, a bulk
      data transmission is needed. For that, there are multiple ways to



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      do it.

      The first option is to utilize one of existing protocols that is
      independent of the GRASP stack. For example, a session
      connectivity can be established to the storing peer, and over the
      connection the bulky data can be transmitted part by part. In this
      case, the IS module should support basic TCP-based session
      protocols such as HTTP(s) or native TCP.

      The second option is to directly use GRASP itself for bulky data
      transferring. [I-D.carpenter-anima-grasp-bulk-04].

      6) Information Writing. Once the information block (or a smaller
      block) is received, the IS module of the storing peer will store
      the data block in the local storage is accessible.

      7) (Optional) New Storing Peer Discovery. If the previously
      selected storing peer is not available to store the information
      block, the source IS module will have to identify a new
      destination node to start a new negotiation. In this case, the
      discovery can be done by using discovery GRASP API to identify a
      new candidate, or more complex mechanisms can be introduced.

   Similarly, Getting information from an ANI will be realized in the
   following steps.

      1) ASA-to-IS Request. An ASA accesses the IS module via the APIs
      exposed by the information distribution module. The key/index of
      the interested information will be sent to the IS module. An
      assumption here is that the key/index should be known to an ASA
      before an ASA can ask for the information. This relates to the
      publishing/subscribing of the information, which are handled by
      other modules (e.g. Event Queue with Pub/Sub supported by GRASP).

      2) Storing Peer Mapping. IS module maps the key/index of the
      requested information to a peer that stores the information, and
      prepares the information request. The mapping here follows the
      same mechanism when the information is stored.

      3) Retrieval Negotiation Request. The source IS module sends a
      request to the storing peer and asks if such an information object
      is available.

      4) Retrieval Negotiation Response. The storing peer checks the
      key/index of the information in the request, and replies to the
      source IS module. If the information is found and the information
      block can be afforded within one GRASP message, the information
      will be sent together with the response to the source IS module.



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      5) (Optional) New Destination Request. If the information is not
      found after the source IS module gets the response from the
      originally identified storing peer, the source IS module will have
      to discover the location of the requested information.

   IS module can reuse distributed databases and key value stores like
   NoSQL, Cassandra, DHT technologies. storage and retrieval of
   information are all event-driven responsible by the EQ module.

 4.2.2 Event Queue The Event Queue (EQ) module is to help ASAs to
   publish information to the network and subscribe to interested
   information in asynchronous scenarios. In an ANI, information
   generated on network    nodes is an event labeled with an event ID,
   which is semantically related to the topic of the information. Key
   features of EQ module are summarized as follows.

   1) Event Group: An EQ module provides isolated queues for different
   event groups. If two groups of AFs could have completely different
   purposes, the EQ module allows to create multiple queues where only
   AFs interested in the same topic will be aware of the corresponding
   event queue.

   2) Event Prioritization: Events can have different priorities in ANI.
   This corresponds to how much important or urgent the event implies.
   Some of them are more urgent than regular ones. Prioritization allows
   AFs to differentiate events (i.e. information) they publish or
   subscribe to.

   3) Event Matching: an information consumer has to be identified from
   the queue in order to deliver the information from the provider.
   Event matching keeps looking for the subscriptions in the queue to
   see if there is an exact published event there. Whenever a match is
   found, it will notify the upper layer to inform the corresponding
   ASAs who are the information provider and subscriber(s) respectively.

   The EQ module on every network node operates as follows.

      1) Event ID Generation: If information of an ASA is ready, an
      event ID is generated according to the content of the information.
      This is also related to how the information is stored/saved by the
      IS module introduced before. Meanwhile, the type of the event is
      also specified where it can be of control purpose or user plane
      data.

      2) Priority Specification: According to the type of the event, the
      ASA may specify its priority to say how this event is to be
      processed. By considering both aspects, the priority of the event
      will be determined.



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      3) Event Enqueue: Given the event ID, event group and its
      priority, a queue is identified locally if all criteria can be
      satisfied. If there is such a queue, the event will be simply
      added into the queue, otherwise a new queue will be created to
      accommodate such an event.

      4) Event Propagation: The published event will be propagated to
      the other network nodes in the ANIMA domain. A propagation
      algorithm can be employed to optimize the propagation efficiency
      of the updated event queue states.

      5) Event Match and Notification: While propagating updated event
      states, EQ module in parallel keeps matching published events and
      its interested consumers. Once a match is found, the provider and
      subscriber(s) will be notified for final information retrieval.

   The category of event priority is defined as the following. In
   general, there are two event types:

      1) Network Control Event: This type of events are defined by the
      ANI for operational purposes on network control. A pre-defined
      priority levels for required system messages is suggested. For
      highest level to lowest level, the priority value ranges from
      NC_PRIOR_HIGH to NC_PRIOR_LOW as integer values. The NC_PRIOR_*
      values will be defined later according to the total number system
      events required by the ANI;

      2) Custom ASA Event: This type of events are defined by the ASAs
      of users. This specifies the priority of the message within a
      group of ASAs, therefore it is only effective among ASAs that join
      the same message group. Within the message group, a group
      header/leader has to define a list of priority levels ranging from
      CUST_PRIOR_HIGH to CUST_PRIOR_LOW. Such a definition completely
      depends on the individual purposes of the message group.

      When a system message is delivered, its event type and event
      priority value have to be both specified;

   Event contains the address where the information is stored, after a
   subscriber is notified, it directly retrieves the information from
   the given location.

4.3 Summary

   In summary, the general requirements for the information distribution
   module on each autonomic node are realized by two sub-modules
   handling instant communications and asynchronous communications,
   respectively. For instantaneous mode, node requirements are simple,



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   calling for support for additional signaling. With minimum efforts,
   reusing the existing GRASP is possible.

   For asynchronous mode, information distribution module uses new
   primitives on the wire, and implements an event queue and an
   information storage mechanism. An architectural consideration on ANI
   with the information distribution module is briefly discussed in
   Appendix B.


5. Extending GRASP for Information Distribution

5.1 Realizing Instant P2P Transmission

   This could be a new message in GRASP. In fragmentary CDDL, an Un-
   solicited Synchronization message follows the pattern:

      unsolicited_synch-message = [M_UNSOLIDSYNCH, session-id,
      objective]


   A node MAY actively send a unicast Un-solicited Synchronization
   message with the Synchronization data, to another node. This MAY be
   sent to port GRASP_LISTEN_PORT at the destination address, which
   might be obtained by GRASP Discovery or other possible ways. The
   synchronization data are in the form of GRASP Option(s) for specific
   synchronization objective(s).

5.2 Realizing Instant Selective Flooding

   Since normal flooding is already supported by GRASP, this section
   only defines the selective flooding extension.

   In fragmentary CDDL, the selective flooding follows the pattern:

      selective-flood-option = [O_SELECTIVE_FLOOD, +O_MATCH-CONDITION,
   match-object, action]

         O_MATCH-CONDITION = [O_MATCH-CONDITION, Obj1, match-rule, Obj2]
         Obj1 = text

         match-rule = GREATER / LESS / WITHIN / CONTAIN

         Obj2 = text

         match-object = NEIGHBOR / SELF

         action = FORWARD / DROP



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   The option field encapsulates a match-condition option which
   represents the conditions regarding to continue or discontinue flood
   the current message. For the match-condition option, the Obj1 and
   Obj2 are to objects that need to be compared. For example, the Obj1
   could be the role of the device and Obj2 could be "RSG". The match
   rules between the two objects could be greater, less than, within, or
   contain. The match-object represents of which Obj1 belongs to, it
   could be the device itself or the neighbor(s) intended to be flooded.
   The action means, when the match rule applies, the current device
   just continues flood or discontinues.

5.3 Realizing Subscription as An Event

   In fragmentary CDDL, a Subscription Objective Option follows the
   pattern:

         subscription-objection-option = [SUBSCRIPTION, 2, 2, subobj]
         objective-name = SUBSCRIPTION

         objective-flags = 2

         loop-count = 2

         subobj = text


   This option MAY be included in GRASP M_Synchronization, when
   included, it means this message is for a subscription to a specific
   object.

5.4 Un_Subscription Objective Option

   In fragmentary CDDL, a Un_Subscribe Objective Option follows the
   pattern:

      Unsubscribe-objection-option = [UNSUBSCRIB, 2, 2, unsubobj]
      objective-name = SUBSCRIPTION
      objective-flags = 2
      loop-count = 2
      unsubobj = text

   This option MAY be included in GRASP M_Synchronization, when
   included, it means this message is for a un-subscription to a
   specific object.

5.5 Publishing Objective Option

   In fragmentary CDDL, a Publish Objective Option follows the pattern:



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      publish-objection-option = [PUBLISH, 2, 2, pubobj] objective-name
      = PUBLISH
      objective-flags = 2
      loop-count = 2
      pubobj = text

   This option MAY be included in GRASP M_Synchronization, when
   included, it means this message is for a publish of a specific object
   data.
   6. Security Considerations

   The distribution source authentication could be done at multiple
   layers:

      o  Outer layer authentication: the GRASP communication is within
      ACP (Autonomic Control Plane,
      [I-D.ietf-anima-autonomic-control-plane]). This is the default
      GRASP behavior.

      o  Inner layer authentication: the GRASP communication might not
      be within a protected channel, then there should be embedded
      protection in distribution information itself. Public key
      infrastructure might be involved in this case.

7. IANA Considerations

   TBD.

8.  References

8.1 Normative References

   [I-D.ietf-anima-grasp]
              Bormann, D., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-
              animagrasp-15 (Standard Track), October 2017.

8.2 Informative References

   [RFC7575] Behringer, M., "Autonomic Networking: Definitions and
              Design Goals", RFC 7575, June 2015

   [I-D.ietf-anima-autonomic-control-plane]
              Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
              Control Plane (ACP)", draft-behringer-anima-autonomic-
              control-plane-13, December 2017.

   [I-D.ietf-anima-stable-connectivity-10]



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              Eckert, T., Behringer, M., "Using Autonomic Control Plane
              for Stable Connectivity of Network OAM", draft-ietf-anima-
              stable-connectivity-10, February 2018.

   [I-D.ietf-anima-reference-model]
              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              Pierre P., Liu, B., Nobre, J., and J. Strassner, "A
              Reference Model for Autonomic Networking", draft-ietf-
              anima-reference-model-05, October 2017.

   [I-D.du-anima-an-intent]
              Du, Z., Jiang, S., Nobre, J., Ciavaglia, L., and M.
              Behringer, "ANIMA Intent Policy and Format", draft-
              duanima-an-intent-05 (work in progress), February 2017.

   [I-D.ietf-anima-grasp-api]
              Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic
              Autonomic Signaling Protocol Application Program Interface
              (GRASP API)", draft-ietf-anima-grasp-api-00 (work in
              progress), December 2017.

   [I-D.carpenter-anima-grasp-bulk-04]
              Carpenter, B., Jiang, S., Liu, B., "Transferring Bulk Data
              over the GeneRic Autonomic Signaling Protocol (GRASP)",
              draft-carpenter-anima-grasp-bulk-04 (work in progress),
              July 3, 2019


   [3GPP.29.500]
              3GPP, "Technical Realization of Service Based
              Architecture", 3GPP TS 29.500 15.1.0, 09 2018

   [3GPP.23.501]
              3GPP, "System Architecture for the 5G System", 3GPP TS
              23.501 15.2.0, 6 2018,
              <http://www.3gpp.org/ftp/Specs/html-info/23501.htm>.

   [3GPP.23.502]
              3GPP, "Procedures for the 5G System", 3GPP TS 23.502
              15.2.0, 6 2018, <http://www.3gpp.org/ftp/Specs/html-
              info/23502.htm>.

   [5GAA.use.cases]
              White Paper "Toward fully connected vehicles: Edge
              computing for advanced automotive communications", 5GAA
              <http://5gaa.org/news/toward-fully-connected-vehicles-
              edge-computing-for-advanced-automotive-communications/>




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Authors' Addresses


   Bing Liu
   Huawei Technologies
   Q27, Huawei Campus

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

   Email: leo.liubing@huawei.com


   Sheng Jiang
   Huawei Technologies
   Q27, Huawei Campus
   No.156 Beiqing Road
   Hai-Dian District, Beijing  100095
   P.R. China

   Email: jiangsheng@huawei.com

   Xun Xiao
   Munich Research Center
   Huawei technologies
   Riesstr. 25, 80992, Muenchen, Germany

   Emails: xun.xiao@huawei.com

   Artur Hecker
   Munich Research Center
   Huawei technologies
   Riesstr. 25, 80992, Muenchen, Germany

   Emails: artur.hecker@huawei.com

   Zoran Despotovic
   Munich Research Center
   Huawei technologies
   Riesstr. 25, 80992, Muenchen, Germany

   Emails: zoran.despotovic@huawei.com



Appendix A. Real-world Use Cases of Information Distribution




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   The requirement analysis in Section 3 shows that generally
   information distribution should be better of as an infrastructure
   layer module, which provides to upper layer utilizations. In this
   section, we review some use cases from the real-world where an
   information distribution module with powerful functions do plays a
   critical role there.


   A.1 Service-Based Architecture (SBA) in 3GPP 5G

   In addition to Internet, the telecommunication network (i.e. carrier
   mobile wireless networks) is another world-wide networking system.
   The architecture of the 5G mobile networks from 3GPP has been defined
   to follow a service-based architecture (SBA) where any network
   function (NF) can be dynamically associated with any other NF(s) when
   needed to compose a network service. Note that one NF can
   simultaneously associate with multiple other NFs, instead of being
   physically wired as in the previous generations of mobile networks.
   NFs communicate with each other over service-based interface (SBI),
   which is also standardized by 3GPP [3GPP.23.501].

   In order to realize an SBA network system, detailed requirements are
   further defined to specify how NFs should interact with each other
   with information exchange over the SBI. We now list three
   requirements that are related to information distribution here.

      1) NF Pub/Sub: Any NF should be able to expose its service status
      to the network and any NF should be able to subscribe the service
      status of an NF and get notified if the status is available. A
      concrete example is that a session management function (SMF) can
      subscribe to the REGISTER notification from an access management
      function (AMF) if there is a new user equipment trying to access
      the mobile network [3GPP.23.502].

      2) Network Exposure Function (NEF): A particular network function
      that is required to manage the event exposure and distributions.
      Specifically, SBA requires such a functionality to register
      network events from the other NFs (e.g. AMF, SMF and so on),
      classify the events and properly handle event distributions
      accordingly in terms of different criteria (e.g. priorities)
      [3GPP.23.502].

      3) Network Repository Function (NRF): A particular network
      function where all service status information is stored for the
      whole network. An SBA network system requires all NFs to be
      stateless so as to improve the resilience as well as agility of
      providing network services. Therefore, the information of the
      available NFs and the service status generated by those NFs will



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      be globally stored in NRF as a repository of the system. This
      clearly implies storage capability that keeps the information in
      the network and provides those information when needed. A concrete
      example is that whenever a new NF comes up, it first of all
      registers itself at NRF with its profile. When a network service
      requires a certain NF, it first inquires NRF to retrieve the
      availability information and decides whether or not there is an
      available NF or a new NF must be instantiated [3GPP.23.502].

   (Note: 3GPP CT adopted HTTP2.0/JSON to be the protocol communicating
   between NFs, but autonomic networks can also load HTTP2.0 with in
   ACP.)

   A.2 Vehicle-to-Everything

   Connected car is one of scenarios interested in automotive
   manufacturers, carriers and vendors. 5G Automotive Alliance - an
   industry collaboration organization defines many promising use cases
   where services from car industry should be supported by the 5G mobile
   network. Here we list two examples as follows [5GAA.use.cases].

      1) Software/Firmware Update: Car manufacturers expect that the
      software/firmware of their car products can be remotely
      updated/upgraded via 5G network, instead of onsite visiting their
      4S stores/dealers offline as nowadays. This requires the network
      to provide a mechanism for vehicles to receive the latest software
      updates during a certain period of time. In order to run such a
      service for a car manufacturer, the network shall not be just like
      a network pipe anymore. Instead, information data have to be
      stored in the network, and delivered in a publishing/subscribing
      fashion. For example, the latest release of a software will be
      first distributed and stored at the access edges of the mobile
      network, after that, the updates can be pushed by the car
      manufacturer or pulled by the car owner as needed.

      2) Real-time HD Maps: Autonomous driving clearly requires much
      finer details of road maps. Finer details not only include the
      details of just static road and streets, but also real-time
      information on the road as well as the driving area for both local
      urgent situations and intelligent driving scheduling. This asks
      for situational awareness at critical road segments in cases of
      changing road conditions. Clearly, a huge amount of traffic data
      that are real-time collected will have to be stored and shared
      across the network. This clearly requires the storage capability,
      data synchronization and event notifications in urgent cases from
      the network, which are still missing at the infrastructure layer.

   A.3 Summary



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   Through the general analysis and the concrete examples from the real-
   world, we realize that the ways information are exchanged in the
   coming new scenarios are not just short and instant anymore. More
   advanced as well as diverse information distribution capabilities are
   required and should be generically supported from the infrastructure
   layer. Upper layer applications (e.g. ASAs in ANIMA) access and
   utilize such a unified mechanism for their own services.

Appendix B. Information Distribution Module in ANI

   This section describes how the information distribution module fits
   into the ANI and what extensions of GRASP are required [I-D.ietf-
   anima-grasp].

                +-------------------+
                |       ASAs        |
                +-------------------+
                        ^
                        |
                        v
    +-------------Info-Dist. APIs--------------+
    | +---------------+ +--------------------+ |
    | | Instant Dist. | | Asynchronous Dist. | |
    | +---------------+ +--------------------+ |
    +------------------------------------------+
                        ^
                        |
                        v
                +---GRASP APIs----+
                |       ACP         |
                +-----------------+

   Figure 1. Information Distribution Module and GRASP Extension.

   As the Fig 1 shows, the information distribution module two sub-
   modules for instant and asynchronous information distributions,
   respectively, and provides APIs to ASAs. Specific Behaviors of
   modules are described in Section 5.


Appendix C. Asynchronous ID Integrated with GRASP APIs

   Actions triggered to the information distribution module will
   eventually invoke underlying GRASP APIs. Moreover, EQ and IS modules
   are usually correlated. When an AF(ASA) publishes information, not
   only such an event is translated and sent to EQ module, but also the
   information is indexed and stored simultaneously. Similarly, when an
   AF(ASA) subscribes information, not only subscribing event is



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   triggered and sent to EQ module, but also the information will be
   retrieved by IS module at the same time.


   o Storing and publishing information: This action involves both IS
   and EQ modules where a node that can store the information will be
   discovered first and related event will e published to the network.
   For this, GRASP APIs discover(), synchronize() and flood() are
   combined to compose such a procedure. In specific, discover() call
   will specific its objective being to "store_data" and the return
   parameters could be either an ASA_locator who will accept to store
   the data, or an error code indicating that no one could afford such
   data; after that, synchronize() call will send the data to the
   specified ASA_locator and the data will be stored at that node, with
   return of processing results like store_data_ack; meanwhile, such a
   successful event (i.e. data is stored successfully) will be flooded
   via a flood() call to interesting parties (such a multicast group
   existed).


   o Subscribing and getting information: This action involves both IS
   and EQ modules as well where a node that is interested in a topic
   will subscribe the topic by triggering EQ module and if the topic is
   ready IS module will retrieve the content of the topic (i.e. the
   data). GRASP APIs such as register_objective(), flood(),
   synchronize() are combined to compose the procedure. In specific, any
   subscription action received by EQ module will be translated to
   register_objective() call where the interested topic will be the
   parameter inside of the call; the registration will be (selectively)
   flooded to the network by an API call of flood() with the option we
   extended in this draft; once a matched topic is found (because of the
   previous procedure), the node finding such a match will call API
   synchronize() to send the stored data to the subscriber.


















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