Internet DRAFT - draft-ma-core-dhcp-pd
draft-ma-core-dhcp-pd
CoRE Working Group Y. Ma
Internet-Draft X. He
Intended status: Informational Hitachi (China) Research and
Expires: September 2, 2012 Development Corporation
Z. Cao
China Mobile
Mar 2012
dhcp option for CoAP Proxy Discovery
draft-ma-core-dhcp-pd-01
Abstract
CoAP utilizes DNS to discovery the IP address of the CoAP server.
However DNS is heavy for the most resource constrained end-points.
In this case the assistance from CoAP proxy or research directory
(RD) is needed for CoAP transaction. This specification proposes to
define one new dhcp option for proxy/RD discovery for the most
resource constrained end-points.
Status of this Memo
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This Internet-Draft will expire on September 2, 2012.
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used in this document . . . . . . . . . . . . . 3
2. dhcp option for proxy discovery . . . . . . . . . . . . . . . . 3
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
CoAP [I-D.ietf-core-coap] is a RESTful protocol designed for
constrained devices. The ultimate goal of CoAP is to enable the "Web
of Things" concept, which connects the smart sensor network with the
global internet.
CoAP utilizes DNS for CoAP server IP address discovery. However in
some circumstances, DNS is heavy to be implemented in the resource
constrained nodes. In this case the assistance from CoAP proxy is
needed for CoAP transaction.
Also in many M2M scenarios, direct discovery of resources is not
practical due to sleeping nodes, disperse networks, or networks where
multicast traffic is inefficient. These problems can be solved by
employing an entity called a Resource Directory
(RD)[I-D.shelby-core-resource-directory], which hosts descriptions of
resources held on other servers, allowing lookups to be performed for
those resources .
Before the CoAP sensor makes use of the CoAP proxy or RD, it must
know the location of the proxy or RD. There can be multiple ways to
discover the proxy's location, including both static and dynamic
methods. Static configuration is a straightforward way for the
client to access the server. However, in many situations, static
configuration is not enough to meet the requirements.
In another hand, although CoAP is assumed to be running over IPv6,
there are various approaches to implement it over other protocols,
SMS and GRPS for example [I-D.li-core-coap-over-sms]
[I-D.becker-core-coap-sms-gprs]. There are also scenarios where IPv4
is used as the lower layer transport for CoAP. In such case the
dynamic configuration method based on IPv4 protocol suite is
necessary.
1.1. Conventions used in this document
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. dhcp option for proxy discovery
dhcp [RFC2131] provides dynamic methods to deliver configuration
information to the end node. dhcp options [RFC2132] are defined to
specify server information. This document specifies one new dhcp
option for CoAP proxy/rd discovery.
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The CoAP proxy/rd option specifies a list of CoAP proxy or Research
Directory servers available to the client. Servers SHOULD be listed
in order of preference.
The code for the name server option is x. The minimum length for
this option is 4 octets, and the length MUST always be a multiple of
4.
Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+--
| x | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--
CoAP proxy/rd option
3. Security Considerations
TBD.
4. IANA Considerations
This document needs to register one new dhcp option number at IANA.
5. Normative References
[I-D.becker-core-coap-sms-gprs]
Becker, M., Li, K., Kuladinithi, K., and T. Poetsch,
"Transport of CoAP over SMS, USSD and GPRS",
draft-becker-core-coap-sms-gprs-01 (work in progress),
March 2012.
[I-D.ietf-core-coap]
Frank, B., Bormann, C., Hartke, K., and Z. Shelby,
"Constrained Application Protocol (CoAP)",
draft-ietf-core-coap-08 (work in progress), October 2011.
[I-D.li-core-coap-over-sms]
Li, K., "CoAP Over SMS", draft-li-core-coap-over-sms-00
(work in progress), October 2011.
[I-D.shelby-core-resource-directory]
Krco, S. and Z. Shelby, "CoRE Resource Directory",
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draft-shelby-core-resource-directory-02 (work in
progress), October 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
Authors' Addresses
Yuanchen Ma
Hitachi (China) Research and Development Corporation
301, Tower C North, Raycom, 2 Kexuyuan Nanlu, Haidian District
Beijing 100190
China
Email: ycma@hitachi.cn
Xuan He
Hitachi (China) Research and Development Corporation
301, Tower C North, Raycom, 2 Kexuyuan Nanlu, Haidian District
Beijing 100190
China
Email: xhe@hitachi.cn
Zhen Cao
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: zehn.cao@gmail.com
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