draft-ietf-p2psip-drr-11.alt-original		draft-ietf-p2psip-drr-12.original.txt
	P2PSIP N. Zong, Ed.		P2PSIP N. Zong
	Internet-Draft X. Jiang		Internet-Draft X. Jiang
	Intended status: Standards Track R. Even		Intended status: Standards Track R. Even
	Expires: April 24, 2014 Huawei Technologies		Expires: August 29, 2014 Huawei Technologies
	Y. Zhang		Y. Zhang
	CoolPad		CoolPad
	October 21, 2013		February 25, 2014
	An Extension to REsource LOcation And Discovery (RELOAD) Protocol to		An Extension to REsource LOcation And Discovery (RELOAD) Protocol to
	Support Direct Response Routing		Support Direct Response Routing
	draft-ietf-p2psip-drr-11		draft-ietf-p2psip-drr-12
	Abstract		Abstract
	This document proposes an optional extension to REsource LOcation And		This document proposes an optional extension to REsource LOcation And
	Discovery (RELOAD) protocol to support direct response routing mode.		Discovery (RELOAD) protocol to support direct response routing mode.
	RELOAD recommends symmetric recursive routing for routing messages.		RELOAD recommends symmetric recursive routing for routing messages.
	The new optional extension provides a shorter route for responses		The new optional extension provides a shorter route for responses
	reducing the overhead on intermediate peers and describes the		reducing the overhead on intermediate peers and describes the
	potential cases where this extension can be used.		potential cases where this extension can be used.
	skipping to change at page 1, line 39		skipping to change at page 1, line 39
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on April 24, 2014.		This Internet-Draft will expire on August 29, 2014.
	Copyright Notice		Copyright Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2014 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 21		skipping to change at page 2, line 21
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1. SRR and DRR . . . . . . . . . . . . . . . . . . . . . . . 4		3.1. SRR and DRR . . . . . . . . . . . . . . . . . . . . . . . 4
	3.1.1. Symmetric Recursive Routing (SRR) . . . . . . . . . . 4		3.1.1. Symmetric Recursive Routing (SRR) . . . . . . . . . . 4
	3.1.2. Direct Response Routing (DRR) . . . . . . . . . . . . 5		3.1.2. Direct Response Routing (DRR) . . . . . . . . . . . . 5
	3.2. Scenarios where DRR can be used . . . . . . . . . . . . . 6		3.2. Scenarios where DRR can be used . . . . . . . . . . . . . 6
	3.2.1. Managed or closed P2P systems . . . . . . . . . . . . 6		3.2.1. Managed or closed P2P systems . . . . . . . . . . . . 6
	3.2.2. Wireless scenarios . . . . . . . . . . . . . . . . . 6		3.2.2. Wireless scenarios . . . . . . . . . . . . . . . . . 6
	4. Relationship between SRR and DRR . . . . . . . . . . . . . . 6		4. Relationship between SRR and DRR . . . . . . . . . . . . . . 7
	4.1. How DRR works . . . . . . . . . . . . . . . . . . . . . . 7		4.1. How DRR works . . . . . . . . . . . . . . . . . . . . . . 7
	4.2. How SRR and DRR work together . . . . . . . . . . . . . . 7		4.2. How SRR and DRR work together . . . . . . . . . . . . . . 7
	5. DRR extensions to RELOAD . . . . . . . . . . . . . . . . . . 9		5. DRR extensions to RELOAD . . . . . . . . . . . . . . . . . . 8
	5.1. Basic requirements . . . . . . . . . . . . . . . . . . . 9		5.1. Basic requirements . . . . . . . . . . . . . . . . . . . 8
	5.2. Modification to RELOAD message structure . . . . . . . . 10		5.2. Modification to RELOAD message structure . . . . . . . . 8
	5.2.1. State-keeping flag . . . . . . . . . . . . . . . . . 10		5.2.1. State-keeping flag . . . . . . . . . . . . . . . . . 8
	5.2.2. Extensive routing mode . . . . . . . . . . . . . . . 10		5.2.2. Extensive routing mode . . . . . . . . . . . . . . . 8
	5.3. Creating a request . . . . . . . . . . . . . . . . . . . 11		5.3. Creating a request . . . . . . . . . . . . . . . . . . . 9
	5.3.1. Creating a request for DRR . . . . . . . . . . . . . 11		5.3.1. Creating a request for DRR . . . . . . . . . . . . . 9
	5.4. Request and response processing . . . . . . . . . . . . . 12		5.4. Request and response processing . . . . . . . . . . . . . 10
	5.4.1. Destination peer: receiving a request and sending a		5.4.1. Destination peer: receiving a request and sending a
	response . . . . . . . . . . . . . . . . . . . . . . 12		response . . . . . . . . . . . . . . . . . . . . . . 10
	5.4.2. Sending peer: receiving a response . . . . . . . . . 12		5.4.2. Sending peer: receiving a response . . . . . . . . . 10
	6. Overlay configuration extension . . . . . . . . . . . . . . . 12		6. Overlay configuration extension . . . . . . . . . . . . . . . 11
	7. Security considerations . . . . . . . . . . . . . . . . . . . 13		7. Security considerations . . . . . . . . . . . . . . . . . . . 11
	8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 13		8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 11
	8.1. A new RELOAD forwarding option . . . . . . . . . . . . . 13		8.1. A new RELOAD forwarding option . . . . . . . . . . . . . 11
	8.2. A new IETF XML registry . . . . . . . . . . . . . . . . . 13		8.2. A new IETF XML registry . . . . . . . . . . . . . . . . . 11
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13		9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
	10.1. Normative references . . . . . . . . . . . . . . . . . . 14		10.1. Normative references . . . . . . . . . . . . . . . . . . 12
	10.2. Informative references . . . . . . . . . . . . . . . . . 14		10.2. Informative references . . . . . . . . . . . . . . . . . 12
	Appendix A. Optional methods to investigate peer connectivity . 14		Appendix A. Optional methods to investigate peer connectivity . 13
	A.1. Getting addresses to be used as candidates for DRR . . . 15		A.1. Getting addresses to be used as candidates for DRR . . . 13
	A.2. Public reachability test . . . . . . . . . . . . . . . . 16		A.2. Public reachability test . . . . . . . . . . . . . . . . 14
	Appendix B. Comparison on cost of SRR and DRR . . . . . . . . . 15		Appendix B. Comparison on cost of SRR and DRR . . . . . . . . . 15
	B.1. Closed or managed networks . . . . . . . . . . . . . . . 15		B.1. Closed or managed networks . . . . . . . . . . . . . . . 15
	B.2. Open networks . . . . . . . . . . . . . . . . . . . . . . 16		B.2. Open networks . . . . . . . . . . . . . . . . . . . . . . 16
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
	1. Introduction		1. Introduction
	REsource LOcation And Discovery (RELOAD) protocol [I-D.ietf-p2psip-		REsource LOcation And Discovery (RELOAD) protocol [RFC6940]
	base] recommends symmetric recursive routing (SRR) for routing		recommends symmetric recursive routing (SRR) for routing messages and
	messages and describes the extensions that would be required to		describes the extensions that would be required to support additional
	support additional routing algorithms. Other than SRR, two other		routing algorithms. Other than SRR, two other routing options:
	routing options: direct response routing (DRR) and relay peer routing		direct response routing (DRR) and relay peer routing (RPR) are also
	(RPR) are also discussed in Appendix A of [I-D.ietf-p2psip-base]. As		discussed in Appendix A of [RFC6940]. As we show in Section 3, DRR
	we show in section 3, DRR is advantageous over SRR in some scenarios		is advantageous over SRR in some scenarios by reducing load (CPU and
	by reducing load (CPU and link bandwidth) on intermediate peers. For		link bandwidth) on intermediate peers. For example, in a closed
	example, in a closed network where every peer is in the same address		network where every peer is in the same address realm, DRR performs
	realm, DRR performs better than SRR. In other scenarios, using a		better than SRR. In other scenarios, using a combination of DRR and
	combination of DRR and SRR together is more likely to bring benefits		SRR together is more likely to bring benefits than if SRR is used
	than if SRR is used alone.		alone.
	Note that in this document, we focus on DRR routing mode and its		Note that in this document, we focus on DRR routing mode and its
	extensions to RELOAD to produce a standalone solution. Please refer		extensions to RELOAD to produce a standalone solution. Please refer
	to RPR draft [I-D.ietf-p2psip-rpr] for RPR routing mode.		to RPR draft [I-D.ietf-p2psip-rpr] for RPR routing mode.
	We first discuss the problem statement in Section 3, then how to		We first discuss the problem statement in Section 3, then how to
	combine DRR and SRR is presented in Section 4. In Section 5, we give		combine DRR and SRR is presented in Section 4. An extension to
	comparison on the cost of SRR and DRR in both managed and open		RELOAD to support DRR is defined in Section 5. Some optional methods
	networks. An extension to RELOAD to support DRR is proposed in		to check peer connectivity are introduced in Appendix A. In
	Section 6. Some optional methods to check peer connectivity are		Appendix B, we give comparison on the cost of SRR and DRR in both
	introduced in Appendix A.		managed and open networks.
	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 this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	We use the terminology and definitions from the RELOAD base draft		We use the terminology and definitions from the RELOAD base draft
	[I-D.ietf-p2psip-base] extensively in this document. We also use		[RFC6940] extensively in this document. We also use terms defined in
	terms defined in NAT behavior discovery [RFC5780]. Other terms used		NAT behavior discovery [RFC5780]. Other terms used in this document
	in this document are defined inline when used and are also defined		are defined inline when used and are also defined below for
	below for reference.		reference.
	Publicly Reachable: A peer is publicly reachable if it can receive		Publicly Reachable: A peer is publicly reachable if it can receive
	unsolicited messages from any other peer in the same overlay.		unsolicited messages from any other peer in the same overlay.
	Note: "publicly" does not mean that the peers must be on the		Note: "publicly" does not mean that the peers must be on the
	public Internet, because the RELOAD protocol may be used in a		public Internet, because the RELOAD protocol may be used in a
	closed network.		closed network.
	Direct Response Routing (DRR): refers to a routing mode in which		Direct Response Routing (DRR): refers to a routing mode in which
	responses to P2PSIP requests are returned to the sending peer		responses to P2PSIP requests are returned to the sending peer
	directly from the destination peer based on the sending peer's own		directly from the destination peer based on the sending peer's own
	local transport address(es). For simplicity, the abbreviation DRR		local transport address(es). For simplicity, the abbreviation DRR
	is used instead in the rest of the document.		is used instead in the rest of the document.
	Symmetric Recursive Routing (SRR): refers to a routing mode in		Symmetric Recursive Routing (SRR): refers to a routing mode in
	which responses follow the reverse path of the request to get to		which responses follow the reverse path of the request to get to
	the sending peer. For simplicity, the abbreviation SRR is used		the sending peer. For simplicity, the abbreviation SRR is used
	instead in the rest of the document.		instead in the rest of the document.
			Relay Peer Routing (RPR): refers to a routing mode in which
			responses to P2PSIP requests are sent by the destination peer to a
			relay peer transport address who will forward the responses
			towards the sending peer. For simplicity, the abbreviation RPR is
			used instead in the rest of the document.
	3. Overview		3. Overview
	RELOAD is expected to work under a great number of application		RELOAD is expected to work under a great number of application
	scenarios. The situations where RELOAD is to be deployed differ		scenarios. The situations where RELOAD is to be deployed differ
	greatly. For instance, some deployments are global, such as a Skype-		greatly. For instance, some deployments are global, such as a Skype-
	like system intended to provide public service, while others run in		like system intended to provide public service, while others run in
	closed networks of small scale. SRR works in any situation, but DRR		closed networks of small scale. SRR works in any situation, but DRR
	may work better in some specific scenarios.		may work better in some specific scenarios.
	3.1. SRR and DRR		3.1. SRR and DRR
	skipping to change at page 5, line 44		skipping to change at page 5, line 46
	In DRR, peer X receives the request sent by peer A through		In DRR, peer X receives the request sent by peer A through
	intermediate peer B, C and D, as in SRR. However, peer X sends the		intermediate peer B, C and D, as in SRR. However, peer X sends the
	response back directly to peer A based on peer A's local transport		response back directly to peer A based on peer A's local transport
	address. In this case, the response is not routed through		address. In this case, the response is not routed through
	intermediate peers. Figure 2 illustrates DRR. Using a shorter route		intermediate peers. Figure 2 illustrates DRR. Using a shorter route
	means less overhead on intermediate peers, especially in the case of		means less overhead on intermediate peers, especially in the case of
	wireless networks where the CPU and uplink bandwidth is limited. For		wireless networks where the CPU and uplink bandwidth is limited. For
	example, in the absence of NATs, or if the NAT implements endpoint-		example, in the absence of NATs, or if the NAT implements endpoint-
	independent filtering, this is the optimal routing technique. Note		independent filtering, this is the optimal routing technique. Note
	that establishing a secure connection requires multiple round trips.		that establishing a secure connection requires multiple round trips.
	Please refer to Section 5 for cost comparison between SRR and DRR.		Please refer to Appendix B for cost comparison between SRR and DRR.
	A B C D X		A B C D X
	| Request | | | |		| Request | | | |
	|----------->| | | |		|----------->| | | |
	| | Request | | |		| | Request | | |
	| |----------->| | |		| |----------->| | |
	| | | Request | |		| | | Request | |
	| | |----------->| |		| | |----------->| |
	| | | | Request |		| | | | Request |
	| | | |----------->|		| | | |----------->|
	skipping to change at page 7, line 19		skipping to change at page 7, line 24
	send the response. Responses are sent directly to the requesting		send the response. Responses are sent directly to the requesting
	peer.		peer.
	4.2. How SRR and DRR work together		4.2. How SRR and DRR work together
	DRR is not intended to replace SRR. It is better to use these two		DRR is not intended to replace SRR. It is better to use these two
	modes together to adapt to each peer's specific situation. In this		modes together to adapt to each peer's specific situation. In this
	section, we give some informative suggestions on how to transition		section, we give some informative suggestions on how to transition
	between the routing modes in RELOAD.		between the routing modes in RELOAD.
	According to base draft [I-D.ietf-p2psip-base], SRR MUST be		According to base draft [RFC6940], SRR MUST be supported. An overlay
	supported. An overlay MAY be configured to use alternative routing		MAY be configured to use alternative routing algorithms, and
	algorithms, and alternative routing algorithms MAY be selected on a		alternative routing algorithms MAY be selected on a per-message
	per-message basis. I.e., a node in an overlay which supports SRR and		basis. I.e., a node in an overlay which supports SRR and some other
	some other routing algorithm, for example DRR, might use SRR some of		routing algorithm, for example DRR, might use SRR some of the time
	the time and DRR some of the time. A node joining the overlay should		and DRR some of the time. A node joining the overlay should get from
	get from the configuration file the preferred routing mode. If an		the configuration file the preferred routing mode. If an overlay
	overlay runs within a private network and all peers in the system can		runs within a private network and all peers in the system can reach
	reach each other directly, peers MAY send most of the transactions		each other directly, peers MAY send most of the transactions with
	with DRR. On the contrary, using DRR SHOULD be discouraged in the		DRR. On the contrary, using DRR SHOULD not be used in the open
	open Internet or if the administrator does not feel he have enough		Internet or if the administrator does not feel he have enough
	information about the overlay network topology. A new overlay		information about the overlay network topology. A new overlay
	configuration element specifying the usage of DRR is defined in		configuration element specifying the usage of DRR is defined in
	Section 7.		Section 6.
	Alternatively, a peer can collect statistical data on the success of		Alternatively, a peer can collect statistical data on the success of
	the different routing modes based on previous transactions and keep a		the different routing modes based on previous transactions and keep a
	list of non-reachable addresses. Based on this data, the peer will		list of non-reachable addresses. Based on this data, the peer will
	have a clearer view about the success rate of different routing		have a clearer view about the success rate of different routing
	modes. Other than the success rate, the peer can also get data of		modes. Other than the success rate, the peer can also get data of
	finer granularity, for example, the number of retransmission the peer		finer granularity, for example, the number of retransmission the peer
	needs to achieve a desirable success rate.		needs to achieve a desirable success rate.
	A typical strategy for the peer is as follows. A peer chooses to		A typical strategy for the peer is as follows. A peer chooses to
	start with DRR based on the configuration. Based on the success rate		start with DRR based on the configuration. Based on the success rate
	seen from the lost message statistics or responses that used DRR, the		seen from the lost message statistics or responses that used DRR, the
	peer can either continue to offer DRR first or switch to SRR. Note		peer can either continue to offer DRR first or switch to SRR. Note
	that a peer should use the DRR success statistic to decide if to		that a peer should use the DRR success statistic to decide if to
	continue using DRR or fall back to SRR. It is not recommended to		continue using DRR or fall back to SRR. It is not recommended to
	make such decision per specific connection but this is an application		make such decision per specific connection but this is an application
	decision.		decision.
	3) In the cases when N < 256, DRR uses more messages than SRR (but
	still uses fewer hops than SRR). So the consideration on whether
	using DRR or SRR depends on other factors like using less resources
	(bandwidth and processing) from the intermediate peers. Section 4
	provides use cases where DRR has better chance to work or where the
	intermediary resources considerations are important.
	5. DRR extensions to RELOAD		5. DRR extensions to RELOAD
	Adding support for DRR requires extensions to the current RELOAD		Adding support for DRR requires extensions to the current RELOAD
	protocol. In this section, we define the extensions required to the		protocol. In this section, we define the extensions required to the
	protocol, including extensions to message structure and to message		protocol, including extensions to message structure and to message
	processing.		processing.
	5.1. Basic requirements		5.1. Basic requirements
	All peers MUST be able to process requests for routing in SRR, and		All peers MUST be able to process requests for routing in SRR, and
	skipping to change at page 10, line 20		skipping to change at page 8, line 35
	inform intermediate peers if they are allowed to not maintain state		inform intermediate peers if they are allowed to not maintain state
	for a transaction.		for a transaction.
	5.2.1. State-keeping flag		5.2.1. State-keeping flag
	RELOAD allows intermediate peers to maintain state in order to		RELOAD allows intermediate peers to maintain state in order to
	implement SRR, for example for implementing hop-by-hop		implement SRR, for example for implementing hop-by-hop
	retransmission. If DRR is used, the response will not follow the		retransmission. If DRR is used, the response will not follow the
	reverse path, and the state in the intermediate peers will not be		reverse path, and the state in the intermediate peers will not be
	cleared until such state expires. In order to address this issue, we		cleared until such state expires. In order to address this issue, we
	propose a new flag, state-keeping flag, in the message header to		propose a new flag, state-keeping flag, in the ForwardingOption
	indicate whether the state keeping is required in the intermediate		structure to indicate whether the state keeping is required in the
	peers.		intermediate peers.
	flag : 0x08 IGNORE-STATE-KEEPING		flag : 0x08 IGNORE-STATE-KEEPING
	If IGNORE-STATE-KEEPING is set, any peer receiving this message and		If IGNORE-STATE-KEEPING is set, any peer receiving this message and
	which is not the destination of the message SHOULD forward the		which is not the destination of the message SHOULD forward the
	message with the full via_list and SHOULD NOT maintain any internal		message with the full via_list and SHOULD NOT maintain any internal
	state.		state.
	5.2.2. Extensive routing mode		5.2.2. Extensive routing mode
	This draft introduces a new forwarding option for an extensive		This draft introduces a new forwarding option for an extensive
	routing mode. This option conforms to the description in section		routing mode. This option conforms to the description in
	6.3.2.3 of [I-D.ietf-p2psip-base].		Section 6.3.2.3 of [RFC6940].
	We first define a new type to define the new option,		We first define a new type to define the new option,
	extensive_routing_mode:		extensive_routing_mode:
	The option value is illustrated as below, defining the		The option value is illustrated as below, defining the
	ExtensiveRoutingModeOption structure:		ExtensiveRoutingModeOption structure:
	enum {(0),DRR(1),(255)} RouteMode;		enum {(0),DRR(1),(255)} RouteMode;
	struct {		struct {
	RouteMode routemode;		RouteMode routemode;
	skipping to change at page 11, line 4		skipping to change at page 9, line 18
	The option value is illustrated as below, defining the		The option value is illustrated as below, defining the
	ExtensiveRoutingModeOption structure:		ExtensiveRoutingModeOption structure:
	enum {(0),DRR(1),(255)} RouteMode;		enum {(0),DRR(1),(255)} RouteMode;
	struct {		struct {
	RouteMode routemode;		RouteMode routemode;
	OverlayLinkType transport;		OverlayLinkType transport;
	IpAddressPort ipaddressport;		IpAddressPort ipaddressport;
	Destination destinations<1..2^8-1>;		Destination destinations<1..2^8-1>;
	} ExtensiveRoutingModeOption;		} ExtensiveRoutingModeOption;
	The above structure reuses OverlayLinkType, Destination and		The above structure reuses OverlayLinkType, Destination and
	IpAddressPort structure defined in section 6.5.1.1, 6.3.2.2 and		IpAddressPort structure defined in Section 6.5.1.1, 6.3.2.2 and
	6.3.1.1 of [I-D.ietf-p2psip-base].		6.3.1.1 of [RFC6940].
	RouteMode: refers to which type of routing mode is indicated to the		RouteMode: refers to which type of routing mode is indicated to the
	destination peer.		destination peer.
	OverlayLinkType: refers to the transport type which is used to		OverlayLinkType: refers to the transport type which is used to
	deliver responses from the destination peer to the sending peer.		deliver responses from the destination peer to the sending peer.
	IpAddressPort: refers to the transport address that the destination		IpAddressPort: refers to the transport address that the destination
	peer use to send the response to. This will be a sending peer		peer use to send the response to. This will be a sending peer
	address for DRR.		address for DRR.
	skipping to change at page 12, line 9		skipping to change at page 10, line 18
	2.3) ipaddressport set to the peer's associated transport address.		2.3) ipaddressport set to the peer's associated transport address.
	2.4) The destination structure MUST contain one value, defined as		2.4) The destination structure MUST contain one value, defined as
	type node and set with the sending peer's own values.		type node and set with the sending peer's own values.
	5.4. Request and response processing		5.4. Request and response processing
	This section gives normative text for message processing after DRR is		This section gives normative text for message processing after DRR is
	introduced. Here, we only describe the additional procedures for		introduced. Here, we only describe the additional procedures for
	supporting DRR. Please refer to [I-D.ietf-p2psip-base] for RELOAD		supporting DRR. Please refer to [RFC6940] for RELOAD base
	base procedures.		procedures.
	5.4.1. Destination peer: receiving a request and sending a response		5.4.1. Destination peer: receiving a request and sending a response
	When the destination peer receives a request, it will check the		When the destination peer receives a request, it will check the
	options in the forwarding header. If the destination peer can not		options in the forwarding header. If the destination peer can not
	understand extensive_routing_mode option in the request, it MUST		understand extensive_routing_mode option in the request, it MUST
	attempt to use SRR to return an "Error_Unknown_Extension" response		attempt to use SRR to return an "Error_Unknown_Extension" response
	(defined in Section 6.3.3.1 and Section 14.9 of [I-D.ietf-p2psip-		(defined in Section 6.3.3.1 and Section 14.9 of [RFC6940]) to the
	base]) to the sending peer.		sending peer.
	If the routing mode is DRR, the peer MUST construct the Destination		If the routing mode is DRR, the destination peer MUST construct the
	list for the response with only one entry, using the sending peer's		Destination list for the response with only one entry, using the
	Node-ID from the option in the request as the value.		requesting peer's Node-ID from the via list in the request as the
			value.
	In the event that the routing mode is set to DRR and there is not		In the event that the routing mode is set to DRR and there is not
	exactly one destination, the destination peer MUST try to return an		exactly one destination, the destination peer MUST try to return an
	"Error_Unknown_Extension" response (defined in Section 6.3.3.1 and		"Error_Unknown_Extension" response (defined in Section 6.3.3.1 and
	Section 14.9 of [I-D.ietf-p2psip-base]) to the sending peer using		Section 14.9 of [RFC6940]) to the sending peer using SRR.
	SRR.
	After the peer constructs the destination list for the response, it		After the peer constructs the destination list for the response, it
	sends the response to the transport address which is indicated in the		sends the response to the transport address which is indicated in the
	ipaddressport field in the option using the specific transport mode		ipaddressport field in the option using the specific transport mode
	in the Forwardingoption. If the destination peer receives a		in the Forwardingoption. If the destination peer receives a
	retransmit with SRR preference on the message it is trying to respond		retransmit with SRR preference on the message it is trying to respond
	to now, the responding peer SHOULD abort the DRR response and use		to now, the responding peer SHOULD abort the DRR response and use
	SRR.		SRR.
	5.4.2. Sending peer: receiving a response		5.4.2. Sending peer: receiving a response
	Upon receiving a response, the peer follows the rules in [I-D.ietf-		Upon receiving a response, the peer follows the rules in [RFC6940].
	p2psip-base]. The peer SHOULD note if DRR worked in order to decide		The peer SHOULD note if DRR worked in order to decide if to offer DRR
	if to offer DRR again. If the peer does not receive a response until		again. If the peer does not receive a response until the timeout it
	the timeout it SHOULD resend the request using SRR.		SHOULD resend the request using SRR.
	6. Overlay configuration extension		6. Overlay configuration extension
	This document extends the RELOAD overlay configuration (see		This document extends the RELOAD overlay configuration (see
	Section 11.1 of [I-D.ietf-p2psip-base]) by adding one new element,		Section 11.1 of [RFC6940]) by adding one new element, "route-mode",
	"route-mode", inside each "configuration" element.		inside each "configuration" element.
	The Compact Relax NG Grammar for this element is:		The Compact Relax NG Grammar for this element is:
	namespace route-mode = "urn:ietf:params:xml:ns:p2p:route-mode"		namespace route-mode = "urn:ietf:params:xml:ns:p2p:route-mode"
	parameter &= element route-mode:mode { xsd:string }?		parameter &= element route-mode:mode { xsd:string }?
	This namespace is added into the <mandatory-extension> element in the		This namespace is added into the <mandatory-extension> element in the
	overlay configuration file. The defined routing modes include DRR		overlay configuration file. The defined routing modes include DRR
	and RPR.		and RPR.
	Mode can be DRR or RPR and if specified in the configuration should		Mode can be DRR or RPR and if specified in the configuration should
	be the preferred routing mode used by the application.		be the preferred routing mode used by the application.
	7. Security considerations		7. Security considerations
	The normative security recommendations of Section 13 of base draft		The normative security recommendations of Section 13 of base draft
	[I-D.ietf-p2psip-base] are applicable to this document. As a routing		[RFC6940] are applicable to this document. As a routing alternative,
	alternative, the security part of DRR conforms to Section 13.6 of the		the security part of DRR conforms to Section 13.6 of the base draft
	base draft which describes routing security. For example, the DRR		which describes routing security. For example, the DRR routing
	routing option provides the information about the route back to the		option provides the information about the route back to the source.
	source. According to Section 13.6 of the base draft the enter DRR		According to Section 13.6 of the base draft the enter DRR routing
	routing message MUST be digitally signed and sent over by protected		message MUST be digitally signed and sent over by protected channel
	channel to protect the DRR routing information.		to protect the DRR routing information.
	8. IANA considerations		8. IANA considerations
	8.1. A new RELOAD forwarding option		8.1. A new RELOAD forwarding option
	A new RELOAD Forwarding Option type is added to the Forwarding Option		A new RELOAD Forwarding Option type to be added to the RELOAD
	Registry defined in [I-D.ietf-p2psip-base].		Forwarding Option Registry defined in [RFC6940].
	Type: 0x02 - extensive_routing_mode		Type: 0x02 - extensive_routing_mode
	8.2. A new IETF XML registry		8.2. A new IETF XML registry
	This section requests IANA to register the following URN in the "XML		This section requests IANA to register the following URN in the "XML
	Namespaces" class of the "IETF XML Registry" in accordance with		Namespaces" class of the "IETF XML Registry" in accordance with
	[RFC3688].		[RFC3688].
	URI: urn:ietf:params:xml:ns:p2p:route-mode		URI: urn:ietf:params:xml:ns:p2p:route-mode
	skipping to change at page 14, line 15		skipping to change at page 12, line 26
	Lakshminath, Bruce Lowekamp, Stephane Bryant, Marc Petit-Huguenin and		Lakshminath, Bruce Lowekamp, Stephane Bryant, Marc Petit-Huguenin and
	Carlos Jesus Bernardos Cano for their constructive comments.		Carlos Jesus Bernardos Cano for their constructive comments.
	10. References		10. References
	10.1. Normative references		10.1. Normative references
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC2119, March 1997.		Requirement Levels", BCP 14, RFC2119, March 1997.
	[I-D.ietf-p2psip-base] Jennings, C., Lowekamp, B., Rescorla, E.,		[RFC6940] Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and H.
	Baset, S., and H. Schulzrinne, "REsource LOcation And Discovery		Schulzrinne, "REsource LOcation And Discovery (RELOAD) Base
	(RELOAD) Base Protocol", draft-ietf-p2psip-base-26 (work in		Protocol", RFC6940, January 2014.
	progress), February 2013.
	[RFC3688] Mealling, M., "The IETF XML Registry ", BCP 81, RFC3688,		[RFC3688] Mealling, M., "The IETF XML Registry ", BCP 81, RFC3688,
	January 2004.		January 2004.
	10.2. Informative references		10.2. Informative references
	[DTLS] Modadugu, N., Rescorla, E., "The Design and Implementation of		[DTLS] Modadugu, N., Rescorla, E., "The Design and Implementation of
	Datagram TLS", 11th Network and Distributed System Security Symposium		Datagram TLS", 11th Network and Distributed System Security Symposium
	(NDSS), 2004.		(NDSS), 2004.
	[RFC5780] MacDonald, D. and B. Lowekamp, "NAT Behavior Discovery		[RFC5780] MacDonald, D. and B. Lowekamp, "NAT Behavior Discovery
	Using STUN", RFC5780, May 2010.		Using STUN", RFC5780, May 2010.
	[I-D.ietf-p2psip-rpr] Zong, N., Jiang, X., Even, R. and Zhang, Y.,		[I-D.ietf-p2psip-rpr] Zong, N., Jiang, X., Even, R. and Zhang, Y.,
	"An extension to RELOAD to support Relay Peer Routing", draft-ietf-		"An extension to RELOAD to support Relay Peer Routing", draft-ietf-
	p2psip-rpr-11 (work in progress), October 2013.		p2psip-rpr-12 (work in progress), February 2014.
	[IGD2] UPnP Forum, "WANIPConnection:2 Service (http://upnp.org/specs/		[IGD2] UPnP Forum, "WANIPConnection:2 Service (http://upnp.org/specs/
	gw/UPnP-gw-WANIPConnection-v2-Service.pdf)", September 2010.		gw/UPnP-gw-WANIPConnection-v2-Service.pdf)", September 2010.
	[RFC6886] Cheshire, S., Krochmal M., and K. Sekar, "NAT Port Mapping		[RFC6886] Cheshire, S., Krochmal M., and K. Sekar, "NAT Port Mapping
	Protocol (NAT-PMP)", RFC6886, April 2013.		Protocol (NAT-PMP)", RFC6886, April 2013.
	[RFC3424] Daigle, L., "IAB Considerations for UNilateral Self-Address		[RFC3424] Daigle, L., "IAB Considerations for UNilateral Self-Address
	Fixing (UNSAF) Across Network Address Translation", RFC3424, November		Fixing (UNSAF) Across Network Address Translation", RFC3424, November
	2002.		2002.
	12. References
	Appendix A. Optional methods to investigate peer connectivity		Appendix A. Optional methods to investigate peer connectivity
	This section is for informational purposes only for providing some		This section is for informational purposes only for providing some
	mechanisms that can be used when the configuration information does		mechanisms that can be used when the configuration information does
	not specify if DRR can be used. It summarizes some methods which can		not specify if DRR can be used. It summarizes some methods which can
	be used for a peer to determine its own network location compared		be used for a peer to determine its own network location compared
	with NAT. These methods may help a peer to decide which routing mode		with NAT. These methods may help a peer to decide which routing mode
	it may wish to try. Note that there is no foolproof way to determine		it may wish to try. Note that there is no foolproof way to determine
	if a peer is publically reachable, other than via out-of-band		if a peer is publically reachable, other than via out-of-band
	mechanisms. This document addresses the UNSAF [RFC3424] concerns by		mechanisms. This document addresses the UNSAF [RFC3424] concerns by
	specifying a fallback plan to SRR [p2psip-base-draft]. SRR is not an		specifying a fallback plan to SRR [RFC6940]. SRR is not an UNSAF
	UNSAF mechanism. The document does not define any new UNSAF		mechanism. The document does not define any new UNSAF mechanisms.
	mechanisms.
	For DRR to function correctly, a peer may attempt to determine		For DRR to function correctly, a peer may attempt to determine
	whether it is publicly reachable. If it is not, the peers should		whether it is publicly reachable. If it is not, the peers should
	fall back to SRR. If the peer believes it is publically reachable,		fall back to SRR. If the peer believes it is publically reachable,
	DRR may be attempted. NATs and firewalls are two major contributors		DRR may be attempted. NATs and firewalls are two major contributors
	preventing DRR from functioning properly. There are a number of		preventing DRR from functioning properly. There are a number of
	techniques by which a peer can get its reflexive address on the		techniques by which a peer can get its reflexive address on the
	public side of the NAT. After obtaining the reflexive address, a		public side of the NAT. After obtaining the reflexive address, a
	peer can perform further tests to learn whether the reflexive address		peer can perform further tests to learn whether the reflexive address
	is publicly reachable. If the address appears to be publicly		is publicly reachable. If the address appears to be publicly
	skipping to change at page 17, line 21		skipping to change at page 15, line 29
	connection with him. Each intermediate peer receiving the request		connection with him. Each intermediate peer receiving the request
	first checks whether it has a direct connections with the sending		first checks whether it has a direct connections with the sending
	peer. If there is a direct connection, the request is routed to the		peer. If there is a direct connection, the request is routed to the
	next peer. If there is no direct connection, the intermediate peer		next peer. If there is no direct connection, the intermediate peer
	terminates the request and sends the response back directly to the		terminates the request and sends the response back directly to the
	sending peer with the transport address under test.		sending peer with the transport address under test.
	After performing the test, if the peer determines that it may be		After performing the test, if the peer determines that it may be
	publicly reachable, it can try DRR in subsequent transactions.		publicly reachable, it can try DRR in subsequent transactions.
	5. Comparison on cost of SRR and DRR		Appendix B. Comparison on cost of SRR and DRR
	The major advantages in using DRR are in going through less		The major advantages in using DRR are in going through less
	intermediate peers on the response. By doing that it reduces the		intermediate peers on the response. By doing that it reduces the
	load on those peers' resources like processing and communication		load on those peers' resources like processing and communication
	bandwidth.		bandwidth.
	5.1. Closed or managed networks		B.1. Closed or managed networks
	As described in Section 3, many P2P systems run in a closed or		As described in Section 3, many P2P systems run in a closed or
	managed environment (e.g., carrier networks) so that network		managed environment (e.g., carrier networks) so that network
	administrators would know that they could safely use DRR.		administrators would know that they could safely use DRR.
	SRR brings out more routing hops than DRR. Assuming that there are N		SRR brings out more routing hops than DRR. Assuming that there are N
	peers in the P2P system and Chord is applied for routing, the number		peers in the P2P system and Chord is applied for routing, the number
	of hops for a response in SRR and DRR are listed in the following		of hops for a response in SRR and DRR are listed in the following
	table. Establishing a secure connection between the sending peer and		table. Establishing a secure connection between the sending peer and
	the responding peer with (D)TLS requires multiple messages. Note		the responding peer with (D)TLS requires multiple messages. Note
	skipping to change at page 17, line 74		skipping to change at page 16, line 33
	2) In the cases when N > 256 (2^8), DRR also uses fewer messages than		2) In the cases when N > 256 (2^8), DRR also uses fewer messages than
	SRR.		SRR.
	3) In the cases when N < 256, DRR uses more messages than SRR (but		3) In the cases when N < 256, DRR uses more messages than SRR (but
	still uses fewer hops than SRR). So the consideration on whether		still uses fewer hops than SRR). So the consideration on whether
	using DRR or SRR depends on other factors like using less resources		using DRR or SRR depends on other factors like using less resources
	(bandwidth and processing) from the intermediate peers. Section 4		(bandwidth and processing) from the intermediate peers. Section 4
	provides use cases where DRR has better chance to work or where the		provides use cases where DRR has better chance to work or where the
	intermediary resources considerations are important.		intermediary resources considerations are important.
	5.2. Open networks		B.2. Open networks
	In open networks (e.g., Internet) where DRR is not guaranteed to		In open networks (e.g., Internet) where DRR is not guaranteed to
	work, DRR can fall back to SRR if it fails after trial, as described		work, DRR can fall back to SRR if it fails after trial, as described
	in Section 4. Based on the same settings in Section 5.1, the number		in Section 4. Based on the same settings in Section B.1, the number
	of hops, number of messages for a response in SRR and DRR are listed		of hops, number of messages for a response in SRR and DRR are listed
	in the following table.		in the following table.
	Mode | Success | No. of Hops | No. of Msgs		Mode | Success | No. of Hops | No. of Msgs
	-----------------------------------------------------------		-----------------------------------------------------------
	SRR | Yes | log(N) | log(N)		SRR | Yes | log(N) | log(N)
	DRR | Yes | 1 | 1		DRR | Yes | 1 | 1
	| Fail&Fall back to SRR | 1+log(N)| 1+log(N)		| Fail&Fall back to SRR | 1+log(N)| 1+log(N)
	DRR(DTLS) | Yes | 1 | 7+1		DRR(DTLS) | Yes | 1 | 7+1
	| Fail&Fall back to SRR | 1+log(N)| 8+log(N)		| Fail&Fall back to SRR | 1+log(N)| 8+log(N)
	skipping to change at page 17, line 105		skipping to change at page 17, line 18
	number of hops in DRR and SRR is P*1+(N-P)*(1+logN), N*logN,		number of hops in DRR and SRR is P*1+(N-P)*(1+logN), N*logN,
	respectively. The condition for fewer hops in DRR is		respectively. The condition for fewer hops in DRR is
	P*1+(N-P)*(1+logN) < N*logN, which is P/N > 1/logN. This means that		P*1+(N-P)*(1+logN) < N*logN, which is P/N > 1/logN. This means that
	when the number of peers N grows, the required ratio of publicly		when the number of peers N grows, the required ratio of publicly
	reachable peers P/N for fewer hops in DRR decreases. Therefore, the		reachable peers P/N for fewer hops in DRR decreases. Therefore, the
	chance of trying DRR with fewer hops than SRR becomes better as the		chance of trying DRR with fewer hops than SRR becomes better as the
	scale of the network increases.		scale of the network increases.
	Authors' Addresses		Authors' Addresses
	Ning Zong (editor)		Ning Zong
	Huawei Technologies		Huawei Technologies
	Email: zongning@huawei.com		Email: zongning@huawei.com
	Xingfeng Jiang		Xingfeng Jiang
	Huawei Technologies		Huawei Technologies
	Email: jiang.x.f@huawei.com		Email: jiang.x.f@huawei.com
	Roni Even		Roni Even
End of changes. 38 change blocks.
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