One document matched: draft-carpenter-anima-gdn-protocol-00.xml
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<rfc category="std" docName="draft-carpenter-anima-gdn-protocol-00"
ipr="trust200902">
<front>
<title abbrev="GDN Protocol">A Generic Discovery and Negotiation Protocol
for Autonomic Networking</title>
<author fullname="Brian Carpenter" initials="B. E." surname="Carpenter">
<organization abbrev="Univ. of Auckland"></organization>
<address>
<postal>
<street>Department of Computer Science</street>
<street>University of Auckland</street>
<street>PB 92019</street>
<city>Auckland</city>
<region></region>
<code>1142</code>
<country>New Zealand</country>
</postal>
<email>brian.e.carpenter@gmail.com</email>
</address>
</author>
<author fullname="Sheng Jiang" initials="S." surname="Jiang">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus</street>
<street>No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing</city>
<code>100095</code>
<country>P.R. China</country>
</postal>
<email>jiangsheng@huawei.com</email>
</address>
</author>
<author fullname="Bing Liu" initials="B." surname="Liu">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus</street>
<street>No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing</city>
<code>100095</code>
<country>P.R. China</country>
</postal>
<email>leo.liubing@huawei.com</email>
</address>
</author>
<!---->
<date day="" month="" year="2014" />
<abstract>
<t>This document defines a new protocol that enables intelligent devices
to dynamically discover peer devices, to synchronize state with them,
and to negotiate mutual configurations with them. This document only
defines a general protocol as a negotiation platform, while the
negotiation objectives for specific scenarios are to be described in
separate documents.</t>
</abstract>
</front>
<middle>
<section anchor="intro" title="Introduction">
<t>The success of the Internet has made IP-based networks bigger and
more complicated. Large-scale ISP networks have become more and more
problematic for human based management. Also operational costs are
growing quickly. Consequently, there are therefore increased
requirements for autonomy in the networks. General aspects of autonomic
networks are discussed in <xref
target="I-D.irtf-nmrg-autonomic-network-definitions"></xref> and <xref
target="I-D.irtf-nmrg-an-gap-analysis"></xref>. In order to fulfil
autonomy, devices that are more intelligent need to be able to discover
each other, to synchronize state with each other, and negotiate directly
with each other.</t>
<t>Following this Introduction and the definition of useful terminology,
<xref target="reqts"></xref> describes the requirements and application
scenarios for network device negotiation. Then the negotiation
capabilities of various existing protocols are reviewed in <xref
target="current"></xref>. State synchronization, when needed, can be
considered as a special case of negotiation. Prior to negotiation or
synchronization, devices must discover each other. <xref
target="highlevel"></xref> describes a behavior model for a protocol
intended to support discovery, synchronization and negotiation. The
design of Generic Discovery and Negotiation Protocol (GDNP) in <xref
target="Overview"></xref> of this document is mainly based on this
behavior model.</t>
<t>Although many negotiations may happen between horizontally
distributed peers, the main target scenarios are still hierarchical
networks, which is the major structure of current large-scale networks.
Thus, where necessary, we assume that each network element has a
hierarchical superior. Of course, the protocol itself is capable of
being used in a small and/or flat network structure such as a small
office or home network, too.</t>
<t>This document defines a Generic Discovery and Negotiation Protocol
(GDNP), that can be used to perform decision process among distributed
devices or between networks. The newly defined GDNP in this document
adapts a tight certificate-based mechanism, which needs a Public Key
Infrastructure (PKI, <xref target="RFC5280"></xref>) system. The PKI may
be managed by an operator or be autonomic. The document also introduces
a new discovery mechanism, which is based on a neighbor learning process
and is oriented towards negotiation objectives.</t>
<t>It is understood that in realistic deployments, not all devices will
support GDNP. Such mixed scenarios are not discussed in this
specification.</t>
</section>
<!-- intro -->
<section title="Requirements Language and Terminology">
<t>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 <xref
target="RFC2119"></xref> when they appear in ALL CAPS. When these words
are not in ALL CAPS (such as "should" or "Should"), they have their
usual English meanings, and are not to be interpreted as <xref
target="RFC2119"></xref> key words.</t>
<t><list style="symbols">
<t>Discovery: a process by which a device discovers peer devices
according to a specific discovery objective. The discovery results
may be different according to the different discovery objectives.
The discovered peer devices may later be used as negotiation
counterparts.</t>
<t>Negotiation: a process by which two (or more) devices interact
iteratively to agree on parameter settings that best satisfy the
objectives of one or more devices.</t>
<t>State Synchronization: a process by which two (or more) devices
interact iteratively to agree on the current state of parameter
values stored in each device. This is a special case of negotiation
in which information is exchanged but the devices do not request
their peers to change parameter settings. All other definitions
apply to both negotiation and synchronization.</t>
<t>Discovery Objective: a specific functionality, role-based network
element or service agent (TBD) which the discovery initiator intends
to discover. One device may support multiple discovery
objectives.</t>
<t>Discovery Initiator: a device that spontaneously starts discovery
by sending a discovery message referring to a specific discovery
objective.</t>
<t>Discovery Responder: a peer device which responds to the
discovery objective initiated by the discovery initiator.</t>
<t>Negotiation Objective: specific negotiation content, which needs
to be decided in coordination with another network device. It is
naturally based on a specific service or function or action. It
could be a logical, numeric, or string value or a more complex data
structure.</t>
<t>Negotiation Initiator: a device that spontaneously starts
negotiation by sending a request message referring to a specific
negotiation objective.</t>
<t>Negotiation Counterpart: a peer device with which the Negotiation
Initiator negotiates a specific negotiation objective.</t>
<t>Device Identifier: a public key, which identifies the device in
CDNP messages. It is assumed that its associated private key is
maintained in the device only.</t>
<t>Device Certificate: A certificate for a single device, also the
identifier of the device, further described in <xref
target="DeviceID"></xref>.</t>
<t>Device Certificate Tag: a tag, which is bound to the device
identifier. It is used to present Device Certificate in short
form.</t>
</list></t>
</section>
<section anchor="reqts"
title="Requirement Analysis of Discovery, Synchronization and Negotiation">
<t>This section discusses the requirements for discovery, negotiation
and synchronization capabilities.</t>
<section title="Requirements for Discovery">
<t>In an autonomic network we must assume that when a device starts up
it has no information about any peer devices. In some cases, when a
new user session starts up, the device concerned may again lack
information about relevant peer devices. It might be necessary to set
up resources on multiple other devices, coordinated and matched to
each other so that there is no wasted resource. Security settings
might also need updating to allow for the new device or user.
Therefore a basic requirement is that there must be a mechanism by
which a device can discover peer devices. These devices might be
immediate neighbors on the same layer 2 link or they might be more
distant and only accessible via layer 3.</t>
<t>The relevant peer devices may be different for different discovery
objectives. Therefore discovery needs to be repeated as often as
necessary to find peers capable of acting as counterparts for each
objective that a discovery initiator needs to handle. In many
scenarios, discovery process may follow up by negotiation process.
Correspondently, the discovery objective may associate with the
negotiation objective.</t>
<t>In most networks, as mentioned above, there will be some
hierarchical structure. A special case of discovery is that each
device must be able to discover its hierarchical superior for each
negotiation objective that it is capable of handling.</t>
<t>During initialisation, a device must be able to discover the
appropriate trust anchor. Logically, this is just a specific case of
discovery. However, it might be a special case requiring its own
solution. This question requires further study.</t>
</section>
<section title="Requirements for Synchronization and Negotiation Capability">
<t>We start by considering routing protocols, the closest
approximation to autonomic networking in widespread use. Routing
protocols use a largely autonomic model based on distributed devices
that communicate iteratively with each other. However, routing is
mainly based on one-way information announcements (in either
direction), rather than on bi-directional negotiation. The only focus
is reachability, so current routing protocols only consider simple
link status, as up or down. More information, such as latency,
congestion, capacity, and particularly unused capacity, would be
helpful to get better path selection and utilization rate. Also,
autonomic networks need to be able to manage many more dimensions,
such as security settings, power saving, load balancing, etc. A basic
requirement for the protocol is therefore the ability to represent,
discover, synchronize and negotiate almost any kind of network
parameter.</t>
<t>Human intervention in complex situations is costly and error-prone.
Therefore, a negotiation model without human intervention is desirable
whenever the coordination of multiple devices can provide better
overall network performance. Therefore a requirement for the protocol
is to be capable of being installed in any device that would otherwise
need human intervention.</t>
<t>Human intervention in large networks is often replaced by use of a
top-down network management system (NMS). It follows that a
requirement for the protocol is to be capable of being installed in
any device that would otherwise be managed by an NMS, and that it can
co-exist with an NMS.</t>
<t>Since the goal is no human intervention, it is necessary that the
network can in effect "think ahead" before changing its parameters. In
other words there must be a possibility of forecasting the effect of a
change. Stated differently, the protocol must be capable of supporting
a "dry run" of a changed configuration before actually installing the
change.</t>
<!-- These fragments are use cases, not requirements:
<t> Another area is tunnel management, with automatic setup,
maintenance, and removal. A related area is ad hoc routes, without
encapsulation, to handle specific traffic flows (which might be
regarded as a form of software defined networking). </t>
<t>Negotiation of security mechanisms, for example to determine the
strongest possible protection for a given link, is another example.
</t> -->
<t>Status information and traffic metrics need to be shared between
nodes for dynamic adjustment of resources and for monitoring purposes.
While this might be achieved by existing protocols when they are
available, the new protocol needs to be able to support parameter
exchange, including mutual synchronization, even when no negotiation
as such is required.</t>
<t>Recovery from faults and identification of faulty devices should be
as automatic as possible. The protocol needs to be capable of
detecting unexpected events such a negotiation counterpart failing, so
that all devices concerned can initiate a recovery process.</t>
<t>The protocol needs to be able to deal with a wide variety of
negotiation objectives, covering any type of network parameter.
Therefore the protocol will need either an explicit information model
describing its messages, or at least a flexible and extensible message
format. One design consideration is whether to adopt an existing
information model or to design a new one. Another consideration is
whether to be able to carry some or all of the message formats used by
existing configuration protocols.</t>
<t>The protocol needs to be fully secure against forged messages and
man-in-the middle attacks, and as secure as reasonably possible
against denial of service attacks. It needs to be capable of
encryption in order to resist unwanted monitoring, although this
capability may not be required in all deployments.</t>
</section>
</section>
<!-- reqts -->
<section anchor="current"
title="Negotiation Capability Analysis of Current Protocols">
<t>This section discusses various existing protocols with properties
related to the above negotiation and synchronisation requirements. The
purpose is to evaluate whether any existing protocol, or a simple
combination of existing protocols, can meet those requirements.</t>
<t>The analysis does not include discovery protocols. While numerous
protocols include some form of discovery, these all appear to be very
specific in their applicability.</t>
<t>Routing protocols are mainly one-way information announcements. The
receiver makes independent decisions based on the received information
and there is no direct feedback information to the announcing peer. This
remains true even though the protocol is used in both directions between
peer routers; there is state synchronization, but no negotiation, and
each peer runs its route calculations independently.</t>
<t>Simple Network Management Protocol (SNMP) <xref
target="RFC3416"></xref> uses a command/response model not well suited
for peer negotiation. Network Configuration Protocol (NETCONF) <xref
target="RFC6241"></xref> uses an RPC model that does allow positive or
negative responses from the target system, but this is still not
adequate for negotiation.</t>
<t>There are various existing protocols that have elementary negotiation
abilities, such as Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
<xref target="RFC3315"></xref>, Neighbor Discovery (ND) <xref
target="RFC4861"></xref>, Port Control Protocol (PCP) <xref
target="RFC6887"></xref>, Remote Authentication Dial In User Service
(RADIUS) <xref target="RFC2865"></xref>, Diameter <xref
target="RFC6733"></xref>, etc. Most of them are configuration or
management protocols. However, they either provide only a simple
request/response model in a master/slave context or very limited
negotiation abilities.</t>
<t>There are also signalling protocols with an element of negotiation.
For example Resource ReSerVation Protocol (RSVP) <xref
target="RFC2205"></xref> was designed for negotiating quality of service
parameters along the path of a unicast or multicast flow. RSVP is a very
specialised protocol aimed at end-to-end flows. However, it has some
flexibility, having been extended for MPLS label distribution <xref
target="RFC3209"></xref>. A more generic design is General Internet
Signalling Transport (GIST) <xref target="RFC5971"></xref>, but it is
complex, tries to solve many problems, and is also aimed at per-flow
signalling across many hops rather than at device-to-device signalling.
However, we cannot completely exclude extended RSVP or GIST as a
synchronization and negotiation protocol. They do not appear to be
directly useable for peer discovery.</t>
<t>We now consider two protocols that are works in progress at the time
of this writing. Firstly, RESTCONF <xref
target="I-D.ietf-netconf-restconf"></xref> is a protocol intended to
convey NETCONF information expressed in the YANG language via HTTP,
including the ability to transit HTML intermediaries. While this is a
powerful approach in the context of centralised configuration of a
complex network, it is not well adapted to efficient interactive
negotiation between peer devices, especially simple ones that are
unlikely to include YANG processing already.</t>
<t>Secondly, we consider HomeNet Control Protocol (HNCP) <xref
target="I-D.ietf-homenet-hncp"></xref>. This is defined as "a minimalist
state synchronization protocol for Homenet routers." Specific features
are: <list style="symbols">
<t>Every participating node has a unique node identifier.</t>
<t>"HNCP is designed to operate between directly connected neighbors
on a shared link using link-local IPv6 addresses."</t>
<t>Currency of state is maintained by spontaneous link-local
multicast messages.</t>
<t>HNCP discovers and tracks link-local neighbours.</t>
<t>HNCP messages are encoded as a sequence of TLV objects, sent over
UDP.</t>
<t>Authentication depends on a signature TLV (assuming public keys
are associated with node identifiers).</t>
<t>The functionality covered initially includes: site border
discovery, prefix assignment, DNS namespace discovery, and routing
protocol selection.</t>
</list> Clearly HNCP does not completely meet the needs of a general
negotiation protocol, especially due to its limitation to link-local
messages and its strict dependency on IPv6, but at the minimum it is a
very interesting test case for this style of interaction between devices
without needing a central authority.</t>
<t>A proposal has been made for an IP based Generic Control Protocol
(IGCP) <xref target="I-D.chaparadza-intarea-igcp"></xref>. This is aimed
at information exchange and negotiation but not directly at peer
discovery. However, it has many points in common with the present
work.</t>
<t>None of the above solutions appears to completely meet the needs of
discovery, state synchronization and negotiation in the general case.
Neither is there an obvious combination of protocols that does so.
Therefore, the remainder of this document proposes the design of a
protocol that does meet those needs. However, this proposal needs to be
confronted with alternatives such as extension and adaptation of GIST or
HNCP, or combination with IGCP.</t>
</section>
<!-- current -->
<section anchor="Overview" title="GDNP Protocol Overview">
<!--1-->
<section anchor="highlevel" title="High-Level Design Choices">
<!--2-->
<t>This section describes a behavior model and some considerations for
designing a generic discovery and negotiation protocol, which would
act as a platform for different negotiation objectives.</t>
<t>NOTE: This protocol is described here in a stand-alone fashion as a
proof of concept. An elementary version has been prototyped by Huawei
and the Beijing University of Posts and Telecommunications. However,
this is not yet a definitive proposal for IETF adoption. In
particular, adaptation and extension of one of the protocols discussed
in <xref target="current"></xref> might be an option. Also, the
security model outlined below would in practice be part of a general
security mechanism in an autonomic control plane. This whole
specification is subject to change as a result.</t>
<t><list style="symbols">
<t>A generic platform<vspace blankLines="1" />The design of the
network device protocol is desired to be a generic platform, which
is independent from the negotiation contents. It should only take
care of the general intercommunication between negotiation
counterparts. The negotiation contents will vary according to the
various negotiation objectives and the different pairs of
negotiating counterparts.<vspace blankLines="1" /></t>
<t>Security infrastructure and trust relationship<vspace
blankLines="1" />Because this negotiation protocol may directly
cause changes to device configurations and bring significant
impacts to a running network, this protocol must be based on a
restrictive security infrastructure. It should be carefully
managed and monitored so that every device in this negotiation
system behaves well and remains well protected.<vspace
blankLines="1" />On the other hand, a limited negotiation model
might be deployed based on a limited trust relationship. For
example, between two administrative domains, devices might also
exchange limited information and negotiate some particular
configurations based on a limited conventional or contractual
trust relationship.<vspace blankLines="1" /></t>
<t>Discovery and negotiation designed together<vspace
blankLines="1" /> The discovery method and the negotiation method
are designed in the same way and can be combined when this is
useful.<vspace blankLines="1" /></t>
<t>A uniform pattern for negotiation contents<vspace
blankLines="1" />The negotiation contents should be defined
according to a uniform pattern. They could be carried either in
TLV (Type, Length and Value) format or in payloads described by a
flexible language, like XML. A protocol design should choose one
of these two. The format must be extensible for unknown future
requirements. As noted above, an existing information model and
existing message format(s) should be considered. <vspace
blankLines="1" /></t>
<t>A simple initiator/responder model<vspace blankLines="1" />
Multi-party negotiations are too complicated to be modeled and
there may be too many dependencies among the parties to converge
efficiently. A simple initiator/responder model is more feasible
and could actually complete multiple-party negotiations by
indirect steps. Naturally this process must be guaranteed to
terminate and must contain tie-breaking rules.<vspace
blankLines="1" /></t>
<t>Organizing of negotiation content<vspace
blankLines="1" />Naturally, the negotiation content should be
organized according to the relevant function or service. The
content from different functions or services should be kept
independent from each other. They should not be combined into a
single option or single session because these contents may be
negotiated with different counterparts or may be different in
response time.<vspace blankLines="1" /></t>
<t>Self aware network device<vspace blankLines="1" />Every network
device should be pre-configured with its role and functions and be
aware of its own capabilities. The roles may be only distinguished
because of network behaviors, which may include forwarding
behaviors, aggregation properties, topology location, bandwidth,
tunnel or translation properties, etc. The role and functions may
depend on the network planning. The capability is typically
decided by the hardware or firmware. These parameters are the
foundation of the negotiation behavior of a specific
device.<vspace blankLines="1" /></t>
<t>Requests and responses in negotiation procedures<vspace
blankLines="1" />The initiator should be able to negotiate with
its relevant negotiation counterpart devices, which may be
different according to the negotiation objective. It may request
relevant information from the negotiation counterpart so that it
can decide its local configuration to give the most coordinated
performance. It may request the negotiation counterpart to make a
matching configuration in order to set up a successful
communication with it. It may request certain simulation or
forecast results by sending some dry run conditions. <vspace
blankLines="1" />Beyond the traditional yes/no answer, the
responder should be able to reply with a suggested alternative if
its answer is 'no'. This would start a bi-directional negotiation
ending in a compromise between the two devices.<vspace
blankLines="1" /></t>
<t>Convergence of negotiation procedures<vspace
blankLines="1" />The negotiation procedure should move towards
convergent results. It means that when a responder makes a
suggestion of a changed condition in a negative reply, it should
be as close as possible to the original request or previous
suggestion. The suggested value of the third or later negotiation
steps should be chosen between the suggested values from the last
two negotiation steps. In any case there must be a mechanism to
guarantee rapid convergence in a small number of steps.<vspace
blankLines="1" /></t>
<t>Dependencies of negotiation<vspace blankLines="1" />In order to
decide a configuration on a device, the device may need
information from neighbors. This can be established through the
above negotiation procedure. However, a given item in a neighbor
may depend on other information from its own neighbors, which may
need another negotiation procedure to obtain or decide. Therefore,
there are dependencies among negotiation procedures. There need to
be clear boundaries and convergence mechanisms for these
negotiation dependencies. Also some mechanisms are needed to avoid
loop dependencies.<vspace blankLines="1" /></t>
<t>End of negotiation<vspace blankLines="1" />A single negotiation
procedure also needs ending conditions if it does not converge. A
limited number of rounds, for example three, should be set on the
devices. It may be an implementation choice or a pre-configurable
parameter. However, the protocol design needs to clearly specify
this, so that the negotiation can be terminated properly. In some
cases, a timeout might be needed to end a negotiation. <vspace
blankLines="1" /></t>
<t>Failed negotiation<vspace blankLines="1" />There must be a
well-defined procedure for concluding that a negotiation cannot
succeed, and if so deciding what happens next (deadlock
resolution, tie-breaking, or revert to best-effort
service).<vspace blankLines="1" /></t>
<t>Policy constraints<vspace blankLines="1" />There must be
provision for general policy rules to be applied by all devices in
the network (e.g., security rules, prefix length, resource sharing
rules). However, policy distribution might not use the negotiation
protocol itself.<vspace blankLines="1" /></t>
<t>Management monitoring, alerts and intervention<vspace
blankLines="1" />Devices should be able to report to a monitoring
system. Some events must be able to generate operator alerts and
some provision for emergency intervention must be possible (e.g.
to freeze negotiation in a mis-behaving device). These features
may not use the negotiation protocol itself.</t>
</list></t>
</section>
<!--2-->
<section title="GDNP Protocol Basic Properties and Mechanisms">
<!--2-->
<t></t>
<section title="IP Version Independent">
<!--3-->
<t>To be a generic platform, GDNP should be IP version independent.
In other words, it should be able to run over IPv6 and IPv4. Its
messages and general options are neutral with respect to the IP
version.</t>
<t>However, some functions, such as multicasting or broadcasting on
a link, might need to be IP version dependent. For these parts, the
document defines support for both IP versions separately.</t>
<t></t>
</section>
<!--3-->
<section title="Discovery Mechanism and Procedures">
<!--3-->
<t><list style="symbols">
<t>Separated discovery and negotiation mechanisms<list
style="empty">
<t>Although discovery and negotiation defined together in
the GDNP, they are separated mechanisms. The discovery
process could run independently from the negotiation
process. Upon receiving a discovery (defined in <xref
target="DiscoveryMessage"></xref>) or request message
(defined in <xref target="RequestMessage"></xref>) , the
recipient device should return a message in which it either
indicates itself as a discovery responder or diverts the
initiator towards another more suitable device.</t>
<t>The discovery objective could be network functionalities,
role-based network elements or service agents (TBD). The
discovery results could be utilized by the negotiation
protocol to decide which device the initiator will negotiate
with.</t>
</list></t>
<t>Discovery Procedures<list style="empty">
<t>Discovery starts as on-link operation. The Divert option
can tell the discovery initiator to contact an off-link
discovery objective device. Every DISCOVERY message is sent
by a discovery initiator to the ALL_GDNP_NEIGHBOR multicast
address (<xref target="Constants"></xref>). Every network
device that supports the GDNP always listens to a well-known
(UDP?) port to capture the discovery messages.</t>
<t>If the neighbor device supports a proper discovery
objective, it MAY respond with a Response message (defined
in <xref target="ResponseMessage"></xref>) with locator
option(s). Otherwise, if the neigbor device knows a device
that supports the proper discovery objective (for example
because it discovered the same objective before), it SHOULD
respond with a Response message with a Divert option pointed
to the proper discovery objective.</t>
<t>After a GDNP device successfully discovered a device
supporting a specific objective, it MUST record this
discovery objective. This record may be used for future
negotiation or to pass to another neighbor as a Divert
option. This learning mechanism should be able to support
most network establishment scenarios</t>
</list></t>
<t>Rapid Mode (Discovery/Negotiation binding)<list style="empty">
<t>A DISCOVERY message MAY includes one or more negotiation
objective option(s) to indicate to the discovery objective
that it could directly reply to the discovery initiator with
a Negotiation message for rapid processing, if the discovery
objective could act as the corresponding negotiation
counterpart. However, the indication is only advisory not
prescriptive.</t>
<t>This rapid mode could reduce the interactions between
nodes so that a higher efficiency could be achieved. This
rapid negotiation function SHOULD be configured on or off by
the administrators.</t>
</list></t>
</list></t>
</section>
<!--3-->
<section title="Certificate-based Security Mechanism">
<!--3-->
<t>A certification based security mechanism provides security
properties for CDNP:</t>
<t><list style="symbols">
<t>the identity of a GDNP message sender can be verified by a
recipient.</t>
<t>the integrity of GDNP message can be checked by the recipient
of the message.</t>
<t>anti-replay protection on the GDNP message recipient.</t>
</list>The authority of the GDNP message sender depends on a
Public Key Infrastructure (PKI) system with a Certification
Authority (CA), which should normally be run by the network
operator. In the case of a network with no operator, such as a small
office or home network, the PKI itself needs to be established by an
autonomic process, which is out of scope for this specification.</t>
<t>A Request message MUST carry a Certificate option, defined in
<xref target="CertOption"></xref>. The first Negotiation Message,
responding to a Request message, SHOULD also carry a Certificate
option. Using these messages, recipients build their certificate
stores, indexed by the Device Certificate Tags included in every
GDNP message. This process is described in more detail below.</t>
<t>Every message MUST carry a signature option, defined in <xref
target="SignOption"></xref>.</t>
<t>For now, the authors do not think packet size is a problem. In
this GDNP specification, there SHOULD NOT be multiple certificates
in a single message. The current most used public keys are 1024/2048
bits, some may reach 4096. With overhead included, a single
certificate is less than 500 bytes. Messages should be far shorter
than the normal packet MTU within a modern network.</t>
<section title="Support for algorithm agility">
<!--4-->
<t>Hash functions are used to provide message integrity checks. In
order to provide a means of addressing problems that may emerge in
the future with existing hash algorithms, as recommended in <xref
target="RFC4270"></xref>, a mechanism for negotiating the use of
more secure hashes in the future is provided.</t>
<t>In addition to hash algorithm agility, a mechanism for
signature algorithm agility is also provided.</t>
<t>The support for algorithm agility in this document is mainly a
unilateral notification mechanism from sender to recipient. If the
recipient does not support the algorithm used by the sender, it
cannot authenticate the message. Senders in a single
administrative domain are not required to upgrade to a new
algorithm simultaneously.</t>
<t>So far, the algorithm agility is supported by one-way
notification, rather than negotiation mode. As defined in <xref
target="SignOption"></xref>, the sender notifies the recipient
what hash/signature algorithms it uses. If the responder doesn't
know a new algorithm used by the sender, the negotiation request
would fail. In order to establish a negotiation session, the
sender MAY fall back to an older, less preferred algorithm. To
avoid downgrade attacks it MUST NOT fall back to an algorithm
considered weak.</t>
</section>
<!--4-->
<section title="Message validation on reception">
<!--4-->
<t>When receiving a GDNP message, a recipient MUST discard the
GDNP message if the Signature option is absent, or the Certificate
option is in a Request Message.</t>
<t>For the Request message and the Response message with a
Certification Option, the recipient MUST first check the authority
of this sender following the rules defined in <xref
target="RFC5280"></xref>. After successful authority validation,
an implementation MUST add the sender's certification into the
local trust certificate record indexed by the associated Device
Certificate Tag, defined in <xref target="DeviceID"></xref>.</t>
<t>The recipient MUST now authenticate the sender by verifying the
Signature and checking a timestamp, as specified in <xref
target="TimeCheck"></xref>. The order of two procedures is left as
an implementation decision. It is RECOMMENDED to check timestamp
first, because signature verification is much more computationally
expensive.</t>
<t>The signature field verification MUST show that the signature
has been calculated as specified in <xref
target="SignOption"></xref>. The public key used for signature
validation is obtained from the certificate either carried by the
message or found from a local trust certificate record by
searching the message-carried Device Certificate Tag.</t>
<t>Only the messages that get through both the signature
verifications and timestamp check are accepted and continue to be
handled for their contained CDNP options. Messages that do not
pass the above tests MUST be discarded as insecure messages.</t>
</section>
<!--4-->
<section anchor="TimeCheck" title="TimeStamp checking">
<!--4-->
<t>Recipients SHOULD be configured with an allowed timestamp Delta
value, a "fuzz factor" for comparisons, and an allowed clock drift
parameter. The recommended default value for the allowed Delta is
300 seconds (5 minutes); for fuzz factor 1 second; and for clock
drift, 0.01 second.</t>
<t>The timestamp is defined in the Signature Option, <xref
target="SignOption"></xref>. To facilitate timestamp checking,
each recipient SHOULD store the following information for each
sender:</t>
<t><list style="symbols">
<t>The receive time of the last received and accepted GDNP
message. This is called RDlast.</t>
<t>The time stamp in the last received and accepted GDNP
message. This is called TSlast.</t>
</list>An accepted GDNP message is any successfully verified
(for both timestamp check and signature verification) GDNP message
from the given peer. It initiates the update of the above
variables. Recipients MUST then check the Timestamp field as
follows:</t>
<t><list style="symbols">
<t>When a message is received from a new peer (i.e., one that
is not stored in the cache), the received timestamp, TSnew, is
checked, and the message is accepted if the timestamp is
recent enough to the reception time of the packet, RDnew:
<list style="empty">
<t>-Delta < (RDnew - TSnew) < +Delta</t>
</list><vspace blankLines="1" />The RDnew and TSnew values
SHOULD be stored in the cache as RDlast and TSlast.</t>
<t>When a message is received from a known peer (i.e., one
that already has an entry in the cache), the timestamp is
checked against the previously received GDNP message:<list
style="empty">
<t>TSnew + fuzz > TSlast + (RDnew - RDlast) x (1 -
drift) - fuzz</t>
</list><vspace blankLines="1" />If this inequality does not
hold, the recipient SHOULD silently discard the message. If,
on the other hand, the inequality holds, the recipient SHOULD
process the message. <vspace blankLines="1" />Moreover, if the
above inequality holds and TSnew > TSlast, the recipient
SHOULD update RDlast and TSlast. Otherwise, the recipient MUST
NOT update RDlast or TSlast.</t>
</list>An implementation MAY use some mechanism such as a
timestamp cache to strengthen resistance to replay attacks. When
there is a very large number of nodes on the same link, or when a
cache filling attack is in progress, it is possible that the cache
holding the most recent timestamp per sender will become full. In
this case, the node MUST remove some entries from the cache or
refuse some new requested entries. The specific policy as to which
entries are preferred over others is left as an implementation
decision.</t>
</section>
<!--4-->
</section>
<!--3-->
<section title="Negotiation Procedures">
<!--3-->
<t>A negotiation initiator sends a negotiation request to
counterpart devices, which may be different according to different
negotiation objectives. It may request relevant information from the
negotiation counterpart so that it can decide its local
configuration to give the most coordinated performance. This would
be sufficient in a case where the required function is limited to
state synchronization. It may additionally request the negotiation
counterpart to make a matching configuration in order to set up a
successful communication with it. It may request a certain
simulation or forecast result by sending some dry run conditions.
The details will be defined separately for each type of negotiation
objective.</t>
<t>If the counterpart can immediately apply the requested
configuration, it will give a positive (yes) answer. This will
normally end the negotiation phase immediately. Otherwise it will
give a negative (no) answer. Normally, this will not end the
negotiation phase.</t>
<t>In the negative (no) case, the negotiation counterpart should be
able to reply with a proposed alternative configuration that it can
apply (typically, a configuration that uses fewer resources than
requested by the negotiation initiator). This will start a
bi-directional negotiation to reach a compromise between the two
network devices.</t>
<t>The negotiation procedure is ended when one of the negotiation
peers sends a Negotiation Ending message, which contains an accept
or decline option and does not need a response from the negotiation
peer.</t>
<t>A negotiation procedure concerns one objective and one
counterpart. Both the initiator and the counterpart may take part in
simultaneous negotiations with various other devices, or in
simultaneous negotiations about different objectives. Thus, GDNP is
expected to be used in a multi-threaded mode. Certain negotiation
objectives may have restrictions on multi-threading, for example to
avoid over-allocating resources.</t>
</section>
<!--3-->
</section>
<!--2-->
<section anchor="Constants" title="GDNP Constants">
<!--2-->
<t><list style="symbols">
<t>ALL_GDNP_NEIGHBOR (TBD1)<vspace blankLines="1" />A link-local
scope multicast address used by a GDNP-enabled router to discover
GDNP-enabled neighbor (i.e., on-link) devices . All routers that
support GDNP are members of this multicast group.<list
style="symbols">
<t>IPv6 multicast address: TBD1</t>
<t>IPv4 multicast address: TBD2</t>
</list></t>
<t>GDNP Listen Port (TBD3)<vspace blankLines="1" />A UDP port that
every GDNP-enabled network device always listens to.</t>
</list></t>
</section>
<!--2-->
<section anchor="DeviceID" title="Device Identifier and Certificate Tag">
<!--2-->
<t>A GDNP-enabled Device MUST generate a stable public/private key
pair before it participates in GDNP. There MUST NOT be any way of
accessing the private key via the network or an operator interface.
The device then uses the public key as its identifier, which is
cryptographic in nature. It is a GDNP unique identifier for a GDNP
participant.</t>
<t>It then gets a certificate for this public key, signed by a
Certificate Authority that is trusted by other network devices. The
Certificate Authority SHOULD be managed by the network administrator,
to avoid needing to trust a third party. The signed certificate would
be used for authentication of the message sender. In a managed
network, this certification process could be performed at a central
location before the device is physically installed at its intended
location. In an unmanaged network, this process must be autonomic,
including the bootstrap phase.</t>
<t>A 128-bit Device Certifcate Tag, which is generated by taking a
cryptographic hash over the device certificate, is a short
presentation for GDNP messages. It is the index key to find the device
certificate in a recipient's local trusted certificate record.</t>
<t>The tag value is formed by taking a SHA-1 hash algorithm over the
corresponding device certificate and taking the leftmost 128 bits of
the hash result.</t>
</section>
<!--2-->
<section title="Session Identifier">
<!--2-->
<t>A 24-bit opaque value used to distinguish multiple sessions between
the same two devices. A new Session ID SHOULD be generated for every
new Request message. All follow-up messages in the same negotiation
procedure, which is initiated by the request message, SHOULD carry the
same Session ID.</t>
<t>The Session ID SHOULD have a very low collision rate locally. It is
RECOMMENDED to be generated by a pseudo-random algorithm using a seed
which is unlikely to be used by any other device in the same
network.</t>
</section>
<!--2-->
<section anchor="GDNPMessages" title="GDNP Messages">
<!--2-->
<t>This document defines the following GDNP message format and types.
Message types not listed here are reserved for future use. The numeric
encoding for each message type is shown in parentheses.</t>
<section title="GDNP Message Format">
<!--3-->
<t>All GDNP messages share an identical fixed format header and a
vaiable format area for options. Every Message carries the Device
Certificate Tag of its sender and a Session ID. Options are
presented serially in the options field, with no padding between the
options. Options are byte-aligned.</t>
<t>The following diagram illustrates the format of GDNP
messages:</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MESSAGE_TYPE | Session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Device Certificate Tag |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options (variable length) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
MESSAGE_TYPE Identifies the GDNP message type. 8-bit.
Session ID Identifies this negotiation session, as defined in
Section 6. 24-bit.
Device Certificate Tag
Present the Device Certificate, which identifies
the negotiation devices, as defined in Section 5.4.
The Device Certificate Tag is 128 bit, also defined
in Section 5. It is used as index key to find the
device certificate.
Options GDNP Options carried in this message. Options are
definded in Section 5.7, 5.8 and 5.9.
]]></artwork>
</figure></t>
</section>
<section anchor="DiscoveryMessage" title="Discovery Message">
<t><!--3--><figure>
<artwork><![CDATA[DISCOVERY (1) A discovery initiator sends a DISCOVERY message
to initiate a discovery process.
The discovery initiator sends the DISCOVERY
messages to the link-local ALL_GDNP_NEIGHBOR multicast
address for discovery, and stores the discovery
results (including responding discovery objectives and
corresponding unicast addresses or FQDNs).
A DISCOVERY message MUST include a discovery objective
option defined in Section 5.8.
A DISCOVERY message MAY include one or more negotiation
objective option(s) (defined in Section 5.9) to indicate
the discovery objective that it could directly return to
the discovery initiatior with a Negotiation message for
rapid processing, if the discovery objective could act as
the corresponding negotiation counterpart.]]></artwork>
</figure></t>
<t><!--3--></t>
</section>
<section anchor="ResponseMessage" title="Response Message">
<t><!--3--><figure>
<artwork><![CDATA[RESPONSE (2) A node which receives a DISCOVERY message sends a
Response message to respond to a discovery.
If the responding node itself is the discovery objective
of the discovery, it MUST include at least one kind of
locator option (defined in 5.7.8) to indicate its own
location. A combination of multiple kinds of locator
options (e.g. IP address option + FQDN option) is also
valid.
If the responding node itself is NOT the discovery
objective, but it knows the locator of the discovery
objective, then it SHOULD respond to the discovery with a
divert option (defined in 5.7.2) embedding a locator
option or a combination of multiple kinds of locator
options which indicate the locator(s) of the discovery
objective. ]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="RequestMessage" title="Request Message">
<!--3-->
<t><figure>
<artwork><![CDATA[REQUEST (3) A negotiation requesting node sends the REQUEST message
to the unicast address (directly stored or resolved
from the FQDN) of the negotiation counterpart (selected
from the discovery results).]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="NegotiationMessage" title="Negotiation Message">
<!--3-->
<t><figure>
<artwork><![CDATA[NEGOTIATION (4)A negotiation counterpart sends a NEGOTIATION
message in response to a REQUEST message, a
Negotiation message, or a DISCOVERY message
in a negotiation process which may need
multiple steps.]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="NegotiationEndingMessage"
title="Negotiation-ending Message">
<!--3-->
<t><figure>
<artwork><![CDATA[NEGOTIATION-ENDING (5)
A negotiation counterpart sends an NEGOTIATION-EDNING
message to close the negotiation. It MUST contain
one, but only one of accept/decline option,
defined in Section 8. It could be sent either by the
requesting node or the responding node.]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="ConfirmWaitingMessage"
title="Confirm-waiting Message">
<!--3-->
<t><figure>
<artwork><![CDATA[CONFIRM-WAITING (6)
A responding node sends a CONFIRM-WAITING message to
indicate the requesting node to wait for a further
negotiation response. It might be that the local
process needs more time or that the negotiation
depends on another triggered negotiation. This
message MUST NOT include any other options than the
WAITING option defined in Section 8.5.]]></artwork>
</figure></t>
</section>
<!--3-->
</section>
<!--2-->
<section anchor="GDNPOptions" title="GDNP General Options">
<!--2-->
<t>This section defines the GDNP general option for the negotiation
protocol signalling. Option type 10~64 is reserved for GDNP general
options defined in the future.</t>
<section title="Format of GDNP Options">
<!--3-->
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data |
| (option-len octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code An unsigned integer identifying the specific option
type carried in this option.
Option-len An unsigned integer giving the length of the
option-data field in this option in octets.
Option-data The data for the option; the format of this data
depends on the definition of the option.
]]></artwork>
</figure>GDNP options are scoped by using encapsulation. If an
option contains other options, the outer Option-len includes the
total size of the encapsulated options, and the latter apply only to
the outer option.</t>
</section>
<!--3-->
<section anchor="DivertOption" title="Divert Option">
<!--3-->
<t>The divert option is used to redirect a GDNP request to another
node, which may be more appropriate for the intended negotiation. It
may redirect to an entity that is known as a specific negotiation
counterpart or a default gateway or a hierarchically upstream
devices. The divert option MUST only be encapsulated in
Negotiation-ending messages. If found elsewhere, it SHOULD be
silently ignored.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DIVERT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator Option (s) of Diversion Device(s) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_DIVERT (1).
Option-len The total length of diverted destination
sub-option(s) in octets.
Locator Option (s) of Diverted Device(s)
Embedded Locator Option(s), defined in Section 5.7.8,
that point to diverted destination device(s).
]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="AcceptOption" title="Accept Option">
<!--3-->
<t>The accept option is used to indicate the negotiation counterpart
that the proposed negotiation content is accepted.</t>
<t>The accept option MUST only be encapsulated in Negotiation-ending
messages. If found elsewhere, it SHOULD be silently ignored.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ACCEPT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_ACCEPT (2).
Option-len 0.]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="DeclineOption" title="Decline Option">
<!--3-->
<t>The decline option is used to indicate the negotiation
counterpart the proposed negotiation content is declined and end the
negotiation process.</t>
<t>The decline option MUST only be encapsulated in
Negotiation-ending messages. If found elsewhere, it SHOULD be
silently ignored.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DECLINE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_DECLINE (3).
Option-len 0.]]></artwork>
</figure></t>
<t>Notes: there are scenarios where a negotiation counterpart wants
to decline the proposed negotiation content and continue the
negotiation process. For these scenarios, the negotiation
counterpart SHOULD use a Response message, with either an objective
option that contains at least one data field with all bits set to 1
to indicate a meaningless initial value, or a specific objective
option that provides further conditions for convergence.</t>
</section>
<!--3-->
<section anchor="WaitingTimeOption" title="Waiting Time Option ">
<!--3-->
<t>The waiting time option is used to indicate that the negotiation
counterpart needs to wait for a further negotiation response, since
the processing might need more time than usual or it might depend on
another triggered negotiation.</t>
<t>The waiting time option MUST only be encapsulated in
Confirm-waiting messages. If found elsewhere, it SHOULD be silently
ignored.</t>
<t>The counterpart SHOULD send a Response message or another
Confirm-waiting message before the current waiting time expires. If
not, the initiator SHOULD abandon or restart the negotiation
procedure, to avoid an indefinite wait.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_WAITING | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_WAITING (4).
Option-len 4, in octets.
Time The time is counted in millisecond as a unit.]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="CertOption" title="Certificate Option">
<!--3-->
<t>The Certificate option carries the certificate of the sender. The
format of the Certificate option is as follows:</t>
<t><figure>
<artwork align="center"><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION Certificate | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Certificate (variable length) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_CERT_PARAMETER (5)
Option-len Length of certificate in octets
Public key A variable-length field containing a certificate
]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="SignOption" title="Signature Option">
<!--3-->
<t>The Signature option allows public key-based signatures to be
attached to a GDNP message. The Signature option is REQUIRED in
every GDNP message and could be any place within the GDNP message.
It protects the entire GDNP header and options. A TimeStamp has been
integrated in the Signature Option for anti-replay protection. The
format of the Signature option is described as follows:</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIGNATURE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id | SA-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp (64-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Signature (variable length) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_SIGNATURE (6)
Option-len 12 + Length of Signature field in octets.
HA-id Hash Algorithm id. The hash algorithm is used for
computing the signature result. This design is
adopted in order to provide hash algorithm agility.
The value is from the Hash Algorithm for GDNP
registry in IANA. The initial value assigned
for SHA-1 is 0x0001.
SA-id Signature Algorithm id. The signature algorithm is
used for computing the signature result. This
design is adopted in order to provide signature
algorithm agility. The value is from the Signature
Algorithm for GDNP registry in IANA. The initial
value assigned for RSASSA-PKCS1-v1_5 is
0x0001.
Timestamp The current time of day (NTP-format timestamp
[RFC5905] in UTC (Coordinated Universal Time), a
64-bit unsigned fixed-point number, in seconds
relative to 0h on 1 January 1900.). It can reduce
the danger of replay attacks.
Signature A variable-length field containing a digital
signature. The signature value is computed with
the hash algorithm and the signature algorithm, as
described in HA-id and SA-id. The signature
constructed by using the sender's private key
protects the following sequence of octets:
1. The GDNP message header.
2. All GDNP options including the Signature option
(fill the signature field with zeroes).
The signature field MUST be padded, with all 0, to
the next 16 bit boundary if its size is not an even
multiple of 8 bits. The padding length depends on
the signature algorithm, which is indicated in the
SA-id field.
]]></artwork>
</figure></t>
</section>
<!--3-->
<section anchor="LocatorOption" title="Locator Options">
<!--3-->
<t>These locator options are used to present a device's or
interface's reachability information. They are Locator IPv4 Address
Option, Locator IPv6 Address Option and Locator FQDN (Fully
Qualified Domain Name) Option.</t>
<section title="Locator IPv4 address option">
<!--4-->
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_LOCATOR_IPV4ADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4-Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_LOCATOR_IPV4ADDR (7)
Option-len 4, in octets.
IPv4-Address The IPv4 address locator of the device/interface. ]]></artwork>
</figure></t>
</section>
<!--4-->
<section title="Locator IPv6 address option">
<!--4-->
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_LOCATOR_IPV6ADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6-Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_LOCATOR_IPV6ADDR (8).
Option-len 16, in octets.
IPv6-Address The IPv6 address locator of the device/interface.]]></artwork>
</figure>Note: link-local IPv6 address SHOULD be avoided when
this option is used in the Divert option. It may create a
connection problem.</t>
</section>
<!--4-->
<section title="Locator FQDN option">
<!--4-->
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_FQDN | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Fully Qualified Domain Name |
| (variable length) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_FQDN (9).
Option-len Length of Fully Qualified Domain Name in octets.
Domain-Name The Fully Qualified Domain Name of the entity.]]></artwork>
</figure></t>
</section>
<!--4-->
</section>
<!--3-->
<!---->
</section>
<!--2-->
<section anchor="DisobjOption" title="Discovery Objective Option">
<t>The discovery objective option is to express the discovery
objectives that the initiating node wants to discover.</t>
<t><figure>
<artwork><![CDATA[ 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DISOBJ | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Expression of Discovery Objectives (TBD) |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_DISOBJ (TBD).
Option-len The total length in octets.
Expression of Discovery Objectives (TBD)
This field is to express the discovery objectives
that the initiating node wants to discover. It might
be network functionality, role-based network element
or service agent.
]]></artwork>
</figure></t>
</section>
<!--2-->
<section anchor="ObjOption"
title="Negotiation Objective Options and Considerations">
<!--2-->
<t>The Negotiation Objective Options contain negotiation objectives,
which are various according to different functions/services. They MUST
be carried by Discovery, Request or Negotiation Messages only.
Objective options SHOULD be assigned an option type greater than 64 in
the GDNP option table.</t>
<t>For most scenarios, there SHOULD be initial values in the
negotiation requests. Consequently, the Objective options SHOULD
always be completely presented in a Request message. If there is no
initial value, the bits in the value field SHOULD all be set to 1 to
indicate a meaningless value, unless this is inappropriate for the
specific negotiation objective.</t>
<section title="Organizing of GDNP Options">
<!--3-->
<t>Naturally, a negotiation objective, which is based on a specific
service or function or action, SHOULD be organized as a single GDNP
option. It is NOT RECOMMENDED to organize multiple negotiation
objectives into a single option.</t>
<t>A negotiation objective may have multiple parameters. Parameters
can be categorized into two class: the obligatory ones presented as
fixed fields; and the optional ones presented in TLV sub-options. It
is NOT RECOMMENDED to split parameters in a single objective into
multiple options, unless they have different response periods. An
exception scenario may also be described by split objectives.</t>
</section>
<!--3-->
<section title="Vendor Specific Options ">
<!--3-->
<t>Option codes 128~159 have been reserved for vendor specific
options. Multiple option codes have been assigned because a single
vendor may use multiple options simultaneously. These vendor
specific options are highly likely to have different meanings when
used by different vendors. Therefore, they SHOULD NOT be used
without an explicit human decision. They are not suitable for
unmanaged networks such as home networks.</t>
</section>
<!--3-->
<section title="Experimental Options">
<!--3-->
<t>Option code 176~191 have been reserved for experimental options.
Multiple option codes have been assigned because a single experiment
may use multiple options simultaneously. These experimental options
are highly likely to have different meanings when used for different
experiments. Therefore, they SHOULD NOT be used without an explicit
human decision. They are not suitable for unmanaged networks such as
home networks.</t>
</section>
<!--3-->
</section>
<!--2-->
<section title="Items for Future Work">
<!--2-->
<t>There are a few open design questions that are worthy of more work
in the near future, as listed below:</t>
<t><list style="symbols">
<t>UDP vs TCP: For now, this specification has chosen UDP as
message transport mechanism. However, this is not closed yet. UDP
is good for short conversations, fitting the divert scenarios
well. However, it may have issues with large packets. TCP is good
for stable and long sessions, with a little bit of time
consumption during the session establishment stage. If messages
exceed a reasonable MTU, a TCP mode may be necessary.</t>
<t>Message encryption: should GDNP messages be (optionally)
encrypted as well as signed, to protect against internal
eavesdropping or monitoring within the network?</t>
<t>TLS or DTLS vs built-in security mechanism. For now, this
specification has chosen a PKI based build-in security mechanism.
However, TLS or DTLS might be chosen as security infrastructure
for simplification reasons.</t>
<t>Timeout for lost Negotiation Ending and other messages to be
added.</t>
<t>GDNP currently requires every participant to have an
NTP-synchronized clock. Is this OK for low-end devices?</t>
<t>Would use of MDNS have any impact on the Locator FQDN
option?</t>
<t>Use case. A use case may help readers to understand the
applicability of this specification. However, the authors have not
yet decided whether to have a separate document or have it in this
document. General uses cases for AN have been developed, but they
are not specific enough for this purpose.</t>
<t>Rules about how data items are defined in a negotiation
objective. Maybe a formal information model is needed.</t>
<t>We currently assume that there is only one counterpart for each
discovery action. If this is false or one negotiation request
receives multiple different responses, how does the initiator
choose between them? Could it split them into multiple follow-up
negotiations?</t>
<t>Alternatives to TLV format. It may be useful to provide a
generic method of carrying negotiation objectives in a high-level
format such as YANG or XML schema. It may also be useful to
provide a generic method of carrying existing configuration
information such as DHCP(v6) or IPv6 RA messages. These features
could be provided by encapsulating such messages in their own
TLVs.</t>
</list></t>
</section>
<!--2-->
</section>
<!--1-->
<section anchor="security" title="Security Considerations">
<t>It is obvious that a successful attack on negotiation-enabled nodes
would be extremely harmful, as such nodes might end up with a completely
undesirable configuration. Security considerations are in the following
aspects as the following.</t>
<t>- Authentication<list style="hanging">
<t>A cryptographically authenticated identity for each device is
needed in an autonomic network. It is not safe to assume that a
large network is physically secured against interference or that all
personnel are trustworthy. Each autonomic device should be capable
of proving its identity and authenticating its messages. One
approach for the negotiation protocol is using certificate-based
security mechanism and its verification mechanism in GDNP message
exchanging provides the authentication and data integrity
protection.</t>
<t>The timestamp mechanism provides an anti-replay function.</t>
<t>Since GDNP is intended to be deployed in a single administrative
domain recommended to operate its own trust anchor and CA, there is
no need for a trusted public third party.</t>
</list></t>
<t>- Privacy<list style="hanging">
<t>Generally speaking, no personal information is expected to be
involved in the negotiation protocol, so there should be no direct
impact on personal privacy. Nevertheless, traffic flow paths, VPNs,
etc. may be negotiated, which could be of interest for traffic
analysis. Also, carriers generally want to conceal details of their
network topology and traffic density from outsiders. Therefore,
since insider attacks cannot be prevented in a large carrier
network, the security mechanism for the negotiation protocol needs
to provide message confidentiality.</t>
</list></t>
<t>- DoS Attack Protection<list style="hanging">
<t>TBD.</t>
</list></t>
</section>
<section anchor="iana" title="IANA Considerations">
<t><xref target="Constants"></xref> defines the following multicast
addresses, which have been assigned by IANA for use by GDNP:</t>
<t><list style="hanging">
<t hangText="ALL_GDNP_NEIGHBOR multicast address">(IPv6): (TBD1)</t>
<t hangText="ALL_GDNP_NEIGHBOR multicast address">(IPv4): (TBD2)</t>
</list></t>
<t><xref target="Constants"></xref> defines the following UDP port,
which have been assigned by IANA for use by GDNP:</t>
<t><list style="hanging">
<t hangText="GDNP Listen Port:">(TBD3)</t>
</list></t>
<t>This document defined a new General Discovery and Negotiation
Protocol. The IANA is requested to create a new GDNP registry. The IANA
is also requested to add two new registry tables to the newly-created
GDNP registry. The two tables are the GDNP Messages table and GDNP
Options table.</t>
<t>Initial values for these registries are given below. Future
assignments are to be made through Standards Action or Specification
Required <xref target="RFC5226"></xref>. Assignments for each registry
consist of a type code value, a name and a document where the usage is
defined.</t>
<t>GDNP Messages table. The values in this table are 16-bit unsigned
integers. The following initial values are assigned in <xref
target="GDNPMessages"></xref> in this document:</t>
<t><figure>
<artwork><![CDATA[ Type | Name | RFCs
---------+-----------------------------+------------
0 |Reserved | this document
1 |Request Message | this document
2 |Negotiation Message | this document
3 |Negotiation-end Message | this document
4 |Confirm-waiting Message | this document
]]></artwork>
</figure>GDNP Options table. The values in this table are 16-bit
unsigned integers. The following initial values are assigned in <xref
target="GDNPOptions"></xref> and <xref target="ObjOption"> </xref> in
this document:</t>
<t><figure>
<artwork><![CDATA[ Type | Name | RFCs
---------+-----------------------------+------------
0 |Reserved | this document
1 |Divert Option | this document
2 |Accept Option | this document
3 |Decline Option | this document
4 |Waiting Time Option | this document
5 |Certificate Option | this document
6 |Sigature Option | this document
7 |Device IPv4 Address Option | this document
8 |Device IPv6 Address Option | this document
9 |Device FQDN Option | this document
10~64 |Reserved for future CDNP | this document
|General Options |
128~159 |Vendor Specific Options | this document
176~191 |Experimental Options | this document
]]></artwork>
</figure>The IANA is also requested to create two new registry tables
in the GDNP Parameters registry. The two tables are the Hash Algorithm
for GDNP table and the Signature Algorithm for GDNP table.</t>
<t>Initial values for these registries are given below. Future
assignments are to be made through Standards Action or Specification
Required <xref target="RFC5226"></xref>. Assignments for each registry
consist of a name, a value and a document where the algorithm is
defined.</t>
<t>Hash Algorithm for GDNP. The values in this table are 16-bit unsigned
integers. The following initial values are assigned for Hash Algorithm
for GDNP in this document:</t>
<t><figure>
<artwork><![CDATA[ Name | Value | RFCs
---------------------+-----------+------------
Reserved | 0x0000 | this document
SHA-1 | 0x0001 | this document
SHA-256 | 0x0002 | this document
]]></artwork>
</figure>Signature Algorithm for GDNP. The values in this table are
16-bit unsigned integers. The following initial values are assigned for
Signature Algorithm for GDNP in this document:</t>
<t><figure>
<artwork><![CDATA[ Name | Value | RFCs
---------------------+-----------+------------
Reserved | 0x0000 | this document
RSASSA-PKCS1-v1_5 | 0x0001 | this document
]]></artwork>
</figure></t>
</section>
<section anchor="ack" title="Acknowledgements">
<t>Valuable comments were received from Zhenbin Li, Dacheng Zhang, Rene
Struik, Dimitri Papadimitriou, and other participants in the ANIMA and
NMRG working group.</t>
<t>This document was produced using the xml2rfc tool <xref
target="RFC2629"></xref>.</t>
</section>
<section anchor="changes" title="Change log [RFC Editor: Please remove]">
<t>draft-carpenter-anima-discovery-negotiation-protocol-00, combination
of draft-jiang-config-negotiation-ps-03 and
draft-jiang-config-negotiation-protocol-02, 2014-10-08.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC2119;
<?rfc include='reference.RFC.5280'?>
</references>
<references title="Informative References">
&RFC2629;
<?rfc include='reference.RFC.5226'?>
<?rfc include='reference.RFC.4270'?>
<?rfc include='reference.RFC.5905'?>
<?rfc include='reference.RFC.6733'?>
<?rfc include='reference.RFC.2865'?>
<?rfc include='reference.RFC.4861'?>
<?rfc include='reference.RFC.5971'?>
<?rfc include='reference.RFC.6241'?>
<?rfc include='reference.RFC.3209'?>
<?rfc include='reference.RFC.2205'?>
<?rfc include='reference.RFC.3416'?>
<?rfc include='reference.RFC.3315'?>
<?rfc include='reference.RFC.6887'?>
<?rfc include='reference.I-D.ietf-homenet-hncp'?>
<?rfc include='reference.I-D.ietf-netconf-restconf'?>
<?rfc include='reference.I-D.chaparadza-intarea-igcp'?>
&DRAFT-AN-def;
&DRAFT-AN-gap;
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-22 12:39:47 |