Internet DRAFT - draft-kaplan-dnsext-enum-sip-source-ref-opt-code
draft-kaplan-dnsext-enum-sip-source-ref-opt-code
Network Working Group H. Kaplan
Internet Draft Acme Packet
Intended status: Informational R. Walter
Expires: April 24, 2012 NetNumber
P. Gorman
Sprint Nextel
M. Maharishi
TNS
October 24, 2011
EDNS Option Code for SIP and PSTN Source Reference Info
draft-kaplan-dnsext-enum-sip-source-ref-opt-code-03
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Abstract
This document requests an IANA allocation for an EDNS0 Option-Code,
per [RFC2671], for a UTF-8 encoded string field containing a URI for
private use. The intended use of this field is for providing SIP
and PSTN-type source information for ENUM-resolution DNS queries, in
private DNS server environments such as Private ENUM.
Table of Contents
1. Introduction..................................................2
2. Terminology...................................................3
3. Applicability.................................................3
4. OPTION-DATA Format............................................3
5. Security Considerations.......................................3
6. IANA Considerations...........................................4
7. Acknowledgments...............................................4
8. References....................................................4
8.1. Normative References.....................................4
8.2. Informative References...................................4
Authors' Addresses................................................4
1. Introduction
In many VoIP domains, private DNS servers are used to provide ENUM
resolution for SIP request routing purposes. Devices in such
domains, such as SIP Proxies and PSTN Gateways, which are the DNS
clients set to use the private DNS servers for ENUM resolution, need
to provide the server(s) with some additional private meta-data
concerning the source of the SIP request that triggered the DNS
query, which may aid the server(s) in providing an answer. The
additional data is in the form of a URI-formatted UTF-8 string,
which needs to be provided in the DNS query request. The Extension
Mechanism for DNS (EDNS) defined in [RFC2671] provides a suitable
means by which to encode such a string into the DNS request, using
the OPT RR and a new EDNS0 Option-Code indicating this field use.
This document requests IANA for assignment of such an Option-Code,
for providing SIP and PSTN-type source reference information in DNS
requests used for ENUM, in private, controlled environments only.
This is neither applicable to, nor appropriate for, the general
public Internet DNS; the only reason this document exists is to
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obtain a reserved option code number, for interoperability among
vendors within private, restricted environments.
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 RFC 2119. The
terminology in this document conforms to RFC 2828, "Internet
Security Glossary".
Private DNS server: a DNS server which does not use the IANA-base
tree, nor the "e164.arpa" suffix, and is deployed for specific name
resolution purposes in a controlled, restricted environment.
3. Applicability
This draft requests a new Option code value based on [EDNS0].
4. OPTION-DATA Format
The format of the OPTION-DATA contents is a UTF-8 [RFC2279] text
string, with no character termination (the OPTION-LENGTH field
identifies the length).
For the private use defined for this option code, the contents of
the UTF-8 string are a URI, typically a SIP or TEL URI, including
the "sip:" or "tel:" schemes. Non-UTF-8 characters, or characters
not allowed in the ABNF rules for a SIP-URI or TEL-URI format per
[RFC3261] or [RFC3966] MUST be escaped per those formats.
The usage and source of the URI content is outside the scope of this
document, and are documented in [draft-enum-sip-routing].
The query option is of a multi-hop, transitive nature. As such,
this mechanism will only work in restricted DNS server use cases
where all the DNS servers (and intermediate caches) are known to
support the extension. The primary use-case for this is in Private
ENUM deployments.
5. Security Considerations
There are privacy concerns with regard to passing SIP/PSTN source
reference information in a DNS query. The intent of this option is
for a purely private use, in a controlled environment. Clients MUST
NOT use this option mechanism if they do not know the DNS query will
only be processed by private DNS servers in a controlled
environment, for example through explicit configuration that such is
the case.
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6. IANA Considerations
This document requests that IANA register in the "Domain Name System
(DNS) Parameters" registry at http://www.iana.org/assignments/dns-
parameters in sub-registry "DNS EDNS0 Options", a new option named
"SIP/PSTN Source Reference Info".
7. Acknowledgments
Thanks to Tom Creighton (Comcast), James Yu (Neustar), Nick Russell
(Vodafone), Colin Pons (KPN), and Raja Gopal (Nominum) for their
input and support. Funding for the RFC Editor function is provided
by the IETF Administrative Support Activity (IASA).
8. References
8.1. Normative References
[RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 2279, January 1998.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC
2671, August 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.
[RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC
3966, December 2004.
8.2. Informative References
[draft-enum-sip-routing] Kaplan, H., Pons, C., Gorman, P., "Routing
SIP Requests with ENUM", draft-kaplan-enum-sip-routing-04, October
24, 2011.
Authors' Addresses
Hadriel Kaplan
Acme Packet
100 Crosby Dr.
Bedford, MA 01730
USA
Email: hkaplan@acmepacket.com
Robert H. Walter
NetNumber, Inc.
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650 Suffolk Street, Suite 307
Lowell, MA 01854
USA
Email: rwalter@netnumber.com
Pierce Gorman
Sprint Nextel Corporation
6220 Sprint Parkway
MS: KSOPHD0504 - 5D208
Overland Park, KS 66251
Email: pierce.gorman@sprint.com
Manjul Maharishi
TNS Inc.
1939 Roland Clarke Place
Reston, VA 20191
USA
Email: mmaharishi@tnsi.com
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