Internet DRAFT - draft-jiang-config-negotiation-protocol
draft-jiang-config-negotiation-protocol
Network Working Group S. Jiang
Internet-Draft Huawei Technologies Co., Ltd
Intended status: Standards Track B. Carpenter
Expires: December 28, 2014 Univ. of Auckland
B. Liu
Huawei Technologies Co., Ltd
June 26, 2014
Configuration Discovery and Negotiation Protocol for Network Devices
draft-jiang-config-negotiation-protocol-02
Abstract
This document defines a new protocol that enables intelligent devices
to dynamically discover and negotiate their configuration with
counterpart devices. 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.
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
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and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on December 28, 2014.
Copyright Notice
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language and Terminology . . . . . . . . . . . . 4
3. CDNP Protocol Overview . . . . . . . . . . . . . . . . . . . 4
3.1. IP Version Independent . . . . . . . . . . . . . . . . . 5
3.2. Objective Oriented Discovery Mechanism . . . . . . . . . 5
3.3. Neighbor Diverting Discovery Mechanism . . . . . . . . . 5
3.4. Certificate-based Security Mechanism . . . . . . . . . . 6
3.4.1. Support for algorithm agility . . . . . . . . . . . . 7
3.4.2. Message validation on reception . . . . . . . . . . . 7
3.4.3. TimeStamp checking . . . . . . . . . . . . . . . . . 8
3.5. Negotiation Procedures . . . . . . . . . . . . . . . . . 9
4. CDNP Constants . . . . . . . . . . . . . . . . . . . . . . . 10
5. Device Identifier and Certificate Tag . . . . . . . . . . . . 10
6. Session Identifier . . . . . . . . . . . . . . . . . . . . . 11
7. CDNP Messages . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. CDNP Messsage Format . . . . . . . . . . . . . . . . . . 11
7.2. Request Message . . . . . . . . . . . . . . . . . . . . . 12
7.3. Negotiation Message . . . . . . . . . . . . . . . . . . . 12
7.4. Negotiation-ending Message . . . . . . . . . . . . . . . 13
7.5. Confirm-waiting Message . . . . . . . . . . . . . . . . . 13
8. CDNP General Options . . . . . . . . . . . . . . . . . . . . 13
8.1. Format of CDNP Options . . . . . . . . . . . . . . . . . 13
8.2. Divert Option . . . . . . . . . . . . . . . . . . . . . . 14
8.3. Accept Option . . . . . . . . . . . . . . . . . . . . . . 15
8.4. Decline Option . . . . . . . . . . . . . . . . . . . . . 15
8.5. Waiting Time Option . . . . . . . . . . . . . . . . . . . 16
8.6. Certificate Option . . . . . . . . . . . . . . . . . . . 17
8.7. Signature Option . . . . . . . . . . . . . . . . . . . . 17
8.8. Locator Options . . . . . . . . . . . . . . . . . . . . . 18
8.8.1. Locator IPv4 address option . . . . . . . . . . . . . 19
8.8.2. Locator IPv6 address option . . . . . . . . . . . . . 19
8.8.3. Locator FQDN option . . . . . . . . . . . . . . . . . 19
9. Objective Options and Considerations . . . . . . . . . . . . 20
9.1. Organizing of CDNP Options . . . . . . . . . . . . . . . 20
9.2. Vendor Specific Options . . . . . . . . . . . . . . . . . 21
9.3. Experimental Options . . . . . . . . . . . . . . . . . . 21
10. Items for Future Work . . . . . . . . . . . . . . . . . . . . 21
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
14. Change log [RFC Editor: Please remove] . . . . . . . . . . . 24
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
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15.1. Normative References . . . . . . . . . . . . . . . . . . 25
15.2. Informative References . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction
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
[I-D.irtf-nmrg-autonomic-network-definitions] and
[I-D.irtf-nmrg-an-gap-analysis]. In order to fulfil autonomy,
devices that are more intelligent need to be able to negotiate
directly with each other. [I-D.jiang-config-negotiation-ps]
describes the requirements and application scenarios for network
device negotiation. It also describes a behavior model of a generic
negotiation protocol. Prior to negotiation, devices must discover
each other. The design of Configuration Discovery and Negotiation
Protocol (CDNP) in this document is mainly based on this behavior
model.
Although many negotiations may happen between distributed horizontal
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.
This document defines a generic discovery and negotiation protocol,
named Configuration Discovery and Negotiation Protocol (CDNP), that
can be used to control decision process among distributed devices or
between networks. The newly defined CDNP in this document adapts a
tight certificate-based mechanism, which needs a Public Key
Infrastracture (PKI, [RFC5280]) 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.
It is understood that in realistic deployments, not all devices will
support CDNP. Such mixed scenarios are not discussed in this
specification.
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2. Requirements Language and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119] when they appear in ALL CAPS. When these words are not in
ALL CAPS (such as "should" or "Should"), they have their usual
English meanings, and are not to be interpreted as [RFC2119] key
words.
o 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.
o Negotiation Initiator: a device that spontaneously starts
discovery or negotiation by sending a request message referring to
a specific negotiation objective.
o Negotiation Counterpart: a peer device with which the Negotiation
Initiator negotiates a specific negotiation objective.
o Device Identifier: a public key, which identifies the device in
CDNP messages. It is assumed that its associated private key is
maintained in the device only.
o Device Certificate: A certificate for a single device, also the
identitier of the device, further described in Section 5.
o Device Certificate Tag: a tag, which is bound to the device
identitier. It is used to present Device Certificate in short
form.
3. CDNP Protocol Overview
The Configuration Discovery and Negotiation protocol is designed to
be a generic platform, which is independent from the negotiation
contents. It only takes care of the general intercommunication
between negotiation counterparts. The negotiation contents vary,
giving the various negotiation objectives and the different pairs of
negotiating counterparts. CDNP runs over UDP.
The CDNP has been designed based on simple initiator/responder model,
while multiple-party negotiations could be completed by indirect
steps. The initiator requests a particular objective and the
counterpart responds accordingly.
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3.1. IP Version Independent
To be a generic platform, CDNP 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.
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.
3.2. Objective Oriented Discovery Mechanism
Typically, one network device has multiple functions. It may be
involved in different negotiation processes for different negotiation
objectives. Therefore, the traditional topology-oriented device
discovery mechanisms are not sufficient for CDNP. A new discovery
mechanism is needed to find negotiation counterparts based on a
specific negotiation objective. As a result, an objective-based
discovery mechanism is described in this document.
For every new negotiation objective, the negotiation initiator needs
to start a new discovery process in order to find the proper
negotiation counterpart. Because a listening CDNP-enabled device has
to know the requested negotiation objective to decide whether it is a
proper negotiation counterpart and make a response, the discovery
process needs to be tightly coupled with the request process.
Therefore, in this document, the discovery process is merged into the
request process. There is no need for an independent discovery
message and process.
3.3. Neighbor Diverting Discovery Mechanism
We now discuss the general flow of Request, Negotiation, and
Negotiation-Ending messages, and Accept, Decline and Divert options.
Details of the options are given later.
Discovery starts as on-link operation. However, negotiation may
continue either on-link or off-link. The Divert option can tell the
negotiation initiator to contact an off-link counterpart.
Every Request message is sent by a negotiation initiator to the
ALL_CDNP_NEIGHBOR multicast address (Section 4).
If the neighbor device is a proper negotiation counterpart, it MAY
respond with a Negotiation message to start a negotiation process, or
with a Negotiation-Ending message in the case of a clear Accept or
Decline.
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If the neigbor device is not a proper negotiation counterpart for the
objective given in the Request message, but knows a proper
negotiation counterpart, for example because it negotiated the same
objective with that other negotiation counterpart before, it SHOULD
respond with a Negotiation-Ending message with a Divert option
pointed to the proper negotiation counterpart. If the neigbor device
is not a proper negotiation counterpart, but does not know a proper
negotiation counterpart, it SHOULD respond with a Negotiation-Ending
message with a Divert option pointed to its hierachical upstream
device.
After a CDNP device successfully negotiated a specific objective with
a negotiation counterpart, it SHOULD record this negotiation
counterpart with this objective type locally. 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.
3.4. Certificate-based Security Mechanism
A certification based security mechanism provides security properties
for CDNP:
o the identity of a CDNP message sender can be verified by a
recipient.
o the integrity of CDNP message can be checked by the recipient of
the message.
o anti-replay protection on the CDNP message recipient.
The authority of the CDNP message sender depends on a Public Key
Infrastructure (PKI) system with a Certification Authority (CA),
which should normally be run by the network operator. In the case of
a network with no operator, such as a small office or home network,
the PKI itself needs to be established by an autonomic process, which
is out of scope for this specification.
A Request message MUST carry a Certificate option, defined in
Section 8.6. The first Negotiation Message, responding to a Request
message, SHOULD also carry a Certificate option. Using these
messages, recipients build their certificate stores, indexed by the
Device Certificate Tags included in every CDNP message. This process
is described in more detail below.
Every message MUST carry a signature option, defined in Section 8.7.
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For now, the authors do not think packet size is a problem. In this
CDNP 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.
3.4.1. Support for algorithm agility
Hash functions are used to provide message integrity checks. In
order to provide a means of addressing problems that may emerge in
the future with existing hash algorithms, as recommended in
[RFC4270], a mechanism for negotiating the use of more secure hashes
in the future is provided.
In addition to hash algorithm agility, a mechanism for signature
algorithm agility is also provided.
The support for algorithm agility in this document is mainly a
unilateral notification mechanism from sender to recipient. If the
recipient does not support the algorithm used by the sender, it
cannot authenticate the message. Senders in a single administrative
domain are not required to upgrade to a new algorithm simultaneously.
So far, the algorithm agility is supported by one-way notification,
rather than negotiation mode. As defined in Section 8.7, the sender
notifies the recipient what hash/signature algorithms it uses. If
the responder doesn't know a new algorithm used by the sender, the
negotiation request would fail. In order to establish a negotiation
session, the sender MAY fall back to an older, less preferred
algorithm. To avoid downgrade attacks it MUST NOT fall back to an
algorithm considered weak.
3.4.2. Message validation on reception
When receiving a CDNP message, a recipient MUST discard the CDNP
message if the Signature option is absent, or the Certificate option
is in a Request Message.
For the Request message and the Response message with a Certification
Option, the recipient MUST first check the authority of this sender
following the rules defined in [RFC5280]. After successful authority
validation, an implementation MUST add the sender's certification
into the local trust certificate record indexed by the associated
Device Certificate Tag, defined in Section 5.
The recipient MUST now authenticate the sender by verifying the
Signature and checking a timestamp, as specified in Section 3.4.3.
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The order of two procedures is left as an implementation decision.
It is RECOMMENDED to check timestamp first, because signature
verification is much more computationally expensive.
The signature field verification MUST show that the signature has
been calculated as specified in Section 8.7. The public key used for
signature validation is obtained from the certificate either carried
by the message or found from a local trust certificate record by
searching the message-carried Device Certicate Tag.
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.
3.4.3. TimeStamp checking
Recipients SHOULD be configured with an allowed timestamp Delta
value, a "fuzz factor" for comparisons, and an allowed clock drift
parameter. The recommended default value for the allowed Delta is
300 seconds (5 minutes); for fuzz factor 1 second; and for clock
drift, 0.01 second.
The timestamp is defined in the Signature Option, Section 8.7. To
facilitate timestamp checking, each recipient SHOULD store the
following information for each sender:
o The receive time of the last received and accepted CDNP message.
This is called RDlast.
o The time stamp in the last received and accepted CDNP message.
This is called TSlast.
An accepted CDNP message is any successfully verified (for both
timestamp check and signature verification) CDNP message from the
given peer. It initiates the update of the above variables.
Recipients MUST then check the Timestamp field as follows:
o When a message is received from a new peer (i.e., one that is not
stored in the cache), the received timestamp, TSnew, is checked,
and the message is accepted if the timestamp is recent enough to
the reception time of the packet, RDnew:
-Delta < (RDnew - TSnew) < +Delta
The RDnew and TSnew values SHOULD be stored in the cache as RDlast
and TSlast.
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o When a message is received from a known peer (i.e., one that
already has an entry in the cache), the timestamp is checked
against the previously received CDNP message:
TSnew + fuzz > TSlast + (RDnew - RDlast) x (1 - drift) - fuzz
If this inequality does not hold, the recipient SHOULD silently
discard the message. If, on the other hand, the inequality holds,
the recipient SHOULD process the message.
Moreover, if the above inequality holds and TSnew > TSlast, the
recipient SHOULD update RDlast and TSlast. Otherwise, the
recipient MUST NOT update RDlast or TSlast.
An implementation MAY use some mechanism such as a timestamp cache to
strengthen resistance to replay attacks. When there is a very large
number of nodes on the same link, or when a cache filling attack is
in progress, it is possible that the cache holding the most recent
timestamp per sender will become full. In this case, the node MUST
remove some entries from the cache or refuse some new requested
entries. The specific policy as to which entries are preferred over
others is left as an implementation decision.
3.5. Negotiation Procedures
A negotiation initiator sends a negotiation request to discovered
negotiation 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. 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 result by sending some
dry run conditions. The details will be defined separately for each
type of negotiation objective.
If the counterpart can immediately apply the requested confguration,
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.
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.
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The negotiation procedure is ended when one of the negotiation peers
sends a Negotiation Ending message, which contains an accept or
decline option and does not need a response from the negotiation
peer.
A negotiation procedure concerns one objective and one counterpart.
Both the initiator and the counterpart may take part in simultaneous
negotiations with various other devices, or in simultaneous
negotiations about different objectives. Thus, CDNP 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.
4. CDNP Constants
o ALL_CDNP_NEIGHBOR (TBD1)
A link-local scope multicast address used by a CDNP-enabled router
to discover CDNP-enabled neighbor (i.e., on-link) devices . All
routers that support CDNP are members of this multicast group.
* IPv6 multicast address: TBD1
* IPv4 multicast address: TBD2
o CDNP Listen Port (TBD3)
A UDP port that every CDNP-enabled network device always listens
to.
5. Device Identifier and Certificate Tag
A CDNP-enabled Device MUST generate a stable public/private key pair
before it participates in CDNP. 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 CDNP unique identifier for a CDNP
participant.
It then gets a certificate for this public key, signed by a
Certificate Authority that is trusted by other network devices. The
Certificate Authority SHOULD be managed 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.
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A 128-bit Device Certifcate Tag, which is generated by taking a
cryptographic hash over the device certificate, is a short
presentation for CDNP messages. It is the index key to find the
device certificate in a recipient's local trusted certificate record.
The tag value is formed by taking a SHA-1 hash algorithm over the
corresponding device certificate and taking the leftmost 128 bits of
the hash result.
6. Session Identifier
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 followup messages in the same negotiation
procedure, which is initiated by the request message, SHOULD carry
the same Session ID.
The Session ID SHOULD have a very low collision rate locally. It is
RECOMMENDED to be generated by a pseudo-random algorithm using a seed
which is unlikely to be used by any other device in the same network.
7. CDNP Messages
This document defines the following CDNP 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.
7.1. CDNP Messsage Format
All CDNP 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.
The following diagram illustrates the format of CDNP messages:
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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 CDNP 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 deviceas, as defined in Section 5.
The Device Certificate Tag is 128 bit, also defined
in Section 5. It is used as index key to find the
device certificate.
Options CDNP Options carried in this message. Options are
definded in Section 8.
7.2. Request Message
REQUEST (1) A negotiation requesting node sends a REQUEST message
to initiate a negotiation.
If the requesting node does not know any negotiation
counterpart, it sends the REQUEST messages to the
link-local ALL_CDNP_NEIGHBOR multicast address.
If the requesting node re-contacts a known negotiation
counterpart, it sends the REQUEST message to the
unicast address of the negotiation counterpart
directly.
7.3. Negotiation Message
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NEGOTIATION (2)A negotiation counterpart sends an NEGOTIATION
message in response to a REQUEST message or a
Negotiation message in a negotiation process which
may need multiple steps.
7.4. Negotiation-ending Message
NEGOTIATION-ENDING (3)
A negotiation counterpart sends an NEGOTIATION-EDNING
message to close the negotiation. It MUST contain
one, but only one of accept/decline/divert option,
defined in Section 8. It could be sent either by the
requesting node or the responding node.
7.5. Confirm-waiting Message
CONFIRM-WAITING (4)
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.
8. CDNP General Options
This section defines the CDNP general option for the negotiation
protocol signalling. Option type 10~64 is reserved for CDNP general
options defined in the future.
8.1. Format of CDNP Options
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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.
CDNP 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.
8.2. Divert Option
The divert option is used to redirect a CDNP 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.
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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
Emedded Locator Option(s), defined in Section 8.8,
that point to diverted destination device(s).
8.3. Accept Option
The accept option is used to indicate the negotiation counterpart
that the proposed negotiation content is accepted.
The accept option MUST only be encapsulated in Negotiation-ending
messages. If found elsewhere it SHOULD be silently ignored.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ACCEPT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_ACCEPT (2).
Option-len 0.
8.4. Decline Option
The decline option is used to indicate the negotiation counterpart
the proposed negotiation content is declined and end the negotiation
process.
The decline option MUST only be encapsulated in Negotiation-ending
messages. If found elsewhere it SHOULD be silently ignored.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DECLINE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_DECLINE (3).
Option-len 0.
Notes: there are scenarios where a negotiation counterpart wants to
decline the proposed negotiation content and continue the negotiation
process. For these scenarios, the negotiation counterpart SHOULD use
a Response message, with either an objective option that contains at
least one data field with all bits set to 1 to indicate a meaningless
initial value, or a specific objective option that provides further
conditions for convergence.
8.5. Waiting Time Option
The waiting time option is used to indicate that the negotiation
counterpart needs to wait for a further negotiation response, since
the processing might need more time than usual or it might depend on
another triggered negotiation.
The waiting time option MUST only be encapsulated in Confirm-waiting
messages. If found elsewhere it SHOULD be silently ignored.
The counterpart SHOULD send a Response message or another Confirm-
waiting message before the current waiting time expires. If not, the
initiator SHOULD abandon or restart the negotiation procedure, to
avoid an indefinite wait.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_WAITING | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_WAITING (4).
Option-len 4, in octets.
Time The time is counted in millisecond as a unit.
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8.6. Certificate Option
The Certificate option carries the certificate of the sender. The
format of the Certificate option is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION Certificate | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Certificate (variable length) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_CERT_PARAMETER (5)
Option-len Length of certificate in octets
Public key A variable-length field containing a certificate
8.7. Signature Option
The Signature option allows public key-based signatures to be
attached to a CDNP message. The Signature option is REQUIRED in
every CDNP message and could be any place within the CDNP message.
It protects the entire CDNP header and options. A TimeStamp has been
integrated in the Signature Option for anti-replay protection. The
format of the Signature option is described as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIGNATURE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-id | SA-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp (64-bit) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Signature (variable length) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_SIGNATURE (6)
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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 CDNP
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 CDNP 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 CDNP message header.
2. All CDNP 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.
8.8. Locator Options
These locator options are used to present a device's or interface's
reachability information. They are Locator IPv4 Address Option,
Locator IPv6 Address Option and Locator FQDN (Fully Qualified Domain
Name) Option.
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8.8.1. Locator IPv4 address option
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_LOCATOR_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.
8.8.2. Locator IPv6 address option
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_LOCATOR_IPV6ADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6-Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option-code OPTION_LOCATOR_IPV6ADDR (8).
Option-len 16, in octets.
IPv6-Address The IPv6 address locator of the device/interface.
Note: link-local IPv6 address SHOULD be avoided when this option is
used in the Divert option. It may create a connection problem.
8.8.3. Locator FQDN option
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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.
9. Objective Options and Considerations
The Objective options contains negotiation objectives, which are
various according to different functions/services. They MUST be
carried by Request or Negotiation Messages only. Objective options
SHOULD be assigned an option type greater than 64 in the CDNP option
table.
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.
9.1. Organizing of CDNP Options
Naturally, a negotiation objective, which is based on a specific
service or function or action, SHOULD be organized as a single CDNP
option. It is NOT RECOMMENDED to organize multiple negotiation
objectives into a single option.
A negotiation objective may have multiple parameters. Parameters can
be categorized into two class: the obligatory ones presented as fixed
fields; and the optional ones presented in TLV sub-options. It is
NOT RECOMMENDED to split parameters in a single objective into
multiple options, unless they have different response periods. An
exception scenario may also be described by split objectives.
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9.2. Vendor Specific Options
Option codes 128~159 have been reserved for vendor specific options.
Multiple option codes have been assigned because a single vendor 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.
9.3. Experimental Options
Option code 176~191 have been reserved for experimental options.
Multiple option codes have been assigned because a single experiment
may use multiple options simultaneously. These experimental options
are highly likely to have different meanings when used for different
experiments. Therefore, they SHOULD NOT be used without an explicit
human decision. They are not suitable for unmanaged networks such as
home networks.
10. Items for Future Work
There are a few open design questions that are worthy of more work in
the near future, as listed below:
o UDP vs TCP: For now, this specification has chosen UDP as message
transport mechanism. However, this is not closed yet. UDP is
good for short conversations, fitting the 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 comsumption
during the session establishment stage. If messages exceed a
reasonable MTU, a TCP mode may be necessary.
o Message encryption: should CDNP messages be encrypted as well as
signed, to protect against internal eavesdropping within the
network?
o TLS or DTLS vs built-in security mechanism. For now, this
specifcation has chosen a PKI based build-in security mechanism.
However, TLS or DTLS might be chosen as security infrastructure
for simplification reasons.
o Timeout for lost Negotiation Ending and other messages to be
added.
o CDNP currently requires every participant to have an NTP-
synchronized clock. Is this OK for low-end devices?
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o Would use of MDNS have any impact on the Locator FQDN option?
o 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.
o Rules about how data items are defined in a negotiation objective.
Maybe a formal information model is needed.
o We currently assume that there is only one counterpart for each
discovery action. If this is false or one negotiation request
receives multiple different responses, how does the initator
choose between them? Could it split them into multiple follow-up
negotiations?
o Alternatives to TLV format. It may be useful to provide a generic
method of carrying negotiation objectives in a high-level format
such as YANG or an 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.
11. Security Considerations
Using certificate-based security mechanism and its verification
mechanism in CDNP message exchanging provides the authentication and
data integrity protection. The timestamp mechanism provides an anti-
replay function.
Since CDNP is intended to be deployed in a single administrative
domain recommended to operate its own CA, there is no need for a
trusted third party.
12. IANA Considerations
Section 4 defines the following mtwpulticast addresses, which have
been assigned by IANA for use by CDNP:
ALL_CDNP_NEIGHBOR multicast address (IPv6): (TBD1)
ALL_CDNP_NEIGHBOR multicast address (IPv4): (TBD2)
Section 4 defines the following UDP port, which have been assigned by
IANA for use by CDNP:
CDNP Listen Port: (TBD3)
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This document defined a new Configuration Discovery and Negotiation
Protocol. The IANA is requested to create a new CDNP registry. The
IANA is also requested to add two new registry tables to the newly-
created CDNP registry. The two tables are the CDNP Messages table
and CDNP Options table.
Initial values for these registries are given below. Future
assignments are to be made through Standards Action or Specification
Required [RFC5226]. Assignments for each registry consist of a type
code value, a name and a document where the usage is defined.
CDNP Messages table. The values in this table are 16-bit unsigned
integers. The following initial values are assigned in Section 7 in
this document:
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
CDNP Options table. The values in this table are 16-bit unsigned
integers. The following initial values are assigned in Section 8 and
Section 9 in this document:
Type | Name | RFCs
---------+-----------------------------+------------
0 |Reserved | this document
1 |Divert Option | this document
2 |Accept Option | this document
3 |Decline Option | this document
4 |Waiting Time Option | this document
5 |Certificate Option | this document
6 |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
The IANA is also requested to create two new registry tables in the
CDNP Parameters registry. The two tables are the Hash Algorithm for
CDNP table and the Signature Algorithm for CDNP table.
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Initial values for these registries are given below. Future
assignments are to be made through Standards Action or Specification
Required [RFC5226]. Assignments for each registry consist of a name,
a value and a document where the algorithm is defined.
Hash Algorithm for CDNP. The values in this table are 16-bit
unsigned integers. The following initial values are assigned for
Hash Algorithm for CDNP in this document:
Name | Value | RFCs
---------------------+-----------+------------
Reserved | 0x0000 | this document
SHA-1 | 0x0001 | this document
SHA-256 | 0x0002 | this document
Signature Algorithm for CDNP. The values in this table are 16-bit
unsigned integers. The following initial values are assigned for
Signature Algorithm for CDNP in this document:
Name | Value | RFCs
---------------------+-----------+------------
Reserved | 0x0000 | this document
RSASSA-PKCS1-v1_5 | 0x0001 | this document
13. Acknowledgements
Valuable comments were received from Zhenbin Li and Dacheng Zhang,
and other participants in the xxx working group.
This document was produced using the xml2rfc tool [RFC2629].
14. Change log [RFC Editor: Please remove]
draft-jiang-config-negotiation-protocol-02: adapted scope to include
discovery, multiple threads, mentioned YANG etc. encapsulation,
2013-06-26.
draft-jiang-config-negotiation-protocol-01: corrections and
additions, 2014-04-21.
draft-jiang-config-negotiation-protocol-00: original version,
2013-10-19.
15. References
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15.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
15.2. Informative References
[I-D.irtf-nmrg-an-gap-analysis]
Behringer, M., Carpenter, B., and S. Jiang, "Gap Analysis
for Autonomic Networking", draft-irtf-nmrg-an-gap-
analysis-00 (work in progress), April 2014.
[I-D.irtf-nmrg-autonomic-network-definitions]
Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking - Definitions and Design Goals", draft-irtf-
nmrg-autonomic-network-definitions-00 (work in progress),
December 2013.
[I-D.jiang-config-negotiation-ps]
Jiang, S., Yin, Y., and B. Carpenter, "Network
Configuration Negotiation Problem Statement and
Requirements", draft-jiang-config-negotiation-ps-03 (work
in progress), May 2014.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic
Hashes in Internet Protocols", RFC 4270, November 2005.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
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Authors' Addresses
Sheng Jiang
Huawei Technologies Co., Ltd
Q14, Huawei Campus
No.156 Beiqing Road
Hai-Dian District, Beijing 100095
P.R. China
Email: jiangsheng@huawei.com
Brian Carpenter
Department of Computer Science
University of Auckland
PB 92019
Auckland 1142
New Zealand
Email: brian.e.carpenter@gmail.com
Bing Liu
Huawei Technologies Co., Ltd
Q14, Huawei Campus
No.156 Beiqing Road
Hai-Dian District, Beijing 100095
P.R. China
Email: leo.liubing@huawei.com
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