| 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
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.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 28, 2014.
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
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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.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] when they appear in ALL CAPS. When these words are not in ALL CAPS (such as "should" or "Should"), they have their usual English meanings, and are not to be interpreted as [RFC2119] key words.
The 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.
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.
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.
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.
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.
A certification based security mechanism provides security properties for CDNP:
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.
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.
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.
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. 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.
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:
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:
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.
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.
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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
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)
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.
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.
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.
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.
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.
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.
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.
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.
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.
There are a few open design questions that are worthy of more work in the near future, as listed below:
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.
Section 4 defines the following mtwpulticast addresses, which have been assigned by IANA for use by CDNP:
Section 4 defines the following UDP port, which have been assigned by IANA for use by CDNP:
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
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
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
Name | Value | RFCs
---------------------+-----------+------------
Reserved | 0x0000 | this document
RSASSA-PKCS1-v1_5 | 0x0001 | this document
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].
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.
| [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. |