rfc9507.original		rfc9507.txt
	ICNRG S. Mastorakis		Internet Research Task Force (IRTF) S. Mastorakis
	Internet-Draft University of Notre Dame		Request for Comments: 9507 University of Notre Dame
	Intended status: Experimental D. Oran		Category: Experimental D. Oran
	Expires: 18 February 2024 Network Systems Research and Design		ISSN: 2070-1721 Network Systems Research and Design
	I. Moiseenko		I. Moiseenko
	Apple Inc		Apple Inc.
	J. Gibson		J. Gibson
	R. Droms		R. Droms
	Unaffiliated		Unaffiliated
	17 August 2023		March 2024
	ICN Traceroute Protocol Specification		Information-Centric Networking (ICN) Traceroute Protocol Specification
	draft-irtf-icnrg-icntraceroute-11
	Abstract		Abstract
	This document presents the design of an ICN Traceroute protocol.		This document presents the design of an Information-Centric
	This includes the operation of both the client and the forwarder.		Networking (ICN) Traceroute protocol. This includes the operation of
			both the client and the forwarder.
	This document is a product of the Information-Centric Networking		This document is a product of the Information-Centric Networking
	Research Group (ICNRG) of the IRTF.		Research Group (ICNRG) of the IRTF.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This document is not an Internet Standards Track specification; it is
	provisions of BCP 78 and BCP 79.		published for examination, experimental implementation, and
			evaluation.
	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document defines an Experimental Protocol for the Internet
	and may be updated, replaced, or obsoleted by other documents at any		community. This document is a product of the Internet Research Task
	time. It is inappropriate to use Internet-Drafts as reference		Force (IRTF). The IRTF publishes the results of Internet-related
	material or to cite them other than as "work in progress."		research and development activities. These results might not be
			suitable for deployment. This RFC represents the consensus of the
			Information-Centric Networking Research Group of the Internet
			Research Task Force (IRTF). Documents approved for publication by
			the IRSG are not candidates for any level of Internet Standard; see
			Section 2 of RFC 7841.
	This Internet-Draft will expire on 18 February 2024.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfc9507.
	Copyright Notice		Copyright Notice
	Copyright (c) 2023 IETF Trust and the persons identified as the		Copyright (c) 2024 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 (https://trustee.ietf.org/		Provisions Relating to IETF Documents
	license-info) in effect on the date of publication of this document.		(https://trustee.ietf.org/license-info) in effect on the date of
	Please review these documents carefully, as they describe your rights		publication of this document. Please review these documents
	and restrictions with respect to this document.		carefully, as they describe your rights and restrictions with respect
			to this document.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction
	1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3		1.1. Requirements Language
	2. Background on IP-Based Traceroute Operation . . . . . . . . . 3		2. Background on IP-Based Traceroute Operation
	3. Traceroute Functionality Challenges and Opportunities in		3. Traceroute Functionality Challenges and Opportunities in ICN
	ICN . . . . . . . . . . . . . . . . . . . . . . . . . . . 4		4. ICN Traceroute CCNx Packet Formats
	4. ICN Traceroute CCNx Packet Format . . . . . . . . . . . . . . 6		4.1. ICN Traceroute Request CCNx Packet Format
	4.1. ICN Traceroute Request CCNx Packet Format . . . . . . . . 6		4.2. ICN Traceroute Reply CCNx Packet Format
	4.2. Traceroute Reply CCNx Packet Format . . . . . . . . . . . 8		5. ICN Traceroute NDN Packet Formats
	5. ICN Traceroute NDN Packet Format . . . . . . . . . . . . . . 12		5.1. ICN Traceroute Request NDN Packet Format
	5.1. ICN Traceroute Request NDN Packet Format . . . . . . . . 12		5.2. ICN Traceroute Reply NDN Packet Format
	5.2. Traceroute Reply NDN Packet Format . . . . . . . . . . . 13		6. Forwarder Operation
	6. Forwarder Operation . . . . . . . . . . . . . . . . . . . . . 14		7. Protocol Operation for Locally Scoped Namespaces
	7. Protocol Operation For Locally-Scoped Namespaces . . . . . . 15		8. Security Considerations
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 16		9. IANA Considerations
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		10. References
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17		10.1. Normative References
	10.1. Normative References . . . . . . . . . . . . . . . . . . 17		10.2. Informative References
	10.2. Informative References . . . . . . . . . . . . . . . . . 17		Appendix A. Traceroute Client Application (Consumer) Operation
	Appendix A. Traceroute Client Application (Consumer)		Authors' Addresses
	Operation . . . . . . . . . . . . . . . . . . . . . . . . 18
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
	1. Introduction		1. Introduction
	In TCP/IP, routing and forwarding are based on IP addresses. To		In TCP/IP, routing and forwarding are based on IP addresses. To
	ascertain the route to an IP address and to measure the transit		ascertain the route to an IP address and to measure the transit
	delays, the traceroute utility is commonly used. In ICN, routing and		delays, the traceroute utility is commonly used. In Information-
	forwarding are based on name prefixes. To this end, the problem of		Centric Networking (ICN), routing and forwarding are based on name
	ascertaining the characteristics (i.e., transit forwarders and		prefixes. To this end, the ability to ascertain the characteristics
	delays) of at least one of the available routes to a name prefix is a		of at least one of the available routes to a name prefix is a
	fundamendal requirement for instrumentation and network management.		fundamental requirement for instrumentation and network management.
			These characteristics include, among others, route properties such as
			which forwarders were transited and the delay incurred through
			forwarding.
	In order to carry out meaningful experimentation and deployment of		In order to carry out meaningful experimentation and deployment of
	ICN protocols, tools to manage and debug the operation of ICN		ICN protocols, new tools analogous to ping and traceroute used for
	architectures and protocols are needed analogous to ping and		TCP/IP are needed to manage and debug the operation of ICN
	traceroute used for TCP/IP. This document describes the design of a		architectures and protocols. This document describes the design of a
	management and debugging protocol analogous to the traceroute		management and debugging protocol analogous to the traceroute
	protocol of TCP/IP, which will aid the experimental deployment of ICN		protocol of TCP/IP; this new management and debugging protocol will
	protocols. As the community continues its experimentation with ICN		aid the experimental deployment of ICN protocols. As the community
	architectures and protocols, the design of ICN Traceroute might		continues its experimentation with ICN architectures and protocols,
	change accordingly. ICN Traceroute is designed as a tool to		the design of ICN Traceroute might change accordingly. ICN
	troubleshoot ICN architectures and protocols. As such, this document		Traceroute is designed as a tool to troubleshoot ICN architectures
	is classified as an experimental RFC.		and protocols. As such, this document is classified as an
			Experimental RFC.
	This specification uses the terminology defined in [RFC8793].		This specification uses the terminology defined in [RFC8793].
	This document is not an Internet Standards Track specification; it is		This RFC represents the consensus of the Information-Centric
	published for examination, experimental implementation, and		Networking Research Group (ICNRG) of the Internet Research Task Force
	evaluation. This document defines an Experimental Protocol for the		(IRTF).
	Internet community. This document is a product of the Internet
	Research Task Force (IRTF). The IRTF publishes the results of
	Internet-related research and development activities. These results
	might not be suitable for deployment. This RFC represents the
	consensus of the Information-Centric Networking Research Group of the
	Internet Research Task Force (IRTF). Documents approved for
	publication by the IRSG are not candidates for any level of Internet
	Standard; see Section 2 of RFC 7841.
	1.1. Requirements Language		1.1. Requirements Language
	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", "NOT RECOMMENDED", "MAY", and
	document are to be interpreted as described in BCP 14 [RFC2119]		"OPTIONAL" in this document are to be interpreted as described in
	[RFC8174] when, and only when, they appear in all capitals, as shown		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	here.		capitals, as shown here.
	2. Background on IP-Based Traceroute Operation		2. Background on IP-Based Traceroute Operation
	In IP-based networks, traceroute is based on the expiration of the		In IP-based networks, traceroute is based on the expiration of the
	Time To Live (TTL) IP header field. Specifically, a traceroute		Time To Live (TTL) IP header field. Specifically, a traceroute
	client sends consecutive packets (depending on the implementation and		client sends consecutive packets (depending on the implementation and
	the user-specified behavior such packets can be either UDP datagrams,		the user-specified behavior, such packets can be either UDP
	ICMP Echo Request or TCP SYN packets) with a TTL value increased by		datagrams, ICMP Echo Request packets, or TCP SYN packets) with a TTL
	1, essentially performing a expanding ring search. In this way, the		value increased by 1, essentially performing an expanding ring
	first IP packet sent will expire at the first router along the path,		search. In this way, the first IP packet sent will expire at the
	the second IP packet at the second router along the path, etc, until		first router along the path, the second IP packet at the second
	the router (or host) with the specified destination IP address is		router along the path, etc., until the router (or host) with the
	reached. Each router along the path towards the destination,		specified destination IP address is reached. Each router along the
	responds by sending back an ICMP Time Exceeded packet, unless		path towards the destination responds by sending back an ICMP Time
	explicitly prevented from doing so by a security policy.		Exceeded packet, unless explicitly prevented from doing so by a
			security policy.
	The IP-based traceroute utility operates on IP addresses, and in		The IP-based traceroute utility operates on IP addresses and in
	particular depends on the IP packets having source IP addresses that		particular depends on the IP packets having source IP addresses that
	are used as the destination address for replies. Given that ICN		are used as the destination address for replies. Given that ICN
	forwards based on names rather than destination IP addresses, that		forwards based on names rather than destination IP addresses, that
	the names do not refer to unique endpoints (multi-destination), and		the names do not refer to unique endpoints (multi-destination), and
	that the packets do not contain source addresses, a substantially		that the packets do not contain source addresses, a substantially
	different approach is needed.		different approach is needed.
	3. Traceroute Functionality Challenges and Opportunities in ICN		3. Traceroute Functionality Challenges and Opportunities in ICN
	In the NDN and CCN protocols, the communication paradigm is based		In the Named Data Networking (NDN) and Content-Centric Networking
	exclusively on named objects. An Interest is forwarded across the		(CCNx) protocols, the communication paradigm is based exclusively on
	network based on its name. Eventually, it retrieves a content object		named objects. An Interest message is forwarded across the network
	either from a producer application or some forwarder's Content Store		based on its name. Eventually, it retrieves a Content Object from
	(CS).		either a producer application or some forwarder's Content Store (CS).
	An ICN network differs from an IP network in at least 4 important		An ICN network differs from an IP network in at least four important
	ways:		ways (four of which are as follows):
	* IP identifies interfaces to an IP network with a fixed-length		* IP identifies interfaces to an IP network with a fixed-length
	address, and delivers IP packets to one or more interfaces. ICN		address and delivers IP packets to one or more interfaces. ICN
	identifies units of data in the network with a variable length		identifies units of data in the network with a variable-length
	name consisting of a hierarchical list of segments.		name consisting of a hierarchical list of segments.
	* An IP-based network depends on the IP packets having source IP		* An IP-based network depends on the IP packets having source IP
	addresses that are used as the destination address for replies.		addresses that are used as the destination address for replies.
	On the other hand, ICN Interests do not have source addresses and		On the other hand, ICN Interests do not have source addresses, and
	they are forwarded based on names, which do not refer to a unique		they are forwarded based on names, which do not refer to a unique
	end-point. Data packets follow the reverse path of the Interests		endpoint. Data packets follow the reverse path of the Interests
	based on hop-by-hop state created during Interest forwarding.		based on hop-by-hop state created during Interest forwarding.
	* An IP network supports multi-path, single destination, stateless		* An IP network supports multi-path, single-destination, stateless
	packet forwarding and delivery via unicast, a limited form of		packet forwarding and delivery via unicast; a limited form of
	multi-destination selected delivery with anycast, and group-based		multi-destination selected delivery with anycast; and group-based
	multi-destination delivery via multicast. In contrast, ICN		multi-destination delivery via multicast. In contrast, ICN
	supports multi-path and multi-destination stateful Interest		supports multi-path and multi-destination stateful Interest
	forwarding and multi-destination data delivery to units of named		forwarding and multi-destination data delivery to units of named
	data. This single forwarding semantic subsumes the functions of		data. This single forwarding semantic subsumes the functions of
	unicast, anycast, and multicast. As a result, consecutive (or		unicast, anycast, and multicast. As a result, consecutive (or
	retransmitted) ICN Interest messages may be forwarded through an		retransmitted) ICN Interest messages may be forwarded through an
	ICN network along different paths, and may be forwarded to		ICN network along different paths and may be forwarded to
	different data sources (e.g., end-node applications, in-network		different data sources (e.g., end-node applications, in-network
	storage) holding a copy of the requested unit of data. The		storage) holding a copy of the requested unit of data. The
	ability to discover multiple available (or potentially all) paths		ability to discover multiple available (or potentially all) paths
	towards a name prefix is a desirable capability for an ICN		towards a name prefix is a desirable capability for an ICN
	traceroute protocol, since it can be beneficial for congestion		Traceroute protocol, since it can be beneficial for congestion
	control purposes. Knowing the number of available paths for a		control purposes. Knowing the number of available paths for a
	name can also be useful in cases that Interest forwarding based on		name can also be useful in cases where Interest forwarding based
	application semantics/preferences is desirable.		on application semantics/preferences is desirable.
	* In the case of multiple Interests with the same name arriving at a		* In the case of multiple Interests with the same name arriving at a
	forwarder, a number of Interests may be aggregated in a common		forwarder, a number of Interests may be aggregated in a common
	Pending Interest Table (PIT) entry. Depending on the lifetime of		Pending Interest Table (PIT) entry. Depending on the lifetime of
	a PIT entry, the round-trip time an Interest-Data exchange might		a PIT entry, the round-trip time of an Interest-Data exchange
	significantly vary (e.g., it might be shorter than the full round-		might vary significantly (e.g., it might be shorter than the full
	trip time to reach the original content producer). To this end,		round-trip time to reach the original content producer). To this
	the round-trip time experienced by consumers might also vary even		end, the round-trip time experienced by consumers might also vary
	under constant network load.		even under constant network load.
	These differences introduce new challenges, new opportunities and new		These differences introduce new challenges, new opportunities, and
	requirements in the design of ICN traceroute. Following this		new requirements regarding the design of ICN Traceroute. Following
	communication model, a traceroute client should be able to express		this communication model, a traceroute client should be able to
	traceroute requests directed to a name prefix and receive responses.		express traceroute requests directed to a name prefix and receive
			responses.
	Our goals are the following:		Our goals are as follows:
	* Trace one or more paths towards an ICN forwarder (for		* Trace one or more paths towards an ICN forwarder (for
	troubleshooting purposes).		troubleshooting purposes).
	* Trace one or more paths along which an named data of an		* Trace one or more paths through which a named data object can be
	application can be reached in the sense that Interest packets can		reached in the sense that Interest packets can be forwarded
	be forwarded toward it.		towards the application hosting the object.
	* Test whether a specific named object is cached in some on-path CS,		* Test whether a specific named object is cached in some on-path CS,
	and, if so, trace the path towards it and return the identity of		and, if so, trace the path towards it and return the identity of
	the corresponding forwarder.		the corresponding forwarder.
	* Perform transit delay network measurements.		* Perform transit delay network measurements.
	To this end, a traceroute target name can represent:		To this end, a traceroute target name can represent:
	* An administrative name that has been assigned to a forwarder.		* An administrative name that has been assigned to a forwarder.
	Assigning a name to a forwarder implies the presence of a		Assigning a name to a forwarder implies the presence of a
	management application running locally, which handles Operations,		management application running locally that handles Operations,
	Administration and Management (OAM) operations.		Administration, and Maintenance (OAM) operations.
	* A name that includes an application's namespace as a prefix.		* A name that includes an application's namespace as a prefix.
	* A named object that might reside in some in-network storage.		* A named object that might reside in some in-network storage.
	In order to provide stable and reliable diagnostics, it is desirable		In order to provide stable and reliable diagnostics, it is desirable
	that the packet encoding of a traceroute request enable the		that the packet encoding of a traceroute request enable the
	forwarders to distinguish this request from a normal Interest, while		forwarders to distinguish this request from a normal Interest while
	also preserving forwarding behavior as similar as possible to that		also diverging as little as possible from the forwarding behavior for
	for an Interest packet. In the same way, the encoding of a		an Interest packet. In the same way, the encoding of a traceroute
	traceroute reply should allow for processing as similar as possible		reply should minimize any processing differences from those employed
	to that of a data packet by the forwarders.		for a data packet by the forwarders.
	The term "traceroute session" is used for an iterative process during		The term "traceroute session" is used for an iterative process during
	which an endpoint client application generates a number of traceroute		which an endpoint client application generates a number of traceroute
	requests to successively traverse more distant hops in the path until		requests to successively traverse more distant hops in the path until
	it receives a final traceroute reply from a forwarder. It is		it receives a final traceroute reply from a forwarder. It is
	desirable that ICN traceroute be able to discover a number of paths		desirable that ICN Traceroute be able to discover a number of paths
	towards the expressed prefix within the same session or subsequent		towards the expressed prefix within the same session or subsequent
	sessions. To discover all the hops in a path, we need a mechanism		sessions. To discover all the hops in a path, we need a mechanism
	(Interest Steering) to steer requests along different paths. Such a		(Interest Steering) to steer requests along different paths. Such a
	capability was initially published in [PATHSTEERING] and has been		capability was initially published in [PATHSTEERING] and has been
	specified for CCNx and NDN in [I-D.irtf-icnrg-pathsteering].		specified for CCNx and NDN in [RFC9531].
	It is also important, in the case of traceroute requests for the same		In the case of traceroute requests for the same prefix from different
	prefix from different sources, to have a mechanism to avoid		sources, it is also important to have a mechanism to avoid
	aggregating those requests in the PIT. To this end, we need some		aggregating those requests in the PIT. To this end, we need some
	encoding in the traceroute requests to make each request for a common		encoding in the traceroute requests to make each request for a common
	prefix unique, and hence avoid PIT aggregation and further enabling		prefix unique, hence avoiding PIT aggregation and further enabling
	the exact matching of a response with a particular traceroute packet.		the exact matching of a response with a particular traceroute packet.
	The packet types and format are presented in Section 4. The		The packet types and formats are presented in Section 4. Procedures
	procedures, e.g. the procedures for determining and indicating that a		for determining and indicating that a destination has been reached
	destination has been reached, are specified in Section 6.		are included in Section 6.
	4. ICN Traceroute CCNx Packet Format		4. ICN Traceroute CCNx Packet Formats
	In this section, we present the CCNx packet format [RFC8609] of ICN		In this section, we present the CCNx packet formats [RFC8609] of ICN
	traceroute, where messages exist within outermost containments		Traceroute where messages exist within outermost containments
	(packets). Specifically, we propose two types of traceroute packets,		(packets). Specifically, we propose two types of traceroute packets:
	a traceroute request and a traceroute reply packet type.		a traceroute request and a traceroute reply.
	4.1. ICN Traceroute Request CCNx Packet Format		4.1. ICN Traceroute Request CCNx Packet Format
	The format of the traceroute request packet is presented below:		The format of the traceroute request packet is presented below:
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | | |		| | | |
	| Version | TrRequest | PacketLength |		| Version | PT_TR_REQUEST | PacketLength |
	| | | |		| | | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | | | |		| | | | |
	| HopLimit | Reserved | Flags | HeaderLength |		| HopLimit | Reserved | Flags | HeaderLength |
	| | | | |		| | | | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	/ /		/ /
	/ Path label TLV /		/ Path Label TLV /
	/ /		/ /
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Traceroute Request Message TLVs |		| Traceroute Request Message TLVs |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 1: Traceroute Request CCNx Packet Format		Figure 1: Traceroute Request CCNx Packet Format
	The existing packet header fields have similar functionality to the		The existing packet header fields have functionality similar to that
	header fields of a CCNx Interest packet. The value of the packet		of the header fields of a CCNx Interest packet. The value of the
	type field is TrRequest. See Section 9 for the value assignment.		packet type field is PT_TR_REQUEST. See Section 9 for the value
			assignment.
	Compared to the typical format of a CCNx packet header [RFC8609],		In contrast to the typical format of a CCNx packet header [RFC8609],
	there is a new optional fixed header added to the packet header:		there is a new optional fixed header added to the packet header:
	* A Path Steering hop-by-hop header TLV, which is constructed hop-		* A Path Steering hop-by-hop header TLV, which is constructed hop by
	by-hop in the traceroute reply and included in the traceroute		hop in the traceroute reply and included in the traceroute request
	request to steer consecutive requests expressed by a client		to steer consecutive requests expressed by a client towards a
	towards a common or different forwarding paths. The Path label		common forwarding path or different forwarding paths. The Path
	TLV is specified in [I-D.irtf-icnrg-pathsteering]		Label TLV is specified in [RFC9531].
	The message of a traceroute request is presented below:		The message of a traceroute request is presented below:
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | |		| | |
	| MessageType = 1 | MessageLength |		| MessageType = 0x05 | MessageLength |
	| | |		| | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Name TLV |		| Name TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 2: Traceroute Request Message Format		Figure 2: Traceroute Request Message Format
	The traceroute request message is of type Interest in order to		The traceroute request message is of type T_DISCOVERY. The Name TLV
	leverage the Interest forwarding behavior provided by the network.		has the structure described in [RFC8609]. The name consists of the
	The Name TLV has the structure described in [RFC8609]. The name		target (destination) prefix appended with a nonce typed name as its
	consists of the target (destination) prefix appended with a nonce		last segment. The nonce can be encoded as a base64-encoded string
	typed name as its last segment. The nonce can be encoded as a		with the URL-safe alphabet as defined in Section 5 of [RFC4648], with
	base64-encoded string with the URL-safe alphabet as defined in		padding omitted. The format of this TLV is a 64-bit nonce. See
	Section 5 of [RFC4648], with padding omitted. The format of this TLV		[RFC9508] for the value assignment. The purpose of the nonce is to
	is a 64-bit nonce. See Section 9 for the value assignment. The		avoid Interest aggregation and allow client matching of replies with
	purpose of the nonce is to avoid Interest aggregation and allow		requests. As described below, the nonce is ignored for CS checking.
	client matching of replies with requests. As described below, the
	nonce is ignored for CS checking.
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | |		| | |
	| Name_Nonce_Type | Name_Nonce_Length = 8 |		| Name_Nonce_Type | Name_Nonce_Length = 8 |
	| | |		| | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| |		| |
	| |		| |
	| Name_Nonce_Value |		| Name_Nonce_Value |
	| |		| |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 3: Name Nonce Typed Segment TLV		Figure 3: Name Nonce Typed Segment TLV
	4.2. Traceroute Reply CCNx Packet Format		4.2. ICN Traceroute Reply CCNx Packet Format
	The format of a traceroute reply packet is presented below:		The format of a traceroute reply packet is presented below:
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | | |		| | | |
	| Version | TrReply | PacketLength |		| Version | PT_TR_REPLY | PacketLength |
	| | | |		| | | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | | |		| | | |
	| Reserved | Flags | HeaderLength |		| Reserved | Flags | HeaderLength |
	| | | |		| | | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Path label TLV |		| Path Label TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Traceroute Reply Message TLVs |		| Traceroute Reply Message TLVs |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 4: Traceroute Reply CCNx Packet Format		Figure 4: Traceroute Reply CCNx Packet Format
	The header of a traceroute reply consists of the header fields of a		The header of a traceroute reply consists of the header fields of a
	CCNx Content Object and a hop-by-hop path steering TLV. The value of		CCNx Content Object and a hop-by-hop Path Steering TLV. The value of
	the packet type field is TrReply. See Section 9 for the value		the packet type field is PT_TR_REPLY. See Section 9 for the value
	assignment.		assignment.
	A traceroute reply message is of type Content Object, contains a Name		A traceroute reply message is of type T_OBJECT and contains a Name
	TLV (name of the corresponding traceroute request), a PayloadType TLV		TLV (name of the corresponding traceroute request), a PayloadType
	and an ExpiryTime TLV with a value of 0 to indicate that replies must		TLV, and an ExpiryTime TLV with a value of 0 to indicate that replies
	not be returned from network caches.		must not be returned from network caches.
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | |		| | |
	| MessageType = 2 | MessageLength |		| MessageType = 0x06 | MessageLength |
	| | |		| | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Name TLV |		| Name TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| PayloadType TLV |		| PayloadType TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| ExpiryTime TLV |		| ExpiryTime TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 5: Traceroute Reply Message Format		Figure 5: Traceroute Reply Message Format
	The PayloadType TLV is presented below. It is of type		The PayloadType TLV is presented below. It is of type
	T_PAYLOADTYPE_DATA, and the data schema consists of 3 TLVs:		T_PAYLOADTYPE_DATA, and the data schema consists of three TLVs:
	1) the name of the sender of this reply (with the same structure as		1) the name of the sender of this reply (with the same structure as
	a CCNx Name TLV),		a CCNx Name TLV),
	2) the sender's signature of their own name (with the same structure		2) the sender's signature of their own name (with the same structure
	as a CCNx ValidationPayload TLV),		as a CCNx ValidationPayload TLV), and
	3) a TLV with return codes to indicate whether the request was		3) a TLV with return codes to indicate whether the request was
	satisfied due to the existence of a local application, a CS hit		satisfied due to the existence of a local application, a CS hit,
	or a match with a forwarder's name, or the HopLimit value of the		a match with a forwarder's name, or the HopLimit value of the
	corresponding request reached 0.		corresponding request reaching 0.
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | |		| | |
	| T_PAYLOADTYPE_DATA | Length |		| T_PAYLOADTYPE_DATA | Length |
	| | |		| | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Sender's Name TLV |		| Sender's Name TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| Sender's Signature TLV |		| Sender's Signature TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| TrReply Code TLV |		| PT_TR_REPLY Code TLV |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 6: Traceroute Reply Message Format		Figure 6: Traceroute Reply PayloadType TLV Format
	The goal of including the name of the sender in the reply is to		The goal of including the name of the sender in the reply is to
	enable the user to reach this entity directly to ask for further		enable the user to reach this entity directly to ask for further
	management/administrative information using generic Interest-Data		management/administrative information using generic Interest-Data
	exchanges or by employing a more comprehensive management tool such		exchanges or by employing a more comprehensive management tool, such
	as CCNInfo [RFC9344] after a successful verification of the sender's		as CCNinfo [RFC9344], after a successful verification of the sender's
	name.		name.
	The structure of the TrReply Code TLV is presented below (16-bit		The structure of the PT_TR_REPLY Code TLV is presented below (16-bit
	value). The assigned values are the following:		value). The four assigned values are as follows:
	1: Indicates that the target name matched the administrative name of		1: Indicates that the target name matched the administrative name of
	a forwarder (as served by its internal management application).		a forwarder (as served by its internal management application).
	2: Indicates that the target name matched a prefix served by an		2: Indicates that the target name matched a prefix served by an
	application (other than the internal management application of a		application (other than the internal management application of a
	forwarder).		forwarder).
	3: Indicates that the target name matched the name of an object in a		3: Indicates that the target name matched the name of an object in a
	forwarder's CS.		forwarder's CS.
	4: Indicates that the the Hop limit reached the 0 value.		4: Indicates that the HopLimit reached 0.
	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
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| | |		| | |
	| TrReply_Code_Type | TrReply_Code_Length = 2 |		| PT_TR_REPLY_Code_Type | PT_TR_REPLY_Code_Length = 2 |
	| | |		| | |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	| |		| |
	| TrReply_Code_Value |		| PT_TR_REPLY_Code_Value |
	| |		| |
	+---------------+---------------+---------------+---------------+		+---------------+---------------+---------------+---------------+
	Figure 7: TrReply Code TLV		Figure 7: PT_TR_REPLY Code TLV
	5. ICN Traceroute NDN Packet Format		5. ICN Traceroute NDN Packet Formats
	In this section, we present the ICN traceroute Request and Reply		In this section, we present the ICN Traceroute Request and Reply
	Format according to the NDN packet specification [NDNTLV].		packet formats according to the NDN packet format specification
			[NDNTLV].
	5.1. ICN Traceroute Request NDN Packet Format		5.1. ICN Traceroute Request NDN Packet Format
	A traceroute request is encoded as an NDN Interest packet. Its		A traceroute request is encoded as an NDN Interest packet. Its
	format is the following:		format is as follows:
	TracerouteRequest = INTEREST-TYPE TLV-LENGTH		TracerouteRequest = INTEREST-TYPE TLV-LENGTH
	Name		Name
	MustBeFresh		MustBeFresh
	Nonce		Nonce
	HopLimit		HopLimit
	ApplicationParameters?		ApplicationParameters?
	Figure 8: Traceroute Request NDN Packet Format		Figure 8: Traceroute Request NDN Packet Format
	The name of a request consists of the target name, a nonce value (it		The name of a request consists of the target name, a nonce value (it
	can be the value of the Nonce field) and the suffix "traceroute" to		can be the value of the Nonce field), and the suffix "traceroute" to
	denote that this Interest is a traceroute request (added as a		denote that this Interest is a traceroute request (added as a
	KeywordNameComponent). When the "ApplicationParameters" element is		KeywordNameComponent [NDNTLV]). When the "ApplicationParameters"
	present, a ParametersSha256DigestComponent is added as the last name		element is present, a ParametersSha256DigestComponent (Section 6) is
	segment.		added as the last name segment.
	A traceroute request MAY carry a Path label TLV in the NDN Link		A traceroute request MAY carry a Path Label TLV in the NDN Link
	Adaptation Protocol [NDNLPv2] as specified in		Adaptation Protocol [NDNLPv2] as specified in [RFC9531].
	[I-D.irtf-icnrg-pathsteering].
	Since the NDN packet format does not provide a mechanism to prevent		Since the NDN packet format does not provide a mechanism to prevent
	the network from caching specific data packets, we instead use the		the network from caching specific data packets, we instead use the
	MustBeFresh selector for requests (in combination with a Freshness		MustBeFresh TLV for requests (in combination with a FreshnessPeriod
	Period TLV of value 1 for replies) to avoid fetching cached		TLV with a value of 1 for replies) to avoid fetching cached
	traceroute replies with a freshness period that has expired		traceroute replies with a freshness period that has expired
	[REALTIME].		[REALTIME].
	5.2. Traceroute Reply NDN Packet Format		5.2. ICN Traceroute Reply NDN Packet Format
	A traceroute reply is encoded as an NDN Data packet. Its format is		A traceroute reply is encoded as an NDN Data packet. Its format is
	the following:		as follows:
	TracerouteReply = DATA-TLV TLV-LENGTH		TracerouteReply = DATA-TLV TLV-LENGTH
	Name		Name
	MetaInfo		MetaInfo
	Content		Content
	Signature		Signature
	Figure 9: Traceroute Reply NDN Packet Format		Figure 9: Traceroute Reply NDN Packet Format
	A traceroute reply MAY carry a Path label TLV in the NDN Link		A traceroute reply MAY carry a Path Label TLV in the NDN Link
	Adaptation Protocol [NDNLPv2] as specified in		Adaptation Protocol [NDNLPv2] as specified in [RFC9531], since it
	[I-D.irtf-icnrg-pathsteering], since it might be modified in a hop-		might be modified in a hop-by-hop fashion by the forwarders along the
	by-hop fashion by the forwarders along the reverse path.		reverse path.
	The name of a traceroute reply is the name of the corresponding		The name of a traceroute reply is the name of the corresponding
	traceroute request, while the format of the MetaInfo field is the		traceroute request while the format of the MetaInfo field is as
	following:		follows:
	MetaInfo = META-INFO-TYPE TLV-LENGTH		MetaInfo = META-INFO-TYPE TLV-LENGTH
	ContentType		ContentType
	FreshnessPeriod		FreshnessPeriod
	Figure 10: MetaInfo TLV		Figure 10: MetaInfo TLV
	The value of the ContentType TLV is 0. The value of the		The value of the ContentType TLV is 0. The value of the
	FreshnessPeriod TLV is 1, so that the replies are treated as stale		FreshnessPeriod TLV is 1, so that the replies are treated as stale
	data (almost instantly) as they are received by a forwarder.		data (almost instantly) as they are received by a forwarder.
	The content of a traceroute reply consists of the following 2 TLVs:		The content of a traceroute reply consists of the following two TLVs:
	Sender's name (an NDN Name TLV) and Traceroute Reply Code. There is		Sender's Name (an NDN Name TLV) and Traceroute Reply Code. There is
	no need to have a separate TLV for the sender's signature in the		no need to have a separate TLV for the sender's signature in the
	content of the reply, since every NDN data packet carries the		content of the reply, since every NDN Data packet carries the
	signature of the data producer.		signature of the data producer.
	The Traceroute Reply Code TLV format is the following (with the		The Traceroute Reply Code TLV format is as follows (with the values
	values specified in Section 4.2):		specified in Section 4.2):
	TrReplyCode = TRREPLYCODE-TLV-TYPE TLV-LENGTH 2*OCTET		PT_TR_REPLYCode = TRREPLYCODE-TLV-TYPE TLV-LENGTH 2*OCTET
	Figure 11: Traceroute Reply Code TLV		Figure 11: Traceroute Reply Code TLV
	6. Forwarder Operation		6. Forwarder Operation
	When a forwarder receives a traceroute request, the hop limit value		When a forwarder receives a traceroute request, the HopLimit value is
	is checked and decremented and the target name (i.e, the name of the		checked and decremented, and the target name (i.e., the name of the
	traceroute request without the last nonce name segment as well as the		traceroute request without the last Nonce name segment as well as the
	suffix "traceroute" and the ParametersSha256DigestComponent in the		suffix "traceroute" and the ParametersSha256DigestComponent in the
	case of a request with the NDN packet format) is extracted.		case of a request with the NDN packet format) is extracted.
	If the HopLimit has not expired (its value is greater than 0), the		If the HopLimit has not expired (i.e., is greater than 0), the
	forwarder will forward the request upstream based on CS lookup, PIT		forwarder will forward the request upstream based on CS lookup, PIT
	creation, LPM lookup and the path steering value, if present. If no		creation, Longest Name Prefix Match (LNPM) lookup, and (if present)
	valid next-hop is found, an InterestReturn indicating "No Route" in		the path steering value. If no valid next hop is found, an
	the case of CCNx or a network NACK in the case of NDN is sent		InterestReturn indicating "No Route" in the case of CCNx or a network
	downstream.		NACK in the case of NDN is sent downstream.
	If the HopLimit value is equal to zero, the forwarder generates a		If HopLimit equals 0, the forwarder generates a traceroute reply.
	traceroute reply. This reply includes the forwarder's administrative		This reply includes the forwarder's administrative name and
	name and signature, and a Path label TLV. This TLV initially has a		signature, and a Path Label TLV. This TLV initially has a null
	null value since the traceroute reply originator does not forward the		value, since the traceroute reply originator does not forward the
	request and, thus, does not make a path choice. The reply will also		request and thus does not make a path choice. The reply will also
	include the corresponding TrReply Code TLV.		include the corresponding PT_TR_REPLY Code TLV.
	A traceroute reply will be the final reply of a traceroute session if		A traceroute reply will be the final reply of a traceroute session if
	any of the following conditions are met:		any of the following conditions are met:
	* If a forwarder has been given one or more administrative names,		* If a forwarder has been given one or more administrative names,
	the target name matches one of them.		the target name matches one of them.
	* The target name exactly matches the name of a content-object		* The target name exactly matches the name of a Content Object
	residing in the forwarder's CS (unless the traceroute client		residing in the forwarder's CS (unless the traceroute client
	application has chosen not to receive replies due to CS hits as		application has chosen not to receive replies due to CS hits as
	specified in Appendix A).		specified in Appendix A).
	* The target name matches (in a Longest Prefix Match manner) a FIB		* The target name matches (in an LNPM manner) a FIB entry with an
	entry with an outgoing face referring to a local application.		outgoing face referring to a local application.
	The TrReply Code TLV value of the reply is set to indicate the		The PT_TR_REPLY Code TLV value of the reply is set to indicate the
	specific condition that was met. If none of those conditions was		specific condition that was met. If none of those conditions were
	met, the TrReply Code is set to 4 to indicate that the hop limit		met, the PT_TR_REPLY Code is set to 4 to indicate that the HopLimit
	value reached 0.		reached 0.
	A received traceroute reply will be matched to an existing PIT entry		A received traceroute reply will be matched to an existing PIT entry
	as usual. On the reverse path, the path steering TLV of a reply will		as usual. On the reverse path, the Path Steering TLV of a reply will
	be updated by each forwarder to encode its choice of next-hop(s).		be updated by each forwarder to encode its choice of next hop(s).
	When included in subsequent requests, this path steering TLV allows		When included in subsequent requests, this Path Steering TLV allows
	the forwarders to steer the requests along the same path.		the forwarders to steer the requests along the same path.
	7. Protocol Operation For Locally-Scoped Namespaces		7. Protocol Operation for Locally Scoped Namespaces
	In this section, we elaborate on 2 alternative design approaches in		In this section, we elaborate on two alternative design approaches in
	cases that the traceroute target prefix corresponds to a locally-		cases where the traceroute target prefix corresponds to a locally
	scoped namespace not directly routable from the client's local		scoped namespace not directly routable from the client's local
	network.		network.
	The first approach leverages the NDN Link Object [SNAMP].		The first approach leverages the NDN Link Object [SNAMP].
	Specifically, the traceroute client attaches to the expressed request		Specifically, the traceroute client attaches to the expressed request
	a LINK Object that contains a number of routable name prefixes, based		a Link Object that contains a number of routable name prefixes, based
	on which the request can be forwarded across the Internet until it		on which the request can be forwarded across the Internet until it
	reaches a network region, where the request name itself is routable.		reaches a network region where the request name itself is routable.
	A LINK Object is created and signed by a data producer allowed to		A Link Object is created and signed by a data producer allowed to
	publish data under a locally-scoped namespace. The way that a client		publish data under a locally scoped namespace. The way that a client
	retrieves a LINK Object depends on various network design factors and		retrieves a Link Object depends on various network design factors and
	is out of the scope of the current draft.		is out of scope for this document.
	Based on the current deployment of the LINK Object by the NDN team, a		At the time of this writing, and based on the current deployment of
	forwarder at the border of the region, where an Interest name becomes		the Link Object by the NDN team [NDNLPv2], a forwarder at the border
	routable has to remove the LINK Object from the incoming Interests.		of the region where an Interest name becomes routable has to remove
	The Interest state maintained along the entire forwarding path is		the Link Object from the incoming Interests. The Interest state
	based on the Interest name regardless of whether it was forwarded		maintained along the entire forwarding path is based on the Interest
	based on this name or a prefix in the LINK Object.		name regardless of whether it was forwarded based on this name or a
			prefix in the Link Object.
	The second approach is based on prepending a routable prefix to the		The second approach is based on prepending a routable prefix to the
	locally-scoped name. The resulting prefix will be the name of the		locally scoped name. The resulting prefix will be the name of the
	traceroute requests expressed by the client. In this way, a request		traceroute requests expressed by the client. In this way, a request
	will be forwarded based on the routable part of its name. When it		will be forwarded based on the routable part of its name. When it
	reaches the network region where the original locally-scoped name is		reaches the network region where the original locally scoped name is
	routable, the border forwarder rewrites the request name and deletes		routable, the border forwarder rewrites the request name and deletes
	its routable part. There are two conditions for a forwarder to		its routable part. A forwarder will perform this rewriting operation
	perform this rewriting operation on a request:		on a request if the following two conditions are met:
	1) the routable part of the request name matches a routable name of		1) the routable part of the request name matches a routable name of
	the network region adjacent to the forwarder (assuming that a		the network region adjacent to the forwarder (assuming that a
	forwarder is aware of those names), and		forwarder is aware of those names), and
	2) the remaining part of the request name is routable across the		2) the remaining part of the request name is routable across the
	network region of this forwarder.		network region of this forwarder.
	The state maintained along the path, where the locally-scoped name is		The state along the path depends on whether the request is traversing
	not routable, is based on the routable prefix along with the locally-		the portion of the network where the locally scoped name is routable.
	scoped prefix, while within the network region that the locally-		In this case, the forwarding can be based entirely on the locally
	scoped prefix is routable is based only on it. To ensure that the		scoped name. However, where a portion of the path lies outside the
	generated replies will reach the client, the border forwarder has		region where the locally scoped name is routable, the border router
	also to rewrite the name of a reply and prepend the routable prefix		has to rewrite the name of a reply and prepend the routable prefix of
	of the corresponding request.		the corresponding request to ensure that the generated replies will
			reach the client.
	8. Security Considerations		8. Security Considerations
	A reflection attack could occur in the case of a traceroute reply		A reflection attack could occur in the case of a traceroute reply
	with the CCNx packet format if a compromised forwarder includes in		with the CCNx packet format if a compromised forwarder includes in
	the reply the name of a victim forwarder. This could redirect the		the reply the name of a victim forwarder. This could redirect the
	future administrative traffic towards the victim. To foil such		future administrative traffic towards the victim. To foil such
	reflection attacks, the forwarder that generates a traceroute reply		reflection attacks, the forwarder that generates a traceroute reply
	MUST sign the name included in the payload. In this way, the client		MUST sign the name included in the payload. In this way, the client
	is able to verify that the included name is legitimate and refers to		is able to verify that the included name is legitimate and refers to
	the forwarder that generated the reply. Alternatively, the forwarder		the forwarder that generated the reply. Alternatively, the forwarder
	could include in the reply payload their routable prefix(es) encoded		could include in the reply payload their routable prefix(es) encoded
	as a signed NDN Link Object [SNAMP].		as a signed NDN Link Object [SNAMP].
	This approach does not protect against on-path attacks, where a		This approach does not protect against on-path attacks where a
	compromised forwarder that receives a traceroute reply replaces the		compromised forwarder that receives a traceroute reply replaces the
	forwarder's name and the signature in the message with its own name		forwarder's name and the signature in the message with its own name
	and signature to make the client believe that the reply was generated		and signature to make the client believe that the reply was generated
	by the compromised forwarder. To foil such attack scenarios, a		by the compromised forwarder. To foil such attack scenarios, a
	forwarder can sign the reply message itself. In such cases, the		forwarder can sign the reply message itself. In such cases, the
	forwarder does not have to sign its own name in reply message, since		forwarder does not have to sign its own name in the reply message,
	the message signature protects the message as a whole and will be		since the message signature protects the message as a whole and will
	invalidated in the case of an on-path attack. Additionally, a		be invalidated in the case of an on-path attack. Additionally, a
	forwarder could swap out the name of a traceroute request with the		forwarder could swap out the name of a traceroute request with a name
	name of its choosing. In this case, however, the response with the		of its choosing. In this case, however, the response with the
	spoofed name will not be received by a client, since the change of		spoofed name will not be received by a client, since the change of
	name would invalidate the state in PIT on the path back to the		name would invalidate the state in the PIT on the path back to the
	client.		client.
	Signing each traceroute reply message can be expensive and can		Signing each traceroute reply message can be expensive and can
	potentially lead to computation attacks against forwarders. To		potentially lead to computation attacks against forwarders. To
	mitigate such attack scenarios, the processing of traceroute requests		mitigate such attack scenarios, the processing of traceroute requests
	and the generation of the replies SHOULD be handled by a separate		and the generation of the replies SHOULD be handled by a separate
	management application running locally on each forwarder. Serving		management application running locally on each forwarder. The
	traceroute replies therefore is thereby separated from load on the		serving of traceroute replies is thereby separated from load on the
	forwarder itself. The approaches used by ICN applications to manage		forwarder itself. The approaches used by ICN applications to manage
	load may also apply to the forwarder's management application.		load may also apply to the forwarder's management application.
	Interest flooding attack amplification is possible in the case of the		Interest flooding attack amplification is possible in the case of the
	second approach to deal with locally-scoped namespaces described in		second approach for dealing with locally scoped namespaces as
	Section 7. A border forwarder will have to maintain extra state to		described in Section 7. A border forwarder will have to maintain
	prepend the correct routable prefix to the name of an outgoing reply,		extra state to prepend the correct routable prefix to the name of an
	since the forwarder might be attached to multiple network regions		outgoing reply, since the forwarder might be attached to multiple
	(reachable under different prefixes) or a network region attached to		network regions (reachable under different prefixes) or a network
	this forwarder might be reachable under multiple routable prefixes.		region attached to this forwarder might be reachable under multiple
			routable prefixes.
	We also note that traceroute requests have the same privacy		We also note that traceroute requests have the same privacy
	characteristics as regular Interests.		characteristics as regular Interests.
	9. IANA Considerations		9. IANA Considerations
	IANA will assign TBD1 to "TrRequest" and TBD2 to "TrReplay" in the		IANA has assigned 0x07 to "PT_TR_REQUEST" and 0x08 to "PT_TR_REPLY"
	CCNx Packet Types registry established by [RFC8609].		in the "CCNx Packet Types" registry established by [RFC8609].
	IANA will assign TBD3 to "Nonce" in the CCNx Name Segment Types
	registry established by [RFC8609].
	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, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	skipping to change at page 18, line 5 ¶		skipping to change at line 728 ¶
	[RFC8793] Wissingh, B., Wood, C., Afanasyev, A., Zhang, L., Oran,		[RFC8793] Wissingh, B., Wood, C., Afanasyev, A., Zhang, L., Oran,
	D., and C. Tschudin, "Information-Centric Networking		D., and C. Tschudin, "Information-Centric Networking
	(ICN): Content-Centric Networking (CCNx) and Named Data		(ICN): Content-Centric Networking (CCNx) and Named Data
	Networking (NDN) Terminology", RFC 8793,		Networking (NDN) Terminology", RFC 8793,
	DOI 10.17487/RFC8793, June 2020,		DOI 10.17487/RFC8793, June 2020,
	<https://www.rfc-editor.org/info/rfc8793>.		<https://www.rfc-editor.org/info/rfc8793>.
	10.2. Informative References		10.2. Informative References
	[I-D.irtf-icnrg-pathsteering]		[NDNLPv2] NDN team, "NDNLPv2: Named Data Networking Link Adaptation
	Moiseenko, I. and D. R. Oran, "Path Steering in CCNx and		Protocol v2", February 2023, <https://redmine.named-
	NDN", Work in Progress, Internet-Draft, draft-irtf-icnrg-
	pathsteering-03, 23 July 2023,
	<https://datatracker.ietf.org/doc/html/draft-irtf-icnrg-
	pathsteering-03>.
	[NDNLPv2] "Named Data Networking Link Adaptation Protocol v2",
	various, <https://redmine.named-
	data.net/projects/nfd/wiki/NDNLPv2>.		data.net/projects/nfd/wiki/NDNLPv2>.
	[NDNTLV] "NDN Packet Format Specification.", 2021,		[NDNTLV] NDN project team, "NDN Packet Format Specification",
			February 2024,
	<https://named-data.net/doc/NDN-packet-spec/current/>.		<https://named-data.net/doc/NDN-packet-spec/current/>.
	[PATHSTEERING]		[PATHSTEERING]
	Moiseenko, I. and D. Oran, "Path switching in content		Moiseenko, I. and D. Oran, "Path switching in content
	centric and named data networks", in Proceedings of the		centric and named data networks", ICN '17: Proceedings of
	4th ACM Conference on Information-Centric Networking,		the 4th ACM Conference on Information-Centric Networking,
	2017.		pp. 66-76, DOI 10.1145/3125719.3125721, September 2017,
			<https://dl.acm.org/doi/10.1145/3125719.3125721>.
	[REALTIME] Mastorakis, S., Gusev, P., Afanasyev, A., and L. Zhang,		[REALTIME] Mastorakis, S., Gusev, P., Afanasyev, A., and L. Zhang,
	"Real-Time Data Retrieval in Named Data Networking", in		"Real-Time Data Retrieval in Named Data Networking", 2018
	Proceedings of the 1st IEEE International Conference on		1st IEEE International Conference on Hot Information-
	Hot Topics in Information-Centric Networking, 2017.		Centric Networking (HotICN), Shenzhen, China, pp. 61-66,
			DOI 10.1109/HOTICN.2018.8605992, August 2018,
			<https://ieeexplore.ieee.org/document/8605992>.
	[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data		[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
	Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,		Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
	<https://www.rfc-editor.org/info/rfc4648>.		<https://www.rfc-editor.org/info/rfc4648>.
	[RFC9344] Asaeda, H., Ooka, A., and X. Shao, "CCNinfo: Discovering		[RFC9344] Asaeda, H., Ooka, A., and X. Shao, "CCNinfo: Discovering
	Content and Network Information in Content-Centric		Content and Network Information in Content-Centric
	Networks", RFC 9344, DOI 10.17487/RFC9344, February 2023,		Networks", RFC 9344, DOI 10.17487/RFC9344, February 2023,
	<https://www.rfc-editor.org/info/rfc9344>.		<https://www.rfc-editor.org/info/rfc9344>.
	[SNAMP] Afanasyev, A. and , "SNAMP: Secure namespace mapping to		[RFC9508] Mastorakis, S., Oran, D., Gibson, J., Moiseenko, I., and
	scale NDN forwarding", IEEE Conference on Computer		R. Droms, "Information-Centric Networking (ICN) Ping
	Communications Workshops (INFOCOM WKSHPS), 2015.		Protocol Specification", RFC 9508, DOI 10.17487/RFC9508,
			March 2024, <https://www.rfc-editor.org/info/rfc9508>.
			[RFC9531] Moiseenko, I. and D. Oran, "Path Steering in Content-
			Centric Networking (CCNx) and Named Data Networking
			(NDN)", RFC 9531, DOI 10.17487/RFC9531, March 2024,
			<https://www.rfc-editor.org/info/rfc9531>.
			[SNAMP] Afanasyev, A., Yi, C., Wang, L., Zhang, B., and L. Zhang,
			"SNAMP: Secure namespace mapping to scale NDN forwarding",
			2015 IEEE Conference on Computer Communications Workshops
			(INFOCOM WKSHPS), Hong Kong, China, pp. 281-286,
			DOI 10.1109/INFCOMW.2015.7179398, April 2015,
			<https://ieeexplore.ieee.org/abstract/document/7179398>.
	Appendix A. Traceroute Client Application (Consumer) Operation		Appendix A. Traceroute Client Application (Consumer) Operation
	This section is an informative appendix regarding the proposed		This section is an informative appendix regarding the proposed
	traceroute client operation.		traceroute client operation.
	The client application is responsible for generating traceroute		The client application is responsible for generating traceroute
	requests for prefixes provided by users.		requests for prefixes provided by users.
	The overall process can be iterative: the first traceroute request of		The overall process can be iterative: the first traceroute request of
	each session will have a HopLimit of value 1 to reach the first hop		each session will have a HopLimit of 1 to reach the first hop
	forwarder, the second of value 2 to reach the second hop forwarder		forwarder, the second request will have a HopLimit of 2 to reach the
	and so on and so forth.		second hop forwarder, and so on.
	When generating a series of requests for a specific name, the first		When generating a series of requests for a specific name, the first
	one will typically not include a Path label TLV, since no TLV value		request will typically not include a Path Label TLV, since no TLV
	is known. After a traceroute reply containing a Path label TLV is		value is known. After a traceroute reply containing a Path Label TLV
	received, each subsequent request might include the received path		is received, each subsequent request might include the received path
	steering value in the Path label header TLV to drive the requests		steering value in the Path Label header TLV to drive the requests
	towards a common path as part of checking the network performance.		towards a common path as part of checking network performance. To
	To discover more paths, a client can omit the Path label TLV in		discover more paths, a client can omit the Path Label TLV in future
	future requests. Moreover, for each new traceroute request, the		requests. Moreover, for each new traceroute request, the client has
	client has to generate a new nonce and record the time that the		to generate a new nonce and record the time that the request was
	request was expressed. It will also set the lifetime of a request,		expressed. The client also sets the lifetime of the traceroute
	which will have semantics similar to the lifetime of an Interest.		request, which carries the same semantics as the Interest Lifetime
			[RFC8609] in an Interest.
	Moreover, the client application might not wish to receive replies		Moreover, the client application might not wish to receive replies
	due to CS hits. In CCNx, a mechanism to achieve that would be to use		due to CS hits. In CCNx, a mechanism to achieve that would be to use
	a Content Object Hash Restriction TLV with a value of 0 in the		a Content Object Hash Restriction TLV with a value of 0 in the
	payload of a traceroute request message. In NDN, the exclude filter		payload of a traceroute request message. In NDN, the exclude filter
	selector can be used.		selector can be used.
	When it receives a traceroute reply, the client would typically match		When it receives a traceroute reply, the client would typically match
	the reply to a sent request and compute the round-trip time of the		the reply to a sent request and compute the round-trip time of the
	request. It should parse the Path label value and decode the reply's		request. It should parse the Path Label value and decode the reply's
	payload to parse the sender's name and signature. The client should		payload to parse the sender's name and signature. The client should
	verify that both the received message and the forwarder's name have		verify that both the received message and the forwarder's name have
	been signed by the key of the forwarder, whose name is included in		been signed by the key of the forwarder, whose name is included in
	the payload of the reply (by fetching this forwarder's public key and		the payload of the reply (by fetching this forwarder's public key and
	verifying the contained signature). In the case that the client		verifying the contained signature). In the case that the client
	receives an TrReply Code TLV with a valid value, it can stop sending		receives a PT_TR_REPLY Code TLV with a valid value, it can stop
	requests with increasing HopLimit values and potentially start a new		sending requests with increasing HopLimit values and potentially
	traceroute session.		start a new traceroute session.
	In the case that a traceroute reply is not received for a request		In the case that a traceroute reply is not received for a request
	within a certain time interval (lifetime of the request), the client		within a certain time interval (lifetime of the request), the client
	should time-out and send a new request with a new nonce value up to a		should time out and send a new request with a new nonce value up to a
	maximum number of requests to be sent specified by the user.		maximum number of requests to be sent specified by the user.
	Authors' Addresses		Authors' Addresses
	Spyridon Mastorakis		Spyridon Mastorakis
	University of Notre Dame		University of Notre Dame
	South Bend, IN		South Bend, IN
	United States of America		United States of America
	Email: smastor2@nd.edu		Email: smastor2@nd.edu
	Dave Oran		Dave Oran
	Network Systems Research and Design		Network Systems Research and Design
	Cambridge, MA		Cambridge, MA
	United States of America		United States of America
	Email: daveoran@orandom.net		Email: daveoran@orandom.net
	Ilya Moiseenko		Ilya Moiseenko
	Apple Inc		Apple Inc.
	Cupertino, CA		Cupertino, CA
	United States of America		United States of America
	Email: iliamo@mailbox.org		Email: iliamo@mailbox.org
	Jim Gibson		Jim Gibson
	Unaffiliated		Unaffiliated
	Belmont, MA		Belmont, MA
	United States of America		United States of America
	Email: jcgibson61@gmail.com		Email: jcgibson61@gmail.com
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