SIPPING Working Group V. Hilt Internet-Draft Bell Labs/Alcatel-Lucent Expires: August 31, 2007 G. Camarillo Ericsson J. Rosenberg Cisco Systems February 27, 2007 A User Agent Profile Data Set for Media Policy draft-ietf-sipping-media-policy-dataset-03 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 31, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This specification defines a document format for the media properties of Session Initiation Protocol (SIP) sessions such as codecs or media types used. This format is based on XML and extends the Schema for SIP User Agent Profile Data Sets. It can be used to describe the media properties of a specific SIP session and to express media- Hilt, et al. Expires August 31, 2007 [Page 1] Internet-Draft Media Policy Dataset February 2007 related policies that can be applied to different SIP sessions. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Design Considerations . . . . . . . . . . . . . . . . . . . . 5 3.1. Namespace . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Extensibility . . . . . . . . . . . . . . . . . . . . . . 6 3.3. Inheritance from the Profile Data Set . . . . . . . . . . 6 4. Session Info Documents . . . . . . . . . . . . . . . . . . . . 6 4.1. The Element . . . . . . . . . . . . . . . . 7 4.2. Mapping SDP to Session Info Documents . . . . . . . . . . 7 5. Session Policy Documents . . . . . . . . . . . . . . . . . . . 8 5.1. The Element . . . . . . . . . . . . . . . 8 6. XML-encoded Session Properties . . . . . . . . . . . . . . . . 8 6.1. The Element . . . . . . . . . . . . . . . . 8 6.1.1. The Element . . . . . . . . . . . . . . . 9 6.2. The Element . . . . . . . . . . . . . . . . . . . 9 6.2.1. The Element . . . . . . . . . . . . . . . . . 10 6.3. The Element . . . . . . . . . . . . . . . . . . 11 6.3.1. The Element . . . . . . . . . . . . . . . . . 11 6.4. The Element . . . . . . . . . . . . . . . 12 6.5. The Element . . . . . . . . . . . 12 6.6. The Element . . . . . . . . . . . . 13 6.7. The Element . . . . . . . . . . . . 13 6.7.1. The Element . . . . . . . . . . . 14 6.7.2. The Element . . . . . . . . . . . 15 6.8. The Element . . . . . . . . . . . . . . . . . . 15 6.9. The Element . . . . . . . . . . . . . . . . 16 6.10. The Element . . . . . . . . . . . . . . . . . . 16 6.10.1. The Element . . . . . . . . . . . . . . . . . 16 6.10.2. The Element . . . . . . . . . . . . . . . . 17 6.10.3. The Element . . . . . . . . . . . . . . . . . . 17 6.10.4. The Element . . . . . . . . . . . . . . . . 17 6.10.5. The Element . . . . . . . . . . . . . . 17 6.11. Other Session Properties . . . . . . . . . . . . . . . . . 17 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. Session Policy Documents . . . . . . . . . . . . . . . . . 18 7.2. Session Information Documents . . . . . . . . . . . . . . 19 7.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 19 7.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 20 8. Schema Definition . . . . . . . . . . . . . . . . . . . . . . 22 9. Security Considerations . . . . . . . . . . . . . . . . . . . 26 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 10.1. MIME Registration for application/session-policy+xml . . . 26 10.2. URN Sub-Namespace Registration for Hilt, et al. Expires August 31, 2007 [Page 2] Internet-Draft Media Policy Dataset February 2007 urn:ietf:params:xml:ns:mediadataset . . . . . . . . . . . 27 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 28 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 11.1. Normative References . . . . . . . . . . . . . . . . . . . 28 11.2. Informative References . . . . . . . . . . . . . . . . . . 29 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30 Intellectual Property and Copyright Statements . . . . . . . . . . 31 Hilt, et al. Expires August 31, 2007 [Page 3] Internet-Draft Media Policy Dataset February 2007 1. Introduction The Framework for Session Initiation Protocol (SIP) [17] User Agent Profile Delivery [15] and the Framework for SIP Session Policies [14] define mechanisms to convey session policies and configuration information from a network server to a user agent. The media properties of SIP sessions are an important piece of this policy/ configuration information. Media properties include, for example, the codecs and media-types used in a session, the media- intermediaries to be traversed or the maximum bandwidth available for media streams. This draft defines a document format for media properties of SIP sessions, the Media Policy Dataset Format (MPDF). This format can be used in two ways: first, it can be used to describe the properties of a given SIP session (e.g. the media types and codecs used) in a session info document. Session info documents are usually created based on the session description of a session. Second, the MPDF format can be used to express policies for SIP sessions in a session policy document. In this usage, a document defines properties (e.g. the media types) that can or can not be used in a session, independent of a specific session description. If used with the Framework for SIP Session Policies [14], session info documents are used in conjunction with session-specific policies. A session info document is created by a UA based on the current session description and submitted to the policy server. The policy server examines the session info document, modifies it if necessary (e.g. by removing video streams if video is not permitted) and returns the possibly modified session info document to the UA. Session policy documents on the other hand are used to describe session-independent policies that can be submitted to the UA independent of a specific session. The two types of MPDF documents, session information and session policy documents, share the same set of XML elements to describe session properties. Since the usage of these elements differs between the two document types, they both use different root elements: is the root element for session information documents and is the root element for session policy documents. This enables the recipient of a document to determine the document type and to correctly interpret the media properties defined. A user agent may receive multiple session policy documents from different sources. These documents need to be merged into a single document the user agent can work with. General rules for merging session policy documents are described in [11]. Specific merging Hilt, et al. Expires August 31, 2007 [Page 4] Internet-Draft Media Policy Dataset February 2007 rules for each of the XML elements are described below. Merging is not needed for session information documents. If used for session-specific policies [14], a UA will contact all policy servers for a session sequentially. It will submit the current session info document to the first policy server, receive a policy-compliant version in return, submit this version to the second policy server and so on. The MPDF format is based on XML [13] and extends the Schema for SIP User Agent Profile Data Sets [11] by specifying a data set for media properties. The format also satisfies the requirements of a minimal set of media-level session policy elements as described in [16]. It can be extended through the XML extension mechanisms if additional media properties are needed. A MPDF document MUST be well-formed and MUST be valid according to schemas, including extension schemas, available to the validator and applicable to the XML document. MPDF documents MUST be based on XML 1.0 and MUST be encoded using UTF-8. 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. Design Considerations This section discusses design considerations for a session property language. 3.1. Namespace This specification makes use of XML namespaces [4]. The namespace URIs for schemas defined in this specification are URNs [6], using the namespace identifier 'ietf' defined by [7] and extended by [5]. The namespace URN for the MPDF schema is: urn:ietf:params:xml:ns:mediadataset The MIME type for the Media Policy Dataset Format is: Hilt, et al. Expires August 31, 2007 [Page 5] Internet-Draft Media Policy Dataset February 2007 application/session-policy+xml 3.2. Extensibility The MPDF format is an extension of the Schema for SIP User Agent Profile Data Sets [11]. Elements from the MPDF namespace can be used in conjunction with elements from other extensions of this schema. The MPDF format itself can also be extended using XML extension mechanisms. In particular, elements from different XML namespaces MAY be present within a MPDF document for the purposes of extensibility; elements or attributes from unknown namespaces MUST be ignored. 3.3. Inheritance from the Profile Data Set The MPDF format inherits the following attributes from the Profile Data Set Schema [11]: o Property Access Control: 'visibility' attribute o Policies: 'policy' and 'excluded-policy' attribute o Unidirectional Properties: 'direction' attribute o Preferences: 'q' attribute The use of these attributes is defined individually for each element in the XML format below. The MPDF format also uses the merging algorithms that are specified in the Profile Data Set Schema. The use of these algorithms is defined individually for each element in the XML format below. 4. Session Info Documents Session info documents describe key properties of a SIP session such as the media streams used in the session. Session info documents are typically created by a UA based on an SDP [3] session description or an SDP offer/answer pair [9]. Session info documents are used to exchange session-specific policy information [14] between a UA and a policy server. In this usage, a UA creates a session info document based on its SDP description(s) and sends this document to the policy server. The policy server modifies this document according to the policies that apply to the described session and returns a version of the session info document that is compliant to all policies. For example, if video streams are not permissible under current policies and the UA submits a session info document that contains a video stream, the policy server will Hilt, et al. Expires August 31, 2007 [Page 6] Internet-Draft Media Policy Dataset February 2007 remove the video stream from the XML markup and return the modified session info document to the UA. Session info documents are encoded using the element. 4.1. The Element The element describes the properties of a specific SIP session. The MAY occur multiple times inside a [11] element. The element MUST contain one element. It MAY contain one optional , , , , and element as well as elements from other namespaces. These elements are defined in Section 6. 4.2. Mapping SDP to Session Info Documents UAs typically create session info documents based on an SDP [3] description or the SDP offer/answer pair [9] of a session. If a UA has an SDP offer as well as an answer, it MUST use the answer to fill in the elements of a session info document except for the remote-URI and local-URI elements, which are taken from the remote and local session description respectively. The local session description is the one created locally by the UA (i.e. the offer if the UA has initiated the offer/answer exchange). The remote session description is the one received from the remote UA. The following rules apply when creating a session info document based on SDP description(s): A UA MUST create a separate element for each m= line in an SDP description. It MUST insert the media type from the m= line into a element and MUST create a element for each codec listed in the m= line. The UA MUST create a element for each stream using the port taken from the m= line and the address from the corresponding c= line of the local session description. It MUST create a element using the port and address from the m= and c= lines for the same stream taken from the remote session description if this session description is available. The mapping from a session info document to a SDP description follows the same rules in the reverse direction. Hilt, et al. Expires August 31, 2007 [Page 7] Internet-Draft Media Policy Dataset February 2007 Issue: we may need to define a mapping for other elements as well (e.g. bandwidth). 5. Session Policy Documents Session policy documents describe a policy for SIP sessions. Session policy documents are created independent of a specific session description and express policies that can be applied to different SIP sessions by the recipient of a document. Session policy documents can be used to encode session-independent policies [14]. Session-independent policies are typically created by a policy server and passed to a UA independent of an attempt to establish a session. A UA can apply the policies defined in a session policy document to the SIP sessions it is establishing. For example, a session policy document can contain an element that prohibits the use of video. To set up a session that is compliant to this policy, a UA does not include the media type video in its SDP offer or answer. Session policy documents are encoded using the element. 5.1. The Element The element describes a policy that applies to SIP sessions. The element MAY occur multiple times inside a [11] element. The element MAY contain one optional and multiple (including zero) , , , , , , , and elements as well as elements from other namespaces. These elements are defined in Section 6. 6. XML-encoded Session Properties This section describes XML elements that are used in session info and session policy documents to encode the properties of SIP sessions. 6.1. The Element The element is a container that is used to define a set of media types (e.g. audio, video). A specific media type is included in the set by adding the corresponding element Hilt, et al. Expires August 31, 2007 [Page 8] Internet-Draft Media Policy Dataset February 2007 to this container. The element can be used in session policy or session information document. If used in a session policy document (i.e. inside the container), it defines the media types that can or cannot be used in a session. In a container, it contains the media types that appear in the corresponding session description. This element MAY have the following attribute (see Section 3.3): direction. If used in a element, it MAY have the following additional attributes (see Section 3.3): visibility, excluded-policy. Multiple elements MAY only be present in a container element if each applies to a different set of streams (e.g. one element for incoming and one for outgoing streams). The element MUST contain one or more elements. Merging rule (if used in a container): containers are merged using the "Multiple Enumerated Value Merging Algorithm" defined in [11]. 6.1.1. The Element The element identifies a specific media type. The value of this element MUST be the name of a IANA registered media type (see [3]), such as 'audio', 'video', 'text', or 'application'. This element MAY have the following attribute (see Section 3.3): q. If used in a element, this element MAY have the following additional attribute (see Section 3.3): policy. Media types that have the policy 'allowed' MAY be used and media types with the policy 'disallowed' MUST NOT be used. 6.2. The Element The element is a container that is used to define a set of codecs. A specific codec is included in the set by adding the corresponding element to this container. The element can be used in a session policy or a session information document. If used in a element, it defines the codecs that may or may not be used in a session. A policy MUST allow the use of at least one codec per media type. If Hilt, et al. Expires August 31, 2007 [Page 9] Internet-Draft Media Policy Dataset February 2007 used in a element, it describes the codecs that appear in the corresponding session description. This element MAY have the following attributes (see Section 3.3): direction. If used in a element, this element MAY have the following additional attributes (see Section 3.3): visibility, excluded-policy. Multiple elements MAY only be present in a container element if each applies to a different set of streams (e.g. one element for incoming and one for outgoing streams). The element MUST contain one or more elements. Merging rule (if used in a container): containers are merged using the "Multiple Enumerated Value Merging Algorithm" defined in [11]. 6.2.1. The Element The element identifies a specific codec. The content of this element MUST be a registered MIME type [2] using media-type and subtype (e.g. audio/PCMA or video/H263) and possibly additional registered MIME type parameters. This element MAY have the following attribute (see Section 3.3): q. If used in a element, this element MAY have the following additional attribute (see Section 3.3): policy. Codecs that have the policy 'allowed' MAY be used and codecs with the policy 'disallowed' MUST NOT be used. The element MUST contain one element and MAY contain multiple optional elements. 6.2.1.1. The Element The element contains a MIME type that identifies a codec. The value of this element MUST be a combination of a registered MIME media-type and subtype [2] separated by a "/" (e.g. audio/PCMA, audio/G726-16, video/H263). 6.2.1.2. The Element The element may be needed for some codecs to identify a particular encoding or profile. The value of this element MUST be a name-value pair containing the name and the value of a Hilt, et al. Expires August 31, 2007 [Page 10] Internet-Draft Media Policy Dataset February 2007 registered MIME type parameter for the codec [2]. The name and value are separated by a "=". For example, the parameter "profile=0" can be used to specify a specific profile for the codec "video/ H263-2000". 6.3. The Element The element is a container that is used to describe the media streams used in a session. A element can contain multiple elements. Each element describes the properties (e.g. media type, codecs and IP addresses and ports) of a single media stream. The element is only defined for session information documents (i.e. in a container). The element MUST contain one or more elements. 6.3.1. The Element The element describes a specific media stream. It contains the media type, codecs and media URIs of this stream. A URI consists of the address and a port number contained in a session description for this stream. A UA that generates a element MUST insert the address/port found in the local session description for this media stream into the local-uri element. It MUST insert the address/port of the remote session description into the remote URI, if this address/port is available to the UA. If not, the UA generates a stream element that only contains the local-URI. This element may have the following attributes (see Section 3.3): direction. The element MUST contain one element, one or more elements and one element. It MAY contain one optional element. 6.3.1.1. The Element The element contains a URI that identifies the IP address and port number of the media stream in the local session description. The address part of this URI is contained in the c= element of the local SDP description. The port number part of the URI is contained in the m= element of the stream. Hilt, et al. Expires August 31, 2007 [Page 11] Internet-Draft Media Policy Dataset February 2007 6.3.1.2. The Element The element is structured exactly as the element. However, it contains a URI that identifies the IP address and port number of the described media stream in the remote session description. 6.4. The Element The element defines the overall maximum bandwidth in kilobits per second an entity can/will use for media streams at any point in time. It defines an upper bound for the media bandwidth that includes all media streams in all sessions. This element MAY have the following attribute (see Section 3.3): direction. If used in a element, this element MAY have the following additional attribute (see Section 3.3): visibility. If the element occurs multiple times in a container element, each instance MUST apply to a different set of media streams (i.e. one element for outgoing and one for incoming streams). Merging rule (if used in a container): the lowest max-bandwidth value is used. 6.5. The Element The element defines the maximum bandwidth in kilobits per second an entity can/will use for media streams in one session. It defines an upper bound for the media bandwidth over all media streams in a session. This element MAY have the following attribute (see Section 3.3): direction. If used in a element, this element MAY have the following additional attribute (see Section 3.3): visibility. If the element occurs multiple times in a container element, each instance MUST apply to a different set of media streams (i.e. one element for outgoing and one for incoming streams). Hilt, et al. Expires August 31, 2007 [Page 12] Internet-Draft Media Policy Dataset February 2007 Merging rule (if used in a container): the lowest max-session-bandwidth value is used. 6.6. The Element The element defines the maximum bandwidth in kilobits per second an entity can/will use for a media stream. This element MAY have the following attribute (see Section 3.3): direction. If used in a element, this element MAY have the following additional attribute (see Section 3.3): visibility. If the element occurs multiple times in a container element, each instance MUST apply to a different set of media streams (i.e. one element for outgoing and one for incoming streams). Merging rule (if used in a container): the lowest max-stream-bandwidth value is used. 6.7. The Element The element expresses a policy for routing a media stream through a media intermediary. The purpose of the element is to tell the UA to send a media stream through one (or a chain of) media intermediaries. Instead of sending the media directly to its final destination, the UA instead specifies a source route, which touches each intermediary and then reaches the final recipient. If there are N hops, including the final recipient, there needs to be a way for the media stream to specify N destinations. The element is a container that lists all media intermediaries to be traversed. Media intermediaries should be traversed in the order in which they appear in this list. The topmost entry should be traversed first, the last entry should be traversed last. Different types of intermediaries exist. These intermediaries are not necessarily interoperable and it may not be possible to chain them in an arbitrary order. A element SHOULD therefore only contain intermediary elements of the same type. This element may have the following attributes (see Section 3.3): direction. Hilt, et al. Expires August 31, 2007 [Page 13] Internet-Draft Media Policy Dataset February 2007 If used in a element, this element MAY have the following additional attribute (see Section 3.3): visibility. Multiple elements MAY only be present in a container if each applies to a different set of streams (e.g. one element for incoming and one for outgoing streams). The element MUST contain one or more of the following elements: and . Merging rule (if used in a container): the intermediaries defined in all policies are traversed. In general, local intermediaries should be traversed before remote intermediaries. During the merging process, element values from different servers are ordered using the "Closest Value First Merging Algorithm" [11]. The intermediaries should be traversed in this order. Note: it is not intended that the element replaces connectivity discovery mechanisms such as ICE. Instead of finding media relays that provide connectivity, this element defines a policy for media intermediaries that should be traversed. The set of intermediaries defined in the element and the ones discovered through ICE may overlap but don't have to. 6.7.1. The Element A fixed intermediary relies on pre-configured forwarding rules. The user agent simply sends media to the first media intermediary listed. It can assume that this media intermediary has been pre-configured with a forwarding rule for the media stream and knows where to forward the packets to. The configuration of forwarding rules in the intermediary must be done through other means. The element is optional and MAY occur multiple times inside a element. The element MUST contain one element and MAY contain multiple optional elements. 6.7.1.1. The Element The element contains a URI that identifies the IP address and port number of a media intermediary. The UA uses this URI to send its media streams to the intermediary. If a protocol uses multiple subsequent ports (e.g. RTP), the lowest port number SHOULD be included in the URI. All additional port numbers SHOULD be identified in elements. Hilt, et al. Expires August 31, 2007 [Page 14] Internet-Draft Media Policy Dataset February 2007 6.7.1.2. The Element If a protocol uses multiple subsequent ports (e.g. RTP), the lowest port number SHOULD be included in the element. All additional port numbers SHOULD be identified in elements. 6.7.2. The Element The TURN [12] protocol provides a mechanism for inserting a relay into the media path. Although the main purpose of TURN is NAT traversal, it is possible for a TURN relay to perform other media intermediary functionalities. The user agent establishes a binding on the TURN server and uses this binding to transmit and receive media. The element MUST contain one element and MAY contain multiple optional elements and one optional element. 6.7.2.1. The Element The element contains the shared secret needed to authenticate at the TURN server. 6.8. The Element The element contains an Differentiated Services Codepoint (DSCP) [10] value that should be used to populate the IP DS field of media packets. The contains an integer value that represents a 6 bit field and therefore ranges from 0 to 63. This element may have the following attributes (see Section 3.3): visibility, direction, media-type. The media-type attribute defines that element only applies to streams of a certain media type. For example, it may only apply to audio streams. The value of the 'media-type' attribute MUST be the name of a IANA registered media type (see [3]), such as 'audio', 'video', 'text', or 'application'. The element is optional and MAY occur multiple times inside a container. If the element occurs multiple times, each instance MUST apply to a different media stream (i.e. one element for audio and one for video streams). Hilt, et al. Expires August 31, 2007 [Page 15] Internet-Draft Media Policy Dataset February 2007 Merging rule (if used in a container): the domain that is first traversed by the media stream has precedence and its DSCP value is used. During the merging process, element values from different servers are ordered using the "Closest Value First Merging Algorithm" [11]. The DSCP value from the closest server is used. 6.9. The Element Domains often require that a user agent only uses ports in a certain range for media streams. The element defines a policy for the ports a user agent can use for media. The value of this element consists of a start port and an end port separated by a "-". The start/end port is the first/last port that can be used. This element may have the following attributes (see Section 3.3): visibility. Merging rule (if used in a container): the domain that is first traversed by the media stream has precedence and its local ports value is used. During the merging process, element values from different servers are ordered using the "Closest Value First Merging Algorithm" [11]. The value from the closest server is used. 6.10. The Element The element provides context information about a session policy or session information document. The element MAY contain multiple and an element. If used in a element, the element MAY also contain a element. If used in a element, the element MAY also contain a element. Merging rule (if used in a container): the element is not subject to merging. Information in the context element may be used to assist the user if a conflict occurs during the merging process. 6.10.1. The Element The element contains a URI that identifies the domain which has issued this policy. Hilt, et al. Expires August 31, 2007 [Page 16] Internet-Draft Media Policy Dataset February 2007 The element is optional and MAY occur only once inside a element. The element is only defined inside a element. 6.10.2. The Element The element contains a contact address (e.g. a SIP URI or email address) under which the issuer of this document can be reached. The element is optional and MAY occur multiple times inside a element. 6.10.3. The Element The element provides a short textual description of the policy or session that should be intelligible to the human user. The element is optional and MAY occur only once inside a element. 6.10.4. The Element The element contains the call-ID (as defined in [17]) of the session that is described in this document. The element is only defined inside a element. 6.10.5. The Element The element identifies the request-URI the dialog initiating request of a session is sent to. The element is only defined inside a element. 6.11. Other Session Properties A number of additional elements have been proposed for a media property language. These elements are deemed to be outside the scope of this format. However, they may be defined in extensions of MPDF or other profile data sets. o maximum number of streams o maximum number of sessions o maximum number of streams per session Hilt, et al. Expires August 31, 2007 [Page 17] Internet-Draft Media Policy Dataset February 2007 o external address and port o media transport protocol o outbound proxy o SIP methods o SIP option tags o SIP transport protocol o body disposition o body format o body encryption 7. Examples 7.1. Session Policy Documents The following example describes a session policy document that allows the use of audio and video and prohibits the use of other media types. It allows the use of any codec except G.723 and G.729. The policy also inserts a fixed media intermediary into outgoing media streams. example.com sip:policy_manager@example.com Access network policies audio video audio/G729 audio/G723 192.0.2.0:6000 6001 Hilt, et al. Expires August 31, 2007 [Page 18] Internet-Draft Media Policy Dataset February 2007 7.2. Session Information Documents The following examples contain session descriptions and the session information documents that represent these sessions. Examples 1 and 3 are based on one session description, example 2 is based on two session descriptions (i.e. the offer and answer). 7.2.1. Example 1 Hilt, et al. Expires August 31, 2007 [Page 19] Internet-Draft Media Policy Dataset February 2007 Local SDP session description: v=0 o=alice 2890844526 2890844526 IN IP4 host.anywhere.com s= c=IN IP4 host.anywhere.com t=0 0 m=audio 49562 RTP/AVP 0 1 3 a=rtpmap:0 PCMU/8000 a=rtpmap:1 1016/8000 a=rtpmap:3 GSM/8000 m=video 51234 RTP/AVP 31 34 a=rtpmap:31 H261/90000 a=rtpmap:34 H263/90000 MPDF document: sip:alice@atlanta.com session information audio audio/PCMU audio/1016 audio/GSM host.anywhere.com:49562 video video/H261 video/H263 host.anywhere.com:51234 7.2.2. Example 2 Local SDP session description: v=0 o=alice 2890844526 2890844526 IN IP4 host.anywhere.com s= c=IN IP4 host.anywhere.com t=0 0 Hilt, et al. Expires August 31, 2007 [Page 20] Internet-Draft Media Policy Dataset February 2007 m=audio 49562 RTP/AVP 0 1 3 a=rtpmap:0 PCMU/8000 a=rtpmap:1 1016/8000 a=rtpmap:3 GSM/8000 m=video 51234 RTP/AVP 31 34 a=rtpmap:31 H261/90000 a=rtpmap:34 H263/90000 Remote SDP session description: v=0 o=bob 2890844730 2890844730 IN IP4 host.example.com s= c=IN IP4 host.example.com t=0 0 m=audio 52123 RTP/AVP 0 3 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 m=video 50286 RTP/AVP 31 a=rtpmap:31 H261/90000 MPDF document: sip:alice@atlanta.com session information audio audio/PCMU audio/GSM host.anywhere.com:49562 host.example.com:52123 video video/H261 host.anywhere.com:51234 host.example.com:50286 Hilt, et al. Expires August 31, 2007 [Page 21] Internet-Draft Media Policy Dataset February 2007 8. Schema Definition Note: the schema definition still reflects the -01 version of this draft and needs to be updated. Hilt, et al. Expires August 31, 2007 [Page 22] Internet-Draft Media Policy Dataset February 2007 Hilt, et al. Expires August 31, 2007 [Page 23] Internet-Draft Media Policy Dataset February 2007 Hilt, et al. Expires August 31, 2007 [Page 24] Internet-Draft Media Policy Dataset February 2007 9. 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. 10. IANA Considerations This document registers a new MIME type, application/ session-policy+xml, and registers a new XML namespace. 10.1. 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 [8]. Hilt, et al. Expires August 31, 2007 [Page 26] Internet-Draft Media Policy Dataset February 2007 Encoding considerations: Same as encoding considerations of application/xml as specified in RFC 3023 [8]. Security considerations: See Section 10 of RFC 3023 [8] and Section 9 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: Volker Hilt, Intended usage: COMMON Author/Change controller: The IETF. 10.2. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:mediadataset This section registers a new XML namespace, as per the guidelines in [5] URI: The URI for this namespace is urn:ietf:params:xml:ns:mediadataset. Registrant Contact: IETF, SIPPING working group, , Volker Hilt, Hilt, et al. Expires August 31, 2007 [Page 27] Internet-Draft Media Policy Dataset February 2007 XML: BEGIN Session Policy Namespace

Namespace for Session Policy Information

urn:ietf:params:xml:ns:mediadataset

See RFCXXXX.

END Appendix A. Acknowledgements Many thanks to Allison Mankin, Dan Petrie and Martin Dolly for the discussions and suggestions. Many thanks to Roni Even and Mary Barnes for reviewing the draft and providing feedback. 11. References 11.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Casner, S. and P. Hoschka, "MIME Type Registration of RTP Payload Formats", RFC 3555, July 2003. [3] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006. [4] Layman, A., Hollander, D., and T. Bray, "Namespaces in XML", World Wide Web Consortium FirstEdition REC-xml-names-19990114, January 1999, . [5] Mealling, M., "The IETF XML Registry", draft-mealling-iana-xmlns-registry-05 (work in progress), Hilt, et al. Expires August 31, 2007 [Page 28] Internet-Draft Media Policy Dataset February 2007 June 2003. [6] Moats, R., "URN Syntax", RFC 2141, May 1997. [7] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, August 1999. [8] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [9] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [10] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998. [11] Petrie, D., Lawrence, S., Dolly, M., and V. Hilt, "A Schema and Guidelines for Defining Session Initiation Protocol User Agent Profile Data Sets", draft-petrie-sipping-profile-datasets-04 (work in progress), October 2005. [12] Rosenberg, J., "Obtaining Relay Addresses from Simple Traversal Underneath NAT (STUN)", draft-ietf-behave-turn-02 (work in progress), October 2006. [13] Sperberg-McQueen, C., Maler, E., Yergeau, F., Bray, T., and J. Paoli, "Extensible Markup Language (XML) 1.0 (Third Edition)", World Wide Web Consortium FirstEdition REC-xml-20040204, February 2004, . 11.2. Informative References [14] Hilt, V., Camarillo, G., and J. Rosenberg, "A Framework for Session Initiation Protocol (SIP) Session Policies", draft-ietf-sip-session-policy-framework-01 (work in progress), February 2007. [15] Petrie, D. and S. Channabasappa, "A Framework for Session Initiation Protocol User Agent Profile Delivery", draft-ietf-sipping-config-framework-10 (work in progress), January 2007. [16] Rosenberg, J., "Requirements for Session Policy for the Session Initiation Protocol (SIP)", draft-ietf-sipping-session-policy-req-02 (work in progress), July 2004. Hilt, et al. Expires August 31, 2007 [Page 29] Internet-Draft Media Policy Dataset February 2007 [17] 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/Alcatel-Lucent 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 Cisco Systems 600 Lanidex Plaza Parsippany, NJ 07054 USA Email: jdrosen@cisco.com Hilt, et al. Expires August 31, 2007 [Page 30] Internet-Draft Media Policy Dataset February 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Hilt, et al. Expires August 31, 2007 [Page 31]