Internet DRAFT - draft-hilt-sipping-session-indep-policy

draft-hilt-sipping-session-indep-policy





Session Initiation Proposal                                      V. Hilt
Investigation Working Group                Bell Labs/Lucent Technologies
Internet-Draft                                              G. Camarillo
Expires: November 15, 2004                                      Ericsson
                                                            J. Rosenberg
                                                             dynamicsoft
                                                            May 17, 2004



    Session-Independent Policies for the Session Initiation Protocol
                                 (SIP)
               draft-hilt-sipping-session-indep-policy-01


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 November 15, 2004.


Copyright Notice


   Copyright (C) The Internet Society (2004). All Rights Reserved.


Abstract


   Session policies are often independent of a specific session and
   generally apply to sessions during a certain period of time. This
   draft defines a document format for session-independent session
   policies. It also discusses the use of policy documents with the user
   agent profile delivery framework.







Hilt, et al.           Expires November 15, 2004                [Page 1]
Internet-Draft    Session-Independent Session Policies          May 2004



Table of Contents


   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  User Agent Profile Delivery Framework  . . . . . . . . . . . .  4
     3.1   Use of URIs for Policy Subscriptions . . . . . . . . . . .  4
     3.2   Support of Policy Formats  . . . . . . . . . . . . . . . .  5
   4.  Policy Profile Considerations  . . . . . . . . . . . . . . . .  5
   5.  Session Policy Profile Format  . . . . . . . . . . . . . . . .  6
     5.1   Policy Document Format . . . . . . . . . . . . . . . . . .  6
       5.1.1   Protocols Element  . . . . . . . . . . . . . . . . . .  7
       5.1.2   Media Element  . . . . . . . . . . . . . . . . . . . .  9
     5.2   Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     5.3   Example  . . . . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
     7.1   MIME Registration for application/session-policy+xml . . . 12
     7.2   URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:sessionpolicy . . . . . . . . . . . 12
       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 14
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   A.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
       Intellectual Property and Copyright Statements . . . . . . . . 15





























Hilt, et al.           Expires November 15, 2004                [Page 2]
Internet-Draft    Session-Independent Session Policies          May 2004



1.  Introduction


   Some domains have policies in place, which impact the sessions
   established using the Session Initiation Protocol (SIP). These
   policies are typically needed to support the operation of the network
   infrastructure or certain services. For example, a SIP user agent
   might be located in a domain that is behind a Network Address
   Translator (NAT). This domain might have a  policy in place that
   requires the user agent to contact a TURN [10] relay before setting
   up a session. Information about this policy is essential for a user
   agent to successfully set up a session.


   In another example, SIP is used in a wireless network. The network
   provider has limited resources for media traffic. During periods of
   high activity, the provider would like to restrict codec usage on the
   network to lower rate codecs. In existing approaches, this is
   frequently accomplished by having the proxies examine the SDP [2] in
   the body and remove the higher rate codecs or reject the call and
   require the UA to start over with a different set of codecs. Having
   information about the current policy would enable user agents to
   initiate a session with an acceptable codec.


   In a third example, a domain has established policies regarding the
   type of user agents that can use their network. For example, a domain
   could require that user agents using its network use a particular
   protocol (e.g., SIP) with a set of extensions (e.g., preconditions
   must be used). A user agent needs to know the exact policy of a
   domain in order to be able to use the right configuration to send and
   receive traffic in that domain.


   Some domains have policies in place that are enforced by network
   elements. For example, a domain might have a configuration in which
   all packets containing a certain voice encoding are dropped.
   Unfortunately, enforcement mechanisms usually do not inform the user
   about the policies they are enforcing and silently keep the user from
   doing anything against them. This may lead to the malfunctioning of
   devices that is in-apprehensible to the user. With session policies,
   the user could decide to switch to a different codec or connect to a
   domain with less stringent policies.


   Session policies may be specific to a certain session and may change
   from session to session. Such policies can be set up using the
   framework for session-specific policies [3]. Other session policies
   remain in place for a longer period of time, typically in the range
   of hours or days. In principle, these policies could also be set up
   on a session-to-session basis. However, establishing the same
   policies over and over again is expensive, causing the continuous
   transmission of the same information during session setup, and




Hilt, et al.           Expires November 15, 2004                [Page 3]
Internet-Draft    Session-Independent Session Policies          May 2004



   possibly adding to session setup latencies. It is therefore desirable
   to enable user agents to obtain the policies relevant for them and to
   inform the user agents about changes in these policies.


   Our solution for supporting session-independent session policies is
   to enable user agents to retrieve policies, for example, as part of
   their device configuration. We define a document format for SIP
   session policies. SIP session policy documents can be transmitted
   using RFC3265 [9] and the Framework for SIP User Agent Profile
   Delivery [8]. We discuss the use of this framework for SIP session
   policies. However, session policy documents can also conveyed to user
   agents using other mechanisms.


2.  Terminology


   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
   RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
   described in BCP 14, [1] and indicate requirement levels for
   compliant implementations.


3.  User Agent Profile Delivery Framework


   One way of conveying session policy documents as defined in Section 5
   to a user agent is by using the Framework for SIP User Agent Profile
   Delivery [8]. The following sections describe the use of this
   framework.


3.1  Use of URIs for Policy Subscriptions


   Session-independent policies are frequently provided by the home
   domains of a registered user (i.e. the domain of an
   address-of-record) and the local domain (i.e. the domain the user
   agent is currently connected to). Policies of the local domain may be
   specific to a certain user (i.e. address-of-record) or apply
   generally to all user agents in the network.


   The home domain is responsible for providing SIP service to a user.
   This domain will frequently maintain user preferences and
   subscriptions to services and may provide session-independent
   policies, that are needed to implement them. The local domain is
   responsible for providing IP service to a user agent. It may be the
   same domain as the home domain or a different domain in case the user
   is roaming in a foreign network or obtains SIP services and IP
   connectivity from different providers. The local domain often
   provides policies, which impact the network traffic created by a
   certain user or all devices in general.





Hilt, et al.           Expires November 15, 2004                [Page 4]
Internet-Draft    Session-Independent Session Policies          May 2004



   The following three types of policy URIs are typically of interest
   for a user agent:
   o  "device" policies from the local network that apply to all user
      agents,
   o  "user" policies from the local network for a certain
      address-of-record,
   o  "user" policies from the home domain of an address-of-record.


   The only way to find out if a domain provides policies to a user
   agent is to subscribe to the respective policy URI. It is therefore
   RECOMMENDED that a user agent subscribes to all of the above policy
   URI types. The subscription will be rejected if the respective domain
   does not have policies in place. The creation of these URIs is
   defined in [8].


3.2  Support of Policy Formats


   This specification defines a document format for session policies
   with the MIME type "application/basic-session-policy+xml". A user
   agent which is conform with this specification MUST indicate its
   support for this document format in the Accept header of a SUBSCRIBE.


   Some session policies are required by the network and sessions can't
   be established without using them. An example is a policy enabling
   NAT traversal. Other policies are optional. They are often used by
   services or needed to improve the quality of service in the network.
   Session can be established without using them but may lack the
   respective service or be of a lower quality.


   If the subscriber does not indicate its support for the MIME type
   used by a policy that is mandatory in the Accept header of a
   SUBSCRIBE request, the notifier MUST reject this request with a 406
   "Not Acceptable" response. This way, the subscriber knows that there
   are mandatory policies it does not support, which will cause a
   session setup attempt to fail.


4.  Policy Profile Considerations


   This specification defines an initial profile for session policies
   using the framework for user agent profile delivery. Other profiles
   for different session policies might be defined in additional
   specifications. The following considerations may serve as guidelines
   when developing additional session policy profiles.


   A policy document encodes one or more session policies. Each policy
   package must specify or cite detailed specifications for the syntax
   and semantics associated with the format of such documents.





Hilt, et al.           Expires November 15, 2004                [Page 5]
Internet-Draft    Session-Independent Session Policies          May 2004



   The policy package should support versioning so that the recipients
   of policy document can properly order them. This may be achieved
   using a version attribute.


   Policy documents often have an expiration time. After this time, the
   policies encoded in the document will not be used any more. A policy
   document may contain an expiration attribute.


   A policy document may contain multiple policies. Each policy in the
   document may have a different scope. For example, a policy for
   firewall traversal would only apply to external calls whereas a
   policy limiting the bandwidth available could be in effect during
   peak hours. A policy document may define a scope attribute that
   specifies to which sessions a certain policy applies. Possible scopes
   are:
   o  Time and day: limits the use of a policy to certain times or days.
   o  Local entity: limits the use of a policy to a specific to a
      certain local user. This is in particular useful for devices that
      supports multiple identities.
   o  Remote entity: limits the use of a policy to sessions involving
      certain remote addresses, for example all non-local addresses.
   o  Media streams: limits the use of a policy to certain media
      streams.


   The use of policies may be mandatory or optional. A policy document
   may specify whether a policy is mandatory or optional.


5.  Session Policy Profile Format


   A session policy document is an XML document that MUST be well-formed
   and SHOULD be valid. Policy documents MUST be based on XML 1.0 and
   MUST be encoded using UTF-8. This specification makes use of XML
   namespaces for identifying session policy documents. The namespace
   URI for elements defined by this specification is a URN [5], using
   the namespace identifier 'ietf' defined by RFC 2648 [6] and extended
   by [4]. This URN is:
      urn:ietf:params:xml:ns:sessionpolicy


   A session policy document begins with the root element tag
   "sessionpolicy".


5.1  Policy Document Format


   A session policy document starts with a sessionpolicy element. This
   element has three mandatory attributes:







Hilt, et al.           Expires November 15, 2004                [Page 6]
Internet-Draft    Session-Independent Session Policies          May 2004



      version: This attribute allows the recipient of session policy
      information documents to properly order them. Versions start at 0,
      and increment by one for each new document sent to a subscriber.
      Versions are scoped within a subscription. Versions MUST be
      representable using a 32 bit integer.
      domain: This attribute contains the domain the policy belongs to.
      entity: This attribute contains a URI that identifies the user
      whose policy information is reported in the remainder of the
      document.


   The sessionpolicy element has a series of sessionpolicy sub-elements:
   zero or one protocols element and zero or one media element.


5.1.1  Protocols Element


   The protocols element contains a series of protocol sub-elements.
   Each protocol sub-element contains the policy related to the usage of
   a particular protocol.


   The protocol element has a single mandatory attribute, name. The name
   attribute identifies a protocol the policy of each protocol element
   is referring to. The protocol element has a series of sub-elements:
   methods, option-tags, feature-tags, and bodies.


5.1.1.1  Methods Element


   The methods element contains a default-policy attribute and method
   elements. The default-policy attribute contains the policy for
   methods that are not listed as method elements. A method element has
   two attributes: name and policy. The name attribute identifies a
   method, and the policy attribute contains the policy for that method
   (allowed or disallowed).


5.1.1.2  Option-tags Element


   The option-tags element contains a default-policy attribute and
   option-tag elements. The default-policy attribute contains the policy
   for option-tags that are not listed as option-tag elements. An
   option-tag element has two attributes: name and policy. The name
   attribute identifies a method, and the policy attribute contains the
   policy for that method (mandatory, allowed, or disallowed).


5.1.1.3  Feature-tags Element


   The feature-tags element contains a default-policy attribute and
   feature-tag elements. The default-policy attribute contains the
   policy for feature-tags that are not listed as feature-tag elements.
   An feature-tag element has two attributes: name and policy. The name




Hilt, et al.           Expires November 15, 2004                [Page 7]
Internet-Draft    Session-Independent Session Policies          May 2004



   attribute identifies a method, and the policy attribute contains the
   policy for that method (allowed, or disallowed).


5.1.1.4  Bodies Element


   The bodies element contains a default-policy attribute, a
   default-encryption attribute and body-disposition elements. The
   default-policy attribute contains the policy for body dispositions
   that are not listed as body-disposition elements. The
   default-encryption attribute contains the encryption policy for body
   dispositions that are not listed as body-disposition elements.


   A body-disposition element can have a number of attributes: name,
   policy, default-policy, and encryption. The name attribute identifies
   a body-disposition, and the policy attribute contains the policy for
   that body-disposition (allowed, or disallowed). The default-policy
   attribute contains the policy for body formats that are not listed as
   body-format elements. The encryption attribute indicates whether or
   not encryption is allowed for a particular body disposition.


   A body-disposition element contains body-format elements. A
   body-format element can have a two attributes: name and policy. The
   name attribute identifies a body-format, and the policy attribute
   contains the policy for that body-format (allowed or disallowed).


5.1.1.5  Extensibility


   Other elements from different namespaces MAY be present within a
   protocol element for the purposes of extensibility; elements or
   attributes from unknown namespaces MUST be ignored.


5.1.1.6  Example of a Protocol Element




















Hilt, et al.           Expires November 15, 2004                [Page 8]
Internet-Draft    Session-Independent Session Policies          May 2004



   <protocols>
     <protocol name="SIP">
       <methods default-policy="allowed">
          <method name="MESSAGE" policy="disallowed"/>
       </methods>
       <option-tags default-policy="disallowed">
          <option-tag name="100rel" policy="mandatory"/>
          <option-tag name="preconditions" policy="allowed"/>
       </option-tags>
       <feature-tags default-policy="disallowed">
          <feature-tag name="video" policy="allowed"/>
       </feature-tags>
       <bodies default-policy="allowed" default-encryption="allowed">
          <body-disposition name="session" policy="allowed"
                            encryption="disallowed" default-policy="disallowed">
             <body-format name="application/sdp" policy="allowed"/>
          </body-disposition>
       </bodies>
     </protocol>
   </protocols>



5.1.2  Media Element


   The media element contains the policy related to the characteristics
   of media streams of different types. It has three attributes:
   maxbandwidth, maxnostreams, and default-policy. They contain the
   maximum bandwidth the user can count on, the maximum number of media
   streams that the user is allowed to established at the same time, and
   the default policy (allowed or disallowed) for stream types that are
   not listed as stream elements.


   The media element contains a series of stream elements.


5.1.2.1  Stream Element


   A stream element can have a number of attributes: type, policy,
   maxbandwidth, and maxnostreams. The type attribute identifies a media
   type, and the policy attribute contains the policy for that media
   type (allowed or disallowed).


   The stream element has a number of optional sub-element: the codecs
   element, the transports element and the directions element.


5.1.2.1.1  Codecs Element


   The codecs element contains a default-policy attribute and codec
   elements. The default-policy attribute contains the policy for codecs




Hilt, et al.           Expires November 15, 2004                [Page 9]
Internet-Draft    Session-Independent Session Policies          May 2004



   that are not listed as codec elements. A codec element can have two
   attributes: name and policy. The name attribute identifies a codec
   name, and the policy attribute contains the policy for that codec
   (allowed, or disallowed). The codec name is the encoding name as
   defined by the respective RTP profile.


5.1.2.1.2  Transports Element


   The transports element contains a default-policy attribute and
   transport elements. The default-policy attribute contains the policy
   for transports that are not listed as transport elements. A transport
   element can have two attributes: name and policy. The name attribute
   identifies a transport, and the policy attribute contains the policy
   for that transport (allowed, or disallowed).


5.1.2.1.3  Directions Element


   The directions element contains a default-policy attribute and
   direction elements. The default-policy attribute contains the policy
   for directions that are not listed as direction elements. A direction
   element can have two attributes: name and policy. The name attribute
   identifies a direction (sendrecv, sendonly, recvonly), and the policy
   attribute contains the policy for that direction (allowed, or
   disallowed).


5.1.2.1.4  Extensibility


   Other elements from different namespaces MAY be present within a
   stream element for the purposes of extensibility; elements or
   attributes from unknown namespaces MUST be ignored.


5.1.2.2  Example of a Media Element



   <media maxnostreams="4" default-policy="disallowed">
      <stream type="audio" policy="allowed">
           <codecs default-policy="allowed">
               <codec name="PCMU" policy="disallowed"/>
               <codec name="PCMA" policy="disallowed"/>
           </codecs>
           <transports default-policy="disallowed">
               <transport name="RTP/AVP" policy="allowed"/>
           </transports>
           <directions default-policy="disallowed">
               <direction name="sendonly" policy="allowed"/>
           </directions>
      </stream>
   </media>




Hilt, et al.           Expires November 15, 2004               [Page 10]
Internet-Draft    Session-Independent Session Policies          May 2004



5.2  Schema


   The following is the schema for the application/session-policy+xml
   type:




   <?xml version="1.0" encoding="UTF-8"?>
   TBD




5.3  Example


   The following is is an example of an application/session-policy+xml
   document:



   <?xml version="1.0" encoding="UTF-8"?>
   <sessionpolicy xmlns="urn:ietf:params:xml:ns:sessionpolicy"
                  version="0"
                  domain="example.com"
                  entity="sip:alice@example.com">
    <protocols>
     <protocol name="SIP">
       <methods default-policy="allowed"/>
       <option-tags default-policy="allowed"/>
       <feature-tags default-policy="allowed"/>
       <bodies default-policy="allowed" default-encryption="allowed"/>
     </protocol>
    </protocols>
    <media default-policy="allowed"/>
   </sessionpolicy>



6.  Security Considerations


   Session policy information can be sensitive information. The protocol
   used to distribute it SHOULD ensure privacy, message integrity and
   authentication. Furthermore, the protocol SHOULD provide access
   controls which restrict who can see who else's session policy
   information.


7.  IANA Considerations


   This document registers a new MIME type, application/
   session-policy+xml, and registers a new XML namespace.





Hilt, et al.           Expires November 15, 2004               [Page 11]
Internet-Draft    Session-Independent Session Policies          May 2004



7.1  MIME Registration for application/session-policy+xml


   MIME media type name: application


   MIME subtype name: session-policy+xml


   Mandatory parameters: none


   Optional parameters: Same as charset parameter application/xml as
   specified in RFC 3023 [7].


   Encoding considerations: Same as encoding considerations of
   application/xml as specified in RFC 3023 [7].


   Security considerations: See Section 10 of RFC 3023 [7] and Section 6
   of this specification.


   Interoperability considerations: none.


   Published specification: This document.


   Applications which use this media type: This document type has been
   used to download the session policy of a domain to SIP user agents.


   Additional Information:


   Magic Number: None


   File Extension: .wif or .xml


   Macintosh file type code: "TEXT"


   Personal and email address for further information: Gonzalo
   Camarillo, <Gonzalo.Camarillo@ericsson.com>


   Intended usage: COMMON


   Author/Change controller: The IETF.


7.2  URN Sub-Namespace Registration for
    urn:ietf:params:xml:ns:sessionpolicy


   This section registers a new XML namespace, as per the guidelines in
   [4]


   URI: The URI for this namespace is
   urn:ietf:params:xml:ns:sessionpolicy.





Hilt, et al.           Expires November 15, 2004               [Page 12]
Internet-Draft    Session-Independent Session Policies          May 2004



   Registrant Contact: IETF, SIPPING working group,<sipping@ietf.org>,
   Gonzalo Camarillo, <Gonzalo.Camarillo@ericsson.com>



           XML:


                BEGIN
                <?xml version="1.0"?>
                <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
                          "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
                <html xmlns="http://www.w3.org/1999/xhtml">
                <head>
                  <meta http-equiv="content-type"
                     content="text/html;charset=iso-8859-1"/>
                  <title>Session Policy Namespace</title>
                </head>
                <body>
                  <h1>Namespace for Session Policy Information</h1>
                  <h2>application/session-policy+xml</h2>
                  <p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
                </body>
                </html>
                END



8  References


   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.


   [2]   Handley, M. and V. Jacobson, "SDP: Session Description
         Protocol", RFC 2327, April 1998.


   [3]   Hilt, V. and J. Rosenberg, "A Framework for Session-Specific
         Intermediary Session Policies in SIP", September 2003.


   [4]   Mealling, M., "The IETF XML Registry",
         draft-mealling-iana-xmlns-registry-05 (work in progress), June
         2003.


   [5]   Moats, R., "URN Syntax", RFC 2141, May 1997.


   [6]   Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
         August 1999.


   [7]   Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC
         3023, January 2001.





Hilt, et al.           Expires November 15, 2004               [Page 13]
Internet-Draft    Session-Independent Session Policies          May 2004



   [8]   Petrie, D., "A Framework for SIP User Agent Profile Delivery",
         draft-ietf-sipping-config-framework-02 (work in progress),
         February 2004.


   [9]   Roach, A., "Session Initiation Protocol (SIP)-Specific Event
         Notification", RFC 3265, June 2002.


   [10]  Rosenberg, J., "Traversal Using Relay NAT (TURN)",
         draft-rosenberg-midcom-turn-03 (work in progress), October
         2003.


   [11]  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.



Authors' Addresses


   Volker Hilt
   Bell Labs/Lucent Technologies
   101 Crawfords Corner Rd
   Holmdel, NJ  07733
   USA


   EMail: volkerh@bell-labs.com



   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   Finland


   EMail: Gonzalo.Camarillo@ericsson.com



   Jonathan Rosenberg
   dynamicsoft
   72 Eagle Rock Avenue
   East Hanover, NJ  07936
   USA


   EMail: jdrosen@dynamicsoft.com


Appendix A.  Acknowledgements


   Many thanks to Allison Mankin and Markus Hofmann for their
   contributions to this draft.




Hilt, et al.           Expires November 15, 2004               [Page 14]
Internet-Draft    Session-Independent Session Policies          May 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




Hilt, et al.           Expires November 15, 2004               [Page 15]
Internet-Draft    Session-Independent Session Policies          May 2004



   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.



Acknowledgment


   Funding for the RFC Editor function is currently provided by the
   Internet Society.












































Hilt, et al.           Expires November 15, 2004               [Page 16]