draft-ietf-dhc-slp-06.txt   rfc2610.txt 
Internet Engineering Task Force C. Perkins Network Working Group C. Perkins
INTERNET DRAFT E. Guttman Request for Comments: 2610 E. Guttman
Sun Microsystems Category: Standards Track Sun Microsystems
16 December 1998 June 1999
DHCP Options for Service Location Protocol DHCP Options for Service Location Protocol
draft-ietf-dhc-slp-06.txt
Status of This Memo
This document is a submission by the Dynamic Host Configuration Status of this Memo
Working Group of the Internet Engineering Task Force (IETF).
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Distribution of this memo is unlimited.
This document is an Internet-Draft. Internet-Drafts are working This document specifies an Internet standards track protocol for the
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working documents as Internet-Drafts. Official Protocol Standards" (STD 1) for the standardization state
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Internet-Drafts are draft documents valid for a maximum of six months Copyright Notice
and may be updated, replaced, or obsoleted by other documents at
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Abstract Abstract
The Dynamic Host Configuration Protocol provides a framework for The Dynamic Host Configuration Protocol provides a framework for
passing configuration information to hosts on a TCP/IP network. passing configuration information to hosts on a TCP/IP network.
Entities using the Service Location Protocol need to find out the Entities using the Service Location Protocol need to find out the
address of Directory Agents in order to transact messages. Another address of Directory Agents in order to transact messages. Another
option provides an assignment of scope for configuration of SLP User option provides an assignment of scope for configuration of SLP User
and Service Agents. and Service Agents.
1. Introduction 1. Introduction
The Dynamic Host Configuration Protocol [2] provides a framework The Dynamic Host Configuration Protocol [2] provides a framework for
for passing configuration information to hosts on a TCP/IP network. passing configuration information to hosts on a TCP/IP network.
Entities using the Service Location Protocol, Version 2 [3] need to Entities using the Service Location Protocol, Version 2 [3] and
obtain the address of Directory Agents and Scope configuration. The Service Location Protocol, Version 1 [4] need to obtain the address
Service Location Protocol (SLP) provides a default configuration of Directory Agents and Scope configuration. The Service Location
for Scopes and Directory Agents may be discovered using multicast Protocol (SLP) provides a default configuration for Scopes and
or broadcast. It is useful in a larger deployment to be able Directory Agents may be discovered using multicast or broadcast. It
to configure SLP Agents using DHCP, so as to centralize the is useful in a larger deployment to be able to configure SLP Agents
administration and to deploy SLP in networks where multicast routing using DHCP, so as to centralize the administration and to deploy SLP
is not available. in networks where multicast routing is not available.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [1]. document are to be interpreted as described in [1].
2. Introduction 2. Introduction
The DHCP options described below are used to configure Agents using The DHCP options described below are used to configure Agents using
the Service Location Protocol, Version 2 [3]. the Service Location Protocol, Version 2 [3] and Version 1 [4].
The SLP Directory Agent option is used to configure User Agents and The SLP Directory Agent option is used to configure User Agents and
Service Agents with the location of Directory Agents in the network. Service Agents with the location of Directory Agents in the network.
The SLP Scope Option takes precedence over both default and static The SLP Scope Option takes precedence over both default and static
scope configuration of SLP agents. scope configuration of SLP agents.
3. SLP Directory Agent Option 3. SLP Directory Agent Option
This option specifies the location of one or more SLP Directory This option specifies the location of one or more SLP Directory
Agents. Agents.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code = 78 | Length | a1 | a2 | | Code = 78 | Length | Mandatory | a1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| a3 | a4 | a1 | ... | a2 | a3 | a4 | ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The SLP Directory Agent Option specifies a list of IP addresses The SLP Directory Agent Option specifies a list of IP addresses for
for Directory Agents. Directory Agents MUST be listed in order of Directory Agents. Directory Agents MUST be listed in order of
preference, if there is an order of preference. preference, if there is an order of preference.
The Length value must include one for the 'Mandatory' byte and
include four for each Directory Agent address which follows. Thus,
the Length minus one of the option MUST always be divisible by 4 and
has a minimum value of 5.
The address of the Directory Agent is given in network byte order. The address of the Directory Agent is given in network byte order.
The length of the option MUST always be divisible by 4 and has a
minimum length of 4. The 'Mandatory' byte in the Directory Agent option may be set to
either 0 or 1. If it is set to 1, the SLP User Agent or Service
Agent so configured MUST NOT employ either active or passive
multicast discovery of Directory Agents.
Note that for backward compatibility with some deployed software the
Mandatory byte MUST NOT be set to any byte value for which the high
order bit (0x80) is set.
The Directory Agents listed in this option MUST be configured with The Directory Agents listed in this option MUST be configured with
the a non-empty subset of the scope list that the Agent receiving the the a non-empty subset of the scope list that the Agent receiving the
Directory Agent Option is configured with. See the notes below. Directory Agent Option is configured with. See the notes below.
The SLPv2 specification [3] defines how to use this option. The SLPv2 specification [3] defines how to use this option.
4. SLP Service Scope Option 4. SLP Service Scope Option
The scope list is a comma delimited list which indicates the scopes The scope list is a comma delimited list which indicates the scopes
that a SLP Agent is configured to use. that a SLP Agent is configured to use.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code = 79 | Length | MANDATORY | <Scope List>... | Code = 79 | Length | Mandatory | <Scope List>...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Length indicates the number of bytes which follow. Since the The Length indicates the number of bytes which follow. Since the
Scope-List String is encoded using UTF-8 [4] characters, it may be Scope-List String is encoded using UTF-8 [5] characters, it may be
the cast that the Length is not the same as the number of characters the cast that the Length is not the same as the number of characters
in the Scope-List String. The Length value must include one for the in the Scope-List String. The Length value must include one for the
'MANDATORY' byte. 'Mandatory' byte.
The 'MANDATORY' byte determines whether SLP Agents override their The 'Mandatory' byte determines whether SLP Agents override their
static configuration for scopes with the <Scope List> string static configuration for scopes with the <Scope List> string provided
provided by the option. This allows DHCP administrators to by the option. This allows DHCP administrators to implement a policy
implement a policy of assigning a set of scopes to Agents for service of assigning a set of scopes to Agents for service provision. If the
provision. If the MANDATORY byte is zero, static configuration takes Mandatory byte is 0, static configuration takes precedence over the
precedence over the DHCP provided scope list. If the MANDATORY byte DHCP provided scope list. If the Mandatory byte is 1, the <Scope
is nonzero, the <Scope List> provided in this option MUST be used by List> provided in this option MUST be used by the SLP Agent.
the SLP Agent.
The Scope List String syntax and usage are defined in the SLPv2 The Scope List String syntax and usage are defined in the SLPv2
specification [3]. specification [3].
4.1. Zero Length Scope-List String Configuration 4.1. Zero Length Scope-List String Configuration
A SLP Service Scope Option which indicates a Length of 1 (in other A SLP Service Scope Option which indicates a Length of 1 (in other
words, omitting the <Scope List> string entirely) validly configures words, omitting the <Scope List> string entirely) validly configures
the SLP User Agent to use "User Selectable Scopes." the SLP User Agent to use "User Selectable Scopes."
The SLP Agent will use the aggregated list of scopes of all known The SLP Agent will use the aggregated list of scopes of all known
DAs. If no DAs are known, the UA will use SA discovery to determine DAs. If no DAs are known, the UA will use SA discovery to determine
the list of scopes on the network, as defined in [3]. the list of scopes on the network, as defined in [3].
Note that this configuration is tantamount to removing all Note that this configuration is tantamount to removing all
centralized control of the scope configuration of hosts on the centralized control of the scope configuration of hosts on the
network. This makes it possible for every User Agent to see every network. This makes it possible for every User Agent to see every
service. This may not be desirable as users may not be able to or service. This may not be desirable as users may not be able to or
desire to decide which services are appropriate for them. desire to decide which services are appropriate for them.
skipping to change at page 4, line 5 skipping to change at page 4, line 23
could find that it might rely on fraudulent or otherwise malicious could find that it might rely on fraudulent or otherwise malicious
directory agents to advertise its services. DHCPOFFERs could prevent directory agents to advertise its services. DHCPOFFERs could prevent
the regular SLP framework from functioning by directing clients to the regular SLP framework from functioning by directing clients to
not use multicast, to use nonexistent directory agents and so on. not use multicast, to use nonexistent directory agents and so on.
These difficulties are inherited from the much larger and more These difficulties are inherited from the much larger and more
serious problem, viz. securing or authenticating any information serious problem, viz. securing or authenticating any information
whatsoever from a DHCP server (or client!) is not possible in common whatsoever from a DHCP server (or client!) is not possible in common
DHCP deployments. DHCP deployments.
6. Full Copyright Statement References
Copyright (C) The Internet Society (1997). All Rights Reserved. [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March
1997.
[3] E. Guttman, C. Perkins, J. Veizades, and M. Day, "Service
Location Protocol version 2", Work in Progress.
[4] Veizades, J., Guttman, E., Perkins, C. and S. Kaplan, "Service
Location Protocol", RFC 2165, July 1997.
[5] Yergeau, F., "UTF-8, a transformation format of unicode and ISO
10646", RFC 2279, October 1998.
Authors' Addresses
Charles E. Perkins
Technology Development Group
Mail Stop MPK15-214
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, CA 94025
Phone: +1 650-786-6464
Fax: +1 650-786-6445
EMail: Charles.Perkins@Sun.Com
Web: http://www.svrloc.org/~charliep
Erik Guttman
Technology Development Group
Mail Stop UFRA02
Sun Microsystems, Inc.
Bahnstr. 2
74915 Waibstadt, Germany
Phone: +49 7263 911 701
or: +1 650 786 5992
EMail: Erik.Guttman@Sun.Com
Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph are
are included on all such copies and derivative works. However, included on all such copies and derivative works. However, this
this document itself may not be modified in any way, such as by document itself may not be modified in any way, such as by removing
removing the copyright notice or references to the Internet Society the copyright notice or references to the Internet Society or other
or other Internet organizations, except as needed for the purpose Internet organizations, except as needed for the purpose of
of developing Internet standards in which case the procedures developing Internet standards in which case the procedures for
for copyrights defined in the Internet Standards process must be copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than followed, or as required to translate it into languages other than
English. English.
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
References
[1] S. Bradner. Key words for use in RFCs to Indicate Requirement
Levels. RFC 2119, March 1997.
[2] R. Droms. Dynamic Host Configuration Protocol. RFC 2131, March
1997.
[3] E. Guttman, C. Perkins, J. Veizades, and M. Day. Service
Location Protocol version 2. draft-ietf-svrloc-protocol-v2-11.txt,
October 1998. (work in progress).
[4] F. Yergeau. UTF-8, a transformation format of unicode and ISO
10646. RFC 2279, October 1998.
Author's Address
Questions about this memo can be directed to: Acknowledgement
Charles E. Perkins Erik Guttman Funding for the RFC Editor function is currently provided by the
Technology Development Group Technology Development Group Internet Society.
Mail Stop MPK15-214 Mail Stop UFRA02
Sun Microsystems, Inc. Sun Microsystems, Inc.
15 Network Circle Bahnstr. 2
Menlo Park, CA 94025 74915 Waibstadt, Germany
phone: +1 650-786-6464 phone: +49 7263 911 701
fax: +1 650-786-6445 or: +1 650 786 5992
email: Charles.Perkins@Sun.Com Erik.Guttman@Sun.Com
Web: http://www.svrloc.org/~charliep
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