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ICN Ping Protocol Specification
draft-irtf-icnrg-icnping-06

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Document	Type	Active Internet-Draft (icnrg RG)
	Authors	Spyridon Mastorakis , Jim Gibson , Ilya Moiseenko , Ralph Droms , David R. Oran
	Last updated	2022-05-03
	Replaces	draft-mastorakis-icnrg-icnping
	Stream	Internet Research Task Force (IRTF)
	Intended RFC status	Experimental
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	Additional resources	GitHub Repository Mailing list discussion
Stream	IRTF state	Awaiting IRSG Reviews
	Consensus boilerplate	Unknown
	Document shepherd	Dirk Kutscher
	Shepherd write-up	Show Last changed 2022-04-13
IESG	IESG state	I-D Exists
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	Send notices to	ietf@dkutscher.net

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draft-irtf-icnrg-icnping-06

ICNRG S. Mastorakis
Internet-Draft University of Nebraska at Omaha
Intended status: Experimental J. Gibson
Expires: 4 November 2022 Cisco Systems
I. Moiseenko
Apple Inc
R. Droms
Unaffiliated
D. Oran
Network Systems Research and Design
3 May 2022

ICN Ping Protocol Specification
draft-irtf-icnrg-icnping-06

Abstract

This document presents the design of an ICN Ping protocol. It
includes the operations of both the client and the forwarder. This
document is a product of the IRTF Information-Centric Networking
Research Group (ICNRG).

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

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
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on 4 November 2022.

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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background on IP-Based Ping Operation . . . . . . . . . . . . 4
3. Ping Functionality Challenges and Opportunities in ICN . . . 4
4. ICN Ping Echo CCNx Packet Formats . . . . . . . . . . . . . . 7
4.1. ICN Ping Echo Request CCNx Packet Format . . . . . . . . 7
4.2. Ping Echo Reply CCNx Packet Format . . . . . . . . . . . 8
5. ICN Ping Echo NDN Packet Formats . . . . . . . . . . . . . . 12
5.1. ICN Ping Echo Request NDN Packet Format . . . . . . . . . 12
5.2. Ping Echo Reply NDN Packet Format . . . . . . . . . . . . 13
6. Forwarder Handling . . . . . . . . . . . . . . . . . . . . . 14
7. Protocol Operation For Locally-Scoped Namespaces . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
11.1. Normative References . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . 17
Appendix A. Ping Client Application (Consumer) Operation . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19

1. Introduction

Ascertaining data plane reachability to a destination and taking
coarse performance measurements of round trip time are fundamental
facilities for network administration and troubleshooting. In IP,
where routing and forwarding are based on IP addresses, ICMP echo and
ICMP echo response are the protocol mechanisms used for this purpose,
generally exercised through the familiar ping utility. In ICN, where
routing and forwarding are based on name prefixes, the ability to
ascertain reachability of names is required.

This document proposes protocol mechanisms for a ping equivalent in
ICN (CCNx [RFC8609] and NDN [NDNTLV]) networks. A non-normative
appendix suggests useful properties for an ICN ping client
application, analogous to IP ping, that originates echo requests and
processes echo replies.

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In order to carry out meaningful experimentation and deployment of
ICN protocols, tools to manage and debug the operation of ICN
architectures and protocols are needed analogous to ping and
traceroute used for TCP/IP. This document describes the design of a
management and debugging protocol analogous to the ping protocol of
TCP/IP, which will aid the experimental deployment of ICN protocols.
As the community continues its experimentation with ICN architectures
and protocols, the design of ICN Ping might change accordingly. ICN
Ping is designed as a "first line of defense" tool to troubleshoot
ICN architectures and protocols. As such, this document is
classified as an experimental RFC.

This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation. This document defines an Experimental Protocol for the
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

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].

1.2. Terminology

To aid the understanding of readers, we define the following terms:

* Content object: A network-level packet that carries payload,
uniquely identified by a name, and is directly secured [RFC8793].

* Producer: An ICN entity that creates Data packets and makes them
available for retrieval [RFC8793].

* Producer's name: The name prefix that a request must carry in
order to reach a producer over an ICN network.

* Named Data: A synonym for a content object.

* Round Trip Time (RTT): The time between sending a request for a
specific piece of named data and receiving the corresponding piece
of named data.

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* Sender: An entity that sends a request for named data or a piece
of named data.

* Name of a sender: An alias of producer's name.

* Border forwarder: The forwarder that is the border of a network
region where a producer's name is directly routable (i.e., the
producer's name is present in the FIB of forwarders within this
network region).

2. Background on IP-Based Ping Operation

In IP-based ping, an IP address is specified by the user either
directly, or via translation of a domain name through DNS. The ping
client application sends a number of ICMP Echo Request packets with
the specified IP address as the IP destination address and an IP
address from the client's host as the IP source address.

Each ICMP Echo Request is forwarded across the network based on its
destination IP address. If it eventually reaches the destination,
the destination responds by sending back an ICMP Echo Reply packet to
the IP source address from the ICMP Echo Request.

If an ICMP Echo Request does not reach the destination or the Echo
reply is lost, the ping client times out. Any ICMP error messages,
such as "no route to destination", generated by the ICMP Echo Request
message are returned to the client and reported.

3. Ping Functionality Challenges and Opportunities in ICN

In ICN, the communication paradigm is based exclusively on named
objects. An Interest is forwarded across the network based on the
name prefix that it carries. Eventually, a content object is
retrieved either from a producer application or some forwarder's
Content Store (CS).

IP-based ping was built as an add-on measurement and debugging tool
on top of an already existing network architecture. In ICN, we have
the opportunity to incorporate diagnostic mechanisms directly in the
network layer protocol, and hopefully provide more powerful
diagnostic capability than can be realized through the layered ICMP
Echo approach.

An ICN network differs from an IP network in at least 4 important
ways:

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* IP identifies interfaces to an IP network with a fixed-length
address, and delivers IP packets to one or more of these
interfaces. ICN identifies units of data in the network with a
variable length name consisting of a hierarchical list of name
components.

* An IP-based network depends on the IP packets having source IP
addresses that are used as the destination address for replies.
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
end-point. Data packets follow the reverse path of the Interests
based on hop-by-hop state created during Interest forwarding.

* An IP network supports multi-path, single destination, stateless
packet forwarding and delivery via unicast, a limited form of
multi-destination selected delivery with anycast, and group-based
multi-destination delivery via multicast. In contrast, ICN
supports multi-path and multi-destination stateful Interest
forwarding and multi-destination delivery of named data. This
single forwarding semantic subsumes the functions of unicast,
anycast, and multicast. As a result, consecutive (or
retransmitted) ICN Interest messages may be forwarded through an
ICN network along different paths, and may be forwarded to
different data sources (e.g., end-node applications, in-network
storage) holding a copy of the requested unit of data. This can
lead to a significant variance in round-trip times, which while
resulting in a more robust overall forwarding architecture, has
implications for a network troubleshooting mechanism like ping.

* In the case of multiple Interests with the same name arriving at a
forwarder, a number of Interests may be aggregated in a common
Pending Interest Table (PIT) entry and only one of them forwarded
onward. Depending on the lifetime of a PIT entry, the round-trip
time an Interest-Data exchange might significantly vary (e.g., it
might be shorter than the full round-trip time to reach the
original content producer). To this end, the round-trip time
experienced by consumers might also vary.

These differences introduce new challenges, new opportunities and new
requirements in the design of an ICN ping protocol. Following this
communication model, a ping client should be able to express ping
echo requests with some name prefix and receive responses.

Our goals are the following:

* Test the reachability and the operational state of an ICN
forwarder.

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* Test the reachability of a producer or a data repository (in the
sense of whether Interests for a prefix that it serves can be
forwarded to it) and discover the forwarder with local
connectivity to (an instance of) this producer or repository.

* Test whether a specific named object is cached in some on-path CS,
and, if so, return the administrative name of the corresponding
forwarder.

* Perform some simple network performance measurements.

To this end, a ping name can represent:

* An administrative name that has been assigned to a forwarder.

* A name that includes an application's namespace as a prefix.

* A named object that might reside in some in-network storage.

In order to provide stable and reliable diagnostics, it is desirable
that the packet encoding of a ping echo request enable the forwarders
to distinguish a ping from a normal Interest, while also allowing for
forwarding behavior to be as similar as possible to that of an
Interest packet. In the same way, the encoding of a ping echo reply
should allow for forwarder processing as close as possible to that
used for data packets.

The ping protocol should also enable relatively robust round-trip
time measurements. To this end, it is important to have a mechanism
to steer consecutive ping echo requests for the same name towards an
individual path. Such a capability was initially published in
[PATHSTEERING] and has been specified for CCNx in
[I-D.oran-icnrg-pathsteering].

It is also important, in the case of ping echo requests for the same
name from different sources to have a mechanism to avoid those
requests being aggregated in the PIT. To this end, we need some
encoding in the ping echo requests to make each request for a common
name unique, hence avoiding PIT aggregation and further enabling the
exact match of a response with a particular ping packet.

Note that ICN ping is a protocol that estimates the perceived RTT
based on a single request-reply exchange. A measurement application
is needed to make proper use of this protocol to explore multiple
paths and compute various statistics, such as the variance, average,
maximum and minimum RTT values as well as loss rates.

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4. ICN Ping Echo CCNx Packet Formats

In this section, we describe the Echo Packet Format according to the
CCNx packet format [RFC8569], where messages exist within outermost
containments (packets). Specifically, we specify two types of ping
packets, an echo request and an echo reply packet type.

4.1. ICN Ping Echo Request CCNx Packet Format

The format of the ping echo 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

Figure 1: Echo Request CCNx Packet Format

The existing packet header fields have the same definition as the
header fields of a CCNx Interest packet. The value of the packet
type field is _Echo Request_. The exact numeric value of this field
type is to be assigned in the Packet Type IANA Registry for CCNx (see
section 4.1 of [RFC8569].

Compared to the typical format of a CCNx packet header from
[RFC8569], in order to enable path steering of Echo Requests, there
is an optional fixed header Path label TLV as specified in
[I-D.oran-icnrg-pathsteering] added to the packet header:

The message format of an echo request is presented below:

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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 |
| | |
+---------------+---------------+---------------+---------------+
| |
| Name TLV |
| |
+---------------+---------------+---------------+---------------+

Figure 2: Echo Request Message Format

The echo request message is of type Interest in order to leverage the
Interest forwarding behavior provided by the network. The Name TLV
has the structure described in [RFC8609]. The name consists of the
prefix that we would like to ping appended with a nonce typed name
component as its last component. The exact numeric value of this
field type is to be assigned in the Name Component Type IANA Registry
for CCNx (see section 4.5 of [RFC8609]. The value of this TLV is a
64-bit nonce. The purpose of the nonce is to avoid Interest
aggregation and allow 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

+---------------+---------------+---------------+---------------+
| | |
| Nonce_Type | Nonce_Length = 8 |
| | |
+---------------+---------------+---------------+---------------+
| |
| |
| |
| Nonce_Value |
| |
| |
+---------------+---------------+---------------+---------------+

Figure 3: Nonce Name component TLV for Echo Request messages

4.2. Ping Echo Reply CCNx Packet Format

The format of a ping echo reply packet is presented below:

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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

Figure 4: Echo Reply CCNx Packet Format

The header of an echo reply consists of the header fields of a CCNx
Content Object and a hop-by-hop Path label TLV. The value of the
packet type field is Echo Reply. The exact numeric value of this
field type is to be assigned in the Packet Type IANA Registry for
CCNx (see section 4.1 of [RFC8569]. The Path label header TLV from
[I-D.oran-icnrg-pathsteering] is as defined for the echo request
packet.

A ping echo reply message is of type Content Object, contains a Name
TLV (name of the corresponding echo request), a PayloadType TLV and
an ExpiryTime TLV with a value of 0 to indicate that echo replies
must not be returned from network caches.

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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 |
| | |
+---------------+---------------+---------------+---------------+
| |
| Name TLV |
| |
+---------------+---------------+---------------+---------------+
| |
| PayloadType TLV |
| |
+---------------+---------------+---------------+---------------+
| |
| ExpiryTime TLV |
| |
+---------------+---------------+---------------+---------------+

Figure 5: Echo Reply Message Format

The PayloadType TLV is presented below. It is of type
T_PAYLOADTYPE_DATA, and the data schema consists of 3 TLVs: 1) the
name of the sender of this reply (with the same structure as a CCNx
Name TLV), 2) the sender's signature of their own name (with the same
structure as a CCNx ValidationPayload TLV), 3) a TLV with a return
code to indicate what led to the generation of this reply (i.e.,
existence of a local application, a CS hit or a match with a
forwarder's administrative name as specified in Section 6).

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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 |
| | |
+---------------+---------------+---------------+---------------+
/ /
/ Sender's Name TLV /
/ /
+---------------+---------------+---------------+---------------+
/ /
/ Sender's Signature TLV /
/ /
+---------------+---------------+---------------+---------------+
/ /
/ Echo Reply Code TLV /
/ /
+---------------+---------------+---------------+---------------+

Figure 6: Echo Reply Message Format

The goal of including the name of the sender in the echo reply is to
enable the user to reach this entity directly to ask for further
management/administrative information using generic Interest-Data
exchanges or by employing a more comprehensive management tool such
as CCNInfo [I-D.irtf-icnrg-ccninfo] after a successful verification
of the sender's name.

The structure of the Echo Reply Code TLV is presented below (16-bit
value). The defined values are the following:

* 1: Indicates that the target name matched the administrative name
of a forwarder.

* 2: Indicates that the target name matched a prefix served by an
application.

* 3: Indicates that the target name matched the name of an object in
a forwarder's CS.

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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

+---------------+---------------+---------------+---------------+
| | |
| Echo_Reply_Code_Type | Echo_Reply_Code_Length = 2 |
| | |
+---------------+---------------+---------------+---------------+
| |
| Echo_Reply_Code_Value |
+---------------+---------------+---------------+---------------+

Figure 7: Echo Reply Code TLV

5. ICN Ping Echo NDN Packet Formats

In this section, we present the ICN Ping Echo Request and Reply
Format according to the NDN packet specification [NDNTLV].

5.1. ICN Ping Echo Request NDN Packet Format

An echo request is encoded as an NDN Interest packet. Its format is
the following:

EchoRequest = INTEREST-TYPE TLV-LENGTH
Name
MustBeFresh
Nonce
ApplicationParameters?

Figure 8: Echo Request NDN Packet Format

The name field of an echo request consists of the name prefix to be
pinged, a nonce value (it can be the value of the Nonce field) and
the suffix "ping" to denote that this Interest is a ping request
(added as a KeywordNameComponent). When the "ApplicationParameters"
element is present, a ParametersSha256DigestComponent is added as the
last name component.

The "ApplicationParameters" field of the Request contains a Path
label TLV as specified in [I-D.oran-icnrg-pathsteering].

Since the NDN packet format does not provide a mechanism to prevent
the network from caching specific data packets, we use the
MustBeFresh element for echo requests (in combination with a
Freshness Period TLV of value 1 for echo replies) to avoid fetching
cached echo replies with an expired freshness period [REALTIME].

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5.2. Ping Echo Reply NDN Packet Format

An echo reply is encoded as an NDN Data packet. Its format is the
following:

EchoReply = DATA-TLV TLV-LENGTH
Name
MetaInfo
Content
Signature
Path label TLV

Figure 9: Echo Reply NDN Packet Format

Compared to the format of a regular NDN Data packet, an echo reply
contains a Path label TLV field, which is not included in the
security envelope, since it might be modified in a hop-by-hop fashion
by the forwarders along the reverse path.

The name of an echo reply is the name of the corresponding echo
request, while the format of the MetaInfo field is the following:

MetaInfo = META-INFO-TYPE TLV-LENGTH
ContentType
FreshnessPeriod

Figure 10: MetaInfo TLV

The value of the ContentType TLV is 0. The value of the
FreshnessPeriod TLV is 1, so that the replies are treated as stale
data (almost instantly) as they are received by a forwarder.

The content of an echo reply consists of the following 2 TLVs:
Sender's name (with a structure similar as an NDN Name TLV) and Echo
Reply Code. There is 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 signature of the data producer.

The Echo Reply Code TLV format is the following (with the values
specified in Section 4.2):

EchoReplyCode = ECHOREPLYCODE-TLV-TYPE TLV-LENGTH 2*OCTET

Figure 11: Echo Reply Code TLV

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6. Forwarder Handling

We present the workflow of the forwarder's operation in Figure 12.
When a forwarder receives an echo request, it first extracts the
message's base name (i.e., the request name with the Nonce name
component excluded as well as the suffix "ping" and the
ParametersSha256DigestComponent in the case of an echo request with
the NDN packet format).

In some cases, the forwarder originates an echo reply, sending the
reply downstream through the face on which the echo request was
received. This echo reply includes the forwarder's own name and
signature and the appropriate echo reply code based on the condition
that triggered the reply generation. It also includes a Path label
TLV, initially containing a null value (since the echo reply
originator did not forward the request and, thus, does not make a
path choice).

The forwarder generates and returns an echo reply in the following
cases:

* Assuming that a forwarder has been given one or more
administrative names, the echo request base name exactly matches
any of the forwarder's administrative name(s).

* The echo request's base name exactly matches the name of a
content-object residing in the forwarder's CS (unless the ping
client application has chosen not to receive replies due to CS
hits as specified in Appendix A).

* The echo request base name matches (in a Longest Prefix Match
manner) a FIB entry with an outgoing face referring to a local
application.

If none of the conditions to reply to the echo request are met, the
forwarder will attempt to forward the echo request upstream based on
the path steering value (if present), the results of the FIB LPM
lookup and PIT creation (based on the name including the nonce typed
name component and the suffix "ping" in the case of an echo request
with the NDN packet format). If no valid next-hop is found, an
InterestReturn is sent downstream indicating "no route" (as with a
failed attempt to forward an ordinary Interest).

A received echo reply will be matched to an existing PIT entry as
usual. On the reverse path, the path steering TLV of an echo reply
will be updated by each forwarder to encode its next-hop choice.
When included in subsequent echo requests, this Path label TLV allows
the forwarders to steer the echo requests along the same path.

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------------------------------------------------------------------------
FORWARD PATH
------------------------------------------------------------------------

Request +------+ +-----+ +-----+(path label) +--------+ (match) Request
------> |Admin |->| CS |->| PIT | ------------>| Label |---------------->
| Name | +-----+ +-----+ | Lookup |
|Lookup| | | \ (no path label)+--------+
+------+ | | \ |\ (path label mismatch)
Reply | | | \ | \
<---------+ | v \ | \
(base matches | aggregate \ | \
admin name) | \ | \
| (base \ | +------+ Request
Reply | matches +----------|---->| FIB | -------->
<---------+ cached object) | +------+
| (no | | (base matches
Interest-Return (NACK) v route)| | local app
<----------------------------------------------+<-------+ | face)
<----------------------------------------------------------+
Reply
------------------------------------------------------------------------
REVERSE PATH
------------------------------------------------------------------------

Interest-return(NACK) +-----+ (update path label) Interest-Return(NACK)
<---------------------| |<-----------------------------------------
| |
Reply +------+ | PIT | (update path label) Reply
<------| CS |<------| |<-----------------------------------------
+------+ | |
+-----+
|
| (no match)
v

Figure 12: Forwarder Operation

7. Protocol Operation For Locally-Scoped Namespaces

In this section, we elaborate on 2 alternative design approaches in
cases that the pinged prefix corresponds to a locally-scoped
namespace not directly routable from the client's local network.

The first approach leverages the NDN Link Object [SNAMP].
Specifically, the ping client attaches to the expressed request a
LINK Object that contains a number of routable name prefixes, based
on which the request can be forwarded until it reaches a network

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region where the request name itself is routable. 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 retrieves a LINK
Object depends on various network design factors and is out of the
scope of the current draft.

Based on the current usage of the LINK Object by the NDN team, a
forwarder at the border of the region where an Interest name becomes
routable must remove the LINK Object from incoming Interests. The
Interest state maintained along the entire forwarding path is based
on the Interest name regardless of whether it was forwarded based on
its name or a routable prefix in the LINK Object.

The second approach is based on prepending a routable prefix to the
locally-scoped name. The resulting prefix will be the name of the
echo requests expressed by the client. In this way, a request will
be forwarded based on the routable part of its name. When it reaches
the network region where the original locally-scoped name is
routable, the border forwarder rewrites the request name and deletes
its routable part. There are two conditions for a forwarder to
perform this rewriting operation on a request: 1) the routable part
of the request name matches a routable name of the network region
adjacent to the forwarder (assuming that a forwarder is aware of
those names) and 2) the remaining part of the request name is
routable across the network region of this forwarder.

The state maintained along the path, where the locally-scoped name is
not routable, is based on the routable prefix along with the locally-
scoped prefix. Within the network region that the locally-scoped
prefix is routable, the state is based only on it. To ensure that
the generated replies reach the ping client, the border forwarder has
also to rewrite the name of a reply and prepend the routable prefix
of the corresponding echo request.

8. Security Considerations

A reflection attack could be mounted by a compromised forwarder in
the case of an echo reply with the CCNx packet format if that
forwarder includes in the reply the name of a victim forwarder. This
could convince a client to direct the future administrative traffic
towards the victim. To foil such reflection attacks, the forwarder
that generates a reply 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 the forwarder that generated the reply.
Alternatively, the forwarder could include in the reply payload their
routable prefix(es) encoded as a signed NDN Link Object [SNAMP].

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Interest flooding attack amplification is possible in the case of the
second approach to deal with locally-scoped namespaces described in
Section 7. To eliminate such amplification, a border forwarder will
have to maintain extra state in order to prepend the correct routable
prefix to the name of an outgoing reply, since the forwarder might be
attached to multiple network regions (reachable under different
prefixes) or a network region attached to this forwarder might be
reachable under multiple routable prefixes.

9. IANA Considerations

The exact numeric values of the field types of Echo requests and Echo
replies are to be assigned in the Packet Type IANA Registry for CCNx
(see section 4.1 of [RFC8569].

10. Acknowledgements

The authors would like to thank Mark Stapp for the fruitful
discussion on the objectives of the ICN ping protocol.

11. References

11.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC8569] Mosko, M., Solis, I., and C. Wood, "Content-Centric
Networking (CCNx) Semantics", RFC 8569,
DOI 10.17487/RFC8569, July 2019,
<https://www.rfc-editor.org/info/rfc8569>.

[RFC8609] Mosko, M., Solis, I., and C. Wood, "Content-Centric
Networking (CCNx) Messages in TLV Format", RFC 8609,
DOI 10.17487/RFC8609, July 2019,
<https://www.rfc-editor.org/info/rfc8609>.

[RFC8793] Wissingh, B., Wood, C., Afanasyev, A., Zhang, L., Oran,
D., and C. Tschudin, "Information-Centric Networking
(ICN): Content-Centric Networking (CCNx) and Named Data
Networking (NDN) Terminology", RFC 8793,
DOI 10.17487/RFC8793, June 2020,
<https://www.rfc-editor.org/info/rfc8793>.

11.2. Informative References

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[I-D.irtf-icnrg-ccninfo]
Asaeda, H., Ooka, A., and X. Shao, "CCNinfo: Discovering
Content and Network Information in Content-Centric
Networks", Work in Progress, Internet-Draft, draft-irtf-
icnrg-ccninfo-08, 27 July 2021,
<https://datatracker.ietf.org/doc/html/draft-irtf-icnrg-
ccninfo-08>.

[I-D.oran-icnrg-pathsteering]
Moiseenko, I. and D. Oran, "Path Steering in CCNx and
NDN", Work in Progress, Internet-Draft, draft-oran-icnrg-
pathsteering-04, 25 October 2021,
<https://datatracker.ietf.org/doc/html/draft-oran-icnrg-
pathsteering-04>.

[NDNTLV] "NDN Packet Format Specification.", 2021,
<https://named-data.net/doc/NDN-packet-spec/current/>.

[PATHSTEERING]
Moiseenko, I. and D. Oran, "Path switching in content
centric and named data networks", in Proceedings of the
4th ACM Conference on Information-Centric Networking,
2017.

[REALTIME] Mastorakis, S., Gusev, P., Afanasyev, A., and L. Zhang,
"Real-Time Data Retrieval in Named Data Networking", in
Proceedings of the 1st IEEE International Conference on
Hot Topics in Information-Centric Networking, 2017.

[SNAMP] Afanasyev, A. and , "SNAMP: Secure namespace mapping to
scale NDN forwarding", 2015.

Appendix A. Ping Client Application (Consumer) Operation

This section is an informative appendix regarding the proposed ping
client operation.

The ping client application is responsible for generating echo
requests for prefixes provided by users.

When generating a series of echo requests for a specific name, the
first echo request will typically not include a Path label TLV, since
no TLV value is known. After an echo reply containing a Path label
TLV is received, each subsequent echo request can include the
received path steering value in the Path label header TLV to drive
the requests towards a common path as part of checking network
performance. To discover more paths, a client can omit the path
steering TLV in future requests. Moreover, for each new ping echo

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request, the client has to generate a new nonce and record the time
that the request was expressed. It will also set the lifetime of an
echo request, which will have identical semantics to the lifetime of
an Interest.

Further, the client application might not wish to receive echo
replies due to CS hits. A mechanism to achieve that in CCNx would be
to use a Content Object Hash Restriction TLV with a value of 0 in the
payload of an echo request message. In NDN, the exclude filter
selector can be used.

When it receives an echo reply, the client would typically match 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
payload to parse the the sender's name and signature. The client
should 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 the payload of the reply (by fetching this forwarder's public key
and verifying the contained signature). The client can also decode
the Echo Reply Code TLV to understand the condition that triggered
the generation of the reply.

In the case that an echo reply is not received for a request 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 some
maximum number of requests to be sent specified by the user.

Authors' Addresses

Spyridon Mastorakis
University of Nebraska at Omaha
Omaha, NE
United States of America
Email: smastorakis@unomaha.edu

Jim Gibson
Cisco Systems
Cambridge, MA
United States of America
Email: gibson@cisco.com

Ilya Moiseenko
Apple Inc
Cupertino, CA
United States of America
Email: iliamo@mailbox.org

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Ralph Droms
Unaffiliated
Hopkinton, MA
United States of America
Email: rdroms.ietf@gmail.com

Dave Oran
Network Systems Research and Design
Cambridge, MA
United States of America
Email: daveoran@orandom.net

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ICN Ping Protocol Specification draft-irtf-icnrg-icnping-06

ICN Ping Protocol Specification
draft-irtf-icnrg-icnping-06