Internet DRAFT - draft-li-core-coap-node-id-option
draft-li-core-coap-node-id-option
core K. Li
Internet-Draft R. Sun
Intended status: Standards Track Huawei Technologies
Expires: June 19, 2015 G. Wei
BUPT
December 16, 2014
CoAP Option Extension: NodeId
draft-li-core-coap-node-id-option-02
Abstract
CoAP is a RESTful application protocol for constrained nodes and
networks. This specification provides a simple extension for CoAP,
the NodeId Option. This Option can be used to identify the node,
either the client or the server.
Note
Discussion and suggestions for improvement are requested, and should
be sent to core@ietf.org.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 19, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Justification . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. NodeId Option Extension . . . . . . . . . . . . . . . . . . . 3
2.1. NodeId Option Definition . . . . . . . . . . . . . . . . 3
2.2. Using the NodeId Option . . . . . . . . . . . . . . . . . 3
2.2.1. Registration . . . . . . . . . . . . . . . . . . . . 3
2.2.2. Usage . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Registration example . . . . . . . . . . . . . . . . . . 4
3.2. Notification example . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This specification adds a new option NodeId to CoAP [RFC7252]. The
main purpose is for a node to have a unique identity, named as
NodeId. The NodeId is used by the node, as a sender, to identify
itself to the recipient, during registration and communications.
1.1. Justification
A node is set to have a NodeId and the node nerver changes its
NodeId. There are several scenarios to have the NodeId to identify
the nodes.
In the network, it is quite common for a node to change its IP
address due to rebooting. After the server or client changes its IP
address, the peer of the other side lacks a facility to correlate the
old IP address and the new IP address as the same node. This will
cause the other side to lose some contexts. If the node can use
NodeId after its IP address being changed, it is very easy for the
node to correlate the old IP address and the new one by NodeId.
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In the multicast observation case, after a client sends a multicast
observation request to a group URI, e.g. all.bldg6.example.com, the
client will receive multiple notifications from different servers of
the multicast group with the same token as specified in the multicast
request. As a result, the client can't use token to correlate
multicast request and notification responses. The client may use the
IP address extracted from UDP/IP transport/network layers to
differentiate servers and responses. If a server changes its IP
address and sends back the notification, the client can't determine
where the notification message comes from any more. In this case, if
NodeId is included in the notifications, it can be used to correlate
multicast request and subsequent notifications by the node.
The NodeId can also be used for authentication and authorization of
the node.
1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. NodeId Option Extension
2.1. NodeId Option Definition
+------+---+---+---+---+--------+--------+--------+---------+
| Type | C | U | N | R | Name | Format | Length | Default |
+------+---+---+---+---+--------+--------+--------+---------+
| TBD | - | - | - | - | NodeId | string | 1-255 B| (none) |
+------+---+---+---+---+--------+--------+--------+---------+
The NodeId option is used to identify the node.The value SHOULD be
unique for each node within a Resource Directory server. The value
can be in the form of Binary bits, IMEI (International Mobile
Equipment Identity number), IEEE 802 MAC Address, or other
identifiers which can uniquely identify itself. Usually the value is
pre-configured or pre-previsioned in the node.
2.2. Using the NodeId Option
2.2.1. Registration
When a node registers itself to the Resource Directory server, the
registration request SHOULD contain its node identifier. This node
identifier MAY be included in the NodeId option in the registration
request, or MAY be included in the URI-Query option as specified in
[I-D.ietf-core-resource-directory].
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2.2.2. Usage
This option MAY be used in a CoAP request or response. And it can be
used to correlate the messages for a node in case of IP address
change. As long as a node changes its IP address, the NodeId SHALL
be included in the first request and response and sent in CON
message.
Whenever the node reboots or moves, the NodeId MUST NOT change. And
the node SHOULD send the updated IP address with the NodeId to the RD
server, using the update interface as specified in
[I-D.ietf-core-resource-directory]. This informs the RD server a
mapping relation between the new IP address and the NodeId identified
node.
For the usage of notifications in the observe, when a server in a
group receives a multicast observe request, it SHOULD include a
NodeId option in the notifications. In this way, even the server
changes the IP address, the client can still correlate all the
notifications with this server.
It is recommended to use NodeId as identifier during authentication
and authorization.
Todo: How to use it for authentication and authorization?
This option is "elective". It MUST NOT occur more than once.
3. Example
3.1. Registration example
This section gives a short example with a message flow that
illustrates the use of the NodeId option in a registration request.
This example (Figure 1) shows that the requester includes its NodeId
in the registration request.
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Node RD
| |
| |
+----->| Header: POST (T=CON, Code=1, MID=0x7d38)
| POST | Token: 0x53
| | NodeId: node12345
| | Uri-Path: "rd"
| |
|<-----+ Header: 2.01 Created (T=ACK, Code=69, MID=0x7d38)
| 2.01 | Token: 0x53
| |
| |
Figure 1: NodeId Option in a registration request
3.2. Notification example
This section gives a short example with a message flow that
illustrates the use of the NodeId option in an observe notification.
This example (Section 3.2) shows that the server includes its NodeId
option in an observe notification after IP address changes.
Client Server
| |
| |
+----->| Header: GET (T=CON, Code=1, MID=0x7d38)
| GET | Token: 0x53
| | Observe: 0
| | Uri-host: "all.bldg6.example.com"
| | Uri-Path: "temperature"
| |
|<-----+ Header: 2.05 Content (T=ACK, Code=69, MID=0x7d38)
| 2.05 | Token: 0x53
| | NodeId: node12345
| | Payload: "22.3 C"
| |
| |
Figure 2: NodeId Option in an observe notification
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4. Security Considerations
This presents no security considerations beyond those in section 9
and 11 of the base CoAP specification [RFC7252].
5. IANA Considerations
The IANA is requested to add the following "CoAP Option Numbers"
entry as per Section 12.2 of [RFC7252].
+--------+------------------+----------------+
| Number | Name | Reference |
+--------+------------------+----------------+
| TBD | NodeId | Section 2 |
+--------+------------------+----------------+
6. Acknowledgements
The authors of this draft would like to thank the Esko Dijk, Carsten
Bormann, Bert Greevenbosch and Klaus Hartke for the email discussions
on this issue.
7. References
7.1. Normative References
[I-D.ietf-core-observe]
Hartke, K., "Observing Resources in CoAP", draft-ietf-
core-observe-15 (work in progress), October 2014.
[I-D.ietf-core-resource-directory]
Shelby, Z. and C. Bormann, "CoRE Resource Directory",
draft-ietf-core-resource-directory-02 (work in progress),
November 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, June 2014.
7.2. Informative References
[I-D.bormann-coap-misc]
Bormann, C. and K. Hartke, "Miscellaneous additions to
CoAP", draft-bormann-coap-misc-27 (work in progress),
November 2014.
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Authors' Addresses
Kepeng Li
Huawei Technologies
Huawei Base, Bantian, Longgang District
Shenzhen, Guangdong 518129
P. R. China
Phone: +86-755-28974289
Email: likepeng@huawei.com
Ruinan Sun
Huawei Technologies
Huawei Base, Bantian, Longgang District
Shenzhen, Guangdong 518129
P. R. China
Phone: +86-755-28970171
Email: sunruinan@huawei.com
Gengyu Wei
Beijing University of Posts & Telecommunications
No.10 Xitucheng Road, Haidian District
Beijing 100876
P. R. China
Phone: +86-10-62283067
Email: weigengyu@bupt.edu.cn
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