Internet DRAFT - draft-ietf-anima-grasp-distribution
draft-ietf-anima-grasp-distribution
Network Working Group S. Jiang, Ed.
Internet-Draft BUPT
Updates: 8990 (if approved) B. Liu, Ed.
Intended status: Experimental X. Xiao
Expires: 15 August 2024 A. Hecker
X. Zheng
Huawei Technologies
Y. Zhang
Individual
February 2024
Information Distribution over GRASP
draft-ietf-anima-grasp-distribution-11
Abstract
This document specifies experimental extensions to the GRASP protocol
to enable information distribution capabilities. The extension has
two aspects: 1) new GRASP messages and options; 2) processing
behaviors on the nodes. With these extensions, the GRASP would have
following new capabilities which make it a sufficient tool for
general information distribution: 1) Pub-Sub model of information
processing; 2) one node can actively sending data to another, without
GRASP negotiation procedures; 3) selective flooding mechanism to
allow the ASAs control the flooding scope.
This document updates RFC8990, the GeneRic Autonomic Signaling
Protocol (GRASP)[RFC8990].
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-
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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 4 August 2024.
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Copyright Notice
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Analysis of Information Distribution Modes and
Requirements . . . . . . . . . . . . . . . . . . . . . . 4
3.1. General Modes of Information Distribution . . . . . . . . 4
3.2. Gaps of Current GRASP Protocol . . . . . . . . . . . . . 5
4. GRASP Extensions for Information Distribution . . . . . . . . 5
4.1. Un-solicited Synchronization Message . . . . . . . . . . 6
4.2. Selective-Flooding Option . . . . . . . . . . . . . . . . 6
4.3. Subscription Objective Option . . . . . . . . . . . . . . 7
4.4. Unsubscription Objective Option . . . . . . . . . . . . . 7
4.5. Publishing Objective Option . . . . . . . . . . . . . . . 7
5. Processing Behaviors on GRASP Nodes . . . . . . . . . . . . . 8
5.1. Instant Information Distribution Sub-module . . . . . . . 8
5.1.1. Instant P2P Communication . . . . . . . . . . . . . . 8
5.1.2. Instant Flooding Communication . . . . . . . . . . . 8
5.2. Asynchronous Information Distribution (AID) Sub-module . 9
5.2.1. Information Storage . . . . . . . . . . . . . . . . . 9
5.2.2. Event Queue . . . . . . . . . . . . . . . . . . . . . 11
5.3. Bulk Information Transfer . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 16
10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Asynchronous Information Distribution Integrated with
GRASP APIs . . . . . . . . . . . . . . . . . . . . . . . 17
Appendix B. Possible Use Cases . . . . . . . . . . . . . . . . . 18
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B.1. In-Network Computing (INC) . . . . . . . . . . . . . . . 18
B.2. Vehicle-to-Everything (V2X) Communications . . . . . . . 19
B.3. Smart Home . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
1.1. Background
The GeneRic Autonomic Signaling Protocol (GRASP)[RFC8990] is a
signalling framework and protocol for software components in
controlled networks. These software components can use hop-by-hop
GRASP flooding and discovery mechanisms to announce and discover
services and other information amonst themselves, and GRASP unicast
for end-to-end, peer-to-peer communications.
Note: GRASP defines only the messaging layer, but not transport and
security. It requires a "security and transport substrate" to
supplement that functionality. By specifying different substrates,
GRASP deployment can be adopted to the specific requirements of the
controlled network and applications. For GRASP announcements and
discovery, the substrate primarily needs to provide a hop-by-hop
encrypted, authenticated and and reliable flooding of GRASP messages,
and for GRASP peer to peer communications it requires end-to-end
connectivity between GRASP nodes, such as IP or IPv6 and encrypted,
authenticated and reliable transport connections, such as TLS.
In Autonomic Networks [RFC7575], the software components are called
Autonomic Service Agents (ASAs) [RFC8993], and the nodes of the
controlled network are called autonomic nodes. The Autonomic
Networking Infrastructure (ANI, [RFC8994], [RFC8995]) provides the
substrate for GRASP through Local Device IDentity (LDevID)
certificates, which are zero-touch provisioned via with Bootstrapping
Remote Secure Key protocol (BRSKI) [RFC8995]. The ACP automatically
establishes a hop-by-hop secured connectivity for both hop-by-hop
forwarding of GRASP discovery and flood messages as well as end-to-
end peer-to-peer GRASP messages.
1.2. Overview
Discovery and distribution of information via GRASP as specified in
[RFC8990] is intended for instantaneous consumption: sender and
receiver need to active simultaneously, with only a limited degree of
caching by GRASP possible, but not guaranteed.
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This document defines a series of GRASP extensions in order to
support an asynchronous mode of distributing information called
publishing. These extensions are defined through new GRASP messages
to support asynchronous distribution and mechanisms for their
corresponding processing behaviors in GRASP.
In publishing for retrieval mode, information needs to be stored on
GRASP nodes and must be re-distributed on-demand. Additionally,
conflict resolution is also needed when stored information is updated
with information from multiple sources.
This document also outlines example classes of use cases to describe
different information distribution patterns supported by this
document. This is done through analysis of example existing or
planned mechanisms. While the explicitly analyzed use cases might
have already decided upon non-GRASP based mechanisms, future
instances of the same class would in the opinion to the authors fare
better with the GRASP based approach in various criteria: simpler,
more flexible or more scalable.
2. Requirements Language
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses terminology defined in [RFC7575].
3. Analysis of Information Distribution Modes and Requirements
This section summarizes the general modes of information
distribution. Then Section 3.2 describes gaps of the GRASP protocol
to support these modes of information distribution.
3.1. General Modes of Information Distribution
In a network (either in an Autonomic Network or any other networks),
the way of distributing information could be modeled from the
following two dimensions.
One dimension is from the perspective of the information distribution
participants, there are two categories as below:
1) Point-to-point (P2P) Communication: information is exchanged
between two nodes.
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2) Point-to-Multi point (P2MP) Communication: information exchanges
involve one source node and multiple receiving nodes.
The other dimension is from the timing perspective, also categorized
as two modes as below:
1) Instantaneous mode: a source node sends the actual content (e.g.
control/management signaling, synchronization data and so on to
all interested receiver(s) immediately. Generally, some pre-
configurations are required, where nodes interested in this
information must be already known to all nodes because any source
node must be able to decide, to which node the data is to be sent.
2) Asynchronous mode: here, a source node publishes the content in
some forms in the network, which may later be looked for, found
and retrieved by some other nodes. Here, depending on the size of
the content, either the whole content or only its metadata might
be published into the network. In the latter case the metadata
(e.g. a content descriptor, e.g. a key, and a location in the
network) may be used for the actual retrieval. Importantly, the
source, i.e., here as a publisher, needs to be able to determine
the location, where the information (or its metadata) can be
stored.
Note that in both cases, the total size of transferred information
can be larger than the payload size of a single message of a used
transport protocol (e.g., Synchronization and Flood messages in
GRASP). This document also gives support for bulk data transfer in
Section 5.3.
3.2. Gaps of Current GRASP Protocol
As most of instantaneous information distribution modes and their
requirements have been met by GRASP already, asynchronous information
distribution modes need new functions to be supported. In publishing
for retrieval mode, information needs to be stored and re-distributed
on-demand; additionally, conflict resolution is also needed when
stored information is updated with information from multiple sources.
To extend GRASP to support the requirements, the necessary extensions
are defined in Section 4.
4. GRASP Extensions for Information Distribution
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4.1. Un-solicited Synchronization Message
In [RFC8990], GRASP message headers and options are transmitted in
Concise Binary Object Representation (CBOR) [RFC8949]. They are
described using Concise Data Definition Language (CDDL) [RFC8610].
In this specification, an Un-solicited Synchronization message
follows the pattern, in CDDL:
unsolicited_synch-message = [M_UNSOLIDSYNCH, session-id,
objective]
A node SHOULD actively send a unicast Un-solicited Synchronization
message with the Synchronization data, to another node. This SHOULD
be sent to port GRASP_LISTEN_PORT at the destination address, which
could 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).
4.2. Selective-Flooding Option
In CDDL, a Selective-Flooding option follows the pattern:
Selective-Flooding-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
The option field encapsulates a match-condition option which
represents the conditions regarding to continue or discontinue
flooding of the current message. For the match-condition option, the
Obj1 and Obj2 are two objects that need to be compared. For example,
the Obj1 could be the role of the device and Obj2 could be "PE
Router". 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.
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4.3. Subscription Objective Option
In CDDL, a Subscription Objective Option follows the pattern:
objective = [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.
4.4. Unsubscription Objective Option
In fragmentary CDDL, a Unsubscription Objective Option follows the
pattern:
objective = [Unsubscription, 2, 2, unsubobj]
objective-name = Unsubscription
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.
4.5. Publishing Objective Option
In fragmentary CDDL, a Publishing Objective Option follows the
pattern:
objective = [Publishing, 2, 2, pubobj]
objective-name = Publishing
objective-flags = 2
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loop-count = 2
pubobj = text
This option MAY be included in GRASP M_Synchronization, when
included, it means this message is for active delivery of a specific
object data.
5. Processing Behaviors on GRASP Nodes
This section defines how a GRASP node should behave in order to
support the two identified modes of information distribution is
discussed.
5.1. Instant Information Distribution 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.
5.1.1. Instant P2P Communication
IID sub-module performs instant information transmission for ASAs The
IID sub-module has 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 mentioned 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. An extension to support instant P2P communication on
GRASP is described in Section 4. A node could send a M_UNSOLIDSYNCH
message to the GRASP_LISTEN_PORT of the corresponding node.
5.1.2. Instant Flooding Communication
IID sub-module finishes instant flooding for ASAs. Instant flooding
is for all ASAs. An information sender has to specify a special
destination address of the information and send to all GRASP
neighbors. When those GRASP neighbors IID sub- module receives such
a message, after checking its TTL, it forwards the message to its
respective GRASP neighbors. In order to avoid looping, the existing
GRASP session ID and TTL are used.
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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. An exemplary extension to support
selective flooding on GRASP is described in Section 4.
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_MATCH- CONDITION in Selective-Flooding-option: matching
condition, a set of matching rules such as addresses of
recipients, node features and so on.
* action in Selective-Flooding-option: what the node needs to do
when the Matching Condition is fulfilled. For example, the action
could be forwarding or dropping the distributed message.
Sent information must be included in the message with Selective-
Flooding-option distributed from the sender. The receiving node
reacts by first checking the carried O_MATCH- 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 in Selective-Flooding-option is followed; if a
neighbor is a recipient, the message is sent accordingly.
5.2. 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. First, the AID sub-module enables that the
information can be stored in the network; second, the AID sub-module
provides an information publication and subscription (Pub/Sub)
mechanism for ASAs.
As sketched in the previous section, each GRASP node requires two
modules: 1) Information Storage (IS) module and 2) Event Queue (EQ)
module in the information distribution module. Details of the two
modules are described in the following sections.
5.2.1. Information Storage
The Information Storage (IS) module handles how to save and retrieve
information for ASAs across the network. It makes the index of
information (e.g. by Distributed Hash Table) and maps the index to a
certain GRASP node. Storing information should be realized through
the following steps.
1) ASA-to-IS Negotiation. An ASA calls the API provided by the
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information distribution module (directly supported by the IS sub-
module) to request that the information is stored 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 MUST be handled by
the IS module in order to calculate/map to a peer node in the
network. Not all GRASP nodes may need to support storing
capabilities. Specific implementation details depends on what
information index mechanism (e.g. DHT as mentioned above) is
employed.
3) Storing Peer Negotiation Request. Negotiation request of storing
the information MUST 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. When Storing Peer Negotiation
Request is received, a Negotiation response from the storing peer
MUST be sent back to the source IS module. If the source IS
module gets confirmation that the information can be stored, the
source IS module will prepare to transfer the information block.
Otherwise, if the Negotiation response indicates the information
cannot be stored, a new storing peer MUST be discovered by the
source IS module by using discovery GRASP API to identify a new
candidate.
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 MUST check if the information block can
be afforded by one GRASP message. If so, the information block
MUST be directly sent by calling a GRASP API ([RFC8991]).
Otherwise, a bulk data transmission is needed. It can either
utilize the Bulk Information Transfer defined in Section 5.3, or
utilize one of existing protocols that is independent of the GRASP
stack.
6) Information Writing. Once the information block (or a smaller
block) is received, the IS module of the storing peer MUST store
the data block in the local storage.
Similarly, getting stored information should be realized in the
following steps.
1) ASA-to-IS Request. An ASA accesses the IS module via the APIs
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exposed by the information distribution module. The key/index of
the interested information MUST 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 MUST map 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 MUST send 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 MUST be
sent together with the response to the source IS module;
otherwise, a bulk data transmission is needed, which could be
either the Bulk Information Transfer defined in Section 5.3, or
utilize one of existing protocols that is independent of the GRASP
stack. If the information is not found, the source IS module
SHOULD re-discover an alternative peer which holds 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.
5.2.2. Event Queue
The Event Queue (EQ) module is to help ASAs to publish information to
the network and subscribe/unsubscribe to interested information in
asynchronous scenarios. Extensions to support information
publishing, subscription and unsubscription on GRASP are described in
Section 4. Information generated on GRASP 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 ASAs could have completely
different purposes, the EQ module allows to create multiple queues
where only ASAs interested in the same topic will be aware of the
corresponding event queue.
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2) Event Prioritization: Events SHOULD support different priorities.
This corresponds to how much important or urgent the event is.
Some of them are more urgent than regular ones. Prioritization
allows ASAs to differentiate events (i.e. information) they
publish, subscribe or unsubscribe 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 MUST be 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.
2) Priority Specification: According to the type of the event, the
ASA SHOULD specify its priority to say how this event is to be
processed.
3) Event Enqueue: Given the event ID, event group and its priority,
a queue MUST be identified locally if all criteria can be
satisfied. The event SHOULD be added into the queue, otherwise a
new queue will be created to accommodate such an event.
4) Event Propagation: The published event MUST be propagated to the
other GRASP nodes. A propagation algorithm SHOULD 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 MUST keep matching published events
and its interested consumers. Once a match is found, the provider
and subscriber(s) MUST 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 is defined in support
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of 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 full set of
intermediate NC_PRIOR_* values required is out of scope.
2) Custom ASA Event: This type of events is 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.
5.3. Bulk Information Transfer
Both cases discussed previously are limited to distributing messages
containing GRASP Objective Options that cannot exceed the GRASP
maximum message size of 2048 bytes. This places a limit on the size
of data that can be transferred directly in a GRASP message such as a
Synchronization or Flood operation for instantaneous information
distribution.
There are scenarios where this restriction is a problem. One case is
the distribution of network policy in lengthy YANG formats such as
XML or JSON. Another case might be ASA uploading a log file to the
Network Operations Center (NOC). A third case might be a supervisory
system downloading a software upgrade to a network node. A related
case might be installing the code of a new or updated ASA to a
network node.
Naturally, an existing solution such as a secure file transfer
protocol or secure HTTP might be used for this. Other management
protocols such as syslog [RFC5424] or NETCONF [RFC6241] might also be
used for related purposes, or might be mapped directly over GRASP.
The present document, however, applies to any scenario where it is
preferable to re-use the existing end-to-end connectivity and GRASP
infrastructure to transfer a significant amount of data, rather than
install and configure an additional mechanism.
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The node behavior is to use the GRASP Negotiation process to transfer
and acknowledge multiple blocks of data in successive negotiation
steps, thereby overcoming the GRASP message size limitation. The
emphasis is placed on simplicity rather than efficiency, high
throughput, or advanced functionality. For example, if a transfer
gets out of step or data packets are lost, the strategy is to abort
the transfer and try again. In an enterprise network with low bit
error rates, and with GRASP running over TCP or TLS, this is not
considered a serious issue.
As for any GRASP operation, the two participants are considered to be
ASA, and they communicate using a specific GRASP Objective Option,
containing their own name, some flag bits, a loop count, and a value.
In bulk transfer, we can model the ASA acting as the source of the
transfer as a download server, and the destination as a download
client. No changes or extensions are required to GRASP itself, but
compared to a normal GRASP negotiation, the communication pattern is
slightly asymmetric:
1) The client first discovers the server by the GRASP discovery
mechanism (M_DISCOVERY and M_RESPONSE messages).
2) The client then sends a GRASP negotiation request (M_REQ_NEG
message). The value of the objective expresses the requested item
(e.g., a file name - see the next section for a detailed example).
3) The server replies with a negotiation step (M_NEGOTIATE message).
The value of the objective is the first section of the requested
item (e.g., the first block of the requested file as a raw byte
string).
4) The client replies with a negotiation step (M_NEGOTIATE message).
The value of the objective is a simple acknowledgement (e.g., the
text string 'ACK').
The last two steps SHOULD be repeated until the transfer is complete.
The server SHOULD signal the end by transferring an empty byte string
as the final value. In this case the client responds with a normal
end to the negotiation (M_END message with an O_ACCEPT option).
Errors of any kind SHOULD be handled with the normal GRASP
mechanisms, in particular by an M_END message with an O_DECLINE
option in either direction. In this case the GRASP session
terminates. It is then the client's choice whether to retry the
operation from the start, as a new GRASP session, or to abandon the
transfer. The block size must be chosen such that each step does not
exceed the GRASP message size limit of 2048 bits.
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6. Security Considerations
The distribution source authentication could be done at multiple
layers:
* Outer layer authentication: the GRASP communication is within the
GRASP security and transport substrate, such as peer-to-peer TLS
connections for unicast and hop-by-hop TLS for flooding of GRASP
messages. This is the default GRASP behavior.
* Inner layer authentication: the GRASP communication might not use
a sufficient security and transport substrate, then there should
be embedded protection in distribution information itself through
authenticated GRASP messages.
7. IANA Considerations
This document defines a new GRASP message named "M_UNSOLIDSYNCH" and
a new option named "O_SELECTIVE_FLOOD" which need to be added to the
"GRASP Messages and Options" registry defined by [RFC8990]. This
document also defines three new GRASP Objectives, "Subscription",
"Unsubscription" and "Publishing" which need to be added to the
"GRASP Objective Names" table.
8. Acknowledgements
Valuable comments were received from Zoran Despotovic, Michael
Richardson, Roland Bless, Mohamed Boucadair, Diego Lopez and other
participants in the ANIMA working group.
This document was produced using the xml2rfc tool [RFC7991].
9. Contributors
Brian Carpenter
School of Computer Science
University of Auckland
PB 92019
Auckland 1142
New Zealand
Email: brian.e.carpenter@gmail.com
Toerless Eckert
Futurewei Technologies USA
Santa Clara, 95014
United States of America
Email: tte@cs.fau.de
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424,
DOI 10.17487/RFC5424, March 2009,
<https://www.rfc-editor.org/info/rfc5424>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
[RFC8990] Bormann, C., Carpenter, B., Ed., and B. Liu, Ed., "GeneRic
Autonomic Signaling Protocol (GRASP)", RFC 8990,
DOI 10.17487/RFC8990, May 2021,
<https://www.rfc-editor.org/info/rfc8990>.
[RFC8994] Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
Autonomic Control Plane (ACP)", RFC 8994,
DOI 10.17487/RFC8994, May 2021,
<https://www.rfc-editor.org/info/rfc8994>.
10.2. Informative References
[I-D.ietf-suit-manifest]
Moran, B., Tschofenig, H., Birkholz, H., Zandberg, K., and
O. Rønningstad, "A Concise Binary Object Representation
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(CBOR)-based Serialization Format for the Software Updates
for Internet of Things (SUIT) Manifest", Work in Progress,
Internet-Draft, draft-ietf-suit-manifest-25, 5 February
2024, <https://datatracker.ietf.org/doc/html/draft-ietf-
suit-manifest-25>.
[RFC7575] Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking: Definitions and Design Goals", RFC 7575,
DOI 10.17487/RFC7575, June 2015,
<https://www.rfc-editor.org/info/rfc7575>.
[RFC7991] Hoffman, P., "The "xml2rfc" Version 3 Vocabulary",
RFC 7991, DOI 10.17487/RFC7991, December 2016,
<https://www.rfc-editor.org/info/rfc7991>.
[RFC8991] Carpenter, B., Liu, B., Ed., Wang, W., and X. Gong,
"GeneRic Autonomic Signaling Protocol Application Program
Interface (GRASP API)", RFC 8991, DOI 10.17487/RFC8991,
May 2021, <https://www.rfc-editor.org/info/rfc8991>.
[RFC8993] Behringer, M., Ed., Carpenter, B., Eckert, T., Ciavaglia,
L., and J. Nobre, "A Reference Model for Autonomic
Networking", RFC 8993, DOI 10.17487/RFC8993, May 2021,
<https://www.rfc-editor.org/info/rfc8993>.
[RFC8995] Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995,
May 2021, <https://www.rfc-editor.org/info/rfc8995>.
[The-case-for-in-network-computing-on-demand]
Tokusashi, Y., "The case for in-network computing on
demand", DOI 10.1109/RECONFIG.2018.8641696, February 2019,
<https://ieeexplore.ieee.org/document/8641696>.
Appendix A. Asynchronous Information Distribution Integrated with GRASP
APIs
Actions triggered to the information distribution module will
eventually invoke an underlying GRASP APIs. Moreover, Event Queue
and Instance Storage modules are usually correlated. When an 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 ASA subscribes information, not
only subscribing event is triggered and sent to EQ module, but also
the information will be retrieved by IS module at the same time.
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* 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 specify its objective to be "store_data" and
the return parameters could be either an ASA_locator that 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).
* 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.
Appendix B. Possible Use Cases
This section describes example classes of use cases where information
distribution is required.
B.1. In-Network Computing (INC)
In-network computing (INC) has gained more and more attentions in
recent years [The-case-for-in-network-computing-on-demand]. INC
improves the utilization of the computing resources in the network;
INC also brings the processed results closer to the users, which may
potentially improves the QoS of network services.
Unlike existing network systems, INC deploys computing tasks directly
in the network rather than pushing the tasks to endpoints outside the
network. Therefore, a network device is not just a transport device,
but a mixture of forwarding, routing and computing.
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Proliferation of INC use cases will also make storage capability
support in network devices supporting INC more ubiquitous.
Furthermore, INC agents deployed on network nodes will have to
communicate with each other by exchanging information. There are
several typical applications, where information distribution
capability is required, which are summarized below.
1) Data Backup: There can be multiple computing agents that are
created to serve the same purpose(s). Multiple agents can run for
improved performance aspects such as service resilience, compute
and storage distribution or lower latency access. Multiple agent
form a service set. The instances in the service set can be
deployed at different locations in the network while they need to
keep synchronizing their local states for global consistency. In
this case, the computing agents will have to constantly send and
receive information across the network.
2) Data Aggregation: Multiple computing agents may process different
computing tasks but the derived results have to be aggregated or
combined. Then a collective result can be derived. In this case,
different computing agents collaborate with each other, where
information data is exchanged during the processing. A popular
example is distributed AI or federated learning applications,
where data is stored at different places. In distributed AI model
training, the training data also needs to be distributed. After
that, trained models by distributed agents may need to be
aggregated. Information distribution will be utilized heavily,
combining with local storage.
ASAs running on network nodes are the abstraction of the distributed
agents for the INC use case and can enable all scenarios described
above through information distribution via GRASP.
B.2. Vehicle-to-Everything (V2X) Communications
V2X communication is an inevitable enabling technology that connects
vehicles to networks, where value-added services can be provided and
enhance the functionalities of a vehicle. In this section, we
introduce some use cases that will be closely relevant to information
distribution via GRASP.
1) Real-time and High Definition Maps (HDM): In the era of
autonomous driving, a digital map is not only for navigation, but
real-time and detailed information is required when driving a
vehicle. Real-time situational awareness is essential for
autonomous vehicles especially at critical road segments in cases
of changing road conditions (e.g. new traffic cone detected by
another vehicle some time ago). In addition, the relevant high
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definition local maps have to be available with support from
infrastructure side. In this regard, a digital map should not be
considered static information stored on the vehicle, which is
spontaneously updated in a periodical manner. Instead, it shall
be considered a dynamic distribution based on information
aggregated from the local area and such a distribution shall
consider latency requirement. Clearly, the infrastructure side
shall be able to hold the information in the network sufficiently
close to the relevant area.
2) In-car Infotainment: This is another popular use case where in-
car data demands will increase significantly in the near future.
Today, users use their mobile phone to access the Internet for
retrieving data for work or entertainment purposes. There is
already a consensus among OTTs, carriers and car manufacturers
that vehicle will become the center of information for passengers
onboard. For entertainment, typical scenarios can be stereo HD
video streaming and online gaming; for business purposes, examples
can be mobile conference. This therefore requires the
infrastructure side to be able to schedule and deliver requested
information/data to the users with quality-of-service (QoS)
considerations.
3) Software Update: Software components of connected cars will be
remotely maintained in future. Therefore, software update has to
be supported by the infrastructure side. Although this can be
done by centralized solutions where all vehicles have access to
central clouds, distributed solution where the update components
can be stored in the network and delivered to endpoints in a
distributed manner, cold perform better in terms of load
balancing, reliability, performance and efficiency.
Note that there could be different models to support the potential
use cases above. The first mode is that vehicles are not part of the
GRASP deployment but simply access the edge nodes that are part of
the GRASP deployment through other protocols, and those edge nodes
form the GRASP deployment, which is using GRASP information
distribution to provide information required by the vehicles.
An alternative model is more radical, where the vehicles also belong
to the GRASP deployment, for example forwarding GRASP messages
amongst themselves when forming am edge- mesh network. This model
may further require that all entities, both at the network side and
the end point side, must be able to establish a mutual trust, such as
outlined in the introduction via LDevIDs or other type of mutually
trusted credentials.
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B.3. Smart Home
Smart homes are designed to make home life much easier. Smart homes
refer to a convenient home setup in which appliances and devices can
be remotely controlled from anywhere using a mobile or other network
device over an Internet connection. Today, devices in the smart home
are most often orchestrated over the Internet, allowing users to
remotely control functions such as home security access, temperature,
lighting, and a home theater. In this section, we present some use
cases for which GRASP with information distribution could provide a
better communications infrastructure.
1) Control Information: The control equipment often sends control
information to specific devices in real time. For example, smart
home with lighting control enables home owners to automatically
trigger lighting when and where needed, not only providing comfort
to users but also reducing electricity use. Commonly, a
controlling device sends adjustment instructions to group of
lights according to the ambient brightness in real-time. GRASP
with information distribution can provide a reliable multicast
mechanism that even works when target devices are only plugged in
after the original command.
2) Multi-Device Collaboration: Media and entertainment, which covers
integrated entertainment systems in the home, including access and
sharing of digital content on different devices, has proved to be
the most prolific. Multi-device collaboration means that multiple
devices work together to complete a service. In this case,
distributed shared objects allow automatic synchronization of
state or digital content between two or more devices.
For example, users may watch videos concurrent or consecutively on
different tablets and/or TVs in the home, and use their mobile
phones to comment on and reply to the videos. Persistent watching
state in GRASP can support these work flows. In this way,
concurrency, collaboration, and complementarity can be achieved.
In this case, devices have to synchronize the information via
GRASP instantaneously or delayed to other devices.
3) Software Upgrade: IoT devices might employ the SUIT (Software
Updates for Internet of Things) technology for software upgrade.
The SUIT working group has developed a manifest mechanism
([I-D.ietf-suit-manifest]) to allow the upgrade by fetching
content from a packet. It is a good use of GRASP information
distribution to propagate the manifest file.
Authors' Addresses
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Sheng Jiang (editor)
Beijing University of Posts and Telecommunications
No. 10 Xitucheng Road
Haidian District
Beijing
100083
China
Email: shengjiang@bupt.edu.cn
Bing Liu (editor)
Huawei Technologies
Q5, Huawei Campus
No.156 Beiqing Road
Hai-Dian District, Beijing
100095
P.R. China
Email: leo.liubing@huawei.com
Xun Xiao
Huawei Technologies
Munich Research Center
Huawei Technologies
Riesstr. 25
80992 Muenchen
Germany
Email: xun.xiao@huawei.com
Artur Hecker
Huawei Technologies
Munich Research Center
Huawei Technologies
Riesstr. 25
80992 Muenchen
Germany
Email: artur.hecker@huawei.com
Xiuli Zheng
Huawei Technologies
Q27, Huawei Campus
No.156 Beiqing Road
Hai-Dian District, Beijing
100095
P.R. China
Email: zhengxiuli@huawei.com
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Yanyan Zhang
Individual
Texas
United States of America
Email: linna.purple@gmail.com
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