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Versions: 00 01 02                                                      
Internet Area Working Group                                       Y. Jia
Internet-Draft                                                D. Trossen
Intended status: Informational                                L. Iannone
Expires: January 13, 2022                                         Huawei
                                                               N. Shenoy
                                                               P. Mendes
                                                         D. Eastlake 3rd
                                                                  P. Liu
                                                            China Mobile
                                                           July 12, 2021

       Challenging Scenarios and Problems in Internet Addressing


   The Internet Protocol (IP) has been the major technological success
   in information technology of the last half century.  As the Internet
   becomes pervasive, IP has been replacing communication technology for
   many domain-specific solutions.  However, domains with specific
   requirements as well as communication behaviors and semantics still
   exist and represent what [RFC8799] recognizes as "limited domains".

   This document describes well-recognized scenarios that showcase
   possibly different addressing requirements, which are challenging to
   be accommodated in the IP addressing model.  These scenarios
   highlight issues related to the Internet addressing model and call
   for starting a discussion on a way to re-think/evolve the addressing
   model so to better accommodate different domain-specific

   The issues identified in this document are complemented and deepened
   by a detailed gap analysis in a separate companion document

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/.

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   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 January 13, 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Communication Scenarios in Limited Domains  . . . . . . . . .   4
     2.1.  Communication in Constrained Environments . . . . . . . .   4
     2.2.  Communication within Dynamically Changing Topologies  . .   7
     2.3.  Communication among Moving Endpoints  . . . . . . . . . .   9
     2.4.  Communication Across Services . . . . . . . . . . . . . .  12
     2.5.  Steering Communication Traffic  . . . . . . . . . . . . .  13
     2.6.  Communication with built-in security  . . . . . . . . . .  15
     2.7.  Communication in Alternative Forwarding Architectures . .  15
   3.  Issues in Addressing  . . . . . . . . . . . . . . . . . . . .  17
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .  19
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   7.  Informative References  . . . . . . . . . . . . . . . . . . .  20
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  26
     A.1.  Since draft-jia-intarea-scenarios-problems-addressing-00   26
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   The Internet Protocol (IP), positioned as the unified protocol at the
   (Internet) network layer, is seen by many as key to the innovation
   stemming from Internet-based applications and services.  Even more

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   so, with the success of TCP/IP protocol stack, IP has been gradually
   replacing existing domain-specific protocols, evolving into the core
   protocol of the entire communication system.  At its inception
   roughly 40 years ago [RFC0791], the Internet addressing system,
   represented in the form of the IP address and its locator-based
   semantics, has brought the notion of a 'common addressing for all
   communication'.  Compared to proprietary technology-specific
   solutions, such 'common addressing for all communication' advance
   ensures end-to-end communication from any device connected to the
   Internet to another.

   However, scenarios, associated services, node behaviors, and
   requirements on packet delivery have since been significantly
   extended, with Internet technologies being developed to accommodate
   them in the framework of addressing that stood at the beginning of
   the Internet's development.  This evolution is reflected in the
   concept of the "Limited Domain", first introduced in [RFC8799].  It
   refers to a single physical network, attached to or running in
   parallel with the Internet, or is defined by a set of users and nodes
   distributed over a much wider area, but drawn together by a single
   virtual network over the Internet.  Key to a limited domain is that
   requirements, behaviors, and semantics could be noticeable local and,
   more importantly, specific to the limited domain.  Very often, the
   realization of a limited domain is defined by specific communication
   scenario(s) that exhibit the domain-specific behaviors and pose the
   requirements that lead to the establishment of the limited domain.

   One key architectural aspect, when communicating within limited
   domains, is that of addressing and, therefore, the address structure,
   as well as the semantic that is being used for the routing of
   packets.  The topological location centrality of IP is fundamental
   when reconciling the often differing semantics for 'addressing' that
   can be found in those limited domains.  The result of this
   fundamental role of the single IP addressing is that limited domains
   have to adopt specific solutions, e.g., translating/mapping/
   converting concepts, semantics, and ultimately, domain-specific
   addressing, into the common IP addressing used across limited

   This document advocates flexibility in addressing in order to
   accommodate limited domain specific semantics, while, if possible,
   ensuring a single holistic addressing scheme able to reduce, or even
   entirely remove, the need for aligning the address semantics of
   different limited domains, such as the current topological location
   semantic of the Internet.  Ultimately, such holistic addressing could
   be beneficial to those communication scenarios realized within
   limited domains by improving efficiency, removing of constraints

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   imposed by needing to utilize the limited semantics of IP addressing,
   and/or in other ways.

   In other words, this document revolves around the following question:

      "Should limited domains purely rely on IP addresses and therefore
      deal with the complexity of translating any semantic mismatch
      themselves, or should flexibility for supporting those limited
      domains be a key focus for an evolved Internet addressing?"

   To that end, this document describes well-recognized scenarios in
   limited domains that could benefit from greater flexibility in
   addressing and analyses problems encountered throughout these
   scenarios due to the lack of that flexibility.  The purpose of this
   memo is thus to stimulate discussion on the emerging needs for
   addressing at large with the possibility to fundamentally re-think
   the addressing in the Internet beyond the current objectives of IPv6

   It is important to remark that any change in the addressing, hence at
   the data plane level, leads to changes and challenges at the control
   plane level, i.e., routing.  The latter is an even harder problem
   than just addressing and might need more research efforts that are
   beyond the objective of this document, which focuses solely on the
   data plane.

   The content in this document is complemented by a detailed gap
   analysis, which can be found in [GAP_ANALYSIS], that elaborates on
   the issues identified in this memo in reference to extensions to
   Internet addressing that have attempted to address those issues.

2.  Communication Scenarios in Limited Domains

   The following sub-sections outline a number of scenarios, all of
   which belong to the concept of "limited domains" [RFC8799].  While
   the list of scenarios may look long, this document focuses on
   scenarios with a number of aspects that we observe in those limited
   domains, captured in the sub-section titles.  For each scenario, we
   point at possible challenges, which we will pick upon in Section 3,
   when describing more formally the existing shortcomings in current
   Internet addressing.

2.1.  Communication in Constrained Environments

   In a number of communication scenarios, such as those encountered in
   the Internet of Things (IoT), a simple, low-cost communication
   network is required, and there are limitations for network devices in
   computational power, memory, and energy availability.  In addition to

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   IEEE 802.15.4, i.e., Low-Rate Wireless Personal Area Network
   [LR-WPAN], several limited domains exist through utilizing link layer
   technologies such as Bluetooth Low Energy (BLE) [BLE], Digital
   European Cordless Telecommunications (DECT) - Ultra Low Energy (ULE)
   [DECT-ULE], Master-Slave/Token-Passing (MS/TP) [BACnet], Near-Field-
   Communication (NFC) [ECMA-340], and Power Line Communication (PLC)

   Generally, a group of IoT network devices form a constrained nodes
   network at the edge, and IoT terminals connect to these network
   devices for data transmission.  This type of networks and IoT devices
   in the network require as little computational power as possible,
   small memory requirements, good energy availability to reduce the
   total cost of ownership of the network.  Furthermore, in the context
   of industrial IoT, real-time requirements and scalability make IP
   technology not naturally suitable as communication technology

   The end-to-end principle (detailed in [RFC2775]) requires Internet
   protocols (e.g., IPv6 [RFC8200]) to run on such constrained node
   networks, allowing IoT devices using multiple communication
   technologies to talk on the Internet.  Often, devices located at the
   edge of constrained networks act as gateway devices, usually
   performing header compression ([RFC4919]).  To ensure security and
   reliability, multiple gateways must be deployed.  IoT devices on the
   network can select one of those gateways for traffic passthrough by
   the devices on the (limited domain) network.

   Given the constraints imposed on the computational and possibly also
   communication technology, the usage of a single addressing semantic
   in the form of a 128-bit endpoint identifier, i.e., IPv6 address, may
   pose a challenge when operating such networks.

   Another example of a constrained environment is an aircraft, which
   encompasses not only passenger communication but also the integration
   of real-time data exchange to ensure that processes and functions in
   the cabin are automatically monitored or actuated.  Two possible
   examples are large scale passenger aircraft and military aircraft.

   Large scale passenger aircraft (and their networks) have high
   requirements placed on them for performance, efficiency, and high
   dispatch reliability.  Additionally, due to their size and commercial
   operation, they often have multiple network domains, including high
   criticality Aircraft Control Domain networks, Aircraft Information
   Services Domain, as well as Passenger Information Entertainment
   System Domains.  The onboard presence of multiple domains, especially
   when interconnected, as well as design assurance levels drives a wide

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   variety of traffic requirements and additional security requirements
   on network implementations.

   In what concerns avionics networks, the goal for any aircraft network
   is to be able to send and receive information reliably and
   seamlessly.  From this perspective, the medium with which these
   packets of information are sent is of little consequence so long as
   there is a level of determinism to it.  However, there is currently
   no effective method in implementing wireless inter- and intra-
   communications between all subsystems.  The emerging wireless sensor
   network technology in commercial applications such as smart
   thermostat systems, and smart washer/dryer units could be transposed
   onto aircraft and fleet operations.  The proposal for having an
   Wireless Avionics Intra-Communications (WAIC) system promises
   reduction in the complexity of electrical wiring harness design and
   fabrication, reduction in wiring weight, increased configuration, and
   potential monitoring of otherwise inaccessible moving or rotating
   aircraft parts.  Similar to the IoT concept, WAIC systems consist of
   short-range communications and are a potential candidate for
   passenger entertainment systems, smoke detectors, engine health
   monitors, tire pressure monitoring systems, and other kinds of
   aircraft maintenance systems.

   While there are still many obstacles in terms of network security,
   traffic control, and technical challenges, future WAIC can enable
   real-time seamless communications between aircraft and between ground
   teams and aircraft as opposed to the discrete points of data
   leveraged today in aircraft communications.  For that, WAIC
   infrastructure should also be connected to outside IP based networks
   in order to access edge/cloud facilities for data storage and mining.
   However, the restricted capacity (energy, communication) of most
   aircraft devices (e.g. sensors) and the nature of the transmitted
   data - periodic transmission of small packets - may pose some
   challenges for the usage of a single addressing semantic in the form
   of a 128-bit endpoint identifier, i.e., an IPv6 address.  Moreover,
   most of the aircraft applications and services are focused on the
   data (e.g. temperature of gas tank on left wing) and not on the
   topological location of the data source.  This means that the current
   topological location semantic of IP addresses is not beneficial for
   aircraft applications and services.

   Greater flexibility in Internet addressing may avoid complex and
   energy hungry operations, like header compression and fragmentation,
   necessary to translate protocol headers from one limited domain to
   another, while enabling semantics different from locator-based
   addressing may better support the communication that occurs in those

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2.2.  Communication within Dynamically Changing Topologies

   Communication may occur over networks that exhibit dynamically
   changing topologies.  One such example is that of satellite networks,
   providing global Internet connections through a combination of inter-
   satellite and ground station communication.  With the convergence of
   space-based and terrestrial networks, users can experience seamless
   broadband access, e.g., on cruise ships, flights, and within cars,
   often complemented by and seamlessly switching between Wi-Fi,
   cellular, or satellite based networks at any time.

   The satellite network service provider will plan the transmission
   path of user traffic based on the network coverage, satellite orbit,
   route, and link load, providing potentially high-quality Internet
   connections for users in areas that are not, or hard to be, covered
   by terrestrial networks.  The involved topologies of the satellite
   network will be changing constantly while observing a regular flight
   pattern in relation to other satellite and predictable overflight
   patterns to ground users.

   Although satellite bearer services are capable of transporting IPv4
   and IPv6, as well as associated protocols such as IP Multicast, DNS
   services and routing information, no IP functionality is implemented
   on-board the spacecraft limiting the capability of leveraging for
   instance large scale satellite constellations.

   One of the major constraints of deploying routing capability on board
   a satellite is power consumption.  Due to this, space routers may end
   up being intermittently powered up during a daytime sunlit pass.
   Another limitation of the first generation of IP routers in space was
   the lack of capability to remotely manage and upgrade software while
   in operation.  This will lead to an intermittent operation of the
   space router.

   The limitations faced in early development of IP based satellite
   communication payloads, showed the need to develop a flexible
   networking solution that would only allow delay tolerant
   communications in the present of intermittent connectivity as well as
   a networking solution able to perform in a scenario encompassing
   mobile devices with the capability of storing data, leading to a
   significant reduction of latency, which is the major impairment of
   satellite networks.  However, the inefficiencies of the current
   Internet architecture with regard to different aspects such as
   mobility, traffic management, or content delivery have progressively
   led to the ossification of the Internet.  The root of these
   inefficiencies is the fact that the current Internet host centric
   model does not match the Internet dominant usage, which involves end-
   users exchanging information or accessing services, independently of

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   the device where the information is located or which provides the
   service.  Moreover the current IP addressing schemes, with focus on
   IP unicast addressing with extended deployment of IP multicast and
   some IP anycast do not take advantage of the broadcast nature of
   satellite networks.  Moreover networking platforms based on a name
   (data or service) based addressing scheme would bring several
   potential benefits to satellite networks aiming to tackle their major
   challenges, including high propagation delay and changing network
   topology in the case of LEO constellations.

   Another example is that of vehicular communication, where services
   may be accessed across vehicles, such as self-driving cars, for the
   purpose of collaborative objection recognition (e.g., for collision
   avoidance), road status conveyance (e.g., for pre-warning of road-
   ahead conditions), and other purposes.  Communication may include
   Road Side Units (RSU) with the possibility to create ephemeral
   connections to those RSUs for the purpose of workload offloading,
   joint computation over multiple (vehicular) inputs, and other
   purposes [I-D.ietf-lisp-nexagon].  Communication here may exhibit a
   multi-hop nature, not just involving the vehicle and the RSU over a
   direct link.  Those topologies are naturally changing constantly due
   to the dynamic nature of the involved communication nodes.

   The advent of Flying Ad-hoc NETworks (FANETs) has opened up an
   opportunity to create new added-value services.  Although these
   networks share common features with vehicular ad hoc networks, they
   present several unique characteristics such as energy efficiency,
   mobility degree, the capability of swarming, and the potential large
   scale of swarm networks.  Due to high mobility of FANET nodes, the
   network topology changes more frequently than in a typical vehicular
   ad hoc network.  From a routing point of view, although ad-hoc
   reactive and proactive routing approaches can be used, there are
   other type of routing protocols that have been developed for FANETS,
   such as hybrid routing protocols and position based routing
   protocols, aiming to increase efficiency in large scale networks with
   dynamic topologies.

   Both type of protocols challenge the current Internet addressing
   semantic: in the case of hybrid protocols, two different routing
   strategies are used inside and outside a network zone.  While inside
   a zone packets are routed to a specific destination IP address,
   between zones, query packets are routed to a subset of neighbors as
   determined by a bordercast algorithm.  In the case of position based
   routing protocol, the IP addressing scheme is not used at all, since
   packets are routing to a different identifier, corresponding to the
   geographic location of the destination and not its topological

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   Moreover most of the application/services deployed in FANETs tend to
   be agnostic of the topological location of nodes, being instead focus
   on the location of data or services.  This distinction is even more
   important because is dynamic network such as FANET robust networking
   solutions may rely on the redundancy of data and services, meaning
   that they may be found in more than one device in the network.

   In the aforementioned network technologies, there is a significant
   difference between the high dynamics of the underlying network
   topologies, compared to the relative static nature of terrestrial
   network topology, as reported in [HANDLEY].  As a consequence, the
   notion of a topological network location becomes restrictive in the
   sense that not only the relation between network nodes and user
   endpoint may change, but also the relation between the nodes that
   form the network itself.  This may lead to the challenge of
   maintaining and updating the topological addresses in this constantly
   changing network topology.

   In attempts to utilize entirely different semantics for the
   addressing itself, geographic-based routing, such as in [CARTISEAN],
   has been proposed for MANETs (Mobile Ad-hoc NETworks) through
   providing geographic coordinates based addresses to achieve better
   routing performance, lower overhead, and lower latency [MANET1].

   Flexibility in Internet addressing here would allow for accommodating
   such geographic address semantics into the overall Internet
   addressing, while also enabling name/content-based addressing,
   utilizing the redundancy of many network locations providing the
   possible data.

2.3.  Communication among Moving Endpoints

   When packet switching was first introduced, back in the 60s/70s, it
   was intended to replace the rigid circuit switching with a
   communication infrastructure that was more resilient to failures.  As
   such, the design never really considered communication endpoints as
   mobile.  Even in the pioneering ALOHA [ALOHA] system, despite
   considering wireless and satellite links, the network was considered
   static (with the exception of failures and satellites, which fall in
   what is discussed in Section 2.2).  Ever since, a lot of efforts have
   been devoted to overcome such limitations once it became clear that
   endpoint mobility will become a main (if not THE main) characteristic
   of ubiquitous communication systems.

   The IETF has for a long time worked on solutions that would allow
   extending the IP layer with mobility support.  Because of the
   topological semantic of IP addresses, endpoints need to change
   addresses each time they visit a different network.  However, because

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   routing and endpoint identification is also IP address based, this
   leads to a communication disruption.

   To cope with such a situation, anchor-based Mobile IP mechanisms have
   been introduced ([RFC5177], [RFC6626] [RFC5944], [RFC5275]).  Mobile
   IP is based on a relatively complex and heavy mechanism that makes it
   hard to deploy and it is not very efficient.  Furthermore, it is even
   less suitable than native IP in constrained environments like the
   ones discussed in Section 2.1.

   Alternative approaches to Mobile IP often leverage the introduction
   of some form of overlay.  LISP [I-D.ietf-lisp-introduction], by
   separating the topological semantic from the identification semantic
   of IP addresses, is able to cope with endpoint mobility by
   dynamically mapping endpoint identifiers with routing locators
   [I-D.ietf-lisp-mn].  This comes at the price of an overlay that needs
   its own additional control plane [I-D.ietf-lisp-rfc6833bis].

   Similarly, the NVO3 (Network Virtualization Overlays) Working Group,
   while focusing on Data Center environments, also explored an overlay-
   based solution for multi-tenancy purposes, but also resilient to
   mobility since relocating Virtual Machines (VMs) is common practice.
   NVO3 considered for a long time several data planes that implement
   slightly different flavors of overlays ([RFC8926], [RFC7348],
   [I-D.ietf-intarea-gue]), but lacks an efficient control plane
   specifically tailored for DCs.

   Alternative mobility architectures have also been proposed in order
   to cope with endpoint mobility outside the IP layer itself.  The Host
   Identity Protocol (HIP) [RFC7401] introduced a new namespace in order
   to identify endpoints, namely the Host Identity (HI), while
   leveraging the IP layer for topological location.  On the one hand,
   such an approach needs to revise the way applications interact with
   the network layer, by modifying the DNS (now returning an HI instead
   of an IP address) and applications to use the HIP socket extension.
   On the other hand, early adopters do not necessarily gain any benefit
   unless all communicating endpoints upgrade to use HIP.  In spite of
   this, such a solution may work in the context of a limited domain.

   Another alternative approach is adopted by Information-Centric
   Networking (ICN) [RFC7476].  By making content a first class citizen
   of the communication architecture, the "what" rather than the "where"
   becomes the real focus of the communication.  However, as explained
   in the next sub-section, ICN can run either over the IP layer or
   completely replace it, which in turn can be seen as running the
   Internet and ICN as logically completely separated limited domains.

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   Sometimes, the transport layer gets involved in mobility solutions,
   either by introducing explicit in-band signaling to allow for
   communicating IP address changes (e.g., in SCTP [RFC5061] and MPTCP
   [RFC6182]), or by introducing some form of connection ID that allows
   for identifying a communication independently from IP addresses
   (e.g., the connection ID used in QUIC [QUIC]).

   Unmanned Aircraft Systems (UAS) are examples of moving devices that
   require a stable mobility management scheme since they consist of a
   number of Unmanned Aerial Vehicles (UAV) subordinated to a Ground
   Control Station (GCS).  The information produced by the different
   sensors and electronic devices available at each UAV is collected and
   processed by a software or hardware data acquisition unit, being
   transmitted towards the GCS, where it is inspected and/or analyzed.
   Analogously, control information transmitted from the GCS to the UAV
   enables the execution of control operations over the aircraft, such
   as changing the route planning or the direction pointed by a camera.

   Although UAVs may have redundant links to maintain communications in
   long-range missions (e.g., satellite), most of the communications
   between the GCS and the UAVs take place over wireless data links,
   e.g., based on a radio line-of-sight technology, Wi-Fi or 3G/4G.
   While in some scenarios, UAVs will operate always under the range of
   the same cellular base station, in missions with large range, UAVs
   will move between different cellular or wireless ground
   infrastructure, meaning that the UAV needs to upload its topological
   locator and re-start the ongoing communication sessions.  In such
   cases, most of existing Mobile IP approaches may play a role, as well
   as approaches to split the UAV identifier and the topological
   locator, such as HIP.

   However, while the industry is given the first steps towards evolved
   UAS architectures and communication models, the data-centric
   communication plays an increasing role, where information is named
   and decoupled from its location, and applications/services operate
   over these named data rather than on host-to-host communications.

   In this context, the Data Distribution Service (DDS) has emerged as
   an industry-oriented open standard that follows this approach.  The
   space and time decoupling allowed by DDS is very relevant in any
   dynamic and distributed system, since interacting entities are not
   forced to know each other and are not forced to be simultaneously
   present to exchange data.  Time decoupling can significantly simplify
   the management of intermittent data-links, in particular for wireless
   connectivity between UAS, as well as facilitate seamless UAV mobility
   between GCSs.

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   In the case of using TCP/IP, mobility of UAVs introduces a
   significant challenge.  Consider the case where a GCS is receiving
   telemetry information from a specific UAV.  Assuming that the UAV
   moves and changes its point of attachment to the network, it will
   have to configure a new IP address on its wireless interface.
   However, this is problematic, as the telemetry information is still
   being sent by to the previous IP address of the UAV.  This simple
   example illustrates the necessity to deploy mobility management
   solutions to handle this type of situations.

   However, mobility management solutions increase the complexity of the
   deployment and may impact the performance of data distribution, both
   in terms of signaling/data overhead and communication path delay.
   Considering the specific case of multicast data streams, mobility of
   content producers and consumers is inherently handled by multicast
   routing protocols, which are able to react to changes of location of
   mobile nodes by reconstructing the corresponding multicast delivery
   trees.  Nevertheless, this comes with a cost in terms of signaling
   and data overhead (data may still flow through branches of a
   multicast delivery tree where there are no receivers while the
   routing protocol does not converge).

   Another alternative it to perform the mobility management of
   producers and consumers not at the application layer based on IP
   multicast trees, but on the network layer based on an Information
   Centric Network approach, which was already mentioned in this

   Greater flexibility in addressing may help in dealing with mobility
   more efficiently, e.g., through an augmented semantic that may fulfil
   the mobility requirements [RFC7429].

2.4.  Communication Across Services

   As a communication infrastructure spanning many facets of life, the
   Internet integrates services and resources from various aspects such
   as remote collaboration, shopping, content production as well as
   delivery, education, and many more.  Accessing those services and
   resources directly through URIs has been proposed by methods such as
   those defined in ICN [RFC7476], where providers of services and
   resources can advertise those through unified identifiers without
   additional planning of identifiers and locations for underlying data
   and their replicas.  Users can access required services and resources
   by virtue of using the URI-based identification, with an ephemeral
   relationship built between user and provider, while the building of
   such relationship may be constrained with user- as well as service-
   specific requirements, such as proximity (finding nearest provider),
   load (finding fastest provider), and others.

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   While systems like ICN [CCN] provide an alternative to the locator-
   based addressing of IP, its deployment requires an overlay (over IP)
   or native deployment (alongside IP), the latter with dedicated
   gateways needed for translation.  Underlay deployments are also
   envisioned in [RFC8763], where ICN solutions are being used to
   facilitate communication between IP addressed network endpoints or
   URI-based service endpoints, still requiring gateway solutions for
   interconnection with ICN-based networks as well as IP routing based
   networks (cf., [ICN5G][ICNIP]).

   Although various approaches combining service and location-based
   addressing have been devised, the key challenge here is to facilitate
   a "natural", i.e., direct communication, without the need for
   gateways above the network layer.

   Another aspect of communication across services is that of chaining
   individual services to a larger service.  Here, an identifier would
   be used that serves as a link to next hop destination within the
   chain of single services, as done in the work on Service Function
   Chaining (SFC).  With this, services are identified at the level of
   Layer 2/3 ([RFC7665], [RFC8754], [RFC8595]) or at the level of name-
   based service identifiers like URLs [RFC8677] although the service
   chain identification is carried as an NSH header ([RFC7665], separate
   to the packet identifiers.  The forwarding with the chain of services
   utilizes individual locator-based IP addressing (for L3 chaining) to
   communicate the chained operations from one Service Function
   Forwarder [RFC7665] to another, leading to concerns regarding
   overhead incurred through the stacking of those chained identifiers
   in terms of packet overhead and therefore efficiency in handling in
   the intermediary nodes.

   Greater flexibility in addressing may allow for incorporating
   different information, e.g., service as well as chaining semantics,
   into the overall Internet addressing.

2.5.  Steering Communication Traffic

   Steering traffic within a communication scenario may involve at least
   two aspects, namely (i) limiting certain traffic towards a certain
   set of communication nodes and (ii) constraining the sending of
   packets towards a given destination (or a chain of destinations) with
   metrics that would allow the selection among one or more possible

   One possibility for limiting traffic inside limited domains, towards
   specific objects, e.g., devices, users, or group of them, is subnet
   partition with techniques such as VLAN [RFC5517], VxLAN [RFC7348], or
   more evolved solution like TeraStream [TERASTREAM] realizing such

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   partitioning.  Such mechanisms usually involve significant
   configuration, and even small changes in network and user nodes could
   result in a repartition and possibly additional configuration
   efforts.  Another key aspect is the complete lack of correlation of
   the topological address and any likely more semantic-rich
   identification that could be used to make policy decisions regarding
   traffic steering.  Suitably enriching the semantics of the packet
   address, either that of the sender or receiver, so that such decision
   could be made while minimizing the involvement of higher layer
   mechanisms, is a crucial challenge for improving on network
   operations and speed of such limited domain traffic.

   When making decisions to select one out of a set of possible
   destinations for a packet, IP anycast semantics can be applied albeit
   being limited to the locator semantic of the IP address itself.
   Recent work in [SFCANYCAST] suggests utilizing the notion of IP
   anycast address to encode a "service identifier", which is
   dynamically mapped onto network locations where service instances
   fulfilling the service request may be located.  Scenarios where this
   capability may be utilized are provided in [SFCANYCAST] and include,
   but are not limited to, scenarios such as edge-assisted VR/AR,
   transportation, and digital twins.

   The challenge here lies in the possible encoding of not only the
   service information itself but the constraint information that helps
   the selection of the "best" service instance and which is likely a
   service-specific constraint in relation to the particular scenario.
   The notion of an address here is a conditional (on those constraints)
   one where this conditional part is an essential aspect of the
   forwarding action to be taken.  It needs therefore consideration in
   the definition of what an address is, what is its semantic, and how
   the address structure ought to look like.

   As outlined in the previous sub-section, chaining services are
   another aspect of steering traffic along a chain of constituent
   services, where the chain is identified through either a stack of
   individual identifiers, such as in Segment Routing [RFC8402], or as
   an identifier that serves as a link to next hop destination within
   the chain, such as in Service Function Chaining (SFC).  The latter
   can be applied to services identified at the level of Layer 2/3
   ([RFC7665], [RFC8754], [RFC8595]) or at the level of name-based
   service identifiers like URLs [RFC8677].  However, the overhead
   incurred through the stacking of those chained identifiers is a
   concern in terms of packet overhead and therefore efficiency in
   handling in the intermediary nodes.

   Flexibility in addressing may enable more semantic rich encoding
   schemes that may help in steering traffic at hardware level and

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   speed, without complex mechanisms usually resulting in handling
   packets in the slow path of routers.

2.6.  Communication with built-in security

   Today, strong security and privacy in the Internet is usually
   implemented as an overlay based on the concept of Mix Networks
   ([TOR], [SPHINX]).  Among the various reasons for such approach is
   the limited semantic of current IP addresses, which do not allow to
   natively express security features or trust relationships.  Efforts
   like Cryptographically Generated Addresses (CGA) [RFC3972], provide
   some security features by embedding a truncated public key in the
   last 57-bit of IPv6 address, thereby greatly enhancing authentication
   and security within an IP network via asymmetric cryptography and
   IPsec [RFC4301].  The development of the Host Identity Protocol (HIP)
   [RFC7401] saw the introduction of cryptographic identifiers for the
   newly introduced Host Identity (HI) to allow for enhanced
   accountability, and therefore trust.  The use of those HIs, however,
   is limited by the size of IPv6 128bit addresses.

   Through a greater flexibility in addressing, any security-related
   key, certificate, or identifier could instead be included in a
   suitable address structure without any information loss (i.e., as-is,
   without any truncation or operation as such), avoiding therefore
   compromises such as those in HIP.  Instead, CGAs could be created
   using full length certificates, or being able to support larger HIP
   addresses in a limited domain that uses it.  This could significantly
   help in constructing a trusted and secure communication at the
   network layer, leading to connections that could be considered as
   absolute secure (assuming the cryptography involved is secure).  Even
   more, anti-abuse mechanisms and/or DDoS protection mechanisms like
   the one under discussion in PEARG ([PEARG]) Research Group may
   leverage a greater flexibility of the overall Internet addressing, if
   provided, in order to be more effective.

2.7.  Communication in Alternative Forwarding Architectures

   The performance of communication networks has long been a focus for
   optimization due to the immediate impact on cost of ownership for
   communication service providers.  Technologies like MPLS [RFC3031]
   have been introduced to optimize lower layer communication, e.g., by
   mapping L3 traffic into aggregated labels of forwarding traffic for
   the purposes of, e.g., traffic engineering.

   Even further, other works have emerged in recent years that have
   replaced the notion of packets with other concepts for the same
   purpose of improved traffic engineering and therefore efficiency
   gains.  One such area is that of Software Defined Networks (SDN)

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   [RFC7426], which has highlighted how a majority of Internet traffic
   is better identified by flows, rather than packets.  Based on such
   observation, alternate forwarding architectures have been devised
   that are flow-based or path-based.  With this approach, all data
   belonging to the same traffic stream is delivered over the same path,
   and traffic flows are identified by some connection or path
   identifier rather than by complete routing information, possibly
   enabling fast hardware based switching.

   On the one hand, such a communication model may be more suitable for
   real-time traffic like in the context of Deterministic Networks
   ([DETNET]), where indeed a lot of work has focused on how to
   "identify" packets belonging to the same DETNET flow in order to
   jointly manage the forwarding within the desired deterministic

   On the other hand, it may improve the communication efficiency in
   constrained wireless environments (cf., Section 2.1), by reducing the
   overhead, hence increasing the number of useful bits per second per

   Also, the delivery of information across similar flows may be
   combined into a multipoint delivery of a single return flow, e.g.,
   for scenarios of requests for a video chunk from many clients being
   responded to with a single (multi-destination) flow, as outlined in
   [BIER-MC] as an example.  Another opportunity to improve
   communication efficiency is being pursued in ongoing IETF/IRTF work
   to deliver IP- or HTTP-level packets directly over path-based or
   flow-based transport network solutions, such as in
   [TROSSEN][BIER-MC][ICNIP][ICN5G] with the capability to bundle
   unicast forward communication streams flexibly together in return
   path multipoint relations.  Such capability is particularly opportune
   in scenarios such as chunk-based video retrieval or distributed data
   storage.  However, those solutions currently require gateways to
   "translate" the flow communication into the packet-level addressing
   semantic in the peering IP networks.  Furthermore, the use of those
   alternative forwarding mechanisms often require the encapsulation of
   Internet addressing information, leading to wastage of bandwidth as
   well as processing resources.

   Providing an alternative way of forwarding data has also been the
   motivation for the efforts created in the European Telecommunication
   Standards Institute (ETSI), which formed a Industry Specification
   Group (ISG) named Non-IP Networking (NIN) [ETSI-NIN].  This group
   sets out to develop and standardize a set of protocols leveraging an
   alternative forwarding architecture, such as provided by a flow-based
   switching paradigm.  The deployment of such protocols may be seen to
   form limited domains, still leaving the need to interoperate with the

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   (packet-based forwarding) Internet; a situation possibly enabled
   through a greater flexibility of the addressing used across Internet-
   based and alternative limited domains alike.

   As an alternative to IP routing, EIBP (Extended Internet Bypass
   Protocol) [EIBP] offers a communications model that can work with IP
   in parallel and entirely transparent and independent to any operation
   at network layer.  For this, EIBP proposes the use of physical and/or
   virtual structures in networks and among networks to auto assign
   routable addresses that capture the relative position of routers in a
   network or networks in a connected set of networks, which can be used
   to route the packets between end domains.  EIBP operates at Layer 2.5
   and provides encapsulation (at source domain), routing, and de-
   encapsulation (at destination domain) for packets.  EIBP can forward
   any type of packets between domains.  A resolver to map the domain ID
   to EIBP's edge router addresses is required.  When queried for a
   specific domain, the resolver will return the corresponding edge
   router structured addresses.

   EIBP decouples routing operations from end domain operations,
   offering to serve any domain, without point solutions to specific
   domains.  EIBP also decouples routing IDs or addresses from end
   device/domain addresses.  This allows for accommodation of new and
   upcoming domains.  A domain can extend EIBP's structured addresses
   into the domain, by joining as a nested domain under one or more edge
   routers, or by extending the edge router's structure addresses to its

   A greater flexibility in addressing semantics may reduce the
   aforementioned wastage by accommodating Internet addressing in the
   light of such alternative forwarding architectures, instead enabling
   the direct use of the alternative forwarding information.

3.  Issues in Addressing

   There are a number of issues that we can identify from the
   communication scenarios in Section 2, not claiming to be exhaustive
   in our list:

   1.  Limiting Alternative Address Semantics: Several communication
       scenarios pursue the use of alternative semantics of what
       constitute an 'address' of a packet traversing the Internet,
       which may fall foul of the defined network interface semantic of
       IP addresses.

   2.  Hampering Security: Aligning with the semantic and length
       limitations of IP addressing may hamper the security objectives
       of any new semantic, possibly leading to detrimental effects and

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       possible other workarounds (at the risk of introducing fragility
       rather than security).

   3.  Complicating Traffic Engineering: Utilizing a plethora of non-
       address inputs into the traffic steering decision in real
       networks complicates traffic engineering in that it makes the
       development of suitable policies more complex, while also leading
       to possible contention between methods being used.

   4.  Hampering Efficiency: Extending IP addressing through point-wise
       solutions also hampers efficiency, e.g., through needed re-
       encapsulation (therefore increasing the header processing
       overhead as well as header-to-payload ratio), through introducing
       path stretch, or through requiring compression techniques to
       reduce the header proportion of large addresses when operating in
       constrained environments.

   5.  Fragility: The introduction of point solutions, each of which
       comes with possibly own usages of address or packet fields,
       together with extension-specific operations, increases the
       overall fragility of the resulting system, caused, for instance,
       through contention between feature extensions that were neither
       foreseen in the design nor tested during the implementation

   6.  Extensibility: Accommodating new requirements through ever new
       extensions as an extensibility approach to addressing compounds
       aspects discussed before, i.e., fragility, efficiency etc.  It
       complicates engineering due to the clearly missing boundaries
       against which contentions with other extensions could be managed.
       It complicates standardization since extension-based
       extensibility requires independent, and often lengthy,
       standardization processes.  And ultimately, deployments are
       complicated due to backward compatibility testing required for
       any new extension being integrated into the deployed system.

   The table below shows how the above identified issues do arise
   somehow in our outlined communication scenarios in Section 2.  This
   overview will be deepened in more detail in the gap analysis document

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   |                   | Issue | Issue | Issue | Issue | Issue | Issue |
   |                   | 1     | 2     | 3     | 4     | 5     | 6     |
   | Constrained       |       |       |       | x     | x     | x     |
   | Environments      |       |       |       |       |       |       |
   |                   |       |       |       |       |       |       |
   | Dynamically       | x     |       | x     | x     | x     | x     |
   | Changing          |       |       |       |       |       |       |
   | Topologies        |       |       |       |       |       |       |
   |                   |       |       |       |       |       |       |
   | Moving Endpoints  | x     |       | x     | x     | x     | x     |
   |                   |       |       |       |       |       |       |
   | Across Services   | x     |       | x     | x     | x     | x     |
   |                   |       |       |       |       |       |       |
   | Traffic Steering  | x     |       | x     | x     | x     | x     |
   |                   |       |       |       |       |       |       |
   | Built-in Security | x     | x     |       | x     | x     | x     |
   |                   |       |       |       |       |       |       |
   | Alternative       | x     |       |       | x     |       | x     |
   | Forwarding        |       |       |       |       |       |       |
   | Architectures     |       |       |       |       |       |       |

             Table 1: Issues Involved in Challenging Scenarios

4.  Problem Statement

   This document highlights that the conceptual framework of limited
   domains positions the many extensions to IP addressing as approaches
   to accommodate new requirements in emerging communication scenarios,
   each of which are being often deployed within limited domains.

   While this may be interpreted as a crucial point to the flexibility
   of addressing in the Internet in order to accommodate those ever
   increasing number of communication scenarios, we have identified a
   number of issues (as described in this document) that position the
   existing Internet addressing structure itself as a potential
   hinderance in solving key problems for Internet service provisioning.
   Such problems include supporting new, e.g., service-oriented,
   scenarios more efficiently, with improved security and efficient
   traffic engineering, as well as large scale mobility.

   Referring back to our introductory question on flexibility in
   addressing (or leaving the problem to limited domain solutions to
   deal with), we offer at this stage no definite answer nor do we
   propose or promote specific solutions to the problems here portrayed.
   Instead, this document aims at stimulating discussion on the emerging

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   needs for addressing with the possibility to fundamentally re-think
   the addressing in the Internet beyond the current objectives of IPv6.

   To complement our problem statement in this document, the companion
   gap analysis document [GAP_ANALYSIS] deepens the issues identified in
   Section 3 along key properties of today's Internet addressing.

5.  Security Considerations

   The present memo does not introduce any new technology and/or
   mechanism and as such does not introduce any security threat to the
   TCP/IP protocol suite.

   Nevertheless, it is worth to observe whether or not greater
   flexibility of addressing (as suggested in previous sections) would
   allow to introduce fully featured security in endpoint
   identification, potentially able to eradicate the spoofing problem,
   as one example.  Furthermore, it may be used to include application
   gateways' certificates in order to provide more efficiency, e.g.,
   using web certificates also in the addressing of web services.  While
   increasing security, privacy protection may also be improved.

6.  IANA Considerations

   This document does not include an IANA request.

7.  Informative References

   [ALOHA]    Kuo, F., "The ALOHA System", ACM SIGCOMM Computer
              Communication Review Vol. 25, pp. 41-44,
              DOI 10.1145/205447.205451, January 1995.

   [BACnet]   "BACnet-A Data Communication Protocol for Building
              Automation and Control Networks", ANSI/ASHRAE Standard
              135-2016, January 2016,

   [BIER-MC]  Trossen, D., Rahman, A., Wang, C., and T. Eckert,
              "Applicability of BIER Multicast Overlay for Adaptive
              Streaming Services", draft-ietf-bier-multicast-http-
              response-05 (work in progress), January 2021.

   [BLE]      "Bluetooth Specification", Bluetooth SIG Working Groups,
              n.d., <https://www.bluetooth.com/specifications>.

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              Hughes, L., Shumon, K., and Y. Zhang, "Cartesian Ad Hoc
              Routing Protocols", Ad-Hoc, Mobile, and Wireless
              Networks pp. 287-292, DOI 10.1007/978-3-540-39611-6_27,

   [CCN]      Jacobson, V., Smetters, D., Thornton, J., Plass, M.,
              Briggs, N., and R. Braynard, "Networking named content",
              Proceedings of the 5th international conference on
              Emerging networking experiments and technologies -
              CoNEXT '09, DOI 10.1145/1658939.1658941, 2009.

              "Digital Enhanced Cordless Telecommunications (DECT);
              Common Interface (CI); Part 1: Overview", ETSI European
              Standard, EN 300 175-1, V2.6.1, May 2009,

   [DETNET]   "Deterministic Networking (DetNet)", n.d.,

              EECMA-340, "Near Field Communication - Interface and
              Protocol (NFCIP-1) 3rd Ed.", June 2013.

   [EIBP]     Shenoy, N., Chandraiah, S., and P. Willis, "A Structured
              Approach to Routing in the Internet", First Intl Workshop
              on Semantic Addressing and Routing for Future Networks ,
              June 2021.

              ETSI - European Telecommunication Standards Institute,
              "Non-IP Networking - NIN", n.d.,

              Jia, Y., Trossen, D., Iannone, L., Shenoy, N., and P.
              Mendes, "Gap Analysis in Internet Addressing", July 2021,

   [HANDLEY]  Handley, M., "Delay is Not an Option: Low Latency Routing
              in Space", Proceedings of the 17th ACM Workshop on Hot
              Topics in Networks, DOI 10.1145/3286062.3286075, November

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              Herbert, T., Yong, L., and O. Zia, "Generic UDP
              Encapsulation", draft-ietf-intarea-gue-09 (work in
              progress), October 2019.

              Cabellos, A. and D. Saucez, "An Architectural Introduction
              to the Locator/ID Separation Protocol (LISP)", draft-ietf-
              lisp-introduction-13 (work in progress), April 2015.

              Farinacci, D., Lewis, D., Meyer, D., and C. White, "LISP
              Mobile Node", draft-ietf-lisp-mn-09 (work in progress),
              February 2021.

              Barkai, S., Fernandez-Ruiz, B., ZionB, S., Tamir, R.,
              Rodriguez-Natal, A., Maino, F., Cabellos-Aparicio, A., and
              D. Farinacci, "Network-Hexagons: H3-LISP GeoState &
              Mobility Network", draft-ietf-lisp-nexagon-07 (work in
              progress), February 2021.

              Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
              "Locator/ID Separation Protocol (LISP) Control-Plane",
              draft-ietf-lisp-rfc6833bis-30 (work in progress), November

   [ICN5G]    Ravindran, R., Suthar, P., Trossen, D., Wang, C., and G.
              White, "Enabling ICN in 3GPP's 5G NextGen Core
              Architecture", draft-irtf-icnrg-5gc-icn-04 (work in
              progress), January 2021.

   [ICNIP]    Trossen, D., Robitzsch, S., Reed, M., Al-Naday, M., and J.
              Riihijarvi, "Internet Services over ICN in 5G LAN
              Environments", draft-trossen-icnrg-internet-icn-5glan-04
              (work in progress), October 2020.

              "Standard for Medium Frequency (less than 15 MHz) Power
              Line Communications for Smart Grid Applications", IEEE
              1901.1 IEEE-SA Standards Board, May 2018,

   [LR-WPAN]  "IEEE 802.15.4 - IEEE Standard for Low-Rate Wireless
              Networks", IEEE 802.15 WPAN Task Group 4, May 2020,

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   [MANET1]   Abdallah, A., Abdallah, E., Bsoul, M., and A. Otoom,
              "Randomized geographic-based routing with nearly
              guaranteed delivery for three-dimensional ad hoc network",
              International Journal of Distributed Sensor Networks Vol.
              12, pp. 155014771667125, DOI 10.1177/1550147716671255,
              October 2016.

   [OCADO]    "Ocado Technology's robot warehouse a Hive of IoT
              innovation", n.d., <https://techmonitor.ai/tech-leaders/

   [PEARG]    "Privacy Enhancements and Assessments Research Group -
              PEARG", n.d., <https://irtf.org/pearg>.

   [QUIC]     Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
              and Secure Transport", draft-ietf-quic-transport-34 (work
              in progress), January 2021.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,

   [RFC2775]  Carpenter, B., "Internet Transparency", RFC 2775,
              DOI 10.17487/RFC2775, February 2000,

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031,
              DOI 10.17487/RFC3031, January 2001,

   [RFC3972]  Aura, T., "Cryptographically Generated Addresses (CGA)",
              RFC 3972, DOI 10.17487/RFC3972, March 2005,

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC4919]  Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
              over Low-Power Wireless Personal Area Networks (6LoWPANs):
              Overview, Assumptions, Problem Statement, and Goals",
              RFC 4919, DOI 10.17487/RFC4919, August 2007,

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   [RFC5061]  Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
              Kozuka, "Stream Control Transmission Protocol (SCTP)
              Dynamic Address Reconfiguration", RFC 5061,
              DOI 10.17487/RFC5061, September 2007,

   [RFC5177]  Leung, K., Dommety, G., Narayanan, V., and A. Petrescu,
              "Network Mobility (NEMO) Extensions for Mobile IPv4",
              RFC 5177, DOI 10.17487/RFC5177, April 2008,

   [RFC5275]  Turner, S., "CMS Symmetric Key Management and
              Distribution", RFC 5275, DOI 10.17487/RFC5275, June 2008,

   [RFC5517]  HomChaudhuri, S. and M. Foschiano, "Cisco Systems' Private
              VLANs: Scalable Security in a Multi-Client Environment",
              RFC 5517, DOI 10.17487/RFC5517, February 2010,

   [RFC5944]  Perkins, C., Ed., "IP Mobility Support for IPv4, Revised",
              RFC 5944, DOI 10.17487/RFC5944, November 2010,

   [RFC6182]  Ford, A., Raiciu, C., Handley, M., Barre, S., and J.
              Iyengar, "Architectural Guidelines for Multipath TCP
              Development", RFC 6182, DOI 10.17487/RFC6182, March 2011,

   [RFC6626]  Tsirtsis, G., Park, V., Narayanan, V., and K. Leung,
              "Dynamic Prefix Allocation for Network Mobility for Mobile
              IPv4 (NEMOv4)", RFC 6626, DOI 10.17487/RFC6626, May 2012,

   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,

   [RFC7401]  Moskowitz, R., Ed., Heer, T., Jokela, P., and T.
              Henderson, "Host Identity Protocol Version 2 (HIPv2)",
              RFC 7401, DOI 10.17487/RFC7401, April 2015,

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   [RFC7426]  Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
              Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
              Defined Networking (SDN): Layers and Architecture
              Terminology", RFC 7426, DOI 10.17487/RFC7426, January
              2015, <https://www.rfc-editor.org/info/rfc7426>.

   [RFC7429]  Liu, D., Ed., Zuniga, JC., Ed., Seite, P., Chan, H., and
              CJ. Bernardos, "Distributed Mobility Management: Current
              Practices and Gap Analysis", RFC 7429,
              DOI 10.17487/RFC7429, January 2015,

   [RFC7476]  Pentikousis, K., Ed., Ohlman, B., Corujo, D., Boggia, G.,
              Tyson, G., Davies, E., Molinaro, A., and S. Eum,
              "Information-Centric Networking: Baseline Scenarios",
              RFC 7476, DOI 10.17487/RFC7476, March 2015,

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665,
              DOI 10.17487/RFC7665, October 2015,

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8595]  Farrel, A., Bryant, S., and J. Drake, "An MPLS-Based
              Forwarding Plane for Service Function Chaining", RFC 8595,
              DOI 10.17487/RFC8595, June 2019,

   [RFC8677]  Trossen, D., Purkayastha, D., and A. Rahman, "Name-Based
              Service Function Forwarder (nSFF) Component within a
              Service Function Chaining (SFC) Framework", RFC 8677,
              DOI 10.17487/RFC8677, November 2019,

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,

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Internet-Draft    Scenarios and Problems in Addressing         July 2021

   [RFC8763]  Rahman, A., Trossen, D., Kutscher, D., and R. Ravindran,
              "Deployment Considerations for Information-Centric
              Networking (ICN)", RFC 8763, DOI 10.17487/RFC8763, April
              2020, <https://www.rfc-editor.org/info/rfc8763>.

   [RFC8799]  Carpenter, B. and B. Liu, "Limited Domains and Internet
              Protocols", RFC 8799, DOI 10.17487/RFC8799, July 2020,

   [RFC8926]  Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
              "Geneve: Generic Network Virtualization Encapsulation",
              RFC 8926, DOI 10.17487/RFC8926, November 2020,

              Wion, A., Bouet, M., Iannone, L., and V. Conan,
              "Distributed Function Chaining with Anycast Routing",
              Proceedings of the 2019 ACM Symposium on SDN Research,
              DOI 10.1145/3314148.3314355, April 2019.

   [SPHINX]   Danezis, G. and I. Goldberg, "Sphinx: A Compact and
              Provably Secure Mix Format", 2009 30th IEEE Symposium on
              Security and Privacy, DOI 10.1109/sp.2009.15, May 2009.

              "Deutsche Telekom tests TeraStream, the network of the
              future, in Croatia", n.d.,

   [TOR]      "The Tor Project", n.d., <https://www.torproject.org/>.

   [TROSSEN]  Trossen, D., Sarela, M., and K. Sollins, "Arguments for an
              information-centric internetworking architecture", ACM
              SIGCOMM Computer Communication Review Vol. 40, pp. 26-33,
              DOI 10.1145/1764873.1764878, April 2010.

Appendix A.  Change Log

   *NOTES*: Please remove this section prior to publication of a final
   version of this document.

A.1.  Since draft-jia-intarea-scenarios-problems-addressing-00

   o  Simplify the 'issues' section with simpler bullet list.

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Internet-Draft    Scenarios and Problems in Addressing         July 2021

   o  Several editorial changes to create a clear link with the gap

   o  Added issues and scenarios mapping Table.


   Thanks to Stewart Bryant for useful conversations.  Ron Bonica,
   Toerless Eckert and Brian E.  Carpenter made helpful suggestions.

Authors' Addresses

   Yihao Jia
   Huawei Technologies Co., Ltd
   156 Beiqing Rd.
   Beijing  100095
   P.R. China

   Email: jiayihao@huawei.com

   Dirk Trossen
   Huawei Technologies Duesseldorf GmbH
   Riesstr. 25C
   Munich  80992

   Email: dirk.trossen@huawei.com

   Luigi Iannone
   Huawei Technologies France S.A.S.U.
   18, Quai du Point du Jour
   Boulogne-Billancourt  92100

   Email: luigi.iannone@huawei.com

   Nirmala Shenoy
   Rochester Institute of Technology
   New-York  14623

   Email: nxsvks@rit.edu

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   Paulo Mendes
   Willy-Messerschmitt Strasse 1
   Munich  81663

   Email: paulo.mendes@airbus.com

   Donald E. Eastlake 3rd
   Futurewei Technologies
   2386 Panoramic Circle
   Apopka, FL  32703
   United States of America

   Email: d3e3e3@gmail.com

   Peng Liu
   China Mobile
   32 Xuanwumen West Ave
   Xicheng, Beijing  100053
   P.R. China

   Email: liupengyjy@chinamobile.com

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