Internet DRAFT - draft-fan-core-coap-via-option
draft-fan-core-coap-via-option
CoRE X. Fan
Internet-Draft ZTE
Intended status: Standards Track December 18, 2012
Expires: June 21, 2013
CoAP Via Option Extension
draft-fan-core-coap-via-option-00
Abstract
This document adds an extension option to the Constrained Application
Protocol (CoAP): Via. The Via option is used to indicate the proxies
between the coap client and the coap server.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 21, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Option Definition . . . . . . . . . . . . . . . . . . . . . . 4
3. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
This document adds a new option to the Constrained Application
Protocol : Via. The via option is used to indicate the proxies
between the coap client and the coap server.
1.1. Motivation
A proxy is a CoAP endpoint that can be tasked by CoAP clients to
perform requests on their behalf. Proxy is helpful to reduce
response time, network bandwidth consumption and energy consumption.
There may be zero or more proxies between two endpoints, when an
endpoint receives a coap message, it needs to know the proxies which
have forwarded this message. So this document is intended to define
a new option which can be used to track the message and avoid forward
loops.
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].
The terms Proxy, Coap Client and Coap Server as specified in the
terminology section of [I-D.ietf-core-coap].
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2. Option Definition
+--------+---+---+---+---+------+--------+--------+--------+
| No | C | U | N | R | Name |Format | Length | Default|
+--------+---+---+---+---+------+--------+--------+--------+
| TBD | | | | X | via | string | 1-255 | (none) |
+--------+---+---+---+---+------+--------+--------+--------+
The Via option is "elective" and "safe" . when a proxy doesn't
recognise this option, it can ignore this option.
The value of this option is a string which MUST be globally unique,
e.g., IP address, domain name or any other identifiers of the proxy
endpoint.
The via option can occur more than once.
When a proxy endpoint receives a coap message with via options, the
proxy MUST first check the via options value, if the via option
configured in the proxy endpoint is equal to one of the via options
in the coap message, there occurs a forward loop , the proxy MUST
drop this coap message.
When a proxy endpoint forwards a coap message, it can add a new via
option into the message at the end of the existing via options.
The via option can be used in the request message and/or the response
messages. It is recommended that the proxy can be configured to add
this option into request and/or response message.
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3. Example
In the example below, there are two proxies between client and
server: proxy1 and proxy2 ,the via option are configured with value
"proxy1@test.com" and "proxy2@test.com".
Client Proxy1 Proxy2 Server
| | | |
| no via option | | |
+------------------>| | |
| REQUEST(1) | | |
| |via:proxy1@test.com| |
| +------------------>| |
| | REQUEST(2) | |
| | |via:proxy1@test.com|
| | |via:proxy2@test.com|
| | +------------------>|
| | | REQUEST(3) |
| | | |
| | | no via option |
| | |<------------------+
| | | RESPONSE(4) |
| |via:proxy2@test.com| |
| |<------------------+ |
| | RESPONSE(5) | |
|via:proxy2@test.com| | |
|via:proxy1@test.com| | |
|<------------------+ | |
| RESPONSE(6) | | |
| | | |
(1)Client sends a request message with no via option;
(2)Proxy1 adds a via option into the request message, the option
value is "proxy1@test.com";
(3)Proxy2 adds a via option into the request message following
proxy1, the value is "proxy2@test.com",then the request message has
two via options.
(4)Server responses this request with no via option;
(5)Proxy2 adds a via option into the response message, the option
value is "proxy2@test.com";
(6)Proxy1 add a via option into the response message following
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proxy2, the value is "proxy1@test.com",then the response message has
two via options.
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4. IANA Considerations
The IANA is requested to add the following option number entries:
+--------+----------+------------ +
| Number | Name | Reference |
+--------+----------+-------------+
| TBD | Via | RFCXXXX |
+--------+--------- +-------------+
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5. Security Considerations
However, once there were too many proxies between client and server,
and all the proxies are enabled to add this via option, so that it
will make the length of the message so long , and correspondingly
increase energy consumption or network consumption.
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6. Acknowledgements
TBD
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7. References
7.1. Normative References
[I-D.ietf-core-coap]
Shelby, Z., Hartke, K., Bormann, C., and B. Frank,
"Constrained Application Protocol (CoAP)",
draft-ietf-core-coap-12 (work in progress), October 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[I-D.shelby-core-coap-req]
Shelby, Z., Stuber, M., Sturek, D., Frank, B., and R.
Kelsey, "CoAP Requirements and Features",
draft-shelby-core-coap-req-02 (work in progress),
October 2010.
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Author's Address
Xianyou Fan
ZTE Corporation
Xing Guang Rd, Yu Bei Districtt
Chongqing, Chongqing 401121
P. R. China
Phone: +86-23-67887556
Email: fan.xianyou@zte.com.cn
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