draft-ietf-speermint-architecture-07.txt		draft-ietf-speermint-architecture-08.txt
	Speermint Working Group R. Penno		Speermint Working Group A.Uzelac(Ed.)
	Internet Draft Juniper Networks		Internet Draft Global Crossing
	Intended status: Informational D. Malas		Intended status: Informational
	Expires: May 2009 CableLabs		Expires: September 2009
	S. Khan		March 2, 2009
	Comcast
	A. Uzelac
	Global Crossing
	M. Hammer
	Cisco Systems
	November 3, 2008
	SPEERMINT Peering Architecture		SPEERMINT Peering Architecture
	draft-ietf-speermint-architecture-07		draft-ietf-speermint-architecture-08
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that		This Internet-Draft is submitted to IETF in full conformance with the
	any applicable patent or other IPR claims of which he or she is		provisions of BCP 78 and BCP 79.
	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		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-		other groups may also distribute working documents as Internet-
	Drafts.		Drafts.
	Internet-Drafts are draft documents valid for a maximum of six		Internet-Drafts are draft documents valid for a maximum of six months
	months and may be updated, replaced, or obsoleted by other documents		and may be updated, replaced, or obsoleted by other documents at any
	at any time. It is inappropriate to use Internet-Drafts as		time. It is inappropriate to use Internet-Drafts as reference
	reference material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on January 2008.		This Internet-Draft will expire on September 2, 2009.
	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2008).		Copyright (c) 2009 IETF Trust and the persons identified as the
			document authors. All rights reserved.
	Abstract
	This document defines the SPEERMINT peering architecture, its		This document is subject to BCP 78 and the IETF Trust's Legal
	functional components and peering interface functions. It also		Provisions Relating to IETF Documents
	describes the steps taken to establish a session between two peering		(http://trustee.ietf.org/license-info) in effect on the date of
	domains in the context of the functions defined.		publication of this document. Please review these documents
			carefully, as they describe your rights and restrictions with respect
			to this document.
	Conventions used in this document		Abstract
	The key words "must", "must NOT", "REQUIRED", "SHALL", "SHALL NOT",		This document defines the SPEERMINT peering architecture, its functional
	"should", "should NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		components and peering interface functions. It also describes the steps taken
	document are to be interpreted as described in RFC-2119[1]		to establish a session between two peering domains in the context of the
			functions defined.
	Table of Contents		Table of Contents
	1. Introduction...................................................3		1. Introduction...................................................3
	2. Network Context................................................3		2. Network Context................................................3
	3. Procedures.....................................................6		3. Reference SPEERMINT Architecture...............................4
	4. Reference SPEERMINT Architecture...............................6		4. Procedures of Interdomain SSP Session Establishment............6
	5. Recommended SSP Procedures.....................................8		5. Recommended SSP Procedures.....................................7
	5.1. Originating SSP Procedures................................8		5.1. Originating SSP Procedures................................7
	5.1.1. The Look-Up Function (LUF)...........................8		5.1.1. The Look-Up Function (LUF)...........................7
	5.1.1.1. Target address analysis.........................8		5.1.1.1. Target address analysis.........................7
	5.1.1.2. User ENUM Lookup................................9		5.1.1.2. End User ENUM Lookup............................8
	5.1.1.3. Infrastructure ENUM lookup......................9		5.1.1.3. Infrastructure ENUM lookup......................8
	5.1.2. Location Routing Function (LRF).....................10		5.1.2. Location Routing Function (LRF)......................8
	5.1.2.1. Routing Table..................................10		5.1.2.1. SIP DNS Resolution..............................8
	5.1.2.2. SIP DNS Resolution.............................10		5.1.2.2. Routing Table...................................9
	5.1.2.3. SIP Redirect Server............................11		5.1.2.3. SIP Redirect Server.............................9
	5.1.3. The Signaling Function (SF).........................11		5.1.3. The Signaling Function (SF)..........................9
	5.1.3.1. Establishing a Trusted Relationship............11		5.1.3.1. Establishing a Trusted Relationship.............9
	5.1.3.2. Sending the SIP request........................12		5.1.3.2. Sending the SIP request........................10
	5.2. Terminating SSP Procedures...............................12		5.2. Terminating SSP Procedures...............................10
	5.2.1. The Location Function (LF)..........................12		5.2.1. The Location Function (LF)..........................10
	5.2.1.1. Publish ENUM records...........................12		5.2.1.1. Publish ENUM records...........................10
	5.2.1.2. Publish SIP DNS records........................13		5.2.1.2. Publish SIP DNS records........................11
	5.2.1.3. Subscribe Notify...............................13		5.2.1.3. Subscribe Notify...............................11
	5.2.2. Signaling Function (SF).............................13		5.2.2. Signaling Function (SF).............................11
	5.2.2.1. TLS............................................13		5.2.2.1. TLS............................................11
	5.2.2.2. Receive SIP requests...........................13		5.2.2.2. Receive SIP requests...........................11
	5.3. Target SSP Procedures....................................14		5.3. Target SSP Procedures....................................12
	5.3.1. Signaling Function (SF).............................14		5.3.1. Signaling Function (SF).............................12
	5.3.1.1. TLS............................................14		5.3.1.1. TLS............................................12
	5.3.1.2. Receive SIP requests...........................14		5.3.1.2. Receive SIP requests...........................12
	5.4. Media Function (MF)......................................14		5.4. Media Function (MF)......................................12
	5.5. Policy Considerations....................................14		5.5. Policy Considerations....................................12
	6. Call Control and Media Control Deployment Options.............15		6. Call Control and Media Control Deployment Options.............13
	7. Address space considerations..................................17		7. Address space considerations..................................14
	8. Security Considerations.......................................17		8. Security Considerations.......................................15
	9. IANA Considerations...........................................17		9. IANA Considerations...........................................15
	10. Acknowledgments..............................................17		10. Acknowledgments..............................................15
	11. References...................................................18		11. References...................................................16
	11.1. Normative References....................................18		11.1. Normative References....................................16
	11.2. Informative References..................................19		11.2. Informative References..................................17
	Author's Addresses...............................................20		Author's Addresses...............................................18
	Intellectual Property Statement..................................20
	Disclaimer of Validity...........................................21
	1. Introduction		1. Introduction
	The objective of this document is to define a reference peering		The objective of this document is to define a reference peering architecture in
	architecture in the context of Session PEERing for Multimedia		the context of Session PEERing for Multimedia INTerconnect (SPEERMINT). In this
	INTerconnect (SPEERMINT). In this process, we define the peering		process, we define the peering reference architecture, its functional
	reference architecture (reference, for short), it's functional		components, and peering interface functions from the perspective of a SIP
	components, and peering interface functions from the perspective of		Service provider's (SSP) network.
	a SIP Service provider's (SSP) network.
	This architecture allows the interconnection of two SSPs in layer 5		This architecture allows the interconnection of two SSPs in layer 5 peering as
	peering as defined in the SPEERMINT Requirements [13] and		defined in the SPEERMINT Requirements [14] and Terminology [13] documents.
	Terminology [12] documents.
	Layer 3 peering is outside the scope of this document. Hence, the		Layer 3 peering is outside the scope of this document. Hence, the figures in
	figures in this document do not show routers so that the focus is on		this document do not show routers so that the focus is on Layer 5 protocol
	Layer 5 protocol aspects.		aspects.
	This document uses terminology defined in the SPEERMINT Terminology		This document uses terminology defined in the SPEERMINT Terminology document
	document [12], so the reader should be familiar with all the terms		[13], so the reader should be familiar with all the terms defined there.
	defined there.
	2. Network Context		In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
			"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are
			to be interpreted as described in [RFC2119].
	Figure 1 shows an example network context. Two SSPs can form a Layer		2. Network Context
	5 peering over either the public Internet or private Layer3
	networks. In addition, two or more providers may form a SIP (Layer
	5) federation [13] on either the public Internet or private Layer 3
	networks. This document does not make any assumption whether the SIP
	providers directly peer to each other or through Layer 3 transit
	network as per use case of [16].
	Note that Figure 1 allows for the following potential SPEERMINT		Figure 1 allows for the following potential SPEERMINT peering scenarios:
	peering scenarios:
	o Enterprise to Enterprise across the public Internet		o Enterprise to Enterprise across the public Internet
	o Enterprise to SSP across the public Internet		o Enterprise to SSP across the public Internet
	o SSP to SSP across the public Internet		o SSP to SSP across the public Internet
	o Enterprise to enterprise across a private Layer 3 network		o Enterprise to enterprise across a private Layer 3 network
	o Enterprise to SSP across a private Layer 3 network		o Enterprise to SSP across a private Layer 3 network
	o SSP to SSP across a private Layer 3 network		o SSP to SSP across a private Layer 3 network
	The members of a federation may jointly use a set of functions such
	as location function, signaling function, media function, ENUM
	database or SIP Registrar, SIP proxies, and/or functions that
	synthesize various SIP and non-SIP based applications. Similarly,
	two SSPs may jointly use a set of functions. The functions can be
	either public or private.
	+-------------------+		+-------------------+
	| |		| |
	| Public |		| Public |
	| SIP |		| SIP |
	| Peering |		| Peering |
	| |		| |
	+-------------------+		+-------------------+
	|		|
	-----		-----
	+-----------+ / \ +-----------+		+-----------+ / \ +-----------+
	skipping to change at page 5, line 46		skipping to change at page 4, line 36
	| SSP G |-----------\ /-----------| SSP H |		| SSP G |-----------\ /-----------| SSP H |
	| | -- -- | |		| | -- -- | |
	+-----------+ \____/ +-----------+		+-----------+ \____/ +-----------+
	|		|
	+-------------------+		+-------------------+
	| Private |		| Private |
	| SIP |		| SIP |
	| Peering |		| Peering |
	| |		| |
	+-------------------+		+-------------------+
	Figure 1: SPEERMINT Network Context		Figure 1: SPEERMINT Network Context
	3. Procedures		3. Reference SPEERMINT Architecture
	This document assumes that in order for call to be establish from a
	UAC end user in the initiating peer's network to a UAS in the
	receiving peer's network the following steps are taken:
	1. The analysis of the target address.
	. If the target address represents an intra-SSP resource, the
	behavior is out-of-scope with respect to this draft.
	2. the determination of the target SSP,
	3. the determination of the SF next-hop in the target SSP,
	4. the enforcement of authentication and potentially other
	policies,
	5. the determination of the UAS,
	6. the session establishment,
	7. the transfer of media which could include voice, video, text
	and others,
	8. and the session termination.
	The originating SSP would likely perform steps 1-4, and the
	terminating SSP would likely perform steps 4-5.
	In the case the target SSP is different from the terminating SSP it
	would repeat steps 1-4. This is reflected in Figure 2 that shows the
	target SSP with its own peering functions.
	4. Reference SPEERMINT Architecture
	Figure 2 depicts the SPEERMINT architecture and logical functions		Figure 2 depicts the SPEERMINT architecture and logical functions that form the
	that form the peering between two SSPs.		peering between two SSPs.
	+------+		+------+
	| DNS, |		| DNS, |
	+---------->| Db, |<---------+		+---------->| Db, |<---------+
	| | etc | |		| | etc | |
	| +------+ |		| +------+ |
	| |		| |
	------|-------- -------|-------		------|-------- -------|-------
	/ v \ / v \		/ v \ / v \
	| +--LUF-+ | | +--LUF-+ |		| +--LUF-+ | | +--LUF-+ |
	skipping to change at page 7, line 41		skipping to change at page 5, line 41
	| SSP | | SSP |		| SSP | | SSP |
	| +---MF--+ +---MF--+ |		| +---MF--+ +---MF--+ |
	| | | | | |		| | | | | |
	| | DBE | | DBE | |		| | DBE | | DBE | |
	| | | | | |		| | | | | |
	| +---MF--+ +---MF--+ |		| +---MF--+ +---MF--+ |
	\ / \ /		\ / \ /
	--------------- ---------------		--------------- ---------------
	Figure 2: Reference SPEERMINT Architecture		Figure 2: Reference SPEERMINT Architecture
	The procedures presented in section 3 are implemented by a set of		The following procedures are implemented by a set of peering functions:
	peering functions:
	The Look-Up Function (LUF) provides a mechanism for determining for		The Look-Up Function (LUF) provides a mechanism for determining for a given
	a given request the target domain to which the request should be		request the target domain to which the request should be routed.
	routed.
	The Location Routing Function (LRF) determines for the target domain		The Location Routing Function (LRF) determines for the target domain of a given
	of a given request the location of the SF in that domain and		request the location of the SF in that domain and optionally develops other
	optionally develops other Session Establishment Data (SED) required		Session Establishment Data (SED) required to route the request to that domain.
	to route the request to that domain.
	Signaling Function (SF): Purpose is to perform SIP call routing, to		The Signaling Function (SF) provides SIP call routing, to optionally perform
	optionally perform termination and re-initiation of call, to		termination and re-initiation of call, to optionally implement security and
	optionally implement security and policies on SIP messages, and to		policies on SIP messages, and to assist in discovery/exchange of parameters to
	assist in discovery/exchange of parameters to be used by the Media		be used by the Media Function (MF).
	Function (MF).
	Media Function (MF): Purpose is to perform media related function		The Media Function (MF) provides media related functions such as media
	such as media transcoding and media security implementation between		transcoding, topology hiding and media security implementation between two
	two SIP providers.		SSPs.
	The intention of defining these functions is to provide a framework		The intention of defining these functions is to provide a framework for design
	for design segmentation and allow each one to evolve independently.		segmentation and allow each one to evolve independently.
			4. Procedures of Interdomain SSP Session Establishment
			This document assumes that in order for a session to be established from a UA
			in the originating SSP's network to an UA in the Target SSP's network the
			following steps are taken:
			1. analyze the target address.
			a. If the target address represents an intra-SSP resource, the
			behavior is out-of-scope with respect to this draft.
			2. determine the target SSP (LUF)
			3. determine the SF next-hop in the target SSP (LRF)
			4. enforce authentication and potentially other policies
			5. determine of the UA
			6. establish the session,
			7. transfer of media which could include voice, video, text and others,
			8. terminate the session (BYE)
			The originating SSP would likely perform steps 1-4, and the target SSP would
			likely perform steps 4-5.
			In the case the target SSP changes, then steps 1-4 would be repeated. This is
			reflected in Figure 2 that shows the target SSP with its own peering functions.
	5. Recommended SSP Procedures		5. Recommended SSP Procedures
	This section describes the functions in more detail and provides		This section describes the functions in more detail and provides some
	some recommendations on the role they would play in a SIP call in a		recommendations on the role they would play in a SIP call in a Layer 5 peering
	Layer 5 peering scenario.		scenario.
	Some of the information in the chapter is taken from [14] and is put		Some of the information in the section is taken from [14] and is put here for
	here for continuity purposes.		continuity purposes.
	5.1. Originating SSP Procedures		5.1. Originating SSP Procedures
	5.1.1. The Look-Up Function (LUF)		5.1.1. The Look-Up Function (LUF)
	Purpose is to determine the SF of the target domain of a given		Purpose is to determine the SF of the target domain of a given request and
	request and optionally develop Session Establishment Data (SED)		optionally develop Session Establishment Data.
	[12].
	5.1.1.1. Target address analysis		5.1.1.1. Target address analysis
	When the initiating SSP receives a request to communicate, it		When the originating SSP receives a request to communicate, it analyzes the
	analyzes the target URI to determine whether the call needs to be		target URI to determine whether the call needs to be routed internal or
	terminated internally or externally to its network. The analysis		external to its network. The analysis method is internal to the SSP; thus,
	method is internal to the SSP; thus, outside the scope of SPEERMINT.		outside the scope of SPEERMINT. Note that the SSP may also consult any manner
	Note that the SSP is free to consult any manner of private data		of private data sources to make this determination.
	sources to make this determination.
	If the target address does not represent a resource inside the		If the target address does not represent a resource inside the originating
	initiating SSP's administrative domain or federation of domains, the		SSP's administrative domain or federation of domains, the originating SSP
	initiating SSP resolves the call routing data by using the Location		resolves the call routing data by using the Location Routing Function (LRF).
	Routing Function (LRF).
	For example, if the request to communicate is for an im: or pres:		For example, if the request to communicate is for an im: or pres: URI type, the
	URI type, the initiating peer follows the procedures in [8]. If the		originating SSP follows the procedures in [8]. If the highest priority
	highest priority supported URI scheme is sip: or sips:, the		supported URI scheme is sip: or sips: the originating SSP skips to SIP DNS
	initiating peer skips to SIP DNS resolution in Section 5.1.3.		resolution in Section 5.1.3. Likewise, if the target address is already a sip:
	Likewise, if the target address is already a sip: or sips: URI in an		or sips: URI in an external domain, the originating SSP skips to SIP DNS
	external domain, the initiating peer skips to SIP DNS resolution in		resolution in Section 5.1.2.1.
	Section 5.1.2.2.
	If the target address corresponds to a specific E.164 address, the		If the target address corresponds to a specific E.164 address, the SSP may need
	peer may need to perform some form of number plan mapping according		to perform some form of number plan mapping according to local policy. For
	to local policy. For example, in the United States, a dial string		example, in the United States, a dial string beginning "011 44" could be
	beginning "011 44" could be converted to "+44", or in the United		converted to "+44", or in the United Kingdom "00 1" could be converted to "+1".
	Kingdom "00 1" could be converted to "+1". Once the peer has an		Once the SSP has an E.164 address, it can use ENUM.
	E.164 address, it can use ENUM.
	5.1.1.2. User ENUM Lookup		5.1.1.2. End User ENUM Lookup
	If an external E.164 address is the target, the initiating peer		If an external E.164 address is the target, the originating SSP consults the
	consults the public "User ENUM" rooted at e164.arpa, according to		public "User ENUM" rooted at e164.arpa, according to the procedures described
	the procedures described in RFC 3761. The peer must query for the		in RFC 3761. The SSP must query for the "E2U+sip" enumservice as described in
	"E2U+sip" enumservice as described in RFC 3764 [11], but MAY check		RFC 3764 [11], but MAY check for other enumservices. The originating SSP MAY
	for other enumservices. The initiating peer MAY consult a cache or		consult a cache or alternate representation of the ENUM data rather than actual
	alternate representation of the ENUM data rather than actual DNS		DNS queries. Also, the SSP may skip actual DNS queries if the originating SSP
	queries. Also, the peer may skip actual DNS queries if the		is sure that the target address country code is not represented in e164.arpa.
	initiating peer is sure that the target address country code is not		If a sip: or sips: URI is chosen the SSP skips to Section 5.1.6.
	represented in e164.arpa. If a sip: or sips: URI is chosen the peer
	skips to Section 5.1.6.
	If an im: or pres: URI is retrieved based on an "E2U+im" [10] or		If an im: or pres: URI is chosen for based on an "E2U+im" [8] or "E2U+pres" [9]
	"E2U+pres" [9] enumserver, the peer follows the procedures for		enumserver, the SSP follows the procedures for resolving these URIs to URIs for
	resolving these URIs to URIs for specific protocols such a SIP or		specific protocols such a SIP or XMPP as described in the previous section.
	XMPP as described in the previous section.
	5.1.1.3. Infrastructure ENUM lookup		5.1.1.3. Infrastructure ENUM lookup
	Next the initiating peer checks for a carrier-of-record in a carrier		An originating SSP may check for a carrier-of-record in an Infrastructure ENUM
	ENUM domain according to the procedures described in [12]. As in		domain according to the procedures described in [12]. As in the previous step,
	the previous step, the peer may consult a cache or alternate		the SSP may consult a cache or alternate representation of the ENUM data in
	representation of the ENUM data in lieu of actual DNS queries. The		lieu of actual DNS queries. The SSP first checks for records for the "E2U+sip"
	peer first checks for records for the "E2U+sip" enumservice, then		enumservice, then for the "E2U+pstn" enumservice as defined in [21]. If a
	for the "E2U+pstn" enumservice as defined in [21]. If a terminal		terminal record is found with a sip: or sips: URI, the SSP skips to Section
	record is found with a sip: or sips: URI, the peer skips to Section		5.1.2.1. , otherwise the SSP continues processing according to the next
	5.1.2.2. , otherwise the peer continues processing according to the		section.
	next section.
	5.1.2. Location Routing Function (LRF)		5.1.2. Location Routing Function (LRF)
	The LRF of an Initiating SSP analyzes target address and discovers		The LRF of an Originating SSP analyzes target address and target domain
	the next hop signaling function (SF) in a peering relationship. The		identified by the LUF, and discovers the next hop signaling function (SF) in a
	resource to determine the SF of the target domain might be provided		peering relationship. The resource to determine the SF of the target domain
	by a third-party as in the assisted-peering case.		might be provided by a third-party as in the assisted-peering case.
	5.1.2.1. Routing Table
	If there is no user ENUM records and the initiating peer cannot		5.1.2.1. SIP DNS Resolution
	discover the carrier-of-record or if the initiating peer cannot
	reach the carrier-of-record via SIP peering, the initiating peer
	still needs to deliver the call to the PSTN or reject it. Note that
	the initiating peer may still forward the call to another SSP for
	PSTN gateway termination by prior arrangement using the routing
	table.
	If so, the initiating peer may rewrite the Request-URI to address		Once a sip: or sips: in an external domain is identified as the target, the
	the gateway resource in the target SSP's domain and may forward the		originating SSP may apply local policy to decide whether forwarding requests to
	request on to that SSP using the procedures described in the		the target domain is acceptable. The originating SSP uses the procedures in
	remainder of these steps.		RFC 3263 [4] Section 4 to determine how to contact the receiving SSP. To
			summarize the RFC 3263 procedure: unless these are explicitly encoded in the
			target URI, a transport is chosen using NAPTR records, a port is chosen using
			SRV records, and an address is chosen using A or AAAA records. Note that these
			are queries of records in the global DNS.
	Alternatively to Request-URI re-writing, the initiating peer may		When communicating with another SSP, entities compliant to this document should
	populate the Route header with the address of the gateway resource		select a TLS-protected transport for communication from the originating SSP to
	in the target SSP's domain and forward the request on to that SSP		the receiving SSP if available.
	using the procedures described in the remainder of these steps, but
	applied to the Route header.
	5.1.2.2. SIP DNS Resolution		5.1.2.2. Routing Table
	Once a sip: or sips: in an external domain is selected as the		If there are no End User ENUM records and the Originating SSP cannot discover
	target, the initiating peer may apply local policy to decide whether		the carrier-of-record or if the Originating SSP cannot reach the carrier-of-
	forwarding requests to the target domain is acceptable. If so, the		record via SIP peering, the Originating SSP may deliver the call to the PSTN or
	initiating peer uses the procedures in RFC 3263 [4] Section 4 to		reject it. Note that the originating SSP may forward the call to another SSP
	determine how to contact the receiving peer. To summarize the RFC		for PSTN gateway termination by prior arrangement using the routing table.
	3263 procedure: unless these are explicitly encoded in the target
	URI, a transport is chosen using NAPTR records, a port is chosen
	using SRV records, and an address is chosen using A or AAAA records.
	Note that these are queries of records in the global DNS.
	When communicating with another SSP, entities compliant to this		If so, the originating SSP rewrites the Request-URI to address the gateway
	document should select a TLS-protected transport for communication		resource in the target SSP's domain and MAY forward the request on to that SSP
	from the initiating peer to the receiving peer if available. Note		using the procedures described in the remainder of these steps.
	that this is a single-hop requirement.
	5.1.2.3. SIP Redirect Server		5.1.2.3. SIP Redirect Server
	A SIP Redirect Server may help in resolving the current address of		A SIP Redirect Server using 3XX SIP Redirect is another option in resolving the
	the next-hop SF in the target domain.		next-hop SF of the target domain.
	5.1.3. The Signaling Function (SF)		5.1.3. The Signaling Function (SF)
	The purpose of signaling function is to perform routing of SIP		The purpose of signaling function is to perform routing of SIP messages as well
	messages, to optionally perform termination and re-initiation of a		as optionally implement security and policies on SIP messages, and to assist in
	call, to optionally implement security and policies on SIP messages,		discovery/exchange of parameters to be used by the Media Function (MF).
	and to assist in discovery/exchange of parameters to be used by the
	Media Function (MF).
	The signaling function performs the routing of SIP messages. The		The signaling function performs the routing of SIP messages. The optional
	optional termination and re-initiation of calls are performed by the		termination and re-initiation of calls may be performed by the signaling path
	signaling path border element (SBE).		Session Border Element (SBE).
	Optionally, a SF may perform additional functions such as Session		Optionally, a SF may perform additional functions such as Session Admission
	Admission Control, SIP Denial of Service protection, SIP Topology		Control, SIP Denial of Service protection, SIP Topology Hiding, SIP header
	Hiding, SIP header normalization, and SIP security, privacy and		normalization, and SIP security, privacy and encryption.
	encryption.
	The SF can also process SDP payloads for media information such as		The SF of a SBE can also process SDP payloads for media information such as
	media type, bandwidth, and type of codec; then, communicate this		media type, bandwidth, and type of codec; then, communicate this information to
	information to the media function. Signaling function may optionally		the media function. Signaling function may optionally communicate with the
	communicate with the network to pass Layer 3 related policies [10]		network to pass Layer 3 related policies [10]
	5.1.3.1. Establishing a Trusted Relationship		5.1.3.1. Establishing a Trusted Relationship
	Depending on the security needs and trust relationship between SSPs,		Depending on the security needs and trust relationships between SSPs, different
	different security mechanism can be used to establish SIP calls.		security mechanism can be used to establish SIP calls. These are discussed in
	These are discussed in the following subsections.		the following subsections.
	5.1.3.1.1. TLS connection		5.1.3.1.1. TLS connection
	Once a transport, port, and address are found, the initiating SSP		Once a transport, port, and address are found, the originating SSP will open or
	will open or find a reusable TLS connection to the peer. The		find a reusable TLS connection to the peer. The procedures to authenticate the
	procedures to authenticate the SSP's target domain is specified in		SSP's target domain is specified in [24]
	[24]
	5.1.3.1.2. IPSec		5.1.3.1.2. TLS
	In certain deployments, the use of IPSec between the signaling		If the trust relationship was established through TLS, the originating SSP can
	functions of the originating and terminating domains can be used as		optionally verify and assert the senders identity using the SIP Identity
	a security mechanism instead of TLS.		mechanism.
	5.1.3.1.3. Co-Location		In addition, new requests should contain a valid Identity and Identity-Info
			header as described in [12]. The Identity-Info header must present a domain
			name that is represented in the certificate provided when establishing the TLS
			connection over which the request is sent. The originating SSP should include
			an Identity header on in-dialog requests as well if the From header field value
			matches an identity the originating SSP is willing to assert.
	In this scenario, the SFs are co-located in a physically secure		5.1.3.1.3. IPSec
	location and/or are members of a segregated network. In this case
	messages between the originating and terminating SSPs would be sent
	as clear text.
	5.1.3.2. Sending the SIP request		In certain deployments the use of IPSec between the signaling functions of the
			originating and terminating domains can be used as a security mechanism instead
			of TLS.
	Once a trust relationship between the peers is established, the		5.1.3.1.4. Co-Location
	initiating peer sends the request.
	5.1.3.2.1. TLS		In this scenario the SFs are co-located in a physically secure location and/or
			are members of a segregated network. In this case messages between the
			originating and terminating SSPs would be sent as clear text.
	If the trust relationship was established through TLS, the		5.1.3.2. Sending the SIP request
	initiating peer can optionally verify and assert the sender's
	identity using the SIP Identity mechanism.
	In addition, new requests should contain a valid Identity and		Once a trust relationship between the peers is established, the originating SSP
	Identity-Info header as described in [12]. The Identity-Info header		sends the request.
	must present a domain name that is represented in the certificate
	provided when establishing the TLS connection over which the request
	is sent. The initiating peer should include an Identity header on
	in-dialog requests as well if the From header field value matches an
	identity the initiating peer is willing to assert.
	5.2. Terminating SSP Procedures		5.2. Terminating SSP Procedures
	5.2.1. The Location Function (LF)		5.2.1. The Location Function (LF)
	5.2.1.1. Publish ENUM records		5.2.1.1. Publish ENUM records
	The receiving peer should publish "E2U+SIP" and "E2U+pstn" records		The receiving SSP should participate by publishing "E2U+sip" and "E2U+pstn"
	with sip: or sips: URIs wherever a public carrier ENUM root is		records with sip: or sips: URIs wherever a public Infrastructure ENUM root is
	available. In the event that a public root is not available, a		available. This assumes that the receiving SSP wants to peer by default. When
	publishing to a common ENUM registry with the originating peer will		the receiving SSP does not want to accept traffic from specific originating
	suffice.		SSPs, it may still reject requests on a call-by-call basis.
	This assumes that the receiving peer wants to peer by default. When
	the receiving peer does not want to accept traffic from specific
	initiating peers, it may still reject requests on a call-by-call
	basis.
	5.2.1.2. Publish SIP DNS records		5.2.1.2. Publish SIP DNS records
	To receive peer requests, the receiving peer must ensure that it		To receive SSP requests, the receiving SSP must insure that it publishes
	publishes appropriate NAPTR, SRV, and address (A and/or AAAA)		appropriate NAPTR, SRV, and address (A and/or AAAA) records in the LF relevant
	records in the LF relevant to the originating peer's SF.		to the SSP's SF.
	5.2.1.3. Subscribe Notify		5.2.1.3. Subscribe Notify
	A policy notification function may also be optionally implemented by		Policies function may also be optionally implemented by dynamic subscribe,
	dynamic subscribe, notify, and exchange of policy information and		notify, and exchange of policy information and feature information among SSPs
	feature information among SSPs [21].		[21].
	5.2.2. Signaling Function (SF)		5.2.2. Signaling Function (SF)
	5.2.2.1. TLS		5.2.2.1. TLS
	When the receiving peer receives a TLS client hello, it responds		When the receiving SSP receives a TLS client hello, it responds with its
	with its certificate. The target SSP certificate should be valid		certificate. The Target SSP certificate should be valid and rooted in a well-
	and rooted in a well-known certificate authority. The procedures to		known certificate authority. The procedures to authenticate the SSP's
	authenticate the SSP's originating domain are specified in [24].		originating domain are specified in [24].
	The terminating SF verifies that the Identity header is valid,		The SF of the Target SSP verifies that the Identity header is valid,
	corresponds to the message, corresponds to the Identity-Info header,		corresponds to the message, corresponds to the Identity-Info header, and that
	and that the domain in the From header corresponds to one of the		the domain in the From header corresponds to one of the domains in the TLS
	domains in the TLS client certificate.		client certificate.
	5.2.2.2. Receive SIP requests		5.2.2.2. Receive SIP requests
	Once a trust relationship is established, the receiving peer is		Once a trust relationship is established, the Target SSP is prepared to receive
	prepared to receive incoming SIP requests. For new requests (dialog		incoming SIP requests. For new requests (dialog forming or not) the receiving
	forming or not) the receiving peer verifies if the target (request-		SSP verifies if the target (request-URI) is a domain that for which it is
	URI) is a domain that for which it is responsible. For these		responsible. For these requests, there should be no remaining Route header
	requests, there should be no remaining Route header field values.		field values. For in-dialog requests, the receiving SSP can verify that it
	For in-dialog requests, the receiving peer can verify that it
	corresponds to the top-most Route header field value.		corresponds to the top-most Route header field value.
	The receiving peer may reject incoming requests due to local policy.		The receiving SSP may reject incoming requests due to local policy. When a
	When a request is rejected because the initiating peer is not		request is rejected because the originating SSP is not authorized to peer, the
	authorized to peer, the receiving peer should respond with a 403		receiving SSP should respond with a 403 response with the reason phrase
	response with the reason phrase "Unsupported Peer".		"Unsupported Peer".
	5.3. Target SSP Procedures		5.3. Target SSP Procedures
	5.3.1. Signaling Function (SF)		5.3.1. Signaling Function (SF)
	5.3.1.1. TLS		5.3.1.1. TLS
	When the receiving peer receives a TLS client hello, it responds		When the receiving SSP receives a TLS client hello, it responds with its
	with its certificate. The target SSP certificate should be valid		certificate. The Target SSP's certificate should be valid and rooted in a
	and rooted in a well-known certificate authority. The procedures to		well-known certificate authority. The procedures to authenticate the SSP's
	authenticate the SSP's originating domain are specified in [24].		originating domain are specified in [24].
	If the requests should contain a valid Identity and Identity-Info		If the requests should contain a valid Identity and Identity-Info header as
	header as described in [12] the target SF verifies that the Identity		described in [24] the target SF verifies that the Identity header is valid,
	header is valid, corresponds to the message, corresponds to the		corresponds to the message, corresponds to the Identity-Info header, and that
	Identity-Info header, and that the domain in the From header		the domain in the From header corresponds to one of the domains in the TLS
	corresponds to one of the domains in the TLS client certificate.		client certificate.
	5.3.1.2. Receive SIP requests		5.3.1.2. Receive SIP requests
	The procedures of the SF of the target SSP are the same as the ones		The procedures of the SF of the target SSP are the same as the ones described
	described in section 5.2.2.2 with the addition that it might		in section 5.2.2.2 with the addition that it might establish a connection to
	establish a connection to another target SSP, and in this case use		another target SSP, and in this case use the procedures recommended to an
	the procedures recommended to an originating SSP (section 5.1).		originating SS (section 5.1).
	5.4. Media Function (MF)		5.4. Media Function (MF)
	The purpose of the MF is to perform media related functions such as		The purpose of the MF is to perform media related functions such as media
	media transcoding and media security implementation between two		transcoding and media security implementation between two SSPs.
	SSPs.
	An Example of this is to transform a voice payload from one codec		An Example of this is to transform a voice payload from one codec (e.g., G.711)
	(e.g., G.711) to another (e.g., EvRC). Additionally, the MF may		to another (e.g., EvRC). Additionally, the MF may perform media relaying,
	perform media relaying, media security, privacy, and encryption.		media security, privacy, and encryption.
	5.5. Policy Considerations		5.5. Policy Considerations
	In the context of the SPEERMINT working group when two SSPs peer,		In the context of the SPEERMINT working group when two SSPs peer, there MAY be
	there MAY be a desire to exchange peering policy information		a desire to exchange peering policy information dynamically. There are
	dynamically. There are specifications in progress in the SIPPING		specifications in progress in the SIPPING working group to define policy
	working group to define policy exchange between an UA and a domain		exchange between an UA and a domain [23] and providing profile data to SIP user
	[23] and providing profile data to SIP user agents [24] These		agents [24] These considerations borrow from both.
	considerations borrow from both.
	Following the terminology introduced in [12], this package uses the		Following the terminology introduced in [12], this package uses the terms
	terms Peering Session-Independent and Session-Specific policies in		Peering Session-Independent and Session-Specific policies in the following
	the following context.		context.
	o Peering Session-Independent policies include Diffserv Marking,		o Peering Session-Independent policies include Diffserv Marking, Policing,
	Policing, Session Admission Control, and domain reachabilities,		Session Admission Control, and domain reachabilities, amongst others. The
	amongst others. The time period between Peering Session-		time period between Peering Session-Independent policy changes is much
	Independent policy changes is much greater than the time it		greater than the time it takes to establish a call.
			o Peering Session-Specific polices includes supported connection/call rate,
			total number of connections/calls available, current utilization, amongst
			others. Peering Session-specific policies can change within the time it
	takes to establish a call.		takes to establish a call.
	o Peering Session-Specific polices includes supported		These policies can be SSP dependent or independent, creating the following
	connection/call rate, total number of connections/calls		peering policy definition:
	available, current utilization, amongst others. Peering
	Session-specific policies can change within the time it takes
	to establish a call.
	Likewise, but orthogonal to session dependency, an SSP may have		o SSP Independent or Dependent
	policies that may be peer-dependent or peer-independent. That is,		Session dependent Session
	the session-dependent and session-independent policies may by		independent
	further sub-divided and modified by additional controls that depend
	on which peer SSP or federation with which communications is being
	established.
	6. Call Control and Media Control Deployment Options		6. Call Control and Media Control Deployment Options
	The peering functions can be deployed along the following two		The peering functions can be deployed along the following two dimensions
	dimensions depending upon how the signaling and the media functions		depending upon how the signaling and the media functions along with IP layer
	along with IP layer are implemented:		are implemented:
	Composed or Decomposed: Addresses the question whether the media		Composed or Decomposed: Addresses the question whether the media must flow
	must flow through the same physical and geographic elements as SIP		through the same physical and geographic elements as SIP dialogs and sessions.
	dialogs and sessions.
	Centralized or Distributed: Addresses the question whether the		Centralized or Distributed: Addresses the question whether the logical and
	logical and physical interconnections are in one geographical		physical interconnections are in one geographical location or distributed to
	location or distributed to multiple physical locations on the SSP's		multiple physical locations on the SSP's network.
	network.
	In a composed model, SF and MF functions are implemented in one		In a composed model, SF and MF functions are implemented in one peering logical
	peering logical element.		element.
	Provider A Provider B		Provider A Provider B
	---------- . . ----------		---------- . . ----------
	/ \ . . / \		/ \ . . / \
	| | . _ . | |		| | . _ . | |
	| +----+ . / \_ . +----+ |		| +----+ . / \_ . +----+ |
	| | SF |<-----/ \------| SF | |		| | SF |<-----/ \------| SF | |
	| +-+--+ . /Transit\ . | | |		| +-+--+ . /Transit\ . | | |
	| | | . / IP \ . | | |		| | | . / IP \ . | | |
	| +-+--+ . \ Provider| . | | |		| +-+--+ . | Provider| . | | |
	| | MF |<~~~~\(Option)|~~~~| MF | |		| | MF |<~~~| (Option)|~~~~| MF | |
	| +----+ . \ / . +----+ |		| +----+ . \ / . +----+ |
	| | . \__ _/ . | |		| | . \__ _/ . | |
	\_________ / . . \________ _/		\_________ / . . \________ _/
	---------- ----------		---------- ----------
	--- Signal (SIP)		--- Signal (SIP)
	~~~ Bearer (RTP/IP)		~~~ Bearer (RTP/IP)
	... Scope of peering		... Scope of peering
	Figure 3: Decomposed v. Collapsed Peering		Figure 3: Decomposed v. Collapsed Peering
	The advantage of a collapsed peering architecture is that one-		The advantage of a collapsed peering architecture is that one-element solves
	element solves all peering issues. Disadvantage examples of this		all peering issues. Disadvantage examples of this architecture are single point
	architecture are single point of failure, bottleneck, and complex		of failure, bottleneck, and complex scalability.
	scalability.
	In a decomposed model, SF and MF are implemented in separate peering		In a decomposed model, SF and MF are implemented in separate peering logical
	logical elements. SFs are implemented in a proxy and MFs are		elements. SFs are implemented in a proxy and MFs are implemented in another
	implemented in another logical element. The scaling of signaling		logical element. The scaling of signaling versus scaling of media may differ
	versus scaling of media may differ between applications.		between applications. Decomposing allows each to follow a separate migration
	Decomposing allows each to follow a separate migration path.		path.
	This model allows the implementation of M:N model where one SF is		This model allows the implementation of M:N model where one SF is associated
	associated with multiple peering MF and one peering MF is associated		with multiple peering MF and one peering MF is associated with multiple SFs.
	with multiple SFs. Generally, a vertical protocol associates the		Generally, a vertical protocol associates the relationship between a SF and a
	relationship between a SF and a MF. This architecture reduces the		MF. This architecture reduces the potential of a single point of failure. It
	potential of a single point of failure. It allows separation of the		allows separation of the policy decision point and the policy enforcement
	policy decision point and the policy enforcement point. An example		point. An example of disadvantages is the scaling complexity because of the M:N
	of disadvantages is the scaling complexity because of the M:N		relationship and latency due to the vertical control messages between entities.
	relationship and latency due to the vertical control messages
	between entities.
	7. Address space considerations		7. Address space considerations
	Peering must occur in a common IP address space, which is defined by		Peering must occur in a common IP address space, which is defined by the
	the federation, which may be entirely on the public Internet, or		federation, which may be entirely on the public Internet, or some private
	some private address space. The origination or termination networks		address space. The origination or termination networks may or may not entirely
	may or may not entirely be in the same address space. If they are		be in the same address space. If they are not, then a network address
	not, then a network address translation (NAT) or similar function		translation (NAT) or similar may be needed before the signaling or media is
	may be needed before the signaling or media is presented correctly		presented correctly to the federation. The only requirement is that all
	to the federation. The only requirement is that all associated		associated entities across the peering interface are reachable.
	entities across the peering interface are reachable.
	8. Security Considerations		8. Security Considerations
	In all cases, cryptographic-based security should be maintained as		In all cases, cryptographic-based security should be maintained as an optional
	an optional requirement between peering providers conditioned on the		requirement between peering providers conditioned on the presence or absence of
	presence or absence of underlying physical security of peer		underlying physical security of SSP connections, e.g. within the same secure
	connections, e.g. within the same secure physical building.		physical building.
	In order to maintain a consistent approach, unique and specialized
	security requirements common for the majority of peering
	relationships, should be standardized within the IETF. These
	standardized methods may enable capabilities such as dynamic peering
	relationships across publicly maintained interconnections.
	TODO: Address RFC-3552 BCP items.		In order to maintain a consistent approach, unique and specialized security
			requirements common for the majority of peering relationships, should be
			standardized within the IETF. These standardized methods may enable
			capabilities such as dynamic peering relationships across publicly maintained
			interconnections.
	9. IANA Considerations		9. IANA Considerations
	There are no IANA considerations at this time.		There are no IANA considerations at this time.
	10. Acknowledgments		10. Acknowledgments
	The working group thanks Sohel Khan for his initial architecture		The working group thanks Sohel Khan for his initial architecture
	draft that helped to initiate work on this draft.		draft that helped to initiate work on this draft.
	A portion of this draft is taken from [14] with permission from the		A significant portion of this draft is taken from [14] with
	author R. Mahy. The other important contributor is Otmar Lendl.		permission from the author R. Mahy. The other important contributor
			is Otmar Lendl. Special thanks to Jim McEachern for detailed comments and
			feedback.
	References		11. References
	10.1. Normative References		11.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate		[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels",
	Requirement Levels", BCP 14, RFC 2119, March 1997.		BCP 14, RFC 2119, March 1997.
	[2] Mealling, M. and R. Daniel, "The Naming Authority Pointer		[2] Mealling, M. and R. Daniel, "The Naming Authority Pointer (NAPTR) DNS
	(NAPTR) DNS Resource Record", RFC 2915, September 2000.		Resource Record", RFC 2915, September 2000.
	[3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,		[3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson,
	Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:		J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation
	Session Initiation Protocol", RFC 3261, June 2002.		Protocol", RFC 3261, June 2002.
	[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol		[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP):
	(SIP): Locating SIP Servers", RFC 3263, June 2002.		Locating SIP Servers", RFC 3263, June 2002.
	[5] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and		[5] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and T.
	T. Wright, "Transport Layer Security (TLS) Extensions", RFC		Wright, "Transport Layer Security (TLS) Extensions", RFC 4366, April
	4366, April 2006.		2006.
	[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,		[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A
	"RTP: A Transport Protocol for Real-Time Applications", STD		Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July
	64, RFC 3550, July 2003.		2003.
	[7] Peterson, J., Liu, H., Yu, J., and B. Campbell, "Using E.164		[7] Peterson, J., Liu, H., Yu, J., and B. Campbell, "Using E.164 numbers
	numbers with the Session Initiation Protocol (SIP)", RFC 3824,		with the Session Initiation Protocol (SIP)", RFC 3824, June 2004.
	June 2004.
	[8] Peterson, J., "Address Resolution for Instant Messaging and		[8] Peterson, J., "Address Resolution for Instant Messaging and
	Presence",RFC 3861, August 2004.		Presence",RFC 3861, August 2004.
	[9] Peterson, J., "Telephone Number Mapping (ENUM) Service		[9] Peterson, J., "Telephone Number Mapping (ENUM) Service Registration for
	Registration for Presence Services", RFC 3953, January 2005.		Presence Services", RFC 3953, January 2005.
	[10] ETSI TS 102 333: " Telecommunications and Internet converged		[10] ETSI TS 102 333: " Telecommunications and Internet converged Services
	Services and Protocols for Advanced Networking (TISPAN); Gate		and Protocols for Advanced Networking (TISPAN); Gate control protocol".
	control protocol".
	[11] Peterson, J., "enumservice registration for Session Initiation		[11] Peterson, J., "enumservice registration for Session Initiation Protocol
	Protocol (SIP) Addresses-of-Record", RFC 3764, April 2004.		(SIP) Addresses-of-Record", RFC 3764, April 2004.
	[12] Livingood, J. and R. Shockey, "IANA Registration for an		[12] Livingood, J. and R. Shockey, "IANA Registration for an
	Enumservice Containing PSTN Signaling Information", RFC 4769,		Enumservice Containing PSTN Signaling Information", RFC 4769, November
	November 2006.		2006.
	10.2. Informative References		11.2. Informative References
	[13] Malas, D., "SPEERMINT Terminology", draft-ietf-speermint-		[13] Malas, D., "SPEERMINT Terminology", draft-ietf-speermint-terminology-16
	terminology-16 (work in progress), February 2008.		(work in progress), February 2008.
	[14] Mule, J-F., "SPEERMINT Requirements for SIP-based VoIP		[14] Mule, J-F., "SPEERMINT Requirements for SIP-based VoIP Interconnection",
	Interconnection", draft-ietf-speermint-requirements-04.txt,		draft-ietf-speermint-requirements-04.txt, February 2008.
	February 2008.
	[15] Mahy, R., "A Minimalist Approach to Direct Peering", draft-		[15] Mahy, R., "A Minimalist Approach to Direct Peering", draft-
	mahy-speermint-direct-peering-02.txt, July 2007.		mahy-speermint-direct-peering-02.txt, July 2007.
	[16] Penno, R., et al., "SPEERMINT Routing Architecture Message		[16] Penno, R., et al., "SPEERMINT Routing Architecture Message
	Flows", draft-ietf-speermint-flows-02.txt", April 2007.		Flows", draft-ietf-speermint-flows-02.txt", April 2007.
	[17] Houri, A., et al., "RTC Provisioning Requirements", draft-		[17] Houri, A., et al., "RTC Provisioning Requirements", draft-
	houri-speermint-rtc-provisioning-reqs-00.txt, June, 2006.		houri-speermint-rtc-provisioning-reqs-00.txt, June, 2006.
	[18] Habler, M., et al., "A Federation based VOIP Peering		[18] Habler, M., et al., "A Federation based VOIP Peering
	Architecture", draft-lendl-speermint-federations-03.txt,		Architecture", draft-lendl-speermint-federations-03.txt, September 2006.
	September 2006.
	[19] Mahy, R., "A Telephone Number Mapping (ENUM) Service		[19] Mahy, R., "A Telephone Number Mapping (ENUM) Service
	Registration for Instant Messaging (IM) Services", draft-ietf-		Registration for Instant Messaging (IM) Services", draft-ietf-
	enum-im-service-03 (work in progress), March 2006.		enum-im-service-03 (work in progress), March 2006.
	[20] Haberler, M. and R. Stastny, "Combined User and Carrier ENUM		[20] Haberler, M. and R. Stastny, "Combined User and Carrier ENUM in the
	in the e164.arpa tree", draft-haberler-carrier-enum-03 (work		e164.arpa tree", draft-haberler-carrier-enum-03 (work in progress),
	in progress), March 2006.		March 2006.
	[21] Penno, R., Malas D., and Melampy, P., "A Session Initiation		[21] Penno, R., Malas D., and Melampy, P., "A Session Initiation
	Protocol (SIP) Event package for Peering", draft-penno-		Protocol (SIP) Event package for Peering", draft-penno-sipping-peering-
	sipping-peering-package-00 (work in progress), September 2006.		package-00 (work in progress), September 2006.
	[22] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML",		[22] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML", W3C REC
	W3C REC REC-xml-names-19990114, January 1999.		REC-xml-names-19990114, January 1999.
	[23] Burger, E (Ed.), "A Mechanism for Content Indirection in		[23] Burger, E (Ed.), "A Mechanism for Content Indirection in
	Session Initiation Protocol (SIP) Messages", RFC 4483, May		[24] Gurbani, V., Lawrence, S., and B. Laboratories, "Domain Certificates in
	2006		the Session Initiation Protocol (SIP)", draft-ietf-sip-domain-certs-00
			(work in progress), November 2007.
	[24] Gurbani, V., Lawrence, S., and B. Laboratories, "Domain
	Certificates in the Session Initiation Protocol (SIP)", draft-
	ietf-sip-domain-certs-00 (work in progress), November 2007.
	Author's Addresses		Author's Addresses
	Reinaldo Penno (Editor)		Adam Uzelac
			Global Crossing
			Rochester, NY - USA
			Email: adam.uzelac@globalcrossing.com
			Reinaldo Penno
	Juniper Networks		Juniper Networks
	1194 N Mathilda Avenue		Sunnyvale, CA - USA
	Sunnyvale, CA
	USA
	Email: rpenno@juniper.net		Email: rpenno@juniper.net
	Mike Hammer		Mike Hammer
	Cisco Systems		Cisco Systems
	13615 Dulles Technology Drive		Herndon, VA - USA
	Herndon, VA 20171
	USA
	Email: mhammer@cisco.com		Email: mhammer@cisco.com
	Sohel Khan, Ph.D.		Sohel Khan, Ph.D.
	Comcast Cable Communications		Comcast Cable Communications
	U.S.A		USA
	Email: sohel_khan@cable.comcast.com		Email: sohel_khan@cable.comcast.com
	Daryl Malas		Daryl Malas
	CableLabs		CableLabs
	858 Coal Creek Circle		Louisville, CO - USA
	Louisville, CO 80027
	Email: d.malas@cablelabs.com		Email: d.malas@cablelabs.com
	Adam Uzelac
	Global Crossing
	1120 Pittsford Victor Road
	PITTSFORD, NY 14534
	USA
	Email: adam.uzelac@globalcrossing.com
	Intellectual Property Statement
	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.
	Disclaimer of Validity
	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.
	Copyright Statement
	Copyright (C) The IETF Trust (2008).
	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.
	Acknowledgment
	Funding for the RFC Editor function is currently provided by the
	Internet Society.
End of changes. 120 change blocks.
	493 lines changed or deleted		413 lines changed or added
This html diff was produced by rfcdiff 1.35. The latest version is available from http://tools.ietf.org/tools/rfcdiff/