One document matched: draft-jennings-sipping-instance-id-00.txt
SIPPING WG C. Jennings
Internet-Draft Cisco Systems, Inc.
Expires: August 7, 2004 February 7, 2004
Instance Identifiers for SIP User Agents
draft-jennings-sipping-instance-id-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet-Drafts.
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."
The list of current Internet-Drafts can be accessed at http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 7, 2004.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
There are places in building SIP [2] based communications systems
where it is useful to have a stable identifier for particular user
agents that are used for user communications. This draft defines a
convention for names that can be used to satisfy these needs.
Jennings Expires August 7, 2004 [Page 1]
Internet-Draft SIP UA Instance ID February 2004
Table of Contents
1. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
2. Introduction and Use Cases . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. BNF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8. Security Consideration . . . . . . . . . . . . . . . . . . . . 5
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 5
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
Normative References . . . . . . . . . . . . . . . . . . . . . 6
Informative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 6
Intellectual Property and Copyright Statements . . . . . . . . 7
Jennings Expires August 7, 2004 [Page 2]
Internet-Draft SIP UA Instance ID February 2004
1. Conventions and Definitions
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 [3].
2. Introduction and Use Cases
There are a few cases in which it is convenient to be able to
identify instances of a user agent. Some examples are described. They
all require the name to be stable across reboots of the device.
In the config framework[4], a user agent sends a subscribe to
fetch its configuration. It needs to get the same configuration
each time.
A particular user, Alice, has several user agents that all
register as Alice. A registrar wishes to report which user agent
are currently registered to a network management system. For this
reporting to make sense, each of Alice's user agents must have a
stable name.
A system that is using the dialog package to monitor a particular
user agent would like to be able to assign an alias like "My
Office Phone" for display purposes to that particular user agent.
When several presence user agents are providing presence data, it
must be possible to correlate a particular set of data with the
particular device that provided it.
In all these cases, the user agent could be a software program
running on a computer with more than one user.
3. Requirements
The identifier needs to be unique.
Identifiers are needed for user agents that are in dedicated pieces
of hardware such as IP phones.
Identifiers are needed for software user agents running on multi-user
computers.
In some of the cases with IP phones, it is desirable for this same
identifier to be recorded as a bar code on the outside of the box
that the IP phone comes in.
Jennings Expires August 7, 2004 [Page 3]
Internet-Draft SIP UA Instance ID February 2004
4. Solution
User agents that follow the convention of this document MUST put a
unique identifier in a new tag, called "instance", of the Contact
header when sending a SIP request. They MAY omit this for a
particular sequence of SIP messages if the user has requested it be
removed for privacy reasons.
The unique identifier has no real semantic information other than
uniqueness. In cases in which the user agent runs on a single
computer and this is the only user agent on that computer, the MAC
address of the primary network card is the preferred identifier. In
cases in which it is impossible to use the MAC address, then when the
user agent is first run, it should generate a random 64 bit number
and use this as the identifier. It MUST store this number in some non
volatile storage that is stable over reboots and power outages. The
user agent SHOULD use the same instance identifier tag even if it is
registering different AOR or contacts.
If the identifier is a MAC address, it MUST be formatted as the
letters "MAC-" followed by a 12 digit hexadecimal representation of
the MAC address. The address can not include ":", whitespace, or
other formatting. If the identifier is a random number, it MUST be
formatted as the letters "RANID-" followed by a 16 digit hexadecimal
representation of the number. Note that the identifiers are case
sensitive and all alpha characters are upper case.
The MAC and RANDID identify the namespace for the unique identifier.
In the future this unique identifer namespace may be extended with
other namespaces that use unique identifiers from things like USB,
Bluetooth, or Firewire.
These same identifiers may be used in the user portion of request
URIs when that is appropriate. A SUBSCRIBE for configuration
information is a good example.
5. Discussion
The contact header in a SIP request identifies an address that can be
used to reach the device that is sending the request. This address
may change each time the device running the user agent gets a new IP
address, but it is very reasonable for the display name to give a
unique identifier for what this instance of the user agent wishes to
be known by. Right now SIP does not give any recommendation on what
to place in the field. This document suggests a naming convention for
this.
MAC addresses are usually put on the outside of the box for IP phones
Jennings Expires August 7, 2004 [Page 4]
Internet-Draft SIP UA Instance ID February 2004
in a form that humans can read and also by a barcode scanner.
6. BNF
The following ABNF follows the rules in RFC-2234 [1] and updates the
BNF in RFC 3261.
contact-params = c-p-q / c-p-expires / c-p-instance
/ contact-extentions
c-p-intance = "instance" EQUAL uniq-ident
UHEX = DIGIT / %x41-46 ;uppercase A-F
MAC = %x4d.41.43 ; MAC in caps
RANDID = %x52.41.4e.44.49.44 ; RANDID in caps
uniq-ident = ( mac-ident / rand-ident )
mac-ident = MAC "-" 12UHEX
rand-ident = RANDID "-" 16UHEX
7. Example
The following are some valid Contact headers:
Contact: <sip:alice@host22.example.com>;instance=MAC-123456789ABC
Contact: <sip:alice@host22.example.com>;instance=
RANDID-0123456789ABCDEF
8. Security Consideration
The unique identifer reveals further privacy related information to
other people that see the SIP signalling. Currently user agents put
an IP address or DNS name in the contact header, so the amount of
extra information this reveals is very minimal. The MAC address may
reveal the manufacturer of the user agent.
9. Open Issues
Would this be better in an "Instance-ID" header?
Would this be better in the User-Agent header? Some systems are doing
already doing this.
Is 64 bits the right size for the random identifier?
Is requiring upper case appropriate?
10. Acknowledgments
Jennings Expires August 7, 2004 [Page 5]
Internet-Draft SIP UA Instance ID February 2004
Many thank for the useful comments and improvements from Louis Pratt,
Steve Levy, Rohan Mahy, and Randy Baird as well as the list
discussion from Jonathan Rosenberg.
Normative References
[1] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[2] 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.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
Informative References
[4] Petrie, D., "A Framework for SIP User Agent Configuration",
draft-ietf-sipping-config-framework-00 (work in progress), March
2003.
Author's Address
Cullen Jennings
Cisco Systems, Inc.
170 West Tasman Dr.
MS: SJC-21/2
San Jose, CA 95134
USA
Phone: +1 408 902 3341
EMail: fluffy@cisco.com
Jennings Expires August 7, 2004 [Page 6]
Internet-Draft SIP UA Instance ID February 2004
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (C) The Internet Society (2004). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
Jennings Expires August 7, 2004 [Page 7]
Internet-Draft SIP UA Instance ID February 2004
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Jennings Expires August 7, 2004 [Page 8]
| PAFTECH AB 2003-2026 | 2026-04-22 23:16:23 |