draft-ietf-speermint-architecture-04.txt		draft-ietf-speermint-architecture-05.txt
	Speermint Working Group R. Penno		Speermint Working Group R. Penno
	Internet Draft Juniper Networks		Internet Draft Juniper Networks
	Intended status: Informational D. Malas		Intended status: Informational D. Malas
	Expires: January 2008 Level 3		Expires: August 2008 Level 3
	S. Khan		S. Khan
	Comcast		Comcast
	A. Uzelac		A. Uzelac
	Global Crossing		Global Crossing
	August 10, 2007		February 24, 2008
	SPEERMINT Peering Architecture		SPEERMINT Peering Architecture
	draft-ietf-speermint-architecture-04		draft-ietf-speermint-architecture-05
	Status of this Memo		Status of this Memo
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	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	This document defines the SPEERMINT peering architecture, its		This document defines the SPEERMINT peering architecture, its
	functional components and peering interface functions. It also		functional components and peering interface functions. It also
	describes the steps taken to establish a session between two peering		describes the steps taken to establish a session between two peering
	domains in the context of the functions defined.		domains in the context of the functions defined.
	Conventions used in this document		Conventions used in this document
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC-2119[1]		document are to be interpreted as described in RFC 2119[1]
	Table of Contents		Table of Contents
	1. Introduction...................................................3		1. Introduction...................................................3
	2. Network Context................................................3		2. Network Context................................................4
	3. Procedures.....................................................6		3. Procedures.....................................................5
	4. Reference SPEERMINT Architecture...............................6		4. Reference SPEERMINT Architecture...............................6
	5. Peer Function Examples.........................................8		5. Peer Function Examples.........................................8
	5.1. The Location Function (LF) of an Initiating Provider......8		5.1. The Location Function (LF) of an Initiating Provider......8
	5.1.1. Target address analysis..............................8		5.1.1. Target address analysis..............................8
	5.1.2. User ENUM Lookup.....................................9		5.1.2. User ENUM Lookup.....................................9
	5.1.3. Carrier ENUM lookup.................................10		5.1.3. Carrier ENUM lookup.................................10
	5.1.4. Routing Table.......................................10		5.1.4. Routing Table.......................................10
	5.1.5. SIP DNS Resolution..................................10		5.1.5. SIP DNS Resolution..................................10
	5.1.6. SIP Redirect Server.................................11		5.1.6. SIP Redirect Server.................................11
	5.2. The Location Function (LF) of a Receiving Provider.......11		5.2. The Location Function (LF) of a Receiving Provider.......11
	5.2.1. Publish ENUM records................................11		5.2.1. Publish ENUM records................................11
	5.2.2. Publish SIP DNS records.............................11		5.2.2. Publish SIP DNS records.............................11
	5.2.3. Subscribe Notify....................................11		5.2.3. Subscribe Notify....................................11
	5.3. Signaling Function (SF)..................................11		5.3. Signaling Function (SF)..................................11
	5.4. The Signaling Function (SF) of an Initiating Provider....12		5.4. The Signaling Function (SF) of an Initiating Provider....12
	5.4.1. Setup TLS connection................................12		5.4.1. Setup TLS connection................................12
	5.4.2. IPSec...............................................12		5.4.2. IPSec...............................................12
	5.4.3. Co-Location.........................................13		5.4.3. Co-Location.........................................12
	5.4.4. Send the SIP request................................13		5.4.4. Send the SIP request................................12
	5.5. The Signaling Function (SF) of an Initiating Provider....14		5.5. The Signaling Function (SF) of an Initiating Provider....14
	5.5.1. Verify TLS connection...............................14		5.5.1. Verify TLS connection...............................14
	5.5.2. Receive SIP requests................................14		5.5.2. Receive SIP requests................................14
	5.6. Media Function (MF)......................................15		5.6. Media Function (MF)......................................15
	5.7. Policy Considerations....................................15		5.7. Policy Considerations....................................15
	6. Call Control and Media Control Deployment Options.............16		6. Call Control and Media Control Deployment Options.............16
	7. Address space considerations..................................18		7. Address space considerations..................................17
	8. Security Considerations.......................................18		8. Security Considerations.......................................17
	9. IANA Considerations...........................................18		9. IANA Considerations...........................................18
	10. Acknowledgments..............................................18		10. Acknowledgments..............................................18
	11. References...................................................19		11. References...................................................19
	11.1. Normative References....................................19		11.1. Normative References....................................19
	11.2. Informative References..................................20		11.2. Informative References..................................20
	Author's Addresses...............................................21		Author's Addresses...............................................21
	Intellectual Property Statement..................................21		Intellectual Property Statement..................................21
	Disclaimer of Validity...........................................22		Disclaimer of Validity...........................................22
	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 the context of Session PEERing for Multimedia		architecture in the context of Session PEERing for Multimedia
	INTerconnect (SPEERMINT). In this process, we define the peering		INTerconnect (SPEERMINT). In this process, we define the peering
	reference architecture (reference, for short), it's functional		reference architecture (reference, for short), it's functional
	components, and peering interface functions from the perspective of a		components, and peering interface functions from the perspective of
	real-time communications (Voice and Multimedia) IP Service provider		a SIP [3] Service provider's (SSP) network.
	network.
	This architecture allows the interconnection of two service providers		This architecture allows the interconnection of two SSPs in layer 5
	in layer 5 peering as defined in the SPEERMINT Requirements [13] and		peering as defined in the SPEERMINT Requirements [13] and
	Terminology [12] documents for the purpose SIP-based voice and		Terminology [12] documents.
	multimedia traffic.
	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 this document do not show routers so that the focus is on		figures in this document do not show routers so that the focus is on
	Layer 5 protocol aspects.		Layer 5 protocol aspects.
	This document uses terminology defined in the SPEERMINT Terminology		This document uses terminology defined in the SPEERMINT Terminology
	document [12].		document [12], so the reader should be familiar with all the terms
			defined there.
	2. Network Context		2. Network Context
	Figure 1 shows an example network context. Two SIP providers can form		Figure 1 shows an example network context. Two SSPs can form a Layer
	a Layer 5 peer over either the public Internet or private Layer 3		5 peering over either the public Internet or private Layer3
	networks. In addition, two or more providers may form a SIP (Layer 5)		networks. In addition, two or more providers may form a SIP (Layer
	federation [17] on either the public Internet or private Layer 3		5) federation [13] on either the public Internet or private Layer 3
	networks. This document does not make any assumption whether the SIP		networks. This document does not make any assumption whether the SIP
	providers directly peer to each other or through Layer 3 transit		providers directly peer to each other or through Layer 3 transit
	network as per use case of [16].		network as per use case of [16].
	Note that Figure 1 allows for the following potential SPEERMINT		Note that 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 Service Provider across the public Internet		o Enterprise to SSP across the public Internet
	o Service Provider to Service Provider 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 Service Provider across a private Layer 3 network		o Enterprise to SSP across a private Layer 3 network
	o Service Provider to Service Provider across a private Layer 3		o SSP to SSP across a private Layer 3 network
	network
	The members of a federation may jointly use a set of functions such		The members of a federation may jointly use a set of functions such
	as location peering function, application function, subscriber		as location function, signaling function, media function, ENUM
	database function, SIP proxies, and/or functions that synthesize		database or SIP Registrar, SIP proxies, and/or functions that
	various SIP and non-SIP based applications. Similarly, two providers		synthesize various SIP and non-SIP based applications. Similarly,
	may jointly use a set of peering functions. The federation functions		two SSPs may jointly use a set of functions. The functions can be
	or the peering functions can be either public or private.		either public or private.
	+-------------------+		+-------------------+
			| |
	| Public |		| Public |
	| Peering Function |		| Peering |
	| or |		| Function |
	| Public |		| |
	|Federation Function|
	+-------------------+		+-------------------+
	|		|
	-----		-----
	+-----------+ / \ +-----------+		+-----------+ / \ +-----------+
	|Enterprise | -- -- |Enterprise |		|Enterprise | -- -- |Enterprise |
	|Provider A |-----------/ \-----------|Provider B |		|Provider A |-----------/ \-----------|Provider B |
	+-----------+ -- -- +-----------+		+-----------+ -- -- +-----------+
	/ Public \		/ Public \
	| Internet |		| Internet |
	\ (Layer 3) /		\ (Layer 3) /
	+-----------+ -- -- +-----------+		+-----------+ -- -- +-----------+
	|Service |-----------\ /-----------|Service |		|Service |-----------\ /-----------|Service |
	|Provider C | -- -- |Provider D |		|Provider C | -- -- |Provider D |
	+-----------+ \_____/ +-----------+		+-----------+ \_____/ +-----------+
	| Layer 3 Peering		| Layer 3 Peering
	| Point (out of scope)		| Point (out of scope)
	-----		-----
	+-----------+ / \ +-----------+		+-----------+ / \ +-----------+
	|Enterprise | -- -- |Enterprise |		|Enterprise | -- -- |Enterprise |
	|Provider E |-----------/ \-----------|Provider F |		|Provider E |-----------/ \-----------|Provider F |
	+-----------+ -- Service -- +-----------+		+-----------+ -- Private -- +-----------+
	/ Provider \		/ Network \
	| Private |		| (Layer 3) |
	\ Network /		\ /
	+-----------+ -- (Layer 3) -- +-----------+		+-----------+ -- -- +-----------+
	|Service |-----------\ /-----------|Service |		| SSP G |-----------\ /-----------| SSP H |
	|Provider G | -- -- |Provider H |		| | -- -- | |
	+-----------+ \____/ +-----------+		+-----------+ \____/ +-----------+
	|		|
	+-------------------+		+-------------------+
	| Private |		| Private |
	| Peering Function |		| SIP |
	| or |		| Peering |
	|Federation Function|		| |
	+-------------------+		+-------------------+
	Figure 1: SPEERMINT Network Context		Figure 1: SPEERMINT Network Context
	3. Procedures		3. Procedures
	This document assumes that a call from an end user in the initiating		This document assumes that a call from a UAC end user in the
	peer goes through the following steps to establish a call to an end		initiating peer's network goes through the following steps to
	user in the receiving peer:		establish a call to a UAS in the receiving peer's network:
	1. The analysis of a target address.		1. The analysis of a target address.
	a. If the target address represents an intra-VSP resource,		a. If the target address represents an intra-SSP resource,
	we go directly to step 4.		we go directly to step 4.
	2. the discovery of the receiving peering point address,		2. the discovery of the receiving peering point address,
	3. the enforcement of authentication and other policy,		3. the enforcement of authentication and potentially other
			policies,
	4. the discovery of end user address,		4. the discovery of the UAS,
	5. the routing of SIP messages,		5. the routing of SIP messages,
	6. the session establishment,		6. the session establishment,
	7. the transfer of media,		7. the transfer of media which could include voice, video, text
			and others,
	8. and the session termination.		8. and the session termination.
	4. Reference SPEERMINT Architecture		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 peering between two SIP service providers.		that form the peering between two SSPs.
	+------+		+------+
	| DNS, |		| DNS, |
	+---------| Db, |---------+		+---------->| Db, |<---------+
	| | etc | |		| | etc | |
	| +------+ |		| +------+ |
	| |		| |
	--------------- ---------------		------|-------- -------|-------
	/ \ / \		/ v \ / v \
	| | | |		| +--LUF-+ | | +--LUF-+ |
	| | | |		| | | | | | | |
	| +------+ | | +------+ |		| | | | | | | |
	| | DNS, | | | | DNS, | |		| | | | | | | |
	| | Db, | | | | Db, | |
	| | etc | | | | etc | |
	| +------+ | | +------+ |		| +------+ | | +------+ |
	| | | |
	| | | |
	| +---SF--+ +---SF--+ |
	| | | | | |		| | | | | |
			| | | | | |
			| v | | v |
			| +--LRF-+ | | +--LRF-+ |
			| | | | | | | |
			| | | | | | | |
			| | | | | | | |
			| +------+ | | +------+ |
			| \ | | / |
			| `. | | / |
			| \ | | .' |
			| `. +---SF--+ +---SF--+ / |
			| \| | | | / |
	| | SBE | | SBE | |		| | SBE | | SBE | |
	| Originating | | | | Terminating |		| Originating | | | | Target |
	| +---SF--+ +---SF--+ |		| +---SF--+ +---SF--+ |
	| Domain | | Domain |		| SSP | | SSP |
	| +---MF--+ +---MF--+ |		| +---MF--+ +---MF--+ |
	| SSP | | | | SSP |		| | | | | |
	| | DBE | | DBE | |		| | DBE | | DBE | |
	| | | | | |		| | | | | |
	| +---MF--+ +---MF--+ |		| +---MF--+ +---MF--+ |
	| | | |
	| +----LF---+ +----LF---+ |
	| +-LF--|----+ | | +----|--LS-+ |
	| | | | | | | | | |
	| | SM | | LS | | LS | | SM | |
	| | | | | | | | | |
	| | +----|----+ +----|----+ | |
	| +----------+| |+----------+ |
	| | | |
	| | | |
	\ / \ /		\ / \ /
	--------------- ---------------		--------------- ---------------
	Figure 2: Reference SPEERMINT Architecture		Figure 2: Reference SPEERMINT Architecture
	The procedures presented in Chapter 3 are implemented by a set of		The procedures presented in Chapter 3 are implemented by a set of
	peering functions:		peering functions:
	o Location Function (LF): Purpose is to develop Session		The Look-Up Function (LUF) provides a mechanism for determining for
	Establishment Data (SED) by discovering the Signaling Function		a given request the target domain to which the request should be
	(SF) and the end user's reachable host (IP address and port). The		routed.
	location function is distributed across the Location Server (LS)
	and Session Manager (SM).
	o Signaling Function (SF): Purpose is to perform SIP call routing,		The Location Routing Function (LRF) determines for the target domain
	to optionally perform termination and re-initiation of call, to		of a given request the location of the SF in that domain and
			optionally develops other SED required to route the request to that
			domain.
			Location Function (LF): The Location functions is composed of the
			LUF and LRF functions
			Signaling Function (SF): Purpose is to perform SIP call routing, to
			optionally perform termination and re-initiation of call, to
	optionally implement security and policies on SIP messages, and to		optionally implement security and policies on SIP messages, and to
	assist in discovery/exchange of parameters to be used by the Media		assist in discovery/exchange of parameters to be used by the Media
	Function (MF). The signaling function is located within the		Function (MF).
	Signaling Path Border Element (SBE)
	o Media Function (MF): Purpose is to perform media related function		Media Function (MF): Purpose is to perform media related function
	such as media transcoding and media security implementation		such as media transcoding and media security implementation between
	between two SIP providers. The media function is located within		two SIP providers.
	the Data Path Border Element (DBE).
	The intention of defining these functions is to provide a framework		The intention of defining these functions is to provide a framework
	for design segmentation and allow each one to evolve separately.		for design segmentation and allow each one to evolve independently.
	5. Peer Function Examples		5. Peer Function Examples
	This section describes the peering functions in more detail and		This section describes the functions in more detail and provides
	provides some examples on the role they would play in a SIP call in a		some examples on the role they would play in a SIP call in a Layer 5
	Layer 5 peering scenario.		peering scenario.
	Some of the information in the chapter is taken from [14].		Some of the information in the chapter is taken from [14] and is put
			here for continuity purposes.
	5.1. The Location Function (LF) of an Initiating Provider		5.1. The Location Function (LF) of an Initiating Provider
	Purpose is to develop Session Establishment Data (SED) [12] by		Purpose is to determine the SF of the target domain of a given
	discovering the Signaling Function (SF), and end user's reachable		request and optionally develop Session Establishment Data (SED)
	host (IP address and host). The LF of an Initiating provider analyzes		[12]. The LF of an Initiating SSP analyzes target address and
	target address and discovers the next hop signaling function (SF) in		discovers the next hop signaling function (SF) in a peering
	a peering relationship using DNS, SIP Redirect Server, or a		relationship using the Look-Up Function. The resource to determine
	functional equivalent database.		the SF of the target domain might be provided by a third-party as in
			the assisted-peering case.
	5.1.1. Target address analysis		5.1.1. Target address analysis
	When the initiating provider receives a request to communicate, the		When the initiating SSP receives a request to communicate, it
	initiating provider analyzes the target state data to determine		analyzes the target state data to determine whether the call needs
	whether the call needs to be terminated internal or external to its		to be terminated internal or external to its network. The analysis
	network. The analysis method is internal to the provider's policy;		method is internal to the SSP; thus, outside the scope of SPEERMINT.
	thus, outside the scope of SPEERMINT. Note that the peer is free to		Note that the SSP is free to consult any manner of private data
	consult any manner of private data sources to make this		sources to make this determination.
	determination.
	If the target address does not represent a resource inside the		If the target address does not represent a resource inside the
	initiating peer's administrative domain or federation of domains, the		initiating SSP's administrative domain or federation of domains, the
	initiating provider resolves the call routing data by using the		initiating SSP resolves the call routing data by using the Location
	Location Function (LF). Examples of the LF are the functions of ENUM,		Function (LF).
	Routing Table, SIP DNS, and SIP Redirect Server.
	If the request to communicate is for an im: or pres: URI type, the		If the request to communicate is for an im: or pres: URI type, the
	initiating peer follows the procedures in [8]. If the highest		initiating peer follows the procedures in [8]. If the highest
	priority supported URI scheme is sip: or sips:, the initiating peer		priority supported URI scheme is sip: or sips:, the initiating peer
	skips to SIP DNS resolution in Section 5.1.5. Likewise, if the target		skips to SIP DNS resolution in Section 5.1.5. Likewise, if the
	address is already a sip: or sips: URI in an external domain, the		target address is already a sip: or sips: URI in an external domain,
	initiating peer skips to SIP DNS resolution in Section 5.1.5.		the initiating peer skips to SIP DNS resolution in Section 5.1.5.
	If the target address corresponds to a specific E.164 address, the		If the target address corresponds to a specific E.164 address, the
	peer may need to perform some form of number plan mapping according		peer may need to perform some form of number plan mapping according
	to local policy. For example, in the United States, a dial string		to local policy. For example, in the United States, a dial string
	beginning "011 44" could be converted to "+44", or in the United		beginning "011 44" could be converted to "+44", or in the United
	Kingdom "00 1" could be converted to "+1". Once the peer has an		Kingdom "00 1" could be converted to "+1". Once the peer has an
	E.164 address, it can use ENUM.		E.164 address, it can use ENUM.
	5.1.2. User ENUM Lookup		5.1.2. 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 initiating peer
	consults the public "User ENUM" rooted at e164.arpa, according to the		consults the public "User ENUM" rooted at e164.arpa, according to
	procedures described in RFC 3761. The peer MUST query for the		the procedures described in RFC 3761. The peer MUST query for the
	"E2U+sip" enumservice as described in RFC 3764 [11], but MAY check		"E2U+sip" enumservice as described in RFC 3764 [11], but MAY check
	for other enumservices. The initiating peer MAY consult a cache or		for other enumservices. The initiating peer MAY consult a cache or
	alternate representation of the ENUM data rather than actual DNS		alternate representation of the ENUM data rather than actual DNS
	queries. Also, the peer MAY skip actual DNS queries if the		queries. Also, the peer MAY skip actual DNS queries if the
	initiating peer is sure that the target address country code is not		initiating peer is sure that the target address country code is not
	represented in e164.arpa. If a sip: or sips: URI is chosen the peer		represented in e164.arpa. If a sip: or sips: URI is chosen the peer
	skips to Section 5.1.5.		skips to Section 5.1.5.
	If an im: or pres: URI is chosen for based on an "E2U+im" [10] or		If an im: or pres: URI is chosen for based on an "E2U+im" [10] or
	"E2U+pres" [9] enumserver, the peer follows the procedures for		"E2U+pres" [9] enumserver, the peer follows the procedures for
	resolving these URIs to URIs for specific protocols such a SIP or		resolving these URIs to URIs for specific protocols such a SIP or
	XMPP as described in the previous section.		XMPP as described in the previous section.
	5.1.3. Carrier ENUM lookup		5.1.3. Infrastructure ENUM lookup
	Next the initiating peer checks for a carrier-of-record in a carrier		Next the initiating peer checks for a carrier-of-record in a carrier
	ENUM domain according to the procedures described in [12]. As in the		ENUM domain according to the procedures described in [12]. As in
	previous step, the peer MAY consult a cache or alternate		the previous step, the peer MAY consult a cache or alternate
	representation of the ENUM data in lieu of actual DNS queries. The		representation of the ENUM data in lieu of actual DNS queries. The
	peer first checks for records for the "E2U+sip" enumservice, then for		peer first checks for records for the "E2U+sip" enumservice, then
	the "E2U+pstn" enumservice as defined in [21]. If a terminal record		for the "E2U+pstn" enumservice as defined in [21]. If a terminal
	is found with a sip: or sips: URI, the peer skips to Section 5.1.5,		record is found with a sip: or sips: URI, the peer skips to Section
	otherwise the peer continues processing according to the next		5.1.5, otherwise the peer continues processing according to the next
	section.		section.
	5.1.4. Routing Table		5.1.4. Routing Table
	If there is no user ENUM records and the initiating peer cannot		If there is no user ENUM records and the initiating peer cannot
	discover the carrier-of-record or if the initiating peer cannot reach		discover the carrier-of-record or if the initiating peer cannot
	the carrier-of-record via SIP peering, the initiating peer still		reach the carrier-of-record via SIP peering, the initiating peer
	needs to deliver the call to the PSTN or reject the call. Note that		still needs to deliver the call to the PSTN or reject it. Note that
	the initiating peer MAY still sends the call to another provider for		the initiating peer MAY still forward the call to another SSP for
	PSTN gateway termination by prior arrangement using a routing table.		PSTN gateway termination by prior arrangement using the routing
			table.
	If so, the initiating peer rewrites the Request-URI to address the		If so, the initiating peer rewrites the Request-URI to address the
	gateway resource in the target provider's domain and MAY forward the		gateway resource in the target SSP's domain and MAY forward the
	request on to that provider using the procedures described in the		request on to that SSP using the procedures described in the
	remainder of these steps.		remainder of these steps.
	5.1.5. SIP DNS Resolution		5.1.5. SIP DNS Resolution
	Once a sip: or sips: in an external domain is selected as the target,		Once a sip: or sips: in an external domain is selected as the
	the initiating peer MAY apply local policy to decide whether		target, the initiating peer MAY apply local policy to decide whether
	forwarding requests to the target domain is acceptable. If so, the		forwarding requests to the target domain is acceptable. If so, the
	initiating peer uses the procedures in RFC 3263 [6] Section 4 to		initiating peer uses the procedures in RFC 3263 [4] Section 4 to
	determine how to contact the receiving peer. To summarize the RFC		determine how to contact the receiving peer. To summarize the RFC
	3263 procedure: unless these are explicitly encoded in the target		3263 procedure: unless these are explicitly encoded in the target
	URI, a transport is chosen using NAPTR records, a port is chosen		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.		using SRV records, and an address is chosen using A or AAAA records.
	Note that these are queries of records in the global DNS.		Note that these are queries of records in the global DNS.
	When communicating with a public external peer, entities compliant to		When communicating with a public external peer, entities compliant
	this document MUST only select a TLS-protected transport for		to this document MUST only select a TLS-protected transport for
	communication from the initiating peer to the receiving peer. Note		communication from the initiating peer to the receiving peer. Note
	that this is a single-hop requirement. Either peer MAY insist on		that this is a single-hop requirement. Either peer MAY insist on
	using a sips: URI which asserts that each hop is TLS-protected, but		using a sips: URI which asserts that each hop is TLS-protected, but
	this document does not require protection over each hop.		this document does not require protection over each hop.
	5.1.6. SIP Redirect Server		5.1.6. SIP Redirect Server
	A SIP Redirect Server may help in resolving current address of a		A SIP Redirect Server may help in resolving the current address of a
	mobile target address.		UAS.
	5.2. The Location Function (LF) of a Receiving Provider		5.2. The Location Function (LF) of a Receiving Provider
	5.2.1. Publish ENUM records		5.2.1. Publish ENUM records
	The receiving peer SHOULD participate by publishing "E2U+sip" and		The receiving peer SHOULD participate by publishing "E2U+sip" and
	"E2U+pstn" records with sip: or sips: URIs wherever a public carrier		"E2U+pstn" records with sip: or sips: URIs wherever a public carrier
	ENUM root is available. This assumes that the receiving peer wants		ENUM root is available. This assumes that the receiving peer wants
	to peer by default. Even when the receiving peer does not want to		to peer by default. When the receiving peer does not want to accept
	accept traffic from specific initiating peers, it MAY still reject		traffic from specific initiating peers, it MAY still reject requests
	requests on a case-by-case basis.		on a call-by-call basis.
	5.2.2. Publish SIP DNS records		5.2.2. Publish SIP DNS records
	To receive peer requests, the receiving peer MUST insure that it		To receive peer requests, the receiving peer MUST insure that it
	publishes appropriate NAPTR, SRV, and address (A and/or AAAA) records		publishes appropriate NAPTR, SRV, and address (A and/or AAAA)
	in the global DNS that resolve an appropriate transport, port, and		records in the LF relevant to the peer's SF.
	address to a relevant SIP server.
	5.2.3. Subscribe Notify		5.2.3. Subscribe Notify
	Policy function may also be optionally implemented by dynamic		Policies function may also be optionally implemented by dynamic
	subscribe, notify, and exchange of policy information and feature		subscribe, notify, and exchange of policy information and feature
	information among providers [22].		information among SSPs [22].
	5.3. Signaling Function (SF)		5.3. 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, to optionally perform termination and re-initiation of a		messages, to optionally perform termination and re-initiation of a
	call, to optionally implement security and policies on SIP messages,		call, to optionally implement security and policies on SIP messages,
	and to assist in discovery/exchange of parameters to be used by the		and to assist in discovery/exchange of parameters to be used by the
	Media Function (MF).		Media Function (MF).
	The routing of SIP messages are performed by SIP proxies. The		The signaling function perform the routing of SIP messages. The
	optional termination and re-initiation of calls are performed by		optional termination and re-initiation of calls are performed by the
	B2BUA.		signaling path border element (SBE).
	Optionally, a SF may perform additional functions such as Session		Optionally, a SF may perform additional functions such as Session
	Admission Control, SIP Denial of Service protection, SIP Topology		Admission Control, SIP Denial of Service protection, SIP Topology
	Hiding, SIP header normalization, and SIP security, privacy and		Hiding, SIP header normalization, and SIP security, privacy and
	encryption.		encryption.
	The signaling function can also process SDP payloads for media		The SF can also process SDP payloads for media information such as
	information such as media type, bandwidth, and type of codec; then,		media type, bandwidth, and type of codec; then, communicate this
	communicate this information to the media function. Signaling		information to the media function. Signaling function may optionally
	function may optionally communicate with network layer to pass Layer		communicate with the network to pass Layer 3 related policies [10]
	3 related policies [10]
	5.4. The Signaling Function (SF) of an Initiating Provider		5.4. The Signaling Function (SF) of an Initiating Provider
	5.4.1. Setup TLS connection		5.4.1. Setup TLS connection
	Once a transport, port, and address are found, the initiating peer		Once a transport, port, and address are found, the initiating SSP
	will open or find a reusable TLS connection to the peer. The		will open or find a reusable TLS connection to the peer. The
	initiating provider MUST verify the server certificate which SHOULD		initiating provider MUST verify the server certificate that SHOULD
	be rooted in a well-known certificate authority. The initiating		be rooted in a well-known certificate authority. The initiating SSP
	provider MUST be prepared to provide a TLS client certificate upon		MUST be prepared to provide a TLS client certificate upon request
	request during the TLS handshake. The client certificate MUST		during the TLS handshake. The client certificate MUST contain a DNS
	contain a DNS or URI choice type in the subjectAltName which		or URI choice type in the subjectAltName which corresponds to the
	corresponds to the domain asserted in the host production of the From		domain asserted in the host production of the From header URI. The
	header URI. The certificate SHOULD be valid and rooted in a well-		certificate SHOULD be valid and rooted in a well-known certificate
	known certificate authority.		authority.
	Note that the client certificate MAY contain a list of entries in the		Note that the client certificate MAY contain a list of entries in
	subjectAltName, only one of which has to match the domain in the From		the subjectAltName, only one of which has to match the domain in the
	header URI.		From header URI.
	5.4.2. IPSec		5.4.2. IPSec
	In certain deployments the use of IPSec between the signaling		In certain deployments the use of IPSec between the signaling
	functions of the originating and terminating domains can be used as a		functions of the originating and terminating domains can be used as
	security mechanism instead of TLS.		a security mechanism instead of TLS.
	5.4.3. Co-Location		5.4.3. Co-Location
	In this scenario the signaling functions are co-located in a		In this scenario the SFs are co-located in a
	physically secure location and/or are members of a segregated		physically secure location and/or are members of a segregated
	network. In this case messages between the originating and		network. In this case messages between the originating and
	terminating domains would be sent as clear text.		terminating SSPs would be sent as clear text.
	5.4.4. Send the SIP request		5.4.4. Send the SIP request
	Once a TLS connection between the peers is established, the		Once a TLS connection between the peers is established, the
	initiating peer sends the request. When sending some requests, the		initiating peer sends the request. When sending some requests, the
	initiating peer MUST verify and assert the senders identity using the		initiating peer MUST verify and assert the senders identity using
	SIP Identity mechanism.		the SIP Identity mechanism.
	The domain name in the URI of the From: header MUST be a domain which		The domain name in the URI of the From: header MUST be a domain
	was present in the certificate presented when establishing the TLS		which was present in the certificate provided when establishing the
	connection for this request, even if the user part has an anonymous		TLS connection for this request, even if the user part has an
	value. If the From header contains the user URI parameter with the		anonymous value. If the From header contains the user URI parameter
	value of "phone", the user part of the From header URI MUST be a		with the value of "phone", the user part of the From header URI MUST
	complete and valid tel: URI [9] telephone-subscriber production, and		be a complete and valid tel: URI [9] telephone-subscriber
	SHOULD be a global-number. For example, the following are all		production, and SHOULD be a global-number. For example, the
	acceptable, the first three are encouraged:		following are all acceptable and the first three are encouraged:
			From: "John Doe" john.doe@example.net
	From: "John Doe" <john.doe@example.net>
	From: "+12125551212" <+12125551212@example.net;user=phone>		From: "+12125551212" <+12125551212@example.net;user=phone>
	From: "Anonymous" <anonymous@example.net>		From: "Anonymous" <anonymous@example.net>
	From: <4092;phone-context=+12125554000@example.net;user=phone>		From: <4092;phone-context=+12125554000@example.net;user=phone>
	From: "5551212" <5551212@example.net>		From: "5551212" <5551212@example.net>
	The following are not acceptable:		The following are not acceptable:
	From: "2125551212" <2125551212@example.net;user=phone>		From: "2125551212" <2125551212@example.net;user=phone>
	From: "Anonymous" <anonymous@anonymous.invalid>		From: "Anonymous" <anonymous@anonymous.invalid>
	In addition, for new dialog-forming requests and non-dialog-forming		In addition, new requests MUST contain a valid Identity and
	requests, the request MUST contain a valid Identity and Identity-Info		Identity-Info header as described in [12]. The Identity-Info header
	header as described in [12]. The Identity-Info header must present a		must present a domain name that is represented in the certificate
	domain name which is represented in the certificate presented when		provided when establishing the TLS connection over which the request
	establishing the TLS connection over which the request is sent. The		is sent. The initiating peer SHOULD include an Identity header on
	initiating peer SHOULD include an Identity header on in-dialog		in-dialog requests as well, if the From header field value matches
	requests as well, if the From header field value matches an identity		an identity the initiating peer is willing to assert.
	the initiating peer is willing to assert.
	The initiating peer MAY include any SIP option-tags in Supported,		The initiating peer MAY include any SIP option-tags in Supported,
	Require, or Proxy-Require headers according to procedures in		Require, or Proxy-Require headers according to procedures in
	standards-track SIP extensions. Note however that the initiating		standards-track SIP extensions. Note however that the initiating
	peer MUST be prepared to fallback to baseline SIP functionality as		peer MUST be prepared to fallback to baseline SIP functionality as
	defined by the mandatory-to-implement features of RFC 3261, RFC 3263,		defined by the mandatory-to-implement features of RFC 3261, RFC
	and RFC 3264 [7], except that peers implementing this specification		3263,and RFC 3264 [7], except that peers implementing this
	MUST implement SIP over TLS using the sip: URI scheme, the SIP		specification MUST implement SIP over TLS using the sip: URI scheme,
	Identity header, and RFC 4320 [10] non-INVITE transaction fixes.		the SIP Identity header, and RFC 4320 [10] non-INVITE transaction
			fixes.
	5.5. The Signaling Function (SF) of an Initiating Provider		5.5. The Signaling Function (SF) of an Target Provider
	5.5.1. Verify TLS connection		5.5.1. Verify TLS connection
	When the receiving peer receives a TLS client hello, it responds with		When the receiving peer receives a TLS client hello, it responds
	its certificate. The receiving peer certificate SHOULD be valid and		with its certificate. The receiving peer certificate SHOULD be
	rooted in a well-known certificate authority. The receiving peer		valid and rooted in a well-known certificate authority. The
	MUST request and verify the client certificate during the TLS		receiving peer MUST request and verify the client certificate during
	handshake.		the TLS handshake.
	Once the initiating peer has been authenticated, the receiving peer		Once the initiating peer has been authenticated, the receiving peer
	can authorize communication from this peer based on the domain name		can authorize communication from this peer based on the domain name
	of the peer and the root of its certificate. This allows two		of the peer and the root of its certificate. This allows two
	authorization models to be used, together or separately. In the		authorization models to be used, together or separately. In the
	domain-based model, the receiving peer can allow communication from		domain-based model, the receiving peer can allow communication from
	peers with some trusted administrative domains which use general-		peers with some trusted administrative domains that use general-
	purpose certificate authorities, without explicitly permitting all		purpose certificate authorities, without explicitly permitting all
	domains with certificates rooted in the same authority. It also		domains with certificates rooted in the same authority. It also
	allows a certificate authority (CA) based model where every domain		allows a certificate authority (CA) based model where every domain
	with a valid certificate rooted in some list of CAs is automatically		with a valid certificate rooted in some list of CAs is automatically
	authorized.		authorized.
	5.5.2. Receive SIP requests		5.5.2. Receive SIP requests
	Once a TLS connection is established, the receiving peer is prepared		Once a TLS connection is established, the receiving peer is prepared
	to receive incoming SIP requests. For new dialog-forming requests		to receive incoming SIP requests. For new requests (dialog forming
	and out-of-dialog requests, the receiving peer verifies that the		or not) the receiving peer verifies that the target (request-URI) is
	target (request-URI) is a domain which for which it is responsible.		a domain that for which it is responsible. For these requests, there
	(For these requests, there should be no remaining Route header field		should be no remaining Route header field values. Next the receiving
	values.) Next the receiving verifies that the Identity header is		verifies that the Identity header is valid, corresponds to the
	valid, corresponds to the message, corresponds to the Identity-Info		message, and corresponds to the Identity-Info header, and that the
	header, and that the domain in the From header corresponds to one of		domain in the From header corresponds to one of the domains in the
	the domains in the TLS client certificate.		TLS client certificate.
	For in-dialog requests, the receiving peer can verify that it		For in-dialog requests, the receiving peer can verify that it
	corresponds to the top-most Route header field value. The peer also		corresponds to the top-most Route header field value. The peer also
	validates any Identity header if present.		validates any Identity header if present.
	The receiving peer MAY reject incoming requests due to local policy.		The receiving peer MAY reject incoming requests due to local policy.
	When a request is rejected because the initiating peer is not		When a request is rejected because the initiating peer is not
	authorized to peer, the receiving peer SHOULD respond with a 403		authorized to peer, the receiving peer SHOULD respond with a 403
	response with the reason phrase "Unsupported Peer".		response with the reason phrase "Unsupported Peer".
	5.6. Media Function (MF)		5.6. Media Function (MF)
	Examples of the media function is to transform voice payload from one		The purpose of the MF is to perform media related functions such as
	coding (e.g., G.711) to another (e.g., EvRC), media relaying, media		media transcoding and media security implementation between two
	security, privacy, and encryption.		SSPs.
	Editor's Note: This section will be further updated.		An Example of this is to transform a voice payload from one codec
			(e.g., G.711) to another (e.g., EvRC). Additionally, the MF MAY
			perform media relaying, media security, privacy, and encryption.
	5.7. Policy Considerations		5.7. Policy Considerations
	In the context of the SPEERMINT working group when two Layer 5		In the context of the SPEERMINT working group when two SSPs peer,
	devices (e.g., SIP Proxies) peer, there is a need to exchange peering		there MAY be a desire to exchange peering policy information
	policy information. There are specifications in progress in the		dynamically. There are specifications in progress in the SIPPING
	SIPPING working group to define policy exchange between an UA and a		working group to define policy exchange between an UA and a domain
	domain [23] and providing profile data to SIP user agents [24] These		[23] and providing profile data to SIP user 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 Peering Session-Independent and Session-Specific policies in		terms Peering Session-Independent and Session-Specific policies in
	the following context.		the following context.
	o Peering Session-Independent policies include Diffserv Marking,		o Peering Session-Independent policies include Diffserv Marking,
	Policing, Session Admission Control, domain reachabilities,		Policing, Session Admission Control, and domain reachabilities,
	amongst others. The time period between Peering Session-		amongst others. The time period between Peering Session-
	Independent policy changes is much greater than the time it takes		Independent policy changes is much greater than the time it
	to establish a call.		takes to establish a call.
	o Peering Session-Specific polices includes supported		o Peering Session-Specific polices includes supported
	connection/call rate, total number of connections/calls available,		connection/call rate, total number of connections/calls
	current utilization, amongst others. Peering Session-specific		available, current utilization, amongst others. Peering
	policies can change within the time it takes to establish a call.		Session-specific policies can change within the time it takes
			to establish a call.
	These policies can be Peer dependent or independent, creating the		These policies can be Peer dependent or independent, creating the
	following peering policy tree definition:		following peering policy tree definition:
	Peer Independent		o Peer Independent
	Session dependent		Session dependent
	Session independent		Session independent
	Peer Dependent		o Peer Dependent
	Session dependent		Session dependent
	Session independent		Session independent
	6. Call Control and Media Control Deployment Options		6. Call Control and Media Control Deployment Options
	The peering functions can either be deployed along the following two		The peering functions can either be deployed along the following two
	dimensions depending upon how the signaling function and the media		dimensions depending upon how the signaling function and the media
	function along with IP functions are implemented:		function along with IP functions are implemented:
	Composed or Decomposed: Addresses the question whether the media		Composed or Decomposed: Addresses the question whether the media
	paths must flow through the same physical and geographic nodes as the		must flow through the same physical and geographic elements as SIP
	call signaling,		dialogs and sessions.
	Centralized or Distributed: Addresses the question whether the		Centralized or Distributed: Addresses the question whether the
	logical and physical peering points are in one geographical location		logical and physical peering points are in one geographical location
	or distributed to multiple physical locations on the service provider		or distributed to 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 element.		peering logical element.
	Provider A Provider B		Provider A Provider B
	---------- . . ----------		---------- . . ----------
	/ \ . . / \		/ \ . . / \
	| | . _ . | |		| | . _ . | |
	| +----+ . / \_ . +----+ |		| +----+ . / \_ . +----+ |
	| | SF |<-----/ \------| SF | |		| | SF |<-----/ \------| SF | |
	skipping to change at page 17, line 26		skipping to change at page 16, line 46
	| | . \__ _/ . | |		| | . \__ _/ . | |
	\_________ / . . \________ _/		\_________ / . . \________ _/
	---------- ----------		---------- ----------
	--- 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-element		The advantage of a collapsed peering architecture is that one-
	solves all peering issues. Disadvantage examples of this architecture		element solves all peering issues. Disadvantage examples of this
	are single point failure, bottle neck, and complex scalability.		architecture are single point of failure, bottleneck, and complex
			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 elements. Signaling functions are implemented in a proxy and		logical elements. SFs are implemented in a proxy and MFs are
	media functions are implemented in another logical element. The		implemented in another logical element. The scaling of signaling
	scaling of signaling versus scaling of media may differ between		versus scaling of media may differ between applications.
	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 with multiple peering MF and one peering MF is associated		associated with multiple peering MF and one peering MF is associated
	with multiple peering proxies. Generally, a vertical protocol		with multiple peering proxies. Generally, a vertical protocol
	associates the relationship between a SF and a MF. This architecture		associates the relationship between a SF and a MF. This architecture
	reduces the potential of single point failure. This architecture,		reduces the potential of a single point of failure. It allows
	allows separation of the policy decision point and the policy		separation of the policy decision point and the policy enforcement
	enforcement point. An example of disadvantages is the scaling		point. An example of disadvantages is the scaling complexity because
	complexity because of the M:N relationship and latency due to the		of the M:N relationship and latency due to the vertical control
	vertical control messages between entities.		messages between entities.
	7. Address space considerations		7. Address space considerations
	Peering must occur in a common address space, which is defined by the		Peering must occur in a common address space, which is defined by
	federation, which may be entirely on the public Internet, or some		the federation, which may be entirely on the public Internet, or
	private address space. The origination or termination networks may or		some private address space. The origination or termination networks
	may not entirely be in that same address space. If they are not,		may or may not entirely be in that same address space. If they are
	then a translation (NAT) may be needed before the signaling or media		not, then a network address translation (NAT) or similar may be
	is presented to the federation. The only requirement is that all		needed before the signaling or media is presented correctly to the
	entities across the peering interface are reachable.		federation. The only requirement is that all associated entities
			across the peering interface are reachable.
	8. Security Considerations		8. Security Considerations
	In all cases, cryptographic-based security should be maintained as an		In all cases, cryptographic-based security should be maintained as
	optional requirement between peering providers conditioned on the		an optional requirement between peering providers conditioned on the
	presence or absence of underlying physical security of peer		presence or absence of underlying physical security of peer
	connections, e.g. within the same secure physical building.		connections, e.g. within the same secure physical building.
	In order to maintain a consistent approach, unique and specialized		In order to maintain a consistent approach, unique and specialized
	security requirements common for the majority of peering		security requirements common for the majority of peering
	relationships, should be standardized within the IETF. These		relationships, should be standardized within the IETF. These
	standardized methods may enable capabilities such as dynamic peering		standardized methods may enable capabilities such as dynamic peering
	relationships across publicly maintained interconnections.		relationships across publicly maintained interconnections.
	TODO: Address RFC-3552 BCP items.		TODO: Address RFC-3552 BCP items.
	skipping to change at page 19, line 9		skipping to change at page 19, line 9
	draft that helped to initiate work on this draft.		draft that helped to initiate work on this draft.
	A significant portion of this draft is taken from [14] with		A significant portion of this draft is taken from [14] with
	permission from the author R. Mahy. The other important contributor		permission from the author R. Mahy. The other important contributor
	is Otmar Lendl.		is Otmar Lendl.
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement		[1] Bradner, S., "Key words for use in RFCs to Indicate
	Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", 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 Resource Record", RFC 2915, September 2000.		(NAPTR) DNS 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, J., Sparks, R., Handley, M., and E. Schooler, "SIP:		Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
	Session Initiation Protocol", RFC 3261, June 2002.		Session Initiation Protocol", RFC 3261, June 2002.
	[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol		[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol
	(SIP): Locating SIP Servers", RFC 3263, June 2002.		(SIP): 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. Wright, "Transport Layer Security (TLS) Extensions", RFC		T. Wright, "Transport Layer Security (TLS) Extensions", RFC
	4366, April 2006.		4366, April 2006.
	[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,		[6] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
	"RTP: A Transport Protocol for Real-Time Applications", STD 64,		"RTP: A Transport Protocol for Real-Time Applications", STD
	RFC 3550, July 2003.		64, RFC 3550, July 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 with the Session Initiation Protocol (SIP)", RFC 3824,		numbers 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 Presence Services", RFC 3953, January 2005.		Registration for Presence Services", RFC 3953, January 2005.
	skipping to change at page 20, line 7		skipping to change at page 20, line 7
	[11] Peterson, J., "enumservice registration for Session Initiation		[11] Peterson, J., "enumservice registration for Session Initiation
	Protocol (SIP) Addresses-of-Record", RFC 3764, April 2004.		Protocol (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 2006.		November 2006.
	11.2. Informative References		11.2. Informative References
	[13] Meyer, D., "SPEERMINT Terminology", draft-ietf-speermint-		[13] Malas, D., "SPEERMINT Terminology", draft-ietf-speermint-
	terminology-08 (work in progress), Junly 2007.		terminology-16 (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", draft-ietf-speermint-requirements-02.txt,		Interconnection", draft-ietf-speermint-requirements-03.txt,
	July 2007.		November 2007.
	[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] Lee, Y., "Session Peering Use Case for Cable", draft-lee-		[17] Houri, A., et al., "RTC Provisioning Requirements", draft-
	speermint-use-case-cable-01.txt, June, 2006.
	[18] 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.
	[19] 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.
	[20] 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", RFC 5028
	enum-im-service-03 (work in progress), March 2006.
	[21] Haberler, M. and R. Stastny, "Combined User and Carrier ENUM in		[20] Haberler, M. and R. Stastny, "Combined User and Carrier ENUM
	the e164.arpa tree", draft-haberler-carrier-enum-03 (work in		in the e164.arpa tree", draft-haberler-carrier-enum-03 (work
	progress), March 2006.		in progress), March 2006.
	[22] 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-sipping-		Protocol (SIP) Event package for Peering", draft-penno-
	peering-package-00 (work in progress), September 2006.		sipping-peering-package-01 (work in progress), September 2006.
	[23] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML",		[22] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML",
	W3C REC REC-xml-names-19990114, January 1999.		W3C REC REC-xml-names-19990114, January 1999.
	[24] 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
			2006
	Author's Addresses		Author's Addresses
	Mike Hammer		Mike Hammer
	Cisco Systems		Cisco Systems
	13615 Dulles Technology Drive		13615 Dulles Technology Drive
	Herndon, VA 20171		Herndon, VA 20171
	USA		USA
	Email: mhammer@cisco.com		Email: mhammer@cisco.com
	skipping to change at page 21, line 43		skipping to change at page 21, line 43
	Adam Uzelac		Adam Uzelac
	Global Crossing		Global Crossing
	1120 Pittsford Victor Road		1120 Pittsford Victor Road
	PITTSFORD, NY 14534		PITTSFORD, NY 14534
	USA		USA
	Email: adam.uzelac@globalcrossing.com		Email: adam.uzelac@globalcrossing.com
	Intellectual Property Statement		Intellectual Property Statement
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