draft-ietf-mmusic-media-loopback-18.txt		draft-ietf-mmusic-media-loopback-19.txt
	Internet Draft H. Kaplan (ed.)		Internet Draft H. Kaplan (ed.)
	Expires: August 12, 2012 Acme Packet		Expires: December 12, 2012 Acme Packet
	K. Hedayat		K. Hedayat
	EXFO		EXFO
	N. Venna		N. Venna
	Saperix		Saperix
	P. Jones		P. Jones
	Cisco Systems, Inc.		Cisco Systems, Inc.
	A. Roychowdhury
	Hughes Systique Corp.
	C. SivaChelvan
	Cisco Systems, Inc.
	N. Stratton		N. Stratton
	BlinkMind, Inc.		BlinkMind, Inc.
	March 26, 2012		July 12, 2012
	An Extension to the Session Description Protocol (SDP)		An Extension to the Session Description Protocol (SDP)
	and Real-time Transport Protocol (RTP) for Media Loopback		and Real-time Transport Protocol (RTP) for Media Loopback
	draft-ietf-mmusic-media-loopback-18		draft-ietf-mmusic-media-loopback-19
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted to IETF in full conformance with		This Internet-Draft is submitted to IETF in full conformance with
	the provisions of BCP 78 and BCP 79.		the provisions of BCP 78 and 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.
	skipping to change at page 1, line 44		skipping to change at page 1, line 41
	documents at any time. It is inappropriate to use Internet-Drafts		documents at any time. It is inappropriate to use Internet-Drafts
	as reference material or to cite them other than as "work in		as reference material or to cite them other than as "work in
	progress."		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 August 12, 2012.		This Internet-Draft will expire on December 12, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 35		skipping to change at page 2, line 27
	performance. In particular, media delivery is an area that needs		performance. In particular, media delivery is an area that needs
	attention. One method of meeting these challenges is monitoring		attention. One method of meeting these challenges is monitoring
	the media delivery performance by looping media back to the		the media delivery performance by looping media back to the
	transmitter. This is typically referred to as "active monitoring"		transmitter. This is typically referred to as "active monitoring"
	of services. Media loopback is especially popular in ensuring the		of services. Media loopback is especially popular in ensuring the
	quality of transport to the edge of a given VoIP, Real-time Text or		quality of transport to the edge of a given VoIP, Real-time Text or
	Video over IP service. Today in networks that deliver real-time		Video over IP service. Today in networks that deliver real-time
	media, short of running 'ping' and 'traceroute' to the edge,		media, short of running 'ping' and 'traceroute' to the edge,
	administrators are left without the necessary tools to actively		administrators are left without the necessary tools to actively
	monitor, manage, and diagnose quality issues with their service.		monitor, manage, and diagnose quality issues with their service.
	The extension defined herein adds new SDP media attributes, which		The extension defined herein adds new SDP media types and
	enable establishment of media sessions where the media is looped		attributes, which enable establishment of media sessions where the
	back to the transmitter. Such media sessions will serve as		media is looped back to the transmitter. Such media sessions will
	monitoring and troubleshooting tools by providing the means for		serve as monitoring and troubleshooting tools by providing the
	measurement of more advanced VoIP, Real-time Text and Video over IP		means for measurement of more advanced VoIP, Real-time Text and
	performance metrics.		Video over IP performance metrics.
	Table of Contents		Table of Contents
	1. Introduction..................................................3		1. Introduction..................................................3
	1.1 Use Cases Supported.......................................4		1.1 Use Cases Supported.......................................4
	2. Terminology...................................................6		2. Terminology...................................................6
	3. Overview of Operation.........................................6		3. Overview of Operation.........................................6
	3.1 SDP Offerer Behavior......................................6		3.1 SDP Offerer Behavior......................................6
	3.2 SDP Answerer Behavior.....................................6		3.2 SDP Answerer Behavior.....................................6
	4. New SDP Attributes............................................7		4. New SDP Attributes............................................7
	skipping to change at page 3, line 16		skipping to change at page 3, line 9
	5. Rules for Generating the SDP offer/answer.....................9		5. Rules for Generating the SDP offer/answer.....................9
	5.1 Generating the SDP Offer for Loopback Session.............9		5.1 Generating the SDP Offer for Loopback Session.............9
	5.2 Generating the SDP Answer for Loopback Session...........10		5.2 Generating the SDP Answer for Loopback Session...........10
	5.3 Offerer Processing of the SDP Answer.....................11		5.3 Offerer Processing of the SDP Answer.....................11
	5.4 Modifying the Session....................................12		5.4 Modifying the Session....................................12
	5.5 Establishing Sessions Between Entities Behind NAT........12		5.5 Establishing Sessions Between Entities Behind NAT........12
	6. RTP Requirements.............................................12		6. RTP Requirements.............................................12
	7. Payload formats for Packet loopback..........................13		7. Payload formats for Packet loopback..........................13
	7.1 Encapsulated Payload format..............................13		7.1 Encapsulated Payload format..............................13
	7.2 Direct loopback RTP payload format.......................16		7.2 Direct loopback RTP payload format.......................16
	8. RTCP Requirements............................................17		8. SRTP Behavior................................................17
	9. Congestion Control...........................................17		9. RTCP Requirements............................................17
	10. Examples....................................................18		10. Congestion Control..........................................18
	10.1 Offer for specific media loopback type..................18		11. Examples....................................................18
	10.2 Offer for choice of media loopback type.................18		11.1 Offer for specific media loopback type..................18
	10.3 Answerer rejecting loopback media.......................19		11.2 Offer for choice of media loopback type.................19
	11. Security Considerations.....................................20		11.3 Answerer rejecting loopback media.......................20
	12. Implementation Considerations...............................21		12. Security Considerations.....................................20
	13. IANA Considerations.........................................21		13. Implementation Considerations...............................21
	13.1 SDP Attributes..........................................21		14. IANA Considerations.........................................22
	13.2 MIME Types..............................................22		14.1 SDP Attributes..........................................22
	14. Acknowledgements............................................31		14.2 Media Types.............................................22
	15. Normative References........................................31		15. Acknowledgements............................................31
	16. Informative References......................................32		16. Normative References........................................31
			17. Informative References......................................32
	1. Introduction		1. Introduction
	The overall quality, reliability, and performance of VoIP,		The overall quality, reliability, and performance of VoIP,
	Real-time Text and Video over IP services rely on the performance		Real-time Text and Video over IP services rely on the performance
	and quality of the media path. In order to assure the quality of		and quality of the media path. In order to assure the quality of
	the delivered media there is a need to monitor the performance of		the delivered media there is a need to monitor the performance of
	the media transport. One method of monitoring and managing the		the media transport. One method of monitoring and managing the
	overall quality of real-time VoIP, Text and Video over IP Services		overall quality of real-time VoIP, Text and Video over IP Services
	is through monitoring the quality of the media in an active		is through monitoring the quality of the media in an active
	session. This type of "active monitoring" of services is a method		session. This type of "active monitoring" of services is a method
	of proactively managing the performance and quality of VoIP based		of proactively managing the performance and quality of VoIP based
	skipping to change at page 4, line 9		skipping to change at page 3, line 50
	to request an endpoint to loop media back to the other endpoint and		to request an endpoint to loop media back to the other endpoint and
	to provide media statistics (e.g., RTCP and RTCP XR information).		to provide media statistics (e.g., RTCP and RTCP XR information).
	Another method involves deployment of special endpoints that always		Another method involves deployment of special endpoints that always
	loop incoming media back for sessions. Although the latter method		loop incoming media back for sessions. Although the latter method
	has been used and is functional, it does not scale to support large		has been used and is functional, it does not scale to support large
	networks and introduces new network management challenges.		networks and introduces new network management challenges.
	Further, it does not offer the granularity of testing a specific		Further, it does not offer the granularity of testing a specific
	endpoint that may be exhibiting problems.		endpoint that may be exhibiting problems.
	The extension defined in this document introduces new SDP media		The extension defined in this document introduces new SDP media
	attributes that enable establishment of media sessions where the		types and attributes that enable establishment of media sessions
	media is looped back to the transmitter. The SDP offer/answer		where the media is looped back to the transmitter. The SDP
	model [RFC3264] is used to establish a loopback connection.		offer/answer model [RFC3264] is used to establish a loopback
	Furthermore, this extension provides guidelines on handling RTP		connection. Furthermore, this extension provides guidelines on
	[RFC3550], as well as usage of RTCP [RFC3550] and RTCP XR [RFC3611]		handling RTP [RFC3550], as well as usage of RTCP [RFC3550] and RTCP
	for reporting media related measurements.		XR [RFC3611] for reporting media related measurements.
	1.1 Use Cases Supported		1.1 Use Cases Supported
	As a matter of terminology in this document, packets flow from one		As a matter of terminology in this document, packets flow from one
	peer acting as a "loopback source", to the other peer acting as a		peer acting as a "loopback source", to the other peer acting as a
	"loopback mirror", which in turn returns packets to the loopback		"loopback mirror", which in turn returns packets to the loopback
	source. In advance of the session, the peers negotiate to determine		source. In advance of the session, the peers negotiate to determine
	which one acts in which role, using the SDP offer/answer exchange.		which one acts in which role, using the SDP offer/answer exchange.
	The negotiation also includes details such as the type of loopback		The negotiation also includes details such as the type of loopback
	to be used.		to be used.
	This specification supports three use cases: "encapsulated packet		This specification supports three use cases: "encapsulated packet
	skipping to change at page 6, line 5		skipping to change at page 6, line 5
	type. The packet is taken as close as possible to the analog level,		type. The packet is taken as close as possible to the analog level,
	then re-encoded according to an outgoing format determined by SDP		then re-encoded according to an outgoing format determined by SDP
	negotiation. The reencoded content is returned to the loopback		negotiation. The reencoded content is returned to the loopback
	source as an RTP packet with payload type corresponding to the		source as an RTP packet with payload type corresponding to the
	reencoding format.		reencoding format.
	This usage allows trouble-shooting at the codec level. The		This usage allows trouble-shooting at the codec level. The
	capability for path statistics is limited to what is available from		capability for path statistics is limited to what is available from
	RTCP reports.		RTCP reports.
	2. Terminology		2. Terminology
	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		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
	this document are to be interpreted as described in RFC 2119.		this document are to be interpreted as described in RFC 2119.
	SDP: Session Description Protocol, as defined in [RFC4566]. This		SDP: Session Description Protocol, as defined in [RFC4566]. This
	document assumes the SDP offer/answer model is followed, per		document assumes the SDP offer/answer model is followed, per
	[RFC3264], but does not assume any specific signaling protocol for		[RFC3264], but does not assume any specific signaling protocol for
	carrying the SDP.		carrying the SDP.
	The following terms are borrowed from [RFC3264] definitions: offer,		The following terms are borrowed from [RFC3264] definitions: offer,
	offerer, answer, answerer, and agent.		offerer, answer, answerer, and agent.
	3. Overview of Operation		3. Overview of Operation
	This document defines two loopback 'types', two 'roles', and two		This document defines two loopback 'types', two 'roles', and two
	encoding formats for loopback. For any given SDP offerer or		encoding formats for loopback. For any given SDP offerer or
	answerer pair, one side is the source of RTP packets, while the		answerer pair, one side is the source of RTP packets, while the
	other is the mirror looping packets/media back. Those define the		other is the mirror looping packets/media back. Those define the
	two loopback roles. As the mirror, two 'types' of loopback can be		two loopback roles. As the mirror, two 'types' of loopback can be
	performed: packet-level or media-level. When media-level is used,		performed: packet-level or media-level. When media-level is used,
	there is no further choice of encoding format - there is only one		there is no further choice of encoding format - there is only one
	format: whatever is indicated for normal media, since the "looping"		format: whatever is indicated for normal media, since the "looping"
	is performed at the codec level. When packet-level looping is		is performed at the codec level. When packet-level looping is
	performed, however, the mirror can either send back RTP in an		performed, however, the mirror can either send back RTP in an
	encapsulated format or direct-loopback format. The rest of this		encapsulated format or direct-loopback format. The rest of this
	document describes these loopback types, roles, and encoding		document describes these loopback types, roles, and encoding
	formats, and the SDP offer/answer rules for indicating them.		formats, and the SDP offer/answer rules for indicating them.
	3.1 SDP Offerer Behavior		3.1 SDP Offerer Behavior
	An SDP offerer compliant to this memo and attempting to establish a		An SDP offerer compliant to this memo and attempting to establish a
	media session with media loopback MUST include "loopback" media		media session with media loopback MUST include "loopback" media
	attributes for each individual media description in the offer		attributes for each individual media description in the offer
	message. The offerer MUST look for the "loopback" media attributes		message. The offerer MUST look for the "loopback" media attributes
	in the media description(s) of the response from the answer for		in the media description(s) of the response from the answer for
	confirmation that the request is accepted.		confirmation that the request is accepted.
	3.2 SDP Answerer Behavior		3.2 SDP Answerer Behavior
	An SDP answerer compliant to this specification and receiving an		An SDP answerer compliant to this specification and receiving an
	offer containing media descriptions with the "loopback" media		offer containing media descriptions with the "loopback" media
	attributes MUST acknowledge the request by including the received		attributes MUST acknowledge the request by including the received
	"loopback" media attributes for each media description in its		"loopback" media attributes for each media description in its
	asnwer if it agrees to do the loopback. If the answerer does not		answer if it agrees to do the loopback. If the answerer does not
	want to do loopback or wants to reject the "loopback" request for		want to do loopback or wants to reject the "loopback" request for
	specific media types, it MAY do so as defined in this section.		specific media descriptions, it MUST do so as defined in this
			section.
	An answerer MAY reject an offered stream (either with loopback-		An answerer MAY reject an offered stream (either with loopback-
	source or loopback-mirror) if the loopback-type is not specified,		source or loopback-mirror) if the loopback-type is not specified,
	the specified loopback-type is not supported, or the endpoint		the specified loopback-type is not supported, or the endpoint
	cannot honor the offer for any other reason. The loopback request		cannot honor the offer for any other reason. The loopback request
	MUST be rejected by setting the stream's media port number to zero		MUST be rejected by setting the stream's media port number to zero
	in the answer as defined in RFC 3264 [RFC3264], or by rejecting the		in the answer as defined in RFC 3264 [RFC3264], or by rejecting the
	entire offer (i.e., by rejecting the session request entirely).		entire offer (i.e., by rejecting the session request entirely).
	Note that an answerer that is not compliant to this specification		Note that an answerer that is not compliant to this specification
	and which receives an offer with the "loopback" media attributes		and which receives an offer with the "loopback" media attributes
	would ignore the attributes and treat the incoming offer as a		would ignore the attributes and treat the incoming offer as a
	normal request. If the offerer does not wish to establish a		normal request. If the offerer does not wish to establish a
	"normal" RTP session, it would need to terminate the session upon		"normal" RTP session, it would need to terminate the session upon
	receiving such an answer.		receiving such an answer.
	4. New SDP Attributes		4. New SDP Attributes
	Three new SDP media-level attributes are defined: one indicates the		Three new SDP media-level attributes are defined: one indicates the
	type of loopback, and the other two define the role of the agent.		type of loopback, and the other two define the role of the agent.
	4.1 Loopback Type Attribute		4.1 Loopback Type Attribute
	This specification defines a new 'loopback' attribute, which		This specification defines a new 'loopback' attribute, which
	indicates that the agent wishes to perform loopback, and the type		indicates that the agent wishes to perform loopback, and the type
	of loopack that the agent is able to do. The loopback-type is a		of loopack that the agent is able to do. The loopback-type is a
	property media attribute with the following syntax:		value media attribute [RFC4566] with the following syntax:
	a=loopback:<loopback-type>		a=loopback:<loopback-type>
	Following is the Augmented BNF [RFC5234] for loopback-type:		Following is the Augmented BNF [RFC5234] for loopback-type:
	Loopback-attr = "a=loopback:" SP loopback-type		loopback-attr = "a=loopback:" SP loopback-type
	loopback-type = loopback-choice [1*SP loopback-choice]		loopback-type = loopback-choice [1*SP loopback-choice]
	loopback-choice = loopback-type-pkt / loopback-type-media		loopback-choice = loopback-type-pkt / loopback-type-media
	loopback-type-pkt = "rtp-pkt-loopback"		loopback-type-pkt = "rtp-pkt-loopback"
	loopback-type-media = "rtp-media-loopback"		loopback-type-media = "rtp-media-loopback"
	The loopback-type is used to indicate the type of loopback. The		The loopback-type is used to indicate the type of loopback. The
	loopback-type values are rtp-pkt-loopback, and rtp-media-loopback.		loopback-type values are rtp-pkt-loopback, and rtp-media-loopback.
	rtp-pkt-loopback: In this mode, the RTP packets are looped back to		rtp-pkt-loopback: In this mode, the RTP packets are looped back to
	the sender at a point before the encoder/decoder function in the		the sender at a point before the encoder/decoder function in the
	skipping to change at page 8, line 20		skipping to change at page 8, line 19
	formats that MUST be used for this type of loopback. This type of		formats that MUST be used for this type of loopback. This type of
	loopback applies to the encapsulated and direct loopback use-cases		loopback applies to the encapsulated and direct loopback use-cases
	described in Section 1.1.		described in Section 1.1.
	rtp-media-loopback: This loopback is activated as close as possible		rtp-media-loopback: This loopback is activated as close as possible
	to the analog interface and after the decoder so that the RTP		to the analog interface and after the decoder so that the RTP
	packets are subsequently re-encoded prior to transmission back to		packets are subsequently re-encoded prior to transmission back to
	the sender. This type of loopback applies to the media loopback		the sender. This type of loopback applies to the media loopback
	use-case described in Section 1.1.3.		use-case described in Section 1.1.3.
	4.2 Loopback Role Attributes: loopback-source and loopback-mirror		4.2 Loopback Role Attributes: loopback-source and loopback-mirror
	The loopback role defines two value media attributes that are used		The loopback role defines two property media attributes [RFC4566]
	to indicate the role of the agent generating the SDP offer or		that are used to indicate the role of the agent generating the SDP
	answer. The syntax of the two loopback role media attributes are as		offer or answer. The syntax of the two loopback role media
	follows:		attributes are as follows:
	a=loopback-source		a=loopback-source
	and		and
	a=loopback-mirror		a=loopback-mirror
	loopback-source: This attribute specifies that the entity that		loopback-source: This attribute specifies that the entity that
	generated the SDP is the media source and expects the receiver of		generated the SDP is the media source and expects the receiver of
	the SDP message to act as a loopback-mirror.		the SDP message to act as a loopback-mirror.
	skipping to change at page 9, line 5		skipping to change at page 9, line 5
	generated the SDP will mirror (echo) all received media back to the		generated the SDP will mirror (echo) all received media back to the
	sender of the RTP stream. No media is generated locally by the		sender of the RTP stream. No media is generated locally by the
	looping back entity for transmission in the mirrored stream.		looping back entity for transmission in the mirrored stream.
	The "m=" line in the SDP MUST include all the payload types that		The "m=" line in the SDP MUST include all the payload types that
	will be used during the loopback session. The complete payload		will be used during the loopback session. The complete payload
	space for the session is specified in the "m=" line and the rtpmap		space for the session is specified in the "m=" line and the rtpmap
	attribute is used to map from the payload type number to an		attribute is used to map from the payload type number to an
	encoding name denoting the payload format to be used.		encoding name denoting the payload format to be used.
	5. Rules for Generating the SDP offer/answer		5. Rules for Generating the SDP offer/answer
	5.1 Generating the SDP Offer for Loopback Session		5.1 Generating the SDP Offer for Loopback Session
	If an offerer wishes to make a loopback request, it MUST include		If an offerer wishes to make a loopback request, it MUST include
	both the loopback-type and loopback-role attributes in a valid SDP		both the loopback-type and loopback-role attributes in a valid SDP
	offer:		offer:
	Example: m=audio 41352 RTP/AVP 0 8 100		Example: m=audio 41352 RTP/AVP 0 8 100
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	a=loopback-source		a=loopback-source
	a=rtpmap:0 pcmu/8000		a=rtpmap:0 pcmu/8000
	a=rtpmap:8 pcma/8000		a=rtpmap:8 pcma/8000
	skipping to change at page 9, line 33		skipping to change at page 9, line 33
	since it is implied by default. If either the loopback source or		since it is implied by default. If either the loopback source or
	mirror wish to disable loopback use during a session, the direction		mirror wish to disable loopback use during a session, the direction
	mode attribute "inactive" MUST be used as per [RFC3264]. The		mode attribute "inactive" MUST be used as per [RFC3264]. The
	direction mode attributes "recvonly" and "sendonly" are		direction mode attributes "recvonly" and "sendonly" are
	incompatible with the loopback mechanism and MUST NOT be indicated		incompatible with the loopback mechanism and MUST NOT be indicated
	when generating an SDP Offer or Answer. When receiving an SDP		when generating an SDP Offer or Answer. When receiving an SDP
	Offer or Answer, if "recvonly" or "sendonly" is indicated for		Offer or Answer, if "recvonly" or "sendonly" is indicated for
	loopback, the SDP-receiving agent SHOULD treat it as a protocol		loopback, the SDP-receiving agent SHOULD treat it as a protocol
	failure of the loopback negotiation and terminate the session		failure of the loopback negotiation and terminate the session
	through its normal means (e.g., by sending a SIP BYE if SIP is		through its normal means (e.g., by sending a SIP BYE if SIP is
	used).		used), or reject the offending media stream.
	The offerer may offer more than one loopback-type in the SDP offer.		The offerer may offer more than one loopback-type in the SDP offer.
	The port number and the address in the offer (m/c= lines) indicate		The port number and the address in the offer (m/c= lines) indicate
	where the offerer would like to receive the media stream(s). The		where the offerer would like to receive the media stream(s). The
	payload type numbers indicate the value of the payload the offerer		payload type numbers indicate the value of the payload the offerer
	expects to receive. However, the answer might indicate a subset of		expects to receive. However, the answer might indicate a subset of
	payload type numbers from those given in the offer. In that case,		payload type numbers from those given in the offer. In that case,
	the offerer MUST only send the payload types received in the		the offerer MUST only send the payload types received in the
	answer, per normal SDP offer/answer rules.		answer, per normal SDP offer/answer rules.
	If the offer indicates rtp-pkt-loopback support, the offer MUST		If the offer indicates rtp-pkt-loopback support, the offer MUST
	also contain either an encapsulated or direct loopback encoding		also contain either an encapsulated or direct loopback encoding
	format encoding names, or both, as defined in later sections of		format encoding name, or both, as defined in later sections of this
	this document. If the offer only indicates rtp-media-loopback		document. If the offer only indicates rtp-media-loopback support,
	support, then neither encapsulated nor direct loopback encoding		then neither encapsulated nor direct loopback encoding formats
	formats apply and they MUST NOT be in the offer.		apply and they MUST NOT be in the offer.
	If loopback-type is rtp-pkt-loopback, the loopback-mirror MUST send		If loopback-type is rtp-pkt-loopback, the loopback-mirror MUST send
	and the loopback-source MUST receive the looped back packets		and the loopback-source MUST receive the looped back packets
	encoded in one of the two payload formats (encapsulated RTP or		encoded in one of the two payload formats (encapsulated RTP or
	direct loopback) as defined in section 7.		direct loopback) as defined in section 7.
	Example: m=audio 41352 RTP/AVP 0 8 112		Example: m=audio 41352 RTP/AVP 0 8 112
	a=loopback:rtp-pkt-loopback		a=loopback:rtp-pkt-loopback
	a=loopback-source		a=loopback-source
	a=rtpmap:112 encaprtp/8000		a=rtpmap:112 encaprtp/8000
	Example: m=audio 41352 RTP/AVP 0 8 112		Example: m=audio 41352 RTP/AVP 0 8 112
	a=loopback:rtp-pkt-loopback		a=loopback:rtp-pkt-loopback
	a=loopback-source		a=loopback-source
	a=rtpmap:112 rtploopback/8000		a=rtpmap:112 rtploopback/8000
	5.2 Generating the SDP Answer for Loopback Session		5.2 Generating the SDP Answer for Loopback Session
	As with the offer, an SDP answer for loopback MUST follow SDP		As with the offer, an SDP answer for loopback MUST follow SDP
	offer/answer rules for the direction attribute, but directions of		offer/answer rules for the direction attribute, but directions of
	"sendonly" or "recvonly" do not apply for loopback operation. \		"sendonly" or "recvonly" do not apply for loopback operation and
			hence MUST NOT be used.
	The port number and the address in the answer (m/c= lines) indicate		The port number and the address in the answer (m/c= lines) indicate
	where the answerer would like to receive the media stream. The		where the answerer would like to receive the media stream. The
	payload type numbers indicate the value of the payload types the		payload type numbers indicate the value of the payload types the
	answerer expects to send and receive.		answerer expects to send and receive.
	If an answerer wishes to accept the loopback request it MUST		If an answerer wishes to accept the loopback request it MUST
	include both the loopback role and loopback type attributes in the		include both the loopback role and loopback type attributes in the
	answer. When a stream is offered with the loopback-source		answer. When a stream is offered with the loopback-source
	attribute, the corresponding stream in the response MUST be		attribute, the corresponding stream in the response MUST be
	loopback-mirror and vice versa, provided that answerer is capable		loopback-mirror and vice versa, provided the answerer is capable of
	of supporting the requested loopback-type.		supporting the requested loopback-type.
	For example, if the offer contains the loopback-source attribute:		For example, if the offer contains the loopback-source attribute:
	m=audio 41352 RTP/AVP 0 8		m=audio 41352 RTP/AVP 0 8
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	a=loopback-source		a=loopback-source
	The answer that is capable of supporting the offer MUST contain the		The answer that is capable of supporting the offer must contain the
	loopback-mirror attribute:		loopback-mirror attribute:
	m=audio 12345 RTP/AVP 0 8		m=audio 12345 RTP/AVP 0 8
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	a=loopback-mirror		a=loopback-mirror
	If a stream is offered with multiple loopback type attributes, the		If a stream is offered with multiple loopback type attributes, the
	answer MUST include only one of the loopback types that are		answer MUST include only one of the loopback types that are
	accepted by the answerer. The answerer SHOULD give preference to		accepted by the answerer. The answerer SHOULD give preference to
	the first loopback-type in the SDP offer.		the first loopback-type in the SDP offer.
	For example, if the offer contains:		For example, if the offer contains:
	m=audio 41352 RTP/AVP 0 8 112		m=audio 41352 RTP/AVP 0 8 112
	a=loopback:rtp-media-loopback rtp-pkt-loopback		a=loopback:rtp-media-loopback rtp-pkt-loopback
	a=loopback-source		a=loopback-source
	a=rtpmap:112 encaprtp/8000		a=rtpmap:112 encaprtp/8000
	The answer that is capable of supporting the offer and chooses to		The answer that is capable of supporting the offer and chooses to
	loopback the media using the rtp-media-loopback type MUST contain:		loopback the media using the rtp-media-loopback type must contain:
	m=audio 12345 RTP/AVP 0 8		m=audio 12345 RTP/AVP 0 8
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	a=loopback-mirror		a=loopback-mirror
	As specified in section 7, if the loopback-type is		As specified in section 7, if the loopback-type is
	rtp-pkt-loopback, either the encapsulated RTP payload format or		rtp-pkt-loopback, either the encapsulated RTP payload format or
	direct loopback RTP payload format MUST be used for looped back		direct loopback RTP payload format MUST be used for looped back
	packets.		packets.
	skipping to change at page 11, line 48		skipping to change at page 11, line 50
	a=rtpmap:112 encaprtp/8000		a=rtpmap:112 encaprtp/8000
	m=audio 12345 RTP/AVP 0 8 113		m=audio 12345 RTP/AVP 0 8 113
	a=loopback:rtp-pkt-loopback		a=loopback:rtp-pkt-loopback
	a=loopback-mirror		a=loopback-mirror
	a=rtpmap:113 rtploopback/8000		a=rtpmap:113 rtploopback/8000
	The previous examples used the 'encaprtp' and 'rtploopback'		The previous examples used the 'encaprtp' and 'rtploopback'
	encoding names, which will be defined in sections 7.1.3 and 7.2.3.		encoding names, which will be defined in sections 7.1.3 and 7.2.3.
	5.3 Offerer Processing of the SDP Answer		5.3 Offerer Processing of the SDP Answer
	If the received SDP answer does not contain an a=loopback-mirror or		If the received SDP answer does not contain an a=loopback-mirror or
	a=loopback-source attribute, it is assumed that the loopback		a=loopback-source attribute, it is assumed that the loopback
	extensions are not supported by the remote agent. This is not a		extensions are not supported by the remote agent. This is not a
	protocol failure, and instead merely completes the SDP offer/answer		protocol failure, and instead merely completes the SDP offer/answer
	exchange with whatever normal rules apply; the offerer MAY decide		exchange with whatever normal rules apply; the offerer MAY decide
	to end the established RTP session (if any) through normal means of		to end the established RTP session (if any) through normal means of
	the upper-layer signaling protocol (e.g., by sending a SIP BYE).		the upper-layer signaling protocol (e.g., by sending a SIP BYE).
	5.4 Modifying the Session		5.4 Modifying the Session
	At any point during the loopback session, either participant MAY		At any point during the loopback session, either participant MAY
	issue a new offer to modify the characteristics of the previous		issue a new offer to modify the characteristics of the previous
	session, as defined in section 8 of RFC 3264 [RFC3264]. This also		session, as defined in section 8 of RFC 3264 [RFC3264]. This also
	includes transitioning from a normal media processing mode to		includes transitioning from a normal media processing mode to
	loopback mode, and vice a versa.		loopback mode, and vice versa.
	5.5 Establishing Sessions Between Entities Behind NAT		5.5 Establishing Sessions Between Entities Behind NAT
	ICE/STUN/TURN provide a general solution to establishing media		ICE/STUN/TURN provide a general solution to establishing media
	sessions between entities that are behind NATs, as defined in		sessions between entities that are behind NATs, as defined in
	[RFC5245]. Loopback sessions that involve one or more end points		[RFC5245]. Loopback sessions that involve one or more endpoints
	behind NATs SHOULD use these general solutions wherever possible.		behind NATs SHOULD use these general solutions wherever possible.
	Furthermore, if the mirroring entity is behind a NAT, it MUST send		Furthermore, if the mirroring entity is behind a NAT, it MUST send
	some packets to the identified address/port(s) of the peer, in		some packets to the identified address/port(s) of the peer, in
	order to open the NAT pinhole. Using ICE this would be		order to open the NAT pinhole. Using ICE this would be
	accomplished with the STUN connectivity check process, or through a		accomplished with the STUN connectivity check process, or through a
	TURN server connection. If ICE is not supported, either [RFC6263]		TURN server connection. If ICE is not supported, either [RFC6263]
	or Section 10 of ICE [RFC5245] SHOULD be followed to open the		or Section 10 of ICE [RFC5245] SHOULD be followed to open the
	pinhole and keep the NAT binding alive/refreshed.		pinhole and keep the NAT binding alive/refreshed.
	Note that for any form of NAT traversal to function, symmetric		Note that for any form of NAT traversal to function, symmetric
	RTP/RTCP MUST be used. In other words both agents MUST send		RTP/RTCP [RFC4961] MUST be used. In other words both agents MUST
	packets from the same source address and port they receive packets		send packets from the source address and port they receive packets
	on.		on.
	6. RTP Requirements		6. RTP Requirements
	A looback source MUST NOT send multiple source streams on the same		A loopback source MUST NOT send multiple source streams on the same
	5-tuple, since there is no means for the mirror to indicate which		5-tuple, since there is no means for the mirror to indicate which
	is which in its mirrored RTP packets.		is which in its mirrored RTP packets.
	A loopback mirror that is compliant to this specification and		A loopback mirror that is compliant to this specification and
	accepts media with rtp-pkt-loopback loopback-type MUST loopback the		accepts media with rtp-pkt-loopback loopback type MUST loopback the
	incoming RTP packets using either the encapsulated RTP payload		incoming RTP packets using either the encapsulated RTP payload
	format or the direct loopback RTP payload format as defined in		format or the direct loopback RTP payload format as defined in
	section 7 of this specification.		section 7 of this specification.
	A device that is compliant to this specification and performing the		A device that is compliant to this specification and performing the
	mirroring using the loopback type rtp-media-loopback MUST transmit		mirroring using the loopback type rtp-media-loopback MUST transmit
	all received media back to the sender, unless congestion feedback		all received media back to the sender, unless congestion feedback
	or other lower-layer constraints prevent it from doing so. The		or other lower-layer constraints prevent it from doing so. The
	incoming media MUST be treated as if it were to be played (e.g. the		incoming media MUST be treated as if it were to be played (e.g. the
	media stream MAY receive treatment from PLC algorithms). The		media stream MAY receive treatment from PLC algorithms). The
	mirroring entity MUST re-generate all the RTP header fields as it		mirroring entity MUST re-generate all the RTP header fields as it
	would when transmitting media. The mirroring entity MAY choose to		would when transmitting media. The mirroring entity MAY choose to
	encode the loopback media according to any of the media		encode the loopback media according to any of the media
	descriptions supported by the offering entity. Furthermore, in		descriptions supported by the offering entity. Furthermore, in
	cases where the same media type is looped back, the mirroring		cases where the same media type is looped back, the mirroring
	entity MAY choose to preserve number of frames/packet and bitrate		entity MAY choose to preserve number of frames/packet and bitrate
	of the encoded media according to the received media.		of the encoded media according to the received media.
	7. Payload formats for Packet loopback		7. Payload formats for Packet loopback
	The payload formats described in this section MUST be used by a		The payload formats described in this section MUST be used by a
	loopback-mirror when 'rtp-pkt-loopback' is the specified		loopback-mirror when 'rtp-pkt-loopback' is the specified
	loopback-type. Two different formats are specified here - an		loopback-type. Two different formats are specified here - an
	encapsulated RTP payload format and a direct loopback RTP payload		encapsulated RTP payload format and a direct loopback RTP payload
	format. The encapsulated RTP payload format should be used when		format. The encapsulated RTP payload format should be used when
	the incoming RTP header information needs to be preserved during		the incoming RTP header information needs to be preserved during
	the loopback operation. This is useful in cases where loopback		the loopback operation. This is useful in cases where loopback
	source needs to measure performance metrics in both directions.		source needs to measure performance metrics in both directions.
	However, this comes at the expense of increased packet size as		However, this comes at the expense of increased packet size as
	described in section 7.1. The direct loopback RTP payload format		described in section 7.1. The direct loopback RTP payload format
	should be used when bandwidth requirement prevents the use of		should be used when bandwidth requirements prevent the use of
	encapsulated RTP payload format.		encapsulated RTP payload format.
	To keep the implementation of loopback-mirrors simple it is		7.1 Encapsulated Payload format
	mandated that no payload format other than encapsulated or direct
	loopback formats can be used in the packets generated by a
	loopback-mirror. As described in RFC 3550 [RFC3550], sequence
	numbers and timestamps in the RTP header are generated with initial
	random values for security reasons. If this were not mandated and
	the source payload is sequence number aware, the loopback-mirror
	will be required to understand that payload format to generate
	looped back packets that do not violate RFC 3550 [RFC3550].
	Requiring looped back packets to be in one of the two formats means
	loopback-mirror does not have to look into the actual payload
	received before generating the loopback packets.
	7.1 Encapsulated Payload format
	A received RTP packet is encapsulated in the payload section of the		A received RTP packet is encapsulated in the payload section of the
	RTP packet generated by a loopback-mirror. Each received packet		RTP packet generated by a loopback-mirror. Each received packet
	MUST be encapsulated in a separate encapsulating RTP packet; the		MUST be encapsulated in a separate encapsulating RTP packet; the
	encapsulated packet MUST be fragmented only if required (for		encapsulated packet MUST be fragmented only if required (for
	example: due to MTU limitations).		example: due to MTU limitations).
	7.1.1Usage of RTP Header fields		7.1.1 Usage of RTP Header fields
	Payload Type (PT): The assignment of an RTP payload type for this		Payload Type (PT): The assignment of an RTP payload type for this
	packet format is outside the scope of this document; it is either		packet format is outside the scope of this document; it is either
	specified by the RTP profile under which this payload format is		specified by the RTP profile under which this payload format is
	used or more likely signaled dynamically out-of-band (e.g., using		used or more likely signaled dynamically out-of-band (e.g., using
	SDP; section 7.1.3 defines the name binding).		SDP; section 7.1.3 defines the name binding).
	Marker (M) bit: If the received RTP packet is looped back in		Marker (M) bit: If the received RTP packet is looped back in
	multiple encapsulating RTP packets, the M bit is set to 1 in every		multiple encapsulating RTP packets, the M bit is set to 1 in every
	fragment except the last packet, otherwise it is set to 0.		fragment except the last packet, otherwise it is set to 0.
	skipping to change at page 14, line 36		skipping to change at page 14, line 28
	the loopback-mirror is transmitting this packet to the loopback-		the loopback-mirror is transmitting this packet to the loopback-
	source. The RTP timestamp MUST use the same clock rate as that of		source. The RTP timestamp MUST use the same clock rate as that of
	the encapsulated packet. The initial value of the timestamp SHOULD		the encapsulated packet. The initial value of the timestamp SHOULD
	be random for security reasons (see Section 5.1 of RFC 3550		be random for security reasons (see Section 5.1 of RFC 3550
	[RFC3550]).		[RFC3550]).
	SSRC: set as described in RFC 3550 [RFC3550].		SSRC: set as described in RFC 3550 [RFC3550].
	CC and CSRC fields are used as described in RFC 3550 [RFC3550].		CC and CSRC fields are used as described in RFC 3550 [RFC3550].
	7.1.2RTP Payload Structure		7.1.2 RTP Payload Structure
	The outer RTP header of the encapsulating packet MUST be followed		The outer RTP header of the encapsulating packet MUST be followed
	by the payload header defined in this section. If the received RTP		by the payload header defined in this section, after any header
	packet has to be looped back in multiple encapsulating packets due		extension(s). If the received RTP packet has to be looped back in
	to fragmentation, the encapsulating RTP header in each packet MUST		multiple encapsulating packets due to fragmentation, the
	be followed by the payload header defined in this section. The		encapsulating RTP header in each packet MUST be followed by the
	header is devised so that the loopback-source can decode looped		payload header defined in this section. The header is devised so
	back packets in the presence of moderate packet loss [RFC3550].		that the loopback-source can decode looped back packets in the
			presence of moderate packet loss [RFC3550]. The RTP payload of the
			encapsulating RTP packet starts with the payload header defined in
			this section.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| receive timestamp |		| receive timestamp |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| F | R | CC |M| PT | sequence number |		| F | R | CC |M| PT | sequence number |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| transmit timestamp |		| transmit timestamp |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 15, line 33		skipping to change at page 15, line 33
	encapsulated by creating a new outer RTP header followed by 4 new		encapsulated by creating a new outer RTP header followed by 4 new
	bytes of a receive timestamp, followed by the original received RTP		bytes of a receive timestamp, followed by the original received RTP
	header and payload, except that the first two bits of the received		header and payload, except that the first two bits of the received
	RTP header are overwritten as defined here.		RTP header are overwritten as defined here.
	Receive Timestamp: 32 bits		Receive Timestamp: 32 bits
	The Receive timestamp denotes the sampling instant for when the		The Receive timestamp denotes the sampling instant for when the
	last octet of the received media packet that is being encapsulated		last octet of the received media packet that is being encapsulated
	by the loopback-mirror is received from the loopback-source. The		by the loopback-mirror is received from the loopback-source. The
	Receive timestamp MUST be based on the same clock used by the		same clock rate MUST used by the loopback-source. The initial
	loopback-source. The initial value of the timestamp SHOULD be		value of the timestamp SHOULD be random for security reasons (see
	random for security reasons (see Section 5.1 of RFC 3550		Section 5.1 of RFC 3550 [RFC3550]).
	[RFC3550]).
	Fragmentation (F): 2 bits		Fragmentation (F): 2 bits
	First Fragment (00) /Last Fragment (01) /No Fragmentation(10)/		First Fragment (00) /Last Fragment (01) /No Fragmentation(10)/
	Intermediate Fragment (11). This field identifies how much of the		Intermediate Fragment (11). This field identifies how much of the
	received packet is encapsulated in this packet by the loopback-		received packet is encapsulated in this packet by the loopback-
	mirror. If the received packet is not fragmented, this field is		mirror. If the received packet is not fragmented, this field is
	set to 10; otherwise the packet that contains the first fragments		set to 10; otherwise the packet that contains the first fragments
	sets this field to 00, the packet that contains the last fragment		sets this field to 00, the packet that contains the last fragment
	sets this field to 01, all other packets set this field to 11.		sets this field to 01, all other packets set this field to 11.
	7.1.3Usage of SDP		7.1.3 Usage of SDP
	The payload type number for the encapsulated stream can be		The payload type number for the encapsulated stream can be
	negotiated using SDP. There is no static payload type assignment		negotiated using SDP. There is no static payload type assignment
	for the encapsulating stream, so dynamic payload type numbers MUST		for the encapsulating stream, so dynamic payload type numbers MUST
	be used. The binding to the name is indicated by an rtpmap		be used. The binding to the name is indicated by an rtpmap
	attribute. The name used in this binding is "encaprtp".		attribute. The name used in this binding is "encaprtp".
	The following is an example SDP fragment for encapsulated RTP.		The following is an example SDP fragment for encapsulated RTP.
	m=audio 41352 RTP/AVP 112		m=audio 41352 RTP/AVP 112
	a=rtpmap:112 encaprtp/8000		a=rtpmap:112 encaprtp/8000
	7.2 Direct loopback RTP payload format		7.2 Direct loopback RTP payload format
	The direct loopback RTP payload format can be used in scenarios		The direct loopback RTP payload format can be used in scenarios
	where the 16 byte overhead of the encapsulated payload format is of		where the 16 byte overhead of the encapsulated payload format is of
	concern, or simply due to local policy. When using this payload		concern, or simply due to local policy. When using this payload
	format, the receiver MUST loop back each received RTP packet		format, the receiver MUST loop back each received RTP packet
	payload (not header) in a separate RTP packet.		payload (not header) in a separate RTP packet.
	Because a direct loopback format does not retain the original RTP		Because a direct loopback format does not retain the original RTP
	headers, there will be no indication of the original payload-type		headers, there will be no indication of the original payload-type
	sent to the mirror, in looped returning packets. Therefore, the		sent to the mirror, in looped-back packets. Therefore, the
	loopback source SHOULD only send one payload type per loopback RTP		loopback source SHOULD only send one payload type per loopback RTP
	session, if direct mode is used.		session, if direct mode is used.
	7.2.1Usage of RTP Header fields		7.2.1 Usage of RTP Header fields
	Payload Type (PT): The assignment of an RTP payload type for the		Payload Type (PT): The assignment of an RTP payload type for the
	encapsulating packet format is outside the scope of this document;		encapsulating packet format is outside the scope of this document;
	it is either specified by the RTP profile under which this payload		it is either specified by the RTP profile under which this payload
	format is used or more likely signaled dynamically out-of-band		format is used or more likely signaled dynamically out-of-band
	(e.g., using SDP; section 7.2.3 defines the name binding).		(e.g., using SDP; section 7.2.3 defines the name binding).
	Marker (M) bit: Set to the value in the received packet.		Marker (M) bit: Set to the value in the received packet.
	Extension (X) bit: Defined by the RTP Profile used.		Extension (X) bit: Defined by the RTP Profile used.
	Sequence Number: The RTP sequence number SHOULD be generated by the		Sequence Number: The RTP sequence number SHOULD be generated by the
	loopback-mirror in the usual manner with a constant random offset.		loopback-mirror in the usual manner with a constant random offset,
			as per [RFC3550].
	Timestamp: The RTP timestamp denotes the sampling instant for when		Timestamp: The RTP timestamp denotes the sampling instant for when
	the loopback-mirror is transmitting this packet to the		the loopback-mirror is transmitting this packet to the
	loopback-source. The RTP timestamp MUST be based on the same clock		loopback-source. The same clock rate MUST be used as that of the
	as that of the received RTP packet. The initial value of the		received RTP packet. The initial value of the timestamp SHOULD be
	timestamp SHOULD be random for security reasons (see Section 5.1 of		random for security reasons (see Section 5.1 of RFC 3550
	RFC 3550 [RFC3550]).		[RFC3550]).
	SSRC: set as described in RFC 3550 [RFC3550].		SSRC: set as described in RFC 3550 [RFC3550].
	CC and CSRC fields are used as described in RFC 3550 [RFC3550].		CC and CSRC fields are used as described in RFC 3550 [RFC3550].
	7.2.2RTP Payload Structure		7.2.2 RTP Payload Structure
	This payload format does not define any payload specific headers.		This payload format does not define any payload specific headers.
	The loopback-mirror simply copies the RTP payload data from the		The loopback-mirror simply copies the RTP payload data from the
	payload portion of the RTP packet received from the loopback-		payload portion of the RTP packet received from the loopback-
	source.		source.
	7.2.3Usage of SDP		7.2.3 Usage of SDP
	The payload type number for the payload loopback stream can be		The payload type number for the payload loopback stream can be
	negotiated using a mechanism like SDP. There is no static payload		negotiated using a mechanism like SDP. There is no static payload
	type assignment for the stream, so dynamic payload type numbers		type assignment for the stream, so dynamic payload type numbers
	MUST be used. The binding to the name is indicated by an rtpmap		MUST be used. The binding to the name is indicated by an rtpmap
	attribute. The name used in this binding is "rtploopback".		attribute. The name used in this binding is "rtploopback".
	The following is an example SDP fragment for direct loopback RTP		The following is an example SDP fragment for direct loopback RTP
	format.		format.
	m=audio 41352 RTP/AVP 112		m=audio 41352 RTP/AVP 112
	a=rtpmap:112 rtploopback/8000		a=rtpmap:112 rtploopback/8000
	8. RTCP Requirements		8. SRTP Behavior
			Secure RTP [RFC3711] MAY be used for loopback sessions. SRTP
			operates at a lower logical layer than RTP, and thus if both sides
			negotiate to use SRTP, each side uses its own key, performs
			encryption/decryption, authentication, etc. Therefore the loopback
			function on the mirror occurs after the SRTP packet has been
			decrypted and authenticated, as a normal cleartext RTP packet
			without an MKI or authentication tag; once the cleartext RTP packet
			or payload is mirrored - either at the media-layer, direct packet-
			layer, or encapsulated packet-layer - it is encrypted by the mirror
			using its own key.
			9. RTCP Requirements
	The use of the loopback attribute is intended for monitoring of		The use of the loopback attribute is intended for monitoring of
	media quality of the session. Consequently the media performance		media quality of the session. Consequently the media performance
	information should be exchanged between the offering and the		information should be exchanged between the offering and the
	answering entities. An offering or answering agent that is		answering entities. An offering or answering agent that is
	compliant to this specification SHOULD support RTCP per [RFC3550]		compliant to this specification SHOULD support RTCP per [RFC3550]
	and RTCP-XR per RFC 3611 [RFC3611]. Furthermore, if the offerer or		and RTCP-XR per RFC 3611 [RFC3611]. Furthermore, if the offerer or
	answerer choose to support RTCP-XR, they SHOULD support RTCP-XR		answerer choose to support RTCP-XR, they SHOULD support RTCP-XR
	Loss RLE report block, Duplicate RLE report block, Statistics		Loss RLE report block, Duplicate RLE report block, Statistics
	Summary report block, and VoIP Metric Reports Block per sections		Summary report block, and VoIP Metric Reports Block per sections
	4.1, 4.2, 4.6, and 4.7 of RFC 3611 [RFC3611]. The offerer and the		4.1, 4.2, 4.6, and 4.7 of RFC 3611 [RFC3611]. The offerer and the
	answerer MAY support other RTCP-XR reporting blocks as defined by		answerer MAY support other RTCP-XR reporting blocks as defined by
	RFC 3611 [RFC3611].		RFC 3611 [RFC3611].
	9. Congestion Control		10. Congestion Control
	All the participants in a loopback session SHOULD implement		All the participants in a media-level loopback session SHOULD
	congestion control mechanisms as defined by the RTP profile under		implement congestion control mechanisms as defined by the RTP
	which the loopback mechanism is implemented. For audio video		profile under which the loopback mechanism is implemented. For
	profiles, implementations SHOULD conform to the mechanism defined		audio video profiles, implementations SHOULD conform to the
	in Section 2 of RFC 3551.		mechanism defined in Section 2 of RFC 3551.
	10. Examples		For packet-level loopback types, the loopback source SHOULD
			implement congestion control. The mirror will simply reflect back
			the RTP packets it receives (either in encapsulated or direct
			modes), therefore the source needs to control the congestion of
			both forward and reverse paths by reducing its sending rate to the
			mirror. This keeps the loopback mirror implementation simpler, and
			provides more flexibility for the source performing a loopback
			test.
			11. Examples
	This section provides examples for media descriptions using SDP for		This section provides examples for media descriptions using SDP for
	different scenarios. The examples are given for SIP-based		different scenarios. The examples are given for SIP-based
	transactions and are abbreviated and do not show the complete		transactions and are abbreviated and do not show the complete
	signaling for convenience.		signaling for convenience.
	10.1 Offer for specific media loopback type		11.1 Offer for specific media loopback type
	An agent sends an SDP offer which looks like:		An agent sends an SDP offer which looks like:
	v=0		v=0
	o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com		o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com
	s=-		s=-
	c=IN IP4 host.atlanta.example.com		c=IN IP4 host.atlanta.example.com
	t=0 0		t=0 0
	m=audio 49170 RTP/AVP 0		m=audio 49170 RTP/AVP 0
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	skipping to change at page 18, line 45		skipping to change at page 19, line 20
	c=IN IP4 host.biloxi.example.com		c=IN IP4 host.biloxi.example.com
	t=0 0		t=0 0
	m=audio 49270 RTP/AVP 0		m=audio 49270 RTP/AVP 0
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	a=loopback-mirror		a=loopback-mirror
	a=rtpmap:0 pcmu/8000		a=rtpmap:0 pcmu/8000
	The answerer is accepting to mirror the media from the offerer at		The answerer is accepting to mirror the media from the offerer at
	the media level.		the media level.
	10.2 Offer for choice of media loopback type		11.2 Offer for choice of media loopback type
	An agent sends an SDP offer which looks like:		An agent sends an SDP offer which looks like:
	v=0		v=0
	o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com		o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com
	s=-		s=-
	c=IN IP4 host.atlanta.example.com		c=IN IP4 host.atlanta.example.com
	t=0 0		t=0 0
	m=audio 49170 RTP/AVP 0 112 113		m=audio 49170 RTP/AVP 0 112 113
	a=loopback:rtp-media-loopback rtp-pkt-loopback		a=loopback:rtp-media-loopback rtp-pkt-loopback
	skipping to change at page 19, line 30		skipping to change at page 20, line 4
	v=0		v=0
	o=box 1234567890 1122334455 IN IP4 host.biloxi.example.com		o=box 1234567890 1122334455 IN IP4 host.biloxi.example.com
	s=-		s=-
	c=IN IP4 host.biloxi.example.com		c=IN IP4 host.biloxi.example.com
	t=0 0		t=0 0
	m=audio 49270 RTP/AVP 0 112		m=audio 49270 RTP/AVP 0 112
	a=loopback:rtp-pkt-loopback		a=loopback:rtp-pkt-loopback
	a=loopback-mirror		a=loopback-mirror
	a=rtpmap:0 pcmu/8000		a=rtpmap:0 pcmu/8000
	a=rtpmap:112 encaprtp/8000		a=rtpmap:112 encaprtp/8000
	The answerer is accepting to mirror the media from the offerer at		The answerer is accepting to mirror the media from the offerer at
	the packet level using the encapsulated RTP payload format.		the packet level using the encapsulated RTP payload format.
	10.3 Answerer rejecting loopback media		11.3 Answerer rejecting loopback media
	An agent sends an SDP offer which looks like:		An agent sends an SDP offer which looks like:
	v=0		v=0
	o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com		o=alice 2890844526 2890842807 IN IP4 host.atlanta.example.com
	s=-		s=-
	c=IN IP4 host.atlanta.example.com		c=IN IP4 host.atlanta.example.com
	t=0 0		t=0 0
	m=audio 49170 RTP/AVP 0		m=audio 49170 RTP/AVP 0
	a=loopback:rtp-media-loopback		a=loopback:rtp-media-loopback
	skipping to change at page 20, line 24		skipping to change at page 20, line 43
	Note in this case the answerer did not indicate loopback support,		Note in this case the answerer did not indicate loopback support,
	although it could have and still used a port number of 0 to		although it could have and still used a port number of 0 to
	indicate it does not wish to accept that media session.		indicate it does not wish to accept that media session.
	Alternatively, the answering agent could have simply rejected the		Alternatively, the answering agent could have simply rejected the
	entire SDP offer through some higher-layer signaling protocol means		entire SDP offer through some higher-layer signaling protocol means
	(e.g., by rejecting the SIP INVITE request if the SDP offer was in		(e.g., by rejecting the SIP INVITE request if the SDP offer was in
	the INVITE).		the INVITE).
	11. Security Considerations		12. Security Considerations
	The security considerations of [RFC3264] and [RFC3550] apply.		The security considerations of [RFC3264] and [RFC3550] apply.
	Given that media loopback may be automated without the end user's		Given that media loopback may be automated without the end user's
	knowledge, the answerer of the media loopback should be aware of		knowledge, the answerer of the media loopback should be aware of
	denial of service attacks. It is recommended that session requests		denial of service attacks. It is RECOMMENDED that session requests
	for media loopback be authenticated and the frequency of such		for media loopback be authenticated and the frequency of such
	sessions limited by the answerer.		sessions limited by the answerer.
	If the higher-layer signaling protocol were not authenticated, a		If the higher-layer signaling protocol were not authenticated, a
	malicious attacker could create a session between two parties the		malicious attacker could create a session between two parties the
	attacker wishes to target, with each party acting as the loopback-		attacker wishes to target, with each party acting as the loopback-
	mirror to the other, of rtp-pkt-loopback type. A few RTP packets		mirror to the other, of rtp-pkt-loopback type. A few RTP packets
	sent to either party would then infinitely loop among the two, as		sent to either party would then infinitely loop among the two, as
	fast as they could process them, consuming their resources and		fast as they could process them, consuming their resources and
	network bandwidth.		network bandwidth.
	skipping to change at page 21, line 4		skipping to change at page 21, line 27
	loopback-source, and uses the mirror to reflect the attacker's		loopback-source, and uses the mirror to reflect the attacker's
	packets against a target - perhaps a target the attacker could not		packets against a target - perhaps a target the attacker could not
	reach directly, such as one behind a firewall for example. Or the		reach directly, such as one behind a firewall for example. Or the
	attacker could initiate the session as the loopback-mirror, in the		attacker could initiate the session as the loopback-mirror, in the
	hopes of making the peer generate media against another target.		hopes of making the peer generate media against another target.
	If end-user devices such as mobile phones answer loopback requests		If end-user devices such as mobile phones answer loopback requests
	without authentication and without notifying the end-user, then an		without authentication and without notifying the end-user, then an
	attacker could cause the battery to drain, and possibly deny the		attacker could cause the battery to drain, and possibly deny the
	end-user normal phone service or cause network data usage fees.		end-user normal phone service or cause network data usage fees.
	This could even occur naturally if a legitimate loopback session		This could even occur naturally if a legitimate loopback session
	does not terminate properly and the end device does not have a		does not terminate properly and the end device does not have a
	timeout mechanism for such.		timeout mechanism for such.
	For the reasons noted above, end user devices SHOULD provide a		For the reasons noted above, end user devices SHOULD provide a
	means of indicating to the human user that the device is in a		means of indicating to the human user that the device is in a
	loopback session, even if it is an authenticated session. Devices		loopback session, even if it is an authenticated session. Devices
	which answer or generate loopback sessions SHOULD either perform		that answer or generate loopback sessions SHOULD either perform
	keepalive/refresh tests of the session state through some means, or		keepalive/refresh tests of the session state through some means, or
	time out the session automatically.		time out the session automatically.
	12. Implementation Considerations		13. Implementation Considerations
	The media loopback approach described in this document is a		The media loopback approach described in this document is a
	complete solution that would work under all scenarios. However, it		complete solution that would work under all scenarios. However, it
	is believed that the solution may not be light-weight enough for		is possible that the solution may not be light-weight enough for
	the common case. In light of this concern, this section clarifies		some implementations. In light of this concern, this section
	which features of the loopback proposal MUST be implemented for all		clarifies which features of the loopback proposal MUST be
	implementations and which features MAY be deferred if the complete		implemented for all implementations and which features MAY be
	solution is not desired.		deferred if the complete solution is not desired.
	All implementations MUST at least support the rtp-pkt-loopback mode		All implementations MUST at least support the rtp-pkt-loopback mode
	for loopback-type, with direct media loopback payload encoding. In		for loopback-type, with direct media loopback payload encoding. In
	addition, for the loopback role, all implementations of an SDP		addition, for the loopback role, all implementations of an SDP
	offerer MUST at least be able to act as a loopback-source.		offerer MUST at least be able to act as a loopback-source.
	13. IANA Considerations		14. IANA Considerations
	13.1 SDP Attributes		14.1 SDP Attributes
	This document defines three new media-level SDP attributes. IANA		This document defines three new media-level SDP attributes. IANA
	has registered the following attributes:		has registered the following attributes:
	Contact name: Kaynam Hedayat		Contact name: Kaynam Hedayat
	<kaynam.hedayat@exfo.com>.		<kaynam.hedayat@exfo.com>.
	Attribute name: "loopback".		Attribute name: loopback
	Type of attribute: Media level.		Type of attribute: Media level.
	Subject to charset: No.		Subject to charset: No.
	Purpose of attribute: The 'loopback' attribute is used to		Purpose of attribute: The 'loopback' attribute is used to
	indicate the type of media loopback.		indicate the type of media loopback.
	Allowed attribute values: The parameters to 'loopback' may be		Allowed attribute values: The parameters to 'loopback' may be
	one or more of "rtp-pkt-loopback" and		one or more of "rtp-pkt-loopback" and
	"rtp-media-loopback". See section 5		"rtp-media-loopback". See section 5
	of this document for syntax.		of this document for syntax.
	Contact name: Kaynam Hedayat		Contact name: Kaynam Hedayat
	<kaynam.hedayat@exfo.com>.		<kaynam.hedayat@exfo.com>.
	Attribute name: "loopback-source".		Attribute name: loopback-source
	Type of attribute: Media level.		Type of attribute: Media level.
	Subject to charset: No.		Subject to charset: No.
	Purpose of attribute: The 'loopback-source' attribute		Purpose of attribute: The 'loopback-source' attribute
	specifies that the sender is the media		specifies that the sender is the media
	source and expects the receiver to act		source and expects the receiver to act
	as a loopback-mirror.		as a loopback-mirror.
	Allowed attribute values: None.		Allowed attribute values: None.
	Contact name: Kaynam Hedayat		Contact name: Kaynam Hedayat
	<kaynam.hedayat@exfo.com>.		<kaynam.hedayat@exfo.com>.
	Attribute name: "loopback-mirror".		Attribute name: loopback-mirror
	Type of attribute: Media level.		Type of attribute: Media level.
	Subject to charset: No.		Subject to charset: No.
	Purpose of attribute: The 'loopback-mirror' attribute		Purpose of attribute: The 'loopback-mirror' attribute
	specifies that the receiver will		specifies that the receiver will
	mirror (echo) all received media back		mirror (echo) all received media back
	to the sender of the RTP stream.		to the sender of the RTP stream.
	Allowed attribute values: None.		Allowed attribute values: None.
	13.2 MIME Types		14.2 Media Types
	The IANA has registered the following MIME types:		The IANA has registered the following media types:
	13.2.1 audio/encaprtp		14.2.1 audio/encaprtp
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type audio/encaprtp		Subject: Registration of media type audio/encaprtp
	Type name: audio		Type name: audio
	Subtype name: encaprtp		Subtype name: encaprtp
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate: RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. The typical rate is 8000; other rates
	may be specified.		may be specified. This is specified by the loop back
			source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given VoIP Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.2 video/encaprtp		14.2.2 video/encaprtp
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type video/encaprtp		Subject: Registration of media type video/encaprtp
	Type name: video		Type name: video
	Subtype name: encaprtp		Subtype name: encaprtp
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate: RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Video Over IP Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.3 text/encaprtp		14.2.3 text/encaprtp
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type text/encaprtp		Subject: Registration of media type text/encaprtp
	Type name: text		Type name: text
	Subtype name: encaprtp		Subtype name: encaprtp
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate: RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Real-Time Text Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.4 application/encaprtp		14.2.4 application/encaprtp
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type		Subject: Registration of media type
	application/encaprtp		application/encaprtp
	Type name: application		Type name: application
	Subtype name: encaprtp		Subtype name: encaprtp
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate: RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Real-Time Application Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.5 audio/rtploopback		14.2.5 audio/rtploopback
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type audio/rtploopback		Subject: Registration of media type audio/rtploopback
	Type name: audio		Type name: audio
	Subtype name: rtploopback		Subtype name: rtploopback
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate:RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. The typical rate is 8000; other rates
	may be specified.		may be specified. This is specified by the loop back
			source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given VoIP Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.6 video/rtploopback		14.2.6 video/rtploopback
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type video/rtploopback		Subject: Registration of media type video/rtploopback
	Type name: video		Type name: video
	Subtype name: rtploopback		Subtype name: rtploopback
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate:RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Video Over IP Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.7 text/rtploopback		14.2.7 text/rtploopback
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type text/rtploopback		Subject: Registration of media type text/rtploopback
	Type name: text		Type name: text
	Subtype name: rtploopback		Subtype name: rtploopback
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate:RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Real-Time Text Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	13.2.8 application/rtploopback		14.2.8 application/rtploopback
	To: ietf-types@iana.org		To: ietf-types@iana.org
	Subject: Registration of media type		Subject: Registration of media type
	application/rtploopback		application/rtploopback
	Type name: application		Type name: application
	Subtype name: rtploopback		Subtype name: rtploopback
	Required parameters:		Required parameters:
	rate:RTP timestamp clock rate, which is equal to the		rate:RTP timestamp clock rate, which is equal to the
	sampling rate. The typical rate is 8000; other rates		sampling rate. This is specified by the loop back
	may be specified.		source, and reflected by the mirror.
	Optional parameters: none		Optional parameters: none
	Encoding considerations: This media type is framed		Encoding considerations: This media type is framed.
	binary data.
	Security considerations: See Section 12 of this document.		Security considerations: See Section 12 of this document.
	Interoperability considerations: none		Interoperability considerations: none
	Published specification: This MIME type is described fully		Published specification: This document.
	within this document.
	Applications which use this media type: Applications wishing		Applications which use this media type: Applications wishing
	to monitor and ensure the quality of transport to the		to monitor and ensure the quality of transport to the
	edge of a given VoIP, Real-Time Text or Video Over IP		edge of a given Real-Time Application Service.
	Service.
	Additional information: none		Additional information: none
	Person & email address to contact for further information:		Contact: the authors of this document.
	Kaynam Hedayat
	EMail: kaynam.hedayat@exfo.com
	Intended usage: COMMON		Intended usage: LIMITED USE
	Restrictions on usage: This media type depends on RTP		Restrictions on usage: This media type depends on RTP
	framing, and hence is only defined for transfer via		framing, and hence is only defined for transfer via
	RTP. Transfer within other framing protocols is not		RTP. Transfer within other framing protocols is not
	defined at this time.		defined at this time.
	Author:		Author:
	Kaynam Hedayat.		Kaynam Hedayat.
	Change controller: IETF Audio/Video Transport working		Change controller: IETF Audio/Video Transport working
	group delegated from the IESG.		group delegated from the IESG.
	14. Acknowledgements		15. Acknowledgements
	This document's editor would like to thank the original authors of		This document's editor would like to thank the original authors of
	the document: Kaynam Hedayat, et al. The editor has made fairly		the document: Kaynam Hedayat, Nagarjuna Venna, Paul E. Jones, Arjun
	insignificant changes in the end. Also, we'd like to thank Magnus		Roychowdhury, Chelliah SivaChelvan, and Nathan Stratton. The
	Westerlund, Miguel Garcia, Flemming Andreason, Gunnar Hellstrom,		editor has made fairly insignificant changes in the end. Also,
	Emil Ivov and Dan Wing for their feedback, comments and		we'd like to thank Magnus Westerlund, Miguel Garcia, Flemming
	suggestions.		Andreasen, Gunnar Hellstrom, Emil Ivov and Dan Wing for their
			feedback, comments and suggestions.
	15. Normative References		16. Normative References
	[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer		[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer
	Model with the Session Description Protocol (SDP)",		Model with the Session Description Protocol (SDP)",
	RFC 3264, June 2002.		RFC 3264, June 2002.
	[RFC3550] Schulzrinne, H., Casner, S., Frederick, R. and V.		[RFC3550] Schulzrinne, H., Casner, S., Frederick, R. and V.
	Jacobson, "RTP: A Transport Protocol for Real-Time		Jacobson, "RTP: A Transport Protocol for Real-Time
	Applications", STD 64, RFC 3550, July 2003.		Applications", STD 64, RFC 3550, July 2003.
	[RFC3611] Almeroth, K., Caceres, R., Clark, A., Cole, R.,		[RFC3611] Almeroth, K., Caceres, R., Clark, A., Cole, R.,
	skipping to change at page 32, line 25		skipping to change at page 32, line 8
	[RFC3551] Schulzrinne, H., Casner, S., "RTP Profile for Audio		[RFC3551] Schulzrinne, H., Casner, S., "RTP Profile for Audio
	and Video Conferences with Minimial Control", STD 65,		and Video Conferences with Minimial Control", STD 65,
	RFC 3551, July 2003.		RFC 3551, July 2003.
	[RFC4566] Handley, M., Jacobson, V., Perkins, C., "SDP: Session		[RFC4566] Handley, M., Jacobson, V., Perkins, C., "SDP: Session
	Description Protocol", RFC 4566, July 2006.		Description Protocol", RFC 4566, July 2006.
	[RFC4855] Casner, S., "Media Type Registration of RTP Payload		[RFC4855] Casner, S., "Media Type Registration of RTP Payload
	Formats", RFC 4855, February 2007.		Formats", RFC 4855, February 2007.
	16. Informative References		17. Informative References
	[RFC5245] Rosenberg, J., "Interactive Connectivity		[RFC5245] Rosenberg, J., "Interactive Connectivity
	Establishment (ICE): A Protocol for Network Address		Establishment (ICE): A Protocol for Network Address
	Translator (NAT) Traversal for Offer/Answer		Translator (NAT) Traversal for Offer/Answer
	Protocols", RFC 5245, April 2010.		Protocols", RFC 5245, April 2010.
	[RFC6263] Marjou, X., Sollaud, A., "Application Mechanism for		[RFC6263] Marjou, X., Sollaud, A., "Application Mechanism for
	Keeping Alive the NAT Mappings Associated with RTP /		Keeping Alive the NAT Mappings Associated with RTP /
	RTP Control Protocol (RTCP) Flows", RFC 6263, June		RTP Control Protocol (RTCP) Flows", RFC 6263, June
	2011.		2011.
	skipping to change at page 33, line 21		skipping to change at page 33, line 4
	URI: http://www.exfo.com/		URI: http://www.exfo.com/
	Nagarjuna Venna		Nagarjuna Venna
	Saperix		Saperix
	738 Main Street, #398		738 Main Street, #398
	Waltham, MA 02451		Waltham, MA 02451
	US		US
	EMail: vnagarjuna@saperix.com		EMail: vnagarjuna@saperix.com
	URI: http://www.saperix.com/		URI: http://www.saperix.com/
	Paul E. Jones		Paul E. Jones
	Cisco Systems, Inc.		Cisco Systems, Inc.
	7025 Kit Creek Rd.		7025 Kit Creek Rd.
	Research Triangle Park, NC 27709		Research Triangle Park, NC 27709
	US		US
	EMail: paulej@packetizer.com		EMail: paulej@packetizer.com
	URI: http://www.cisco.com/		URI: http://www.cisco.com/
	Arjun Roychowdhury
	Hughes Systique Corp.
	15245 Shady Grove Rd, Ste 330
	Rockville MD 20850
	US
	EMail: arjun@hsc.com
	URI: http://www. hsc.com/
	Chelliah SivaChelvan
	Cisco Systems, Inc.
	2200 East President George Bush Turnpike
	Richardson, TX 75082
	US
	EMail: chelliah@cisco.com
	URI: http://www.cisco.com/
	Nathan Stratton		Nathan Stratton
	BlinkMind, Inc.		BlinkMind, Inc.
	2027 Briarchester Dr.		2027 Briarchester Dr.
	Katy, TX 77450		Katy, TX 77450
	EMail: nathan@robotics.net		EMail: nathan@robotics.net
	URI: http://www.robotics.net/		URI: http://www.robotics.net/
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