draft-ietf-sip-dhcp-03.txt   draft-ietf-sip-dhcp-04.txt 
Internet Engineering Task Force SIP WG Internet Engineering Task Force SIP WG
Internet Draft G.Nair, H.Schulzrinne Internet Draft H.Schulzrinne, G.Nair
draft-ietf-sip-dhcp-03.txt Columbia University draft-ietf-sip-dhcp-04.txt Columbia University
January 20, 2001 March 24, 2001
Expires: June 2001 Expires: September 2001
DHCP Option for SIP Servers DHCP Option for SIP Servers
STATUS OF THIS MEMO STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 2, line 36 skipping to change at page 2, line 36
This draft specifies a DHCP option [1,5] that allows SIP clients to This draft specifies a DHCP option [1,5] that allows SIP clients to
locate a local SIP server that is to be used for all outbound SIP locate a local SIP server that is to be used for all outbound SIP
requests, a so-called outbound proxy server. (SIP clients MAY contact requests, a so-called outbound proxy server. (SIP clients MAY contact
the address identified in the SIP URL directly, without involving a the address identified in the SIP URL directly, without involving a
local SIP server. However in some circumstances, when firewalls are local SIP server. However in some circumstances, when firewalls are
present, SIP clients need to use a local server for outbound present, SIP clients need to use a local server for outbound
requests.) This is one of many possible solutions for locating the requests.) This is one of many possible solutions for locating the
outbound SIP server; manual configuration is an example of another. outbound SIP server; manual configuration is an example of another.
3 SIP server DHCP options 3 SIP Server DHCP Option
The SIP client obtains a DNS [6] full-qualified domain name (FQDN) The SIP server DHCP option carries a DNS (RFC 1035 [6]) fully-
via a DHCP option. This FQDN is then used by the mechanism described qualified domain name to be used by the SIP client to locate a SIP
in [3] to locate the outbound proxy server. In summary, the domain server. The FQDN is 16-bit Unicode text encoded into an octet stream
name encoded in the string is used first in a DNS SRV lookup and, if using UTF-8 (RFC 2044 [7]). The FQDN in the SIP server option MUST
that fails because of a lack of matching DNS SRV records, in an NOT be null-terminated. It MUST NOT end with a period.
address record lookup. Normative details are contained in [3].
A SIP client obtains a FQDN through the SIP server option, which the
client then uses to locate the outbound proxy server by the mechanism
described in RFC XXXX [3]. In summary, the FQDN is used first in a
DNS SRV lookup and, if that fails because of a lack of matching DNS
SRV records, the FQDN is used in an address record lookup. Normative
details are contained in RFC XXXX [3].
It is possible, but NOT RECOMMENDED that the string is the textual It is possible, but NOT RECOMMENDED that the string is the textual
representation of a network address, e.g., a "dotted quad" for IPv4 representation of a network address, e.g., a "dotted quad" for IPv4
and the hexadecimal representation of RFC 2373 [7]. and the hexadecimal representation of RFC 2373 [8]. Implementations
MUST detect this case by checking whether all characters are decimal
digits or periods.
The code for this option is TBD. The length of the DNS name string is The code for this option is TBD. The length of the DNS name string is
specified in `Len'. The maximum length of this string is 255 octets specified in `Len'. The maximum length of this string is 255 octets
and minimum length is 1 octet. For example, a value may be and minimum length is 1 octet. For example, a value may be
"sip.example.com". "sip.example.com".
Code Len DNS name of SIP server Code Len DNS name of SIP server
+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+--
| TBD | n | s1 | s2 | s3 | s4 | s5 | ... | TBD | n | s1 | s2 | s3 | s4 | s5 | ...
+-----+-----+-----+-----+-----+-----+-----+-- +-----+-----+-----+-----+-----+-----+-----+--
4 Security Consideration 4 Security Consideration
There are no security considerations beyond those described in RFC There are no security considerations beyond those described in RFC
2132, RFC 2543 [2] and RFC XXX [3]. 2131 [1], RFC 2543 [2] and RFC XXXX [3].
5 IANA Considerations 5 IANA Considerations
IANA has assigned a DHCP option number of TBD for the "SIP Servers IANA has assigned a DHCP option number of TBD for the "SIP Servers
DHCP Option" defined in this document. DHCP Option" defined in this document.
6 Acknowledgements 6 Acknowledgements
Robert Elz, Wenyu Jiang, Peter Koch, Thomas Narten, Erik Nordmark, Robert Elz, Wenyu Jiang, Peter Koch, Thomas Narten, Erik Nordmark,
Jonathan Rosenberg, Kundan Singh, Sven Ubik and Bernie Volz provided Jonathan Rosenberg, Kundan Singh, Sven Ubik and Bernie Volz provided
useful feedback. useful feedback.
7 Authors' Addresses 7 Authors' Addresses
Gautam Nair Henning Schulzrinne
Dept. of Computer Science Dept. of Computer Science
Columbia University 1214 Amsterdam Avenue, MC 0401 Columbia University 1214 Amsterdam Avenue, MC 0401
New York, NY 10027 New York, NY 10027
USA USA
electronic mail: gnair@cs.columbia.edu electronic mail: schulzrinne@cs.columbia.edu
Henning Schulzrinne Gautam Nair
Dept. of Computer Science Dept. of Computer Science
Columbia University 1214 Amsterdam Avenue, MC 0401 Columbia University 1214 Amsterdam Avenue, MC 0401
New York, NY 10027 New York, NY 10027
USA USA
electronic mail: schulzrinne@cs.columbia.edu electronic mail: gnair@cs.columbia.edu
8 Bibliography 8 Bibliography
[1] R. Droms, "Dynamic host configuration protocol," Request for [1] R. Droms, "Dynamic host configuration protocol," Request for
Comments 2131, Internet Engineering Task Force, Mar. 1997. Comments 2131, Internet Engineering Task Force, Mar. 1997.
[2] M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP: [2] M. Handley, H. Schulzrinne, E. Schooler, and J. Rosenberg, "SIP:
session initiation protocol," Request for Comments 2543, Internet session initiation protocol," Request for Comments 2543, Internet
Engineering Task Force, Mar. 1999. Engineering Task Force, Mar. 1999.
[3] H. Schulzrinne and J. Rosenberg, "SIP: session initiation [3] H. Schulzrinne and J. Rosenberg, "SIP: Session initiation
protocol -- locating SIP servers," Internet Draft, Internet protocol -- locating SIP servers," Internet Draft, Internet
Engineering Task Force, Jan. 2001. Work in progress. Engineering Task Force, Jan. 2001. Work in progress.
[4] S. Bradner, "Key words for use in RFCs to indicate requirement [4] S. Bradner, "Key words for use in RFCs to indicate requirement
levels," Request for Comments 2119, Internet Engineering Task Force, levels," Request for Comments 2119, Internet Engineering Task Force,
Mar. 1997. Mar. 1997.
[5] S. Alexander and R. Droms, "DHCP options and BOOTP vendor [5] S. Alexander and R. Droms, "DHCP options and BOOTP vendor
extensions," Request for Comments 2132, Internet Engineering Task extensions," Request for Comments 2132, Internet Engineering Task
Force, Mar. 1997. Force, Mar. 1997.
[6] P. V. Mockapetris, "Domain names - implementation and [6] P. V. Mockapetris, "Domain names - implementation and
specification," Request for Comments 1035, Internet Engineering Task specification," Request for Comments 1035, Internet Engineering Task
Force, Nov. 1987. Force, Nov. 1987.
[7] R. Hinden and S. Deering, "IP version 6 addressing architecture," [7] F. Yergeau, "UTF-8, a transformation format of unicode and ISO
10646," Request for Comments 2044, Internet Engineering Task Force,
Oct. 1996.
[8] R. Hinden and S. Deering, "IP version 6 addressing architecture,"
Request for Comments 2373, Internet Engineering Task Force, July Request for Comments 2373, Internet Engineering Task Force, July
1998. 1998.
 End of changes. 

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