draft-ietf-ecrit-dhc-lost-discovery-03.txt   rfc5223.txt 
ECRIT H. Schulzrinne Network Working Group H. Schulzrinne
Internet-Draft Columbia University Request for Comments: 5223 Columbia University
Intended status: Standards Track J. Polk Category: Standards Track J. Polk
Expires: November 30, 2008 Cisco Cisco
H. Tschofenig H. Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
May 29, 2008 August 2008
A Dynamic Host Configuration Protocol (DHCP) based Location-to-Service
Translation Protocol (LoST) Discovery Procedure
draft-ietf-ecrit-dhc-lost-discovery-03.txt
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Abstract Abstract
The Location-to-Service Translation Protocol (LoST) describes an XML- The Location-to-Service Translation (LoST) Protocol describes an XML-
based protocol for mapping service identifiers and geospatial or based protocol for mapping service identifiers and geospatial or
civic location information to service contact Uniform Resource civic location information to service contact Uniform Resource
Locators (URLs). LoST servers can be located anywhere but a Locators (URLs). LoST servers can be located anywhere, but a
placement closer to the end host, e.g., in the access network, is placement closer to the end host, e.g., in the access network, is
desireable. Such a LoST server placement provides benefits in desirable. In disaster situations with intermittent network
disaster situations with intermittent network connectivity regarding connectivity, such a LoST server placement provides benefits
the resiliency of emergency service communication. regarding the resiliency of emergency service communication.
This document describes how a LoST client can discover a LoST server This document describes how a LoST client can discover a LoST server
using the Dynamic Host Configuration Protocol (DHCP). using the Dynamic Host Configuration Protocol (DHCP).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Domain Name Encoding . . . . . . . . . . . . . . . . . . . . . 3 3. Domain Name Encoding . . . . . . . . . . . . . . . . . . . . . 3
4. LoST Server DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4 4. LoST Server DHCPv4 Option . . . . . . . . . . . . . . . . . . . 3
5. LoST Server DHCPv6 Option . . . . . . . . . . . . . . . . . . . 5 5. LoST Server DHCPv6 Option . . . . . . . . . . . . . . . . . . . 4
6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7.1. IANA Consideration for DHCPv4 Option . . . . . . . . . . . 6 7.1. DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . . . 5
7.2. IANA Consideration for DHCPv6 Option . . . . . . . . . . . 6 7.2. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . . 7 10.1. Normative References . . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 9
1. Introduction 1. Introduction
The Location-to-Service Translation Protocol (LoST) The Location-to-Service Translation (LoST) Protocol [RFC5222]
[I-D.ietf-ecrit-lost] describes an XML-based protocol for mapping describes an XML-based protocol for mapping service identifiers and
service identifiers and geospatial or civic location information to geospatial or civic location information to service contact Uniform
service contact Uniform Resource Locators (URLs). Resource Locators (URLs).
In order to interact with a LoST server, the LoST client eventually In order to interact with a LoST server, the LoST client needs to
needs to discover the server's IP address. Several mechanisms can be discover the server's IP address. Several mechanisms can be used to
used to learn this address, including manual configuration. In learn this address, including manual configuration. In environments
environments where the access network itself either deploys a LoST where the access network itself either deploys a LoST server or knows
server or knows a third party that operates a LoST server, DHCP can a third party that operates a LoST server, DHCP can provide the end
provide the end host with a domain name. This domain name is then host with a domain name. This domain name is then used as input to
used as input to the DNS-based resolution mechanism described in LoST the DNS-based resolution mechanism described in LoST [RFC5222] that
[I-D.ietf-ecrit-lost] that reuses the URI-enabled NAPTR specification reuses the URI-enabled NAPTR specification (see [RFC4848]).
(see [RFC4848]).
This document specifies a DHCPv4 and a DHCPv6 option that allows LoST This document specifies a DHCPv4 and a DHCPv6 option that allows LoST
clients to discover local LoST servers. clients to discover local LoST servers.
Section 2 provides terminology. Section 3 shows the encoding of the Section 2 provides terminology. Section 3 shows the encoding of the
domain name. Section 4 describes the DHCPv4 option while Section 5 domain name. Section 4 describes the DHCPv4 option while Section 5
describes the DHCPv6 option, with the same functionality. IANA and describes the DHCPv6 option, with the same functionality. IANA and
Security Considerations complete the document in Section 7 and Security Considerations complete the document in Sections 7 and 8.
Section 8.
2. Terminology 2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 and "OPTIONAL" are to be interpreted as described in RFC 2119
[RFC2119]. [RFC2119].
Within this document, we use terminology from [RFC5012] and Within this document, we use terminology from [RFC5012] and
[I-D.ietf-ecrit-lost]. [RFC5222].
3. Domain Name Encoding 3. Domain Name Encoding
This section describes the encoding of the domain name used in the This section describes the encoding of the domain name used in the
DHCPv4 option shown in Section 4 and also used in the DHCPv6 option DHCPv4 option shown in Section 4 and also used in the DHCPv6 option
shown in Section 5. shown in Section 5.
The domain name is encoded according to Section 3.1 of RFC 1035 The domain name is encoded according to Section 3.1 of RFC 1035
[RFC1035] whereby each label is represented as a one octet length [RFC1035] whereby each label is represented as a one-octet length
field followed by that number of octets. Since every domain name field followed by that number of octets. Since every domain name
ends with the null label of the root, a domain name is terminated by ends with the null label of the root, a domain name is terminated by
a length byte of zero. The high order two bits of every length octet a length byte of zero. The high-order two bits of every length octet
MUST be zero, and the remaining six bits of the length field limit MUST be zero, and the remaining six bits of the length field limit
the label to 63 octets or less. To simplify implementations, the the label to 63 octets or less. To simplify implementations, the
total length of a domain name (i.e., label octets and label length total length of a domain name (i.e., label octets and label length
octets) is restricted to 255 octets or less. octets) is restricted to 255 octets or less.
4. LoST Server DHCPv4 Option 4. LoST Server DHCPv4 Option
The LoST server DHCPv4 option carries a DNS (RFC 1035 [RFC1035]) The LoST server DHCPv4 option carries a DNS (RFC 1035 [RFC1035])
fully-qualified domain name to be used by the LoST client to locate a fully-qualified domain name (FQDN) to be used by the LoST client to
LoST server. locate a LoST server.
The DHCP option for this encoding has the following format: The DHCP option for this encoding has the following format:
Code Len LoST Server Domain Name Code Len LoST Server Domain Name
+-----+-----+-----+-----+-----+-----+-----+---- +-----+-----+-----+-----+-----+-----+-----+----
| TBD1| n | s1 | s2 | s3 | s4 | s5 | ... | 137 | n | s1 | s2 | s3 | s4 | s5 | ...
+-----+-----+-----+-----+-----+-----+-----+---- +-----+-----+-----+-----+-----+-----+-----+----
Figure 1: LoST FQDN DHCPv4 Option Figure 1: LoST FQDN DHCPv4 Option
The values s1, s2, s3, etc. represent the domain name labels in the The values s1, s2, s3, etc. represent the domain name labels in the
domain name encoding. Note that the length field in the DHCPv4 domain name encoding. Note that the length field in the DHCPv4
option represents the length of the entire domain name encoding, option represents the length of the entire domain name encoding,
whereas the length fields in the domain name encoding (see Section 3) whereas the length fields in the domain name encoding (see Section 3)
is the length of a single domain name label. is the length of a single domain name label.
Code: OPTION_V4_LOST (TBD1) Code: OPTION_V4_LOST (137)
Len: Length of the 'LoST Server Domain Name' field Len: Length of the 'LoST Server Domain Name' field
in octets; variable. in octets; variable.
LoST server Domain Name: The domain name of the LoST LoST Server Domain Name: The domain name of the LoST
server for the client to use. server for the client to use.
A DHCPv4 client MAY request a LoST server domain name in an Parameter A DHCPv4 client MAY request a LoST server domain name in a Parameter
Request List option, as described in [RFC2131]. Request List option, as described in [RFC2131].
The encoding of the domain name is described in Section 3. The encoding of the domain name is described in Section 3.
This option contains a single doamin name, and as such MUST contain This option contains a single domain name and, as such, MUST contain
precisely one root label. precisely one root label.
5. LoST Server DHCPv6 Option 5. LoST Server DHCPv6 Option
This section defines a DHCPv6 option to carry a domain name. This section defines a DHCPv6 option to carry a domain name.
The DHCPv6 option has the format shown in Figure 2. The DHCPv6 option has the format shown in Figure 2.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_V6_LOST | option-length | | OPTION_V6_LOST | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LoST Server Domain Name | | LoST Server Domain Name |
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: DHCPv6 Option for LoST Server Domain Name List option-code: OPTION_V6_LOST (51)
option-code: OPTION_V6_LOST (TBD2)
option-length: Length of the 'LoST Server Domain Name' field option-length: Length of the 'LoST Server Domain Name' field
in octets; variable. in octets; variable.
LoST server Domain Name: The domain name of the LoST LoST Server Domain Name: The domain name of the LoST
server for the client to use. server for the client to use.
Figure 2: DHCPv6 Option for LoST Server Domain Name List
A DHCPv6 client MAY request a LoST server domain name in an Options A DHCPv6 client MAY request a LoST server domain name in an Options
Request Option (ORO), as described in [RFC3315]. Request Option (ORO), as described in [RFC3315].
The encoding of the domain name is described in Section 3. The encoding of the domain name is described in Section 3.
This option contains a single doamin name, and as such MUST contain This option contains a single domain name and, as such, MUST contain
precisely one root label. precisely one root label.
6. Example 6. Example
This section shows an example of a DHCPv4 option where the DHCP This section shows an example of a DHCPv4 option where the DHCP
server wants to offer the "example.com" domain name to the client as server wants to offer the "example.com" domain name to the client as
input to the U-NAPTR LoST discovery procedure. This domain name input to the U-NAPTR LoST discovery procedure. This domain name
would be encoded as follows: would be encoded as follows:
+----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|TBD1|13 | 7 |'e'|'x'|'a'|'m'|'p'|'l'|'e'| 3 |'c'|'o'|'m'| 0 | |137 |13 | 7 | e | x | a | m | p | l | e | 3 | c | o | m | 0 |
+----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ +----+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Figure 3: Example for a LoST FQDN DHCPv4 Option Figure 3: Example for a LoST FQDN DHCPv4 Option
7. IANA Considerations 7. IANA Considerations
7.1. IANA Consideration for DHCPv4 Option 7.1. DHCPv4 Option
The following DHCPv4 option code for the Location-to-Service The following DHCPv4 option code for the Location-to-Service
Translation Protocol (LoST) server option must be assigned by IANA: Translation (LoST) Protocol server option has been assigned by IANA:
Option Name Value Described in Option Name Value Described in
----------------------------------------------- -----------------------------------------------
OPTION_V4_LOST TBD1 Section 4 OPTION_V4_LOST 137 Section 4
7.2. IANA Consideration for DHCPv6 Option 7.2. DHCPv6 Option
IANA is requested to assign the following DHCPv6 option codes for the IANA has assigned the following DHCPv6 option code for the Location-
Location-to-Service Translation Protocol (LoST) options: to-Service Translation (LoST) Protocol option:
Option Name Value Described in Option Name Value Described in
------------------------------------------------ ------------------------------------------------
OPTION_V6_LOST TBD2 Section 5 OPTION_V6_LOST 51 Section 5
8. Security Considerations 8. Security Considerations
If an adversary manages to modify the response from a DHCP server or If an adversary manages to modify the response from a DHCP server or
insert its own response, a LoST client could be led to contact a insert its own response, a LoST client could be led to contact a
rogue LoST server under the control of the adversary or be given an rogue LoST server under the control of the adversary or be given an
invalid address. These threats are documented in [RFC5069]. The invalid address. These threats are documented in [RFC5069]. The
security considerations in [RFC2131], [RFC2132] and [RFC3315] are security considerations in [RFC2131], [RFC2132], and [RFC3315] are
applicable to this document. applicable to this document.
With respect to the LoST security mechanisms please refer to [RFC5222] enumerates the LoST security mechanisms.
[I-D.ietf-ecrit-lost].
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Andrew Newton and Leslie Daigle for Andrew Newton reviewed the document and helped simplify the
their draft review and Andy for the proposed simplifications. mechanism. Other helpful input was provided by Jari Arkko, Leslie
Daigle, Vijay K. Gurbani (Gen-ART Review), David W. Hankins, Russ
Mark Stapp and David W. Hankins did the document review for the DHC Housley, Tim Polk, Mark Stapp, and Christian Vogt.
working group as part of the joint working group last call.
We would like to thank Vijay K. Gurbani for the Gen-ART review.
Furthermore, we would like to thank Russ Housley, Tim Polk, Jari
Arkko, and Christian Vogt.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997. Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the
Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
November 2002.
10.2. Informative References 10.2. Informative References
[I-D.ietf-ecrit-lost]
Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", draft-ietf-ecrit-lost-10 (work in progress),
May 2008.
[RFC4848] Daigle, L., "Domain-Based Application Service Location [RFC4848] Daigle, L., "Domain-Based Application Service Location
Using URIs and the Dynamic Delegation Discovery Service Using URIs and the Dynamic Delegation Discovery Service
(DDDS)", RFC 4848, April 2007. (DDDS)", RFC 4848, April 2007.
[RFC5012] Schulzrinne, H. and R. Marshall, "Requirements for [RFC5012] Schulzrinne, H. and R. Marshall, "Requirements for
Emergency Context Resolution with Internet Technologies", Emergency Context Resolution with Internet Technologies",
RFC 5012, January 2008. RFC 5012, January 2008.
[RFC5069] Taylor, T., Tschofenig, H., Schulzrinne, H., and M. [RFC5069] Taylor, T., Tschofenig, H., Schulzrinne, H., and M.
Shanmugam, "Security Threats and Requirements for Shanmugam, "Security Threats and Requirements for
Emergency Call Marking and Mapping", RFC 5069, Emergency Call Marking and Mapping", RFC 5069,
January 2008. January 2008.
[RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", RFC 5222, August 2008.
Authors' Addresses Authors' Addresses
Henning Schulzrinne Henning Schulzrinne
Columbia University Columbia University
Department of Computer Science Department of Computer Science
450 Computer Science Building 450 Computer Science Building
New York, NY 10027 New York, NY 10027
US US
Phone: +1 212 939 7004 EMail: hgs+ecrit@cs.columbia.edu
Email: hgs+ecrit@cs.columbia.edu
URI: http://www.cs.columbia.edu URI: http://www.cs.columbia.edu
James Polk James Polk
Cisco Cisco
2200 East President George Bush Turnpike 2200 East President George Bush Turnpike
Richardson, Texas 75082 Richardson, TX 75082
US US
Email: jmpolk@cisco.com EMail: jmpolk@cisco.com
Hannes Tschofenig Hannes Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
Linnoitustie 6 Linnoitustie 6
Espoo 02600 Espoo 02600
Finland Finland
Phone: +358 (50) 4871445 Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@nsn.com EMail: Hannes.Tschofenig@nsn.com
URI: http://www.tschofenig.priv.at URI: http://www.tschofenig.priv.at
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
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