path: root/doc/rfc/rfc9269.txt

Internet Research Task Force (IRTF)                            P. Suthar
Request for Comments: 9269                                   Google Inc.
Category: Informational                                        M. Stolic
ISSN: 2070-1721                                           A. Jangam, Ed.
                                                      Cisco Systems Inc.
                                                              D. Trossen
                                                     Huawei Technologies
                                                            R. Ravindran
                                                             F5 Networks
                                                             August 2022


     Experimental Scenarios of Information-Centric Networking (ICN)
                   Integration in 4G Mobile Networks

Abstract

   A 4G mobile network uses IP-based transport for the control plane to
   establish the data session at the user plane for the actual data
   delivery.  In the existing architecture, IP-based unicast is used for
   the delivery of multimedia content to a mobile terminal, where each
   user is receiving a separate stream from the server.  From a
   bandwidth and routing perspective, this approach is inefficient.
   Evolved multimedia broadcast and multicast service (eMBMS) provides
   capabilities for delivering contents to multiple users
   simultaneously, but its deployment is very limited or at an
   experimental stage due to numerous challenges.  The focus of this
   document is to list the options for using Information-Centric
   Networking (ICN) in 4G mobile networks and elaborate the experimental
   setups for its further evaluation.  The experimental setups discussed
   provide guidance for using ICN either natively or with an existing
   mobility protocol stack.  With further investigations based on the
   listed experiments, ICN with its inherent capabilities such as
   network-layer multicast, anchorless mobility, security, and optimized
   data delivery using local caching at the edge may provide a viable
   alternative to IP transport in 4G mobile networks.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9269.

Copyright Notice

   Copyright (c) 2022 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.

Table of Contents

   1.  Introduction
   2.  3GPP Terminology and Concepts
   3.  4G Mobile Network Architecture
     3.1.  Network Overview
     3.2.  Mobile Network Quality of Service
     3.3.  Data Transport Using IP
     3.4.  Virtualized Mobile Networks
   4.  Data Transport Using ICN
   5.  Experimental Scenarios for ICN Deployment
     5.1.  General Considerations
     5.2.  Scenarios of ICN Integration
     5.3.  Integration of ICN in 4G Control Plane
     5.4.  Integration of ICN in 4G User Plane
       5.4.1.  Dual Transport (IP/ICN) Mode in Mobile Terminal
       5.4.2.  Using ICN in Mobile Terminal
       5.4.3.  Using ICN in eNodeB
       5.4.4.  Using ICN in Packet Core Gateways (SGW/PGW)
     5.5.  An Experimental Test Setup
   6.  Expected Outcomes from Experimentation
     6.1.  Feeding into ICN Research
     6.2.  Use of Results Beyond Research
   7.  IANA Considerations
   8.  Security and Privacy Considerations
     8.1.  Security Considerations
     8.2.  Privacy Considerations
   9.  Summary
   10. References
     10.1.  Normative References
     10.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   4G mobile technology is built as an all-IP network using routing
   protocols (OSPF, IS-IS, BGP, etc.) to establish network routes.  The
   stickiness of an IP address to a device is the key to getting
   connected to a mobile network.  The same IP address is maintained
   through the session until the device gets detached or moves to
   another network.

   Key protocols used in 4G networks are the General Packet Radio
   Service Tunneling Protocol (GTP), DIAMETER, and other protocols that
   are built on top of IP.  One of the biggest challenges with IP-based
   routing in 4G is that it is not optimized for data transport.  As an
   alternative to IP routing, this document presents and lists the
   possible options for integration of Information-Centric Networking
   (ICN) in 3GPP 4G mobile networks, offering an opportunity to leverage
   inherent ICN capabilities such as in-network caching, multicast,
   anchorless mobility management, and authentication.  This document
   also discusses how those options affect mobile providers and end
   users.

   The goal of the proposed experiments is to present possibilities to
   create simulated environments for evaluation of the benefits of ICN
   protocol deployment in a 4G mobile network in different scenarios
   that have been analyzed in this document.  The consensus of the
   Information-Centric Networking Research Group (ICNRG) is to publish
   this document in order to facilitate experiments to show deployment
   options and qualitative and quantitative benefits of ICN protocol
   deployment in 4G mobile networks.

2.  3GPP Terminology and Concepts

   Access Point Name:  The Access Point Name (APN) is a Fully Qualified
      Domain Name (FQDN) and resolves to a set of gateways in an
      operator's network.  An APN identifies the packet data network
      (PDN) with which a mobile data user wants to communicate.  In
      addition to identifying a PDN, an APN may also be used to define
      the type of service, QoS, and other logical entities inside a
      Gateway General Packet Radio Service Support Node (GGSN) or a
      Packet Data Network Gateway (PGW).

   Control Plane:  The control plane carries signaling traffic and is
      responsible for routing between the eNodeB and the Mobile
      Management Entity (MME), the MME and the Home Subscriber Server
      (HSS), the MME and the Mobile Gateways (SGW/PGW), etc.  Control
      plane signaling is required to authenticate and authorize the
      mobile terminal and establish a mobility session with Mobile
      Gateways (SGW/PGW).  Control plane functions also include system
      configuration and management.

   Dual Address PDN/PDP Type:  The dual address Packet Data Network /
      Packet Data Protocol (PDN/PDP) Type (IPv4v6) is used in 3GPP
      context, in many cases as a synonym for dual stack, i.e., a
      connection type capable of serving IPv4 and IPv6 simultaneously.

   eNodeB:  The eNodeB is a base station entity that supports the Long
      Term Evolution (LTE) air interface.

   Evolved Packet Core:  The Evolved Packet Core (EPC) is an evolution
      of the 3GPP GPRS system characterized by a higher-data-rate,
      lower-latency, packet-optimized system.  The EPC comprises some
      subcomponents of the EPS core such as MME, Mobile Gateways (SGW/
      PGW), and HSS.

   Evolved Packet System:  The Evolved Packet System (EPS) is an
      evolution of the 3GPP GPRS system characterized by a higher-data-
      rate, lower-latency, packet-optimized system that supports
      multiple Radio Access Technologies (RATs).  The EPS comprises the
      EPC together with Evolved Universal Terrestrial Radio Access
      (E-UTRA) and the Evolved Universal Terrestrial Radio Access
      Network (E-UTRAN).

   Evolved UTRAN:  The Evolved UTRAN (E-UTRAN) is a communications
      network sometimes referred to as 4G, and it consists of an eNodeB
      (4G base stations).  The E-UTRAN allows connectivity between the
      User Equipment and the core network.

   Gateway GPRS Support Node:  The Gateway GPRS Support Node (GGSN) is a
      gateway function in the GPRS and 3G network that provides
      connectivity to the Internet or other PDNs.  The host attaches to
      a GGSN identified by an APN that is assigned to it by an operator.
      The GGSN also serves as the topological anchor for addresses/
      prefixes assigned to the User Equipment.

   General Packet Radio Service:  The General Packet Radio Service
      (GPRS) is a packet-oriented mobile data service available to users
      of the 2G and 3G cellular communication systems (the GSM)
      specified by 3GPP.

   GPRS Tunneling Protocol:  The GPRS Tunneling Protocol (GTP)
      [TS29.060] [TS29.274] [TS29.281] is a tunneling protocol defined
      by 3GPP.  It is a network-based mobility protocol that works
      similarly to Proxy Mobile IPv6 (PMIPv6).  However, GTP also
      provides functionality beyond mobility, such as in-band signaling
      related to QoS and charging, among others.

   Home Subscriber Server:  The Home Subscriber Server (HSS) [TS29.336]
      is a database for a given subscriber and was introduced in 3GPP
      Release 5.  It is the entity containing subscription-related
      information to support the network entities that handle calls/
      sessions.

   Mobile Terminal/User Equipment:  The terms User Equipment (UE),
      Mobile Station (MS), Mobile Node (MN), and mobile refer to the
      devices that are hosts with the ability to obtain Internet
      connectivity via a 3GPP network.  An MS comprises the Terminal
      Equipment (TE) and an MT.  The terms MT, MS, MN, and mobile are
      used interchangeably within this document.

   Mobility Management Entity:  The Mobility Management Entity (MME) is
      a network element responsible for control plane functionalities,
      including authentication, authorization, bearer management, Layer
      2 mobility, and so on.  The MME is essentially the control plane
      part of the SGSN in the GPRS.  The user-plane traffic bypasses the
      MME.

   Packet Data Network:  The Packet Data Network (PDN) is a packet-based
      network that either belongs to the operator or is an external
      network such as the Internet or a corporate intranet.  The user
      eventually accesses services in one or more PDNs.  The operator's
      packet core networks are separated from packet data networks by
      either GGSNs or PGWs.

   Packet Data Network Gateway:  The Packet Data Network Gateway (PGW)
      is a gateway function in the EPS, which provides connectivity to
      the Internet or other PDNs.  The host attaches to a PGW identified
      by an APN that is assigned to it by an operator.  The PGW also
      serves as the topological anchor for addresses/prefixes assigned
      to the User Equipment.

   Packet Data Protocol Context:  A Packet Data Protocol (PDP) context
      is the equivalent of a virtual connection between the mobile
      terminal (MT) and a PDN using a specific gateway.

   Packet Data Protocol Type:  A Packet Data Protocol Type (PDP Type)
      identifies the used/allowed protocols within the PDP context.
      Examples are IPv4, IPv6, and IPv4v6 (dual stack).

   Policy and Charging Control:  The Policy and Charging Control (PCC)
      framework is used for QoS policy and charging control.  It has two
      main functions: flow-based charging (including online credit
      control) and policy control (for example, gating control, QoS
      control, and QoS signaling).  It is optional to 3GPP EPS but
      needed if dynamic policy and charging control by means of PCC
      rules based on user and services are desired.

   Public Land Mobile Network:  The Public Land Mobile Network (PLMN) is
      a network operated by a single administration.  A PLMN (and
      therefore also an operator) is identified by the Mobile Country
      Code (MCC) and the Mobile Network Code (MNC).  Each
      (telecommunications) operator providing mobile services has its
      own PLMN.

   Serving Gateway:  The Serving Gateway (SGW) is a gateway function in
      the EPS, which terminates the interface towards the E-UTRAN.  The
      SGW is the Mobility Anchor point for Layer 2 mobility (inter-
      eNodeB handovers).  For each mobile terminal connected with the
      EPS, there is only one SGW at any given point in time.  The SGW is
      essentially the user-plane part of the GPRS's SGSN.

   Serving GPRS Support Node:  The Serving GPRS Support Node (SGSN) is a
      network element located between the Radio Access Network (RAN) and
      the gateway (GGSN).  A per-MT point-to-point (P2P) tunnel between
      the GGSN and SGSN transports the packets between the mobile
      terminal and the gateway.

   User Plane:  The user plane refers to data traffic and the required
      bearers for the data traffic.  In practice, IP is the only data
      traffic protocol used in the user plane.

3.  4G Mobile Network Architecture

   This section provides a high-level overview of typical 4G mobile
   network architecture and the key functions related to the possibility
   of its use with ICN technology.

3.1.  Network Overview

   4G mobile networks are designed to use IP transport for communication
   among different elements such as the eNodeB, MME, SGW, PGW, HSS,
   Policy and Charging Rule Function (PCRF), etc. [GRAYSON].  For
   backward compatibility with 3G, it has support for legacy circuit
   switch features such as voice and SMS through transitional CS
   fallback and flexible IP Multimedia Subsystems (IMS) deployment.  For
   each mobile device attached to the radio (eNodeB), there is a
   separate overlay tunnel (GTP) between the eNodeB and Mobile Gateways
   (i.e., SGW/PGW).

   When any mobile terminal is powered up, it attaches to a mobile
   network based on its configuration and subscription.  After a
   successful attachment procedure, the mobile terminal registers with
   the mobile core network using IPv4 and/or IPv6 addresses based on
   request and capabilities offered by Mobile Gateways.

   The GTP tunnel is used to carry user traffic between gateways and
   mobile terminals, therefore using the unicast delivery for any data
   transfer.  It is also important to understand the overhead of GTP and
   IPsec protocols.  All mobile backhaul traffic is encapsulated using a
   GTP tunnel, which has overhead of 8 bytes on top of IP and UDP
   [NGMN].  Additionally, if IPsec is used for security (which is often
   required if the Service Provider is using a shared backhaul), it adds
   overhead based on the IPsec tunneling model (tunnel or transport) as
   well as the encryption and authentication header algorithm used.  If
   we consider an Advanced Encryption Standard (AES) encryption as an
   example, the overhead can be significant [OLTEANU], particularly for
   smaller payloads.

                                          +-------+  Diameter  +-------+
                                          |  HSS  |------------|  SPR  |
                                          +-------+            +-------+
                                              |                    |
           +------+   +------+      S4        |                +-------+
           |  3G  |---| SGSN |----------------|------+  +------| PCRF  |
        ^  |NodeB |   |      |---------+  +---+      |  |      +-------+
   +-+  |  +------+   +------+   S3    |  |  S6a     |  |Gxc       |
   | |  |                          +-------+         |  |          |Gx
   +-+  |       +------------------|  MME  |------+  |  |          |
   MT   v       |       S1MME      +-------+  S11 |  |  |          |
          +----+-+                              +-------+     +-------+
          |4G/LTE|------------------------------|  SGW  |-----|  PGW  |
          |eNodeB|            S1U               +-------+  +--|       |
          +------+                                         |  +-------+
                                     +---------------------+    |  |
    S1U GTP Tunnel traffic           |          +-------+       |  |
    S2a GRE Tunnel traffic           |S2A       | ePDG  |-------+  |
    S2b GRE Tunnel traffic           |          +-------+  S2B     |SGi
    SGi IP traffic                   |              |              |
                                +---------+   +---------+       +-----+
                                | Trusted |   |Untrusted|       | CDN |
                                |non-3GPP |   |non-3GPP |       +-----+
                                +---------+   +---------+
                                     |             |
                                    +-+           +-+
                                    | |           | |
                                    +-+           +-+
                                    MT            MT

                    Figure 1: 4G Mobile Network Overview

   If we consider the combined impact of GTP, IPsec, and unicast
   traffic, the data delivery is not efficient because of overhead.  The
   IETF has developed various header compression algorithms to reduce
   the overhead associated with IP packets.  Some techniques are RObust
   Header Compression (ROHC) and Enhanced Compression RTP (ECRTP) so
   that the impact of overhead created by GTP, IPsec, etc., is reduced
   to some extent [BROWER].  For commercial mobile networks, 3GPP has
   adopted different mechanisms for header compression to achieve
   efficiency in data delivery [TS25.323]; those solutions can be
   adapted to other data protocols too such as ICN [RFC9139] [TLVCOMP].

3.2.  Mobile Network Quality of Service

   During the mobile terminal attachment procedure, a default bearer is
   created for each mobile terminal and it is assigned to the default
   Access Point Name (APN), which provides the default transport.  For
   any QoS-aware application, one or more new dedicated bearers are
   established between an eNodeB and a Mobile Gateway.  A dedicated
   bearer can be requested by either a mobile terminal or a Mobile
   Gateway based on the direction of the first data flow.  There are
   many bearers (logical paths) established between an eNodeB and a
   Mobile Gateway for each mobile terminal catering to a different data
   flow simultaneously.

   While all traffic within a certain bearer receives the same
   treatment, QoS parameters supporting these requirements can be very
   granular in different bearers.  These values vary for the control,
   management, and user traffic, and can be very different depending on
   application key parameters such as latency, jitter (important for
   voice and other real-time applications), packet loss, and queuing
   mechanism (strict priority, low latency, fair, and so on).

   Implementation of QoS for mobile networks is done at two stages: 1)
   content prioritization/marking and transport marking and 2)
   congestion management.  From the transport perspective, QoS is
   defined at Layer 2 as Class of Service (CoS) and at Layer 3 as
   Differentiated Services (DS).  The mapping of the Differentiated
   Services Code Point (DSCP) to CoS takes place at Layer 2/3 switching
   and routing elements. 3GPP has a specified QoS Class Identifier
   (QCI), which represents different types of content and equivalent
   mappings to the DSCP at the transport layer [TS23.401].  However,
   this requires manual configuration at different elements and is
   therefore prone to possible misconfigurations.

   In summary, QoS configuration in mobile networks for user-plane
   traffic requires synchronization of parameters among different
   platforms.  Normally, QoS in IP is implemented using DiffServ, which
   uses hop-by-hop QoS configuration at each router.  Any inconsistency
   in IP QoS configuration at routers in the forwarding path can result
   in a poor subscriber experience (e.g., a packet classified as high
   priority can go to a lower-priority queue).  By deploying ICN, we
   intend to enhance the subscriber experience using policy-based
   configuration, which can be associated with the named contents
   [ICNQoS] at the ICN forwarder.  Further investigation is underway to
   understand how QoS in ICN [QoS-ICN] can be implemented with reference
   to the ICN QoS guidelines [RFC9064] to meet the QoS requirements
   [RFC4594].

3.3.  Data Transport Using IP

   The data delivered to mobile devices is sent in unicast semantic
   inside the GTP tunnel from an eNodeB to a PDN gateway (PGW) as
   described in 3GPP specifications [TS23.401].  While the technology
   exists to address the issue of possible multicast delivery, there are
   many difficulties related to multicast protocol implementations on
   the RAN side of the network.  By using eMBMS [EMBMS], multicast
   routing can be enabled in mobile backhaul between an eNodeB and
   Mobile Gateways (SGW/PGW); however, for radio interface it requires
   broadcast, which implies that we need a dedicated radio channel.
   Implementation of eMBMS in RAN is still lagging behind due to
   complexities related to client mobility, handovers, and the fact that
   the potential gain to Service Providers may not justify the
   investment, which explains the prevalence of unicast delivery in
   mobile networks.  Techniques to handle multicast (such as LTE-B or
   eMBMS) have been designed to handle pre-planned content delivery,
   such as live content, which contrasts user behavior today, largely
   based on a content (or video) on-demand model.

   To ease the burden on the bandwidth of the Service Gateway interface
   (SGi), caching is introduced in a similar manner as with many
   enterprises.  In mobile networks, whenever possible, cached data is
   delivered.  Caching servers are placed at a centralized location,
   typically in the Service Provider's Data Center, or in some cases
   lightly distributed in packet core locations with the PGW nodes close
   to the Internet and IP services access (SGi).  This is a very
   inefficient concept because traffic must traverse the entire backhaul
   path for the data to be delivered to the end user.  Other issues,
   such as out-of-order delivery, contribute to this complexity and
   inefficiency, which needs to be addressed at the application level.

3.4.  Virtualized Mobile Networks

   The Mobile Gateways deployed in a major Service Provider network are
   based on either dedicated hardware or commercial off-the-shelf (COTS)
   x86 technology.  With the adoption of Mobile Virtual Network
   Operators (MVNOs), public safety networks, and enterprise mobility
   networks, elastic mobile core architecture is needed.  By deploying
   the mobile packet core on a COTS platform, using a Network Function
   Virtualization Infrastructure (NFVI) framework and end-to-end
   orchestration, new deployments can be simplified to provide optimized
   total cost of ownership (TCO).

   While virtualization is growing, and many mobile providers use a
   hybrid architecture that consists of dedicated and virtualized
   infrastructures, the control and data planes are still the same.
   There is also work underway to separate the control and user plane
   for the network to scale better.  Virtualized mobile networks and
   network slicing with control and user-plane separation provide a
   mechanism to evolve the GTP-based architecture towards an OpenFlow
   with signaling based on Software-Defined Networking (SDN) for 4G and
   proposed 5G core.  Some early architecture work for 5G mobile
   technologies provides a mechanism for control and user-plane
   separation and simplifies the mobility call flow by introducing
   OpenFlow-based signaling [ICN5G].  This has been considered by 3GPP
   [EPCCUPS] and is also described in [SDN5G].

4.  Data Transport Using ICN

   For mobile devices, the edge connectivity is between a mobile
   terminal and a router or mobile edge computing (MEC) [MECSPEC]
   element.  Edge computing has the capability of processing client
   requests and segregating control and user traffic at the edge of
   radio rather than sending all requests to the Mobile Gateway.

             +----------+
             | Content  +----------------------------------------+
             | Publisher|                                        |
             +---+---+--+                                        |
                 |   |    +--+             +--+           +--+   |
                 |   +--->|R1|------------>|R2|---------->|R4|   |
                 |        +--+             +--+           +--+   |
                 |                           |   Cached          |
                 |                           v   content         |
                 |                         +--+  at R3           |
                 |                +========|R3|---+              |
                 |                #        +--+   |              |
                 |                #               |              |
                 |                v               v              |
                 |               +-+             +-+             |
                 +---------------| |-------------| |-------------+
                                 +-+             +-+
                              Consumer-1      Consumer-2
                           Mobile Terminal  Mobile Terminal

                         ===> Content flow from cache
                         ---> Content flow from publisher

                         Figure 2: ICN Architecture

   Edge computing transforms a Radio Access Network into an intelligent
   service edge capable of delivering services directly from the edge of
   the network while providing the best possible performance to the
   client.  Edge computing can be an ideal candidate for implementing
   ICN forwarders in addition to its usual function of managing mobile
   termination.  In addition to edge computing, other transport
   elements, such as routers, can work as ICN forwarders.

   Data transport using ICN is different than IP-based transport as it
   introduces uniquely named-data as a core design principle.
   Communication in ICN takes place between the content provider
   (producer) and the end user (consumer), as described in Figure 2.

   Every node in a physical path between a client and a content provider
   is called the ICN forwarder or router.  It can route the request
   intelligently and cache content so it can be delivered locally for
   subsequent requests from any other client.  For mobile networks,
   transport between a client and a content provider consists of a radio
   network + mobile backhaul and IP core transport + Mobile Gateways +
   Internet + Content Delivery Network (CDN).

   To understand the suitability of ICN for mobile networks, we will
   discuss the ICN framework by describing its protocol architecture and
   different types of messages; this will be helpful when considering
   how to use ICN in mobile networks to deliver content more
   efficiently.  ICN uses two types of packets called "interest packet"
   and "data packet" as described in Figure 3.

                  +------------------------------------+
         Interest | +------+     +------+     +------+ |        +-----+
    +-+        ---->|  CS  |---->| PIT  |---->| FIB  |--------->| CDN |
    | |           | +------+     +------+     +------+ |        +-----+
    +-+           |     |      Add  |       Drop |     | Forward
    MT         <--------+      Intf v       Nack v     |
            Data  |                                    |
                  +------------------------------------+



                  +------------------------------------+
    +-+           |  Forward                  +------+ |        +-----+
    | | <-------------------------------------| PIT  |<---------| CDN |
    +-+           |                 | Cache   +--+---+ | Data   +-----+
    MT            |              +--v---+        |     |
                  |              |  CS  |        v     |
                  |              +------+      Discard |
                  +------------------------------------+

             Figure 3: ICN Interest, Data Packet, and Forwarder

   In a 4G network, when a mobile device wants to receive certain
   content, it will send an Interest message to the closest eNodeB.
   Interest packets follow the TLV format [RFC8609] and contain
   mandatory fields such as the name of the content and content-matching
   restrictions (KeyIdRestr and ContentObjectHashRestr) expressed as a
   tuple [RFC8569].  The content-matching tuple uniquely identifies the
   matching data packet for the given Interest packet.  Another
   attribute called "HopLimit" is used to detect looping Interest
   messages.

   An ICN router will receive an Interest packet and lookup if a request
   for such content has arrived earlier from another client.  If so, it
   may be served from the local cache; otherwise, the request is
   forwarded to the next-hop ICN router.  Each ICN router maintains
   three data structures: Pending Interest Table (PIT), Forwarding
   Information Base (FIB), and Content Store (CS).  The Interest packet
   travels hop by hop towards the content provider.  Once the Interest
   packet reaches the content provider, it will return a data packet
   containing information such as content name, signature, and the
   actual data.

   The data packet travels in reverse direction following the same path
   taken by the Interest packet, maintaining routing symmetry.  Details
   about algorithms used in PIT, FIB, CS, and security trust models are
   described in various resources [CCN]; here, we have explained the
   concept and its applicability to the 4G network.

5.  Experimental Scenarios for ICN Deployment

   In 4G mobile networks, both user and control plane traffic have to be
   transported from the edge to the mobile packet core via IP transport.
   The evolution of the existing mobile packet core using Control and
   User Plane Separation (CUPS) [TS23.714] enables flexible networking
   and operations by distributed deployment and the independent scaling
   of control plane and user-plane functions while not affecting the
   functionality of existing nodes subject to this split.

   In this section, we analyze the potential impact of ICN on control
   and user-plane traffic for centralized and disaggregated CUPS-based
   mobile network architecture.  We list various experimental options
   and opportunities to study the feasibility of the deployment of ICN
   in 4G networks.  The proposed experiments would help the network and
   original equipment manufacturer (OEM) designers to understand various
   issues, optimizations, and advantages of the deployment of ICN in 4G
   networks.

5.1.  General Considerations

   In the CUPS architecture, there is an opportunity to shorten the path
   for user-plane traffic by deploying offload nodes closer to the edge
   [OFFLOAD].  With this major architecture change, a User Plane
   Function (UPF) node is placed close to the edge so traffic no longer
   needs to traverse the entire backhaul path to reach the EPC.  In many
   cases, where feasible, the UPF can be collocated with the eNodeB,
   which is also a business decision based on user demand.  Placing a
   Publisher close to the offload site, or at the offload site, provides
   for a significant improvement in user experience, especially with
   latency-sensitive applications.  This capability allows for the
   introduction of ICN and amplifies its advantages.

5.2.  Scenarios of ICN Integration

   The integration of ICN provides an opportunity to further optimize
   the existing data transport in 4G mobile networks.  The various
   opportunities from the coexistence of ICN and IP transport in the
   mobile network are somewhat analogous to the deployment scenarios
   when IPv6 was introduced to interoperate with IPv4 except, with ICN,
   the whole IP stack can be replaced.  We have reviewed [RFC6459] and
   analyzed the impact of ICN on control plane signaling and user-plane
   data delivery.  In general, ICN can be used natively by replacing IP
   transport (IPv4 and IPv6) or as an overlay protocol.  Figure 4
   describes a proposal to modify the existing transport protocol stack
   to support ICN in a 4G mobile network.

                   +----------------+ +-----------------+
                   | ICN App (new)  | |IP App (existing)|
                   +---------+------+ +-------+---------+
                             |                |
                   +---------+----------------+---------+
                   | Transport Convergence Layer (new)  |
                   +------+---------------------+-------+
                          |                     |
                   +------+------+       +------+-------+
                   |ICN function |       | IP function  |
                   |   (New)     |       | (Existing)   |
                   +------+------+       +------+-------+
                          |                     |
                        (```).                (```).
                      (  ICN  '`.           (  IP   '`.
                      ( Cloud   )           ( Cloud   )
                       ` __..'+'             ` __..'+'

                   Figure 4: IP/ICN Convergence Scenarios

   As shown in Figure 4, for applications (running either in the mobile
   terminal or in the content provider system) to use the ICN transport
   option, we propose a new transport convergence layer (TCL).  The TCL
   helps determine the type of transport (such as ICN or IP) as well as
   the type of radio interface (LTE, Wi-Fi, or both) used to send and
   receive traffic based on preference (e.g., content location, content
   type, content publisher, congestion, cost, or QoS).  It helps
   configure and determine the type of connection (native IP or ICN) or
   the overlay mode (ICNoIP or IPoICN) between application and the
   protocol stack (IP or ICN).

   Combined with the existing IP function, the ICN function provides
   support for native ICN and/or the dual transport (ICN/IP)
   functionality.  See Section 5.4.1 for elaborate descriptions of these
   functional layers.

   The TCL can use several mechanisms for transport selection.  It can
   use a per-application configuration through a management interface,
   possibly a user-facing setting realized through a user interface,
   like those used to select cellular over Wi-Fi.  In another option, it
   might use a software API, which an adapted IP application could use
   to specify the type of transport option (such as ICN) to take
   advantage of its benefits.

   Another potential application of TCL is in an implementation of
   network slicing with a local slice management capability or through
   an interface to an external slice manager via an API [GALIS].  This
   solution can enable network slicing for IP and ICN transport
   selection from the mobile terminal itself.  The TCL could apply slice
   settings to direct certain applications traffic over one slice and
   others over another slice, determined by some form of a 'slicing
   policy'.  The slicing policy can be obtained externally from the
   slice manager or configured locally on the mobile terminal.

   From the perspective of applications either on the mobile terminal or
   at a content provider, the following options are possible for
   potential use of ICN natively and/or with IP.

   IP over IP (IPoIP):  In this scenario, the mobile terminal
      applications are tightly integrated with the existing IP transport
      infrastructure.  The TCL has no additional function because
      packets are forwarded directly using an IP protocol stack, which
      sends packets over the IP transport.

   ICN over ICN (ICNoICN):  Similar to case 1, ICN applications tightly
      integrate with the ICN transport infrastructure.  The TCL has no
      additional responsibility because packets are forwarded directly
      using the native ICN protocol stack, which sends packets over the
      ICN transport.

   ICN over IP (ICNoIP):  In this scenario, the underlying IP transport
      infrastructure is not impacted (that is, ICN is implemented as an
      IP overlay between mobile terminal and content provider).  IP
      routing is used from the Radio Access Network (eNodeB) to the
      mobile backhaul, the IP core, and the Mobile Gateway (SGW/PGW).
      The mobile terminal attaches to the Mobile Gateway (SGW/PGW) using
      an IP address.  Also, the data transport between Mobile Gateway
      (SGW/PGW) and content publisher uses IP.  The content provider can
      serve content using either IP or ICN, based on the mobile terminal
      request.

      One of the approaches to implement ICN in mobile backhaul networks
      is described in [MBICN].  It implements a General Tunneling
      Protocol - User Plane (GTP-U) extension header option to
      encapsulate ICN payload in a GTP tunnel.  However, as this design
      runs ICN as an IP overlay, the mobile backhaul can be deployed
      using native IP.  The proposal describes a mechanism where the
      GTP-U tunnel can be terminated by hairpinning the packet before it
      reaches the SGW if an ICN-enabled node is deployed in the mobile
      backhaul (that is, between eNodeB and SGW).  This could be useful
      when an ICN data packet is stored in the ICN node (such as
      repositories and caches) in the tunnel path so that the ICN node
      can reply without going all the way through the mobile core.
      While a GTP-U extension header is used to carry mobile-terminal-
      specific ICN payload, they are not visible to the transport,
      including the SGW.  On the other hand, the PGW can use the mobile
      terminal-specific ICN header extension and ICN payload to set up
      an uplink transport towards a content provider in the Internet.
      In addition, the design assumes a proxy function at the edge to
      perform ICN data retrieval on behalf of a non-ICN end device.

   IP over ICN (IPoICN):  [IPoICN] provides an architectural framework
      for running IP as an overlay over the ICN protocol.  Implementing
      IP services over ICN provides an opportunity to leverage the
      benefits of ICN in the transport infrastructure while there is no
      impact on end devices (MT and access network) as they continue to
      use IP.  IPoICN, however, will require an interworking function
      (IWF) (and Border Gateway) to translate various transport
      primitives.  The IWF function will provide a mechanism for
      protocol translation between IPoICN and the native IP.  After
      reviewing [IPoICN], we understand and interpret that ICN is
      implemented in the transport natively; however, IP is implemented
      in MT, the eNodeB, and the Mobile Gateway (SGW/PGW), which is also
      called a network attach point (NAP).

      For this, said NAP receives an incoming IP or HTTP packet (the
      latter through TCP connection termination) and publishes the
      packet under a suitable ICN name (i.e., the hash over the
      destination IP address for an IP packet or the hash over the FQDN
      of the HTTP request for an HTTP packet) to the ICN network.  In
      the HTTP case, the NAP maintains a pending request mapping table
      to map returning responses to the terminated TCP connection.

   Hybrid ICN (hICN):  An alternative approach to implement ICN over IP
      is provided in Hybrid ICN [HICN].  It describes a novel approach
      to integrate ICN into IPv6 without creating overlays with a new
      packet format as an encapsulation. hICN addresses the content by
      encoding a location-independent name in an IPv6 address.  It uses
      two name components, name prefix and name suffix, that identify
      the source of data and the data segment within the scope of the
      name prefix, respectively.

      At the application layer, hICN maps the name into an IPv6 prefix
      and, thus, uses IP as transport.  As long as the name prefixes,
      which are routable IP prefixes, point towards a mobile GW (PGW or
      local breakout, such as CUPS), there are potentially no updates
      required to any of the mobile core gateways (for example, SGW/
      PGW).  The IPv6 backhaul routes the packets within the mobile
      core. hICN can run in the mobile terminal, the eNodeB, the mobile
      backhaul, or the mobile core.  Finally, as hICN itself uses IPv6,
      it cannot be considered as an alternative transport layer.

5.3.  Integration of ICN in 4G Control Plane

   In this section, we analyze signaling messages that are required for
   different procedures, such as attach, handover, tracking area update,
   and so on.  The goal of this analysis is to see if there are any
   benefits to replacing IP-based protocols with ICN for 4G signaling in
   the current architecture.  It is important to understand the concept
   of point of attachment (POA).  When a mobile terminal connects to a
   network, it has the following POAs:

   1.  eNodeB managing location or physical POA

   2.  Authentication and Authorization (MME, HSS) managing identity or
       authentication POA

   3.  Mobile Gateways (SGW/PGW) managing logical or session management
       POA

   In the current architecture, IP transport is used for all messages
   associated with the control plane for mobility and session
   management.  IP is embedded very deeply into these messages utilizing
   TLV syntax for carrying additional attributes such as a Layer 3
   transport.  The physical POA in the eNodeB handles both mobility and
   session management for any mobile terminal attached to a 4G network.
   The number of mobility management messages between different nodes in
   a 4G network per the signaling procedure is shown in Table 1.

   Normally, two types of mobile terminals attach to the 4G network: SIM
   based (which needs a 3GPP mobility protocol for authentication) or
   non-SIM based (which connects to Wi-Fi networks).  Both device types
   require authentication.  For non-SIM based devices, Authentication,
   Authorization, and Accounting (AAA) is used for authentication.  We
   do not propose to change mobile terminal authentication or mobility
   management messaging for user data transport using ICN.  A separate
   study would be required to analyze the impact of ICN on mobility
   management messages, structures, and flows.  We are merely analyzing
   the viability of implementing ICN as a transport for control plane
   messages.

   It is important to note that if MME and HSS do not support ICN
   transport, they still need to support a mobile terminal capable of
   dual transport or native ICN.  When a mobile terminal initiates an
   attach request using the identity as ICN, MME must be able to parse
   that message and create a session.  MME forwards mobile terminal
   authentication to HSS, so HSS must be able to authenticate an ICN-
   capable mobile terminal and authorize Create Session [TS23.401].

       +===========================+=====+=====+=====+=====+======+
       | 4G Signaling Procedures   | MME | HSS | SGW | PGW | PCRF |
       +===========================+=====+=====+=====+=====+======+
       | Attach                    |  10 |   2 |   3 |   2 |    1 |
       +---------------------------+-----+-----+-----+-----+------+
       | Additional default bearer |   4 |   0 |   3 |   2 |    1 |
       +---------------------------+-----+-----+-----+-----+------+
       | Dedicated bearer          |   2 |   0 |   2 |   2 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | Idle-to-connect           |   3 |   0 |   1 |   0 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | Connect-to-Idle           |   3 |   0 |   1 |   0 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | X2 handover               |   2 |   0 |   1 |   0 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | S1 handover               |   8 |   0 |   3 |   0 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | Tracking area update      |   2 |   2 |   0 |   0 |    0 |
       +---------------------------+-----+-----+-----+-----+------+
       | Total                     |  34 |   2 |  14 |   6 |    3 |
       +---------------------------+-----+-----+-----+-----+------+

                Table 1: Signaling Messages in 4G Gateways

   Anchorless mobility [ALM] provides a fully decentralized solution
   that is control plane agnostic to handle producer mobility in ICN.
   Mobility management at the Layer 3 makes its access agnostic and
   transparent to the end device or the application.  The solution
   discusses handling mobility without having to depend on core network
   functions (e.g., MME); however, a location update to the core network
   may still be required to support legal compliance requirements such
   as lawful intercept and emergency services.  These aspects are open
   for further study.

   One of the advantages of ICN is in the caching and reusing of the
   content, which does not apply to the transactional signaling
   exchange.  After analyzing 4G signaling call flows [TS23.401] and
   message interdependencies (see Table 1), our recommendation is that
   it is not beneficial to use ICN for control plane and mobility
   management functions.  Among the features of ICN design, Interest
   aggregation and content caching are not applicable to control plane
   signaling messages.  Control plane messages are originated and
   consumed by the applications, and they cannot be shared.

5.4.  Integration of ICN in 4G User Plane

   We will consider Figure 1 when discussing different mechanisms to
   integrate ICN in mobile networks.  In Section 5.2, we discussed
   generic experimental setups of ICN integration.  In this section, we
   discuss the specific options of possible use of native ICN in the 4G
   user plane.  The following options are considered:

   1.  Using Dual transport (IP/ICN) mode in mobile terminal

   2.  Using ICN in mobile terminal

   3.  Using ICN in eNodeB

   4.  Using ICN in Mobile Gateways (SGW/PGW)

5.4.1.  Dual Transport (IP/ICN) Mode in Mobile Terminal

   The control and user-plane communications in 4G mobile networks are
   specified in 3GPP documents [TS23.203] and [TS23.401].  It is
   important to understand that a mobile terminal can be either consumer
   (receiving content) or publisher (pushing content for other clients).
   The protocol stack inside the mobile terminal (MT) is complex because
   it must support multiple radio connectivity access to eNodeB(s).

   Figure 5 provides a high-level description of a protocol stack, where
   IP is used at two layers: (1) user-plane communication and (2) UDP
   encapsulation.  User-plane communication takes place between the
   Packet Data Convergence Protocol (PDCP) and Application layer,
   whereas UDP encapsulation is at the GTP protocol stack.

   The protocol interactions and impact of supporting the tunneling of
   an ICN packet into IP or supporting ICN natively are described in
   Figures 5 and 6, respectively.

    +--------+                                               +--------+
    |   App  |                                               |  CDN   |
    +--------+                                               +--------+
    |Transp. | |              |               |              |Transp. |
    |Converg.|.|..............|...............|............|.|Converge|
    +--------+ |              |               | +--------+ | +--------+
    |        |.|..............|...............|.|        |.|.|        |
    | ICN/IP | |              |               | | ICN/IP | | |  ICN/IP|
    |        | |              |               | |        | | |        |
    +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+
    |        |.|.|    |     |.|.|     |     |.|.|     |  | | |        |
    |  PDCP  | | |PDCP|GTP-U| | |GTP-U|GTP-U| | |GTP-U|  | | |   L2   |
    +--------+ | +----------+ | +-----------+ | +-----+  | | |        |
    |   RLC  |.|.|RLC | UDP |.|.| UDP | UDP |.|.|UDP  |L2|.|.|        |
    +--------+ | +----------+ | +-----------+ | +-----+  | | |        |
    |   MAC  |.|.| MAC|  L2 |.|.| L2  | L2  |.|.|  L2 |  | | |        |
    +--------+ | +----------+ | +-----------+ | +--------+ | +--------+
    |   L1   |.|.| L1 |  L1 |.|.| L1  | L1  |.|.|  L1 |L1|.|.|   L1   |
    +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+
        MT     |  BS (eNodeB) |      SGW      |     PGW    |
              Uu             S1U            S5/S8         SGi

        Figure 5: Dual Transport (IP/ICN) Mode in a Mobile Terminal

   The protocols and software stack used inside 4G-capable mobile
   terminals support both 3G and 4G software interworking and handover.
   3GPP Rel.13 specifications and onward describe the use of IP and non-
   IP protocols to establish logical/session connectivity.  We can
   leverage the non-IP protocol-based mechanism to deploy an ICN
   protocol stack in the mobile terminal as well as in an eNodeB and
   Mobile Gateways (SGW/PGW).  The following paragraphs describe per-
   layer considerations of supporting the tunneling of ICN packets into
   IP or supporting ICN natively.

   1.  An existing application layer can be modified to provide options
       for a new ICN-based application and existing IP-based
       applications.  The mobile terminal can continue to support
       existing IP-based applications or can develop new applications to
       support native ICN, ICNoIP, or IPoICN-based transport.  The
       application layer can be provided with an option of selecting
       either ICN or IP transport, as well as radio interface, to send
       and receive data traffic.

       Our proposal is to provide an Application Programming Interface
       (API) to the application developers so they can choose either ICN
       or IP transport for exchanging the traffic with the network.  As
       mentioned in Section 5.2, the TCL function handles the
       interaction of applications with multiple transport options.

   2.  The transport convergence layer helps determine the type of
       transport (such as ICN, hICN, or IP) and type of radio interface
       (LTE, Wi-Fi, or both) used to send and receive traffic.  The
       application layer can make the decision to select a specific
       transport based on preference such as content location, content
       type, content publisher, congestion, cost, QoS, and so on.  There
       can be an API to exchange parameters required for transport
       selection.  Southbound interactions of the TCL will be either to
       IP or to ICN at the network layer.

       When selecting the IPoICN mode, the TCL is responsible for
       receiving an incoming IP or HTTP packet and publishing the packet
       to the ICN network under a suitable ICN name (that is, the hash
       over the destination IP address for an IP packet or the hash over
       the FQDN of the HTTP request for an HTTP packet).

       In the HTTP case, the TCL can maintain a pending request mapping
       table to map, returning responses to the originating HTTP
       request.  The common API will provide a "connection" abstraction
       for this HTTP mode of operation, returning the response over said
       connection abstraction (akin to the TCP socket interface) while
       implementing a reliable transport connection semantic over the
       ICN from the mobile terminal to the receiving mobile terminal or
       the PGW.  If the HTTP protocol stack remains unchanged, therefore
       utilizing the TCP protocol for transfer, the TCL operates in
       local TCP termination mode, retrieving the HTTP packet through
       said local termination.

                    +----------------+ +-----------------+
                    | ICN App (new)  | |IP App (existing)|
                    +---------+------+ +-------+---------+
                              |                |
                    +---------+----------------+---------+
                    | Transport Convergence Layer (new)  |
                    +------+---------------------+-------+
                           |                     |
                    +------+------+       +------+-------+
                    |ICN function |       | IP function  |
                    |   (New)     |       | (Existing)   |
                    +------+------+       +------+-------+
                           |                     |
                    +------+---------------------+-------+
                    | PDCP (updated to support ICN)      |
                    +-----------------+------------------+
                                      |
                    +-----------------+------------------+
                    |          RLC (Existing)            |
                    +-----------------+------------------+
                                      |
                    +-----------------+------------------+
                    |        MAC Layer (Existing)        |
                    +-----------------+------------------+
                                      |
                    +-----------------+------------------+
                    |       Physical L1 (Existing)       |
                    +------------------------------------+

                 Figure 6: Dual Stack ICN Protocol Interactions

   3.  The ICN function (forwarder) is proposed to run in parallel to
       the existing IP layer.  The ICN forwarder forwards the ICN
       packets such as an Interest packet to an eNodeB or a response
       "data packet" from an eNodeB to the application.

   4.  For the dual-transport scenario, when a mobile terminal is not
       supporting ICN as transport, the TCL can use the IP underlay to
       tunnel the ICN packets.  The ICN function can use the IP
       interface to send Interest and Data packets for fetching or
       sending data, respectively.  This interface can use the ICN
       overlay over IP.

   5.  To support ICN at the network layer in the mobile terminal, the
       PDCP layer should be aware of ICN capabilities and parameters.
       PDCP is located in the Radio Protocol Stack in the LTE Air
       interface, between the IP (Network layer) and Radio Link Control
       Layer (RLC).  PDCP performs the following functions [TS36.323]:

       1.  Data transport by listening to the upper layer, formatting,
           and pushing down to the RLC

       2.  Header compression and decompression using ROHC

       3.  Security protections such as ciphering, deciphering, and
           integrity protection

       4.  Radio layer messages associated with sequencing, packet drop
           detection and retransmission, and so on.

   6.  No changes are required for the lower layer such as RLC, Media
       Access Control (MAC), and Physical (L1) as they are not IP aware.

   One key point to understand in this scenario is that ICN is deployed
   as an overlay on top of IP.

5.4.2.  Using ICN in Mobile Terminal

   We can implement ICN natively in the mobile terminal by modifying the
   PDCP layer in 3GPP protocols.  Figure 7 provides a high-level
   protocol stack description where ICN can be used at the following
   different layers:

   1.  User-plane communication

   2.  Transport layer

   ICN transport would be a substitute for the GTP protocol.  The
   removal of the GTP protocol stack is a significant change in the
   mobile architecture and requires a thorough study mainly because it
   is used not just for routing but for mobility management functions
   such as billing, mediation, and policy enforcement.

   The implementation of ICN natively in the mobile terminal leads to a
   changed communication model between the mobile terminal and eNodeB.
   Also, we can avoid tunneling the user-plane traffic from an eNodeB to
   the mobile packet core (SGW/PGW) through a GTP tunnel.

   For native ICN use, an application can be configured to use an ICN
   forwarder, and it does not need the TCL layer.  Also, to support ICN
   at the network layer, the existing PDCP layer may need to be changed
   to be aware of ICN capabilities and parameters.

   The native implementation can provide new opportunities to develop
   new use cases leveraging ICN capabilities such as seamless mobility,
   mobile terminal to mobile terminal content delivery using a radio
   network without traversing the Mobile Gateways, and more.

   +--------+                                                +--------+
   |  App   |                                                |   CDN  |
   +--------+                                                +--------+
   |Transp. | |              |              |              | |Transp. |
   |Converge|.|..............|..............|..............|.|Converge|
   +--------+ |              |              |              | +--------+
   |        |.|..............|..............|..............|.|        |
   | ICN/IP | |              |              |              | |        |
   |        | |              |              |              | |        |
   +--------+ | +----+-----+ | +----------+ | +----------+ | | ICN/IP |
   |        |.|.|    |     | | |          | | |          | | |        |
   |  PDCP  | | |PDCP| ICN |.|.|    ICN   |.|.|    ICN   |.|.|        |
   +--------+ | +----+     | | |          | | |          | | |        |
   |   RLC  |.|.|RLC |     | | |          | | |          | | |        |
   +--------+ | +----------+ | +----------+ | +----------+ | +--------+
   |   MAC  |.|.| MAC|  L2 |.|.|     L2   |.|.|    L2    |.|.|    L2  |
   +--------+ | +----------+ | +----------+ | +----------+ | +--------+
   |   L1   |.|.| L1 |  L1 |.|.|     L1   |.|.|    L1    |.|.|    L1  |
   +--------+ | +----+-----+ | +----------+ | +----------+ | +--------+
       MT     |  BS(eNodeB)  |      SGW     |      PGW     |
              Uu            S1u           S5/S8           SGi

               Figure 7: Using Native ICN in Mobile Terminal

5.4.3.  Using ICN in eNodeB

   The eNodeB is a physical point of attachment for the mobile terminal
   where radio protocols are converted into IP transport protocols for
   dual transport/overlay and native ICN, respectively (see Figures 6
   and 7).  When a mobile terminal performs an attach procedure, it will
   be assigned an identity as either IP or dual transport (IP and ICN)
   or ICN endpoint.  A mobile terminal can initiate data traffic using
   any of the following options:

   1.  Native IP (IPv4 or IPv6)

   2.  Native ICN

   3.  Dual transport IP (IPv4/IPv6) and ICN

   The mobile terminal encapsulates a user data transport request into
   the PDCP layer and sends the information on the air interface to the
   eNodeB, which in turn receives the information and, using PDCP
   [TS36.323], de-encapsulates the air-interface messages and converts
   them to forward-to-core Mobile Gateways (SGW/PGW).  As shown in
   Figure 8, to support ICN natively in an eNodeB, it is proposed to
   provide TCL capabilities in an eNodeB (similar to as provided in MT),
   which provides the following functions:

   1.  It decides the forwarding strategy for a user data request coming
       from the mobile terminal.  The strategy can decide based on
       preference indicated by the application, such as congestion,
       cost, QoS, and so on.

   2.  It uses an eNodeB to provide an open API to external management
       systems in order to provide eNodeB the capability to program the
       forwarding strategies.

                      +---------------+  |
                      | MT request    |  |    ICN          +---------+
                +---->| content using |--+--- transport -->|         |
                |     |ICN protocol   |  |                 |         |
                |     +---------------+  |                 |         |
                |                        |                 |         |
                |     +---------------+  |                 |         |
            +-+ |     | MT request    |  |    IP           |To mobile|
            | |-+---->| content using |--+--- transport -->|    GW   |
            +-+ |     | IP protocol   |  |                 |(SGW/PGW)|
            MT  |     +---------------+  |                 |         |
                |                        |                 |         |
                |     +---------------+  |                 |         |
                |     | MT request    |  |    Dual stack   |         |
                +---->| content using |--+--- IP+ICN    -->|         |
                      |IP/ICN protocol|  |    transport    +---------+
                      +---------------+  |
                          eNodeB        S1u

                 Figure 8: Integration of Native ICN in eNodeB

   3.  The eNodeB can be upgraded to support three different types of
       transport: IP, ICN, and dual transport IP+ICN towards Mobile
       Gateways, as depicted in Figure 8.  It is also proposed to deploy
       IP and/or ICN forwarding capabilities into an eNodeB for
       efficient transfer of data between the eNodeB and Mobile
       Gateways.  The following are choices for forwarding a data
       request towards Mobile Gateways:

       1.  Assuming the eNodeB is IP enabled and the MT requests an IP
           transfer, the eNodeB forwards data over IP.

       2.  Assuming the eNodeB is ICN enabled and the MT requests an ICN
           transfer, the eNodeB forwards data over ICN.

       3.  Assuming the eNodeB is IP enabled and the MT requests an ICN
           transfer, the eNodeB overlays ICN on IP and forwards user-
           plane traffic over IP.

       4.  Assuming the eNodeB is ICN enabled and the MT requests an IP
           transfer, the eNodeB overlays IP on ICN and forwards user-
           plane traffic over ICN [IPoICN].

5.4.4.  Using ICN in Packet Core Gateways (SGW/PGW)

   Mobile Gateways (a.k.a. Evolved Packet Core (EPC)) include SGW and
   PGW, which perform session management for MT from the initial attach
   to disconnection.  When MT is powered on, it performs Network-Access-
   Stratum (NAS) signaling and attaches to PGW after successful
   authentication.  PGW is an anchoring point for MT and is responsible
   for service creations, authorization, maintenance, and so on.  The
   entire functionality is managed using an IP address(es) for MT.

   To implement ICN in EPC, the following functions are proposed:

   1.  Insert ICN attributes in the session management layer for
       additional functionality with IP stack.  The session management
       layer is used for performing attach procedures and assigning
       logical identity to users.  After successful authentication by
       HSS, MME sends a Create Session Request (CSR) to SGW and SGW to
       PGW.

   2.  When MME sends a Create Session Request message (Step 12 in
       [TS23.401]) to SGW or PGW, it includes a Protocol Configuration
       Option (PCO) Information Element (IE) containing MT capabilities.
       We can use PCO IE to carry ICN-related capabilities information
       from MT to PGW.  This information is received from MT during the
       initial attach request in MME.  Details of available TLV, which
       can be used for ICN, are given in subsequent sections.  MT can
       support native IP, ICN+IP, or native ICN.  IP is referred to as
       both IPv4 and IPv6 protocols.

   3.  For ICN+IP-capable MT, PGW assigns the MT both an IP address and
       ICN identity.  MT selects either of the identities during the
       initial attach procedures and registers with the network for
       session management.  For ICN-capable MT, it will provide only ICN
       attachment.  For native IP-capable MT, there is no change.

   4.  To support ICN-capable attach procedures and use ICN for user-
       plane traffic, PGW needs to have full ICN protocol stack
       functionalities.  Typical ICN capabilities include functions such
       as CS, PIT, FIB capabilities, and so on.  If MT requests ICN in
       PCO IE, then PGW registers MT with ICN names.  For ICN
       forwarding, PGW caches content locally using CS functionality.

   5.  PCO IE as described in [TS24.008] (see Figure 10.5.136 on page
       656 and Table 10.5.154 on page 659) provides details for
       different fields.

       1.  Octet 3 (configuration protocols define PDN types), which
           contains details about IPv4, IPv6, both IPv4 and IPv6, or
           ICN.

       2.  Any combination of Octet 4 to Z can be used to provide
           additional information related to ICN capability.  It is most
           important that PCO IE parameters are matched between MT and
           Mobile Gateways (SGW/PGW) so they can be interpreted properly
           and the MT can attach successfully.

   6.  The ICN functionalities in SGW and PGW should be matched with MT
       and the eNodeB because they will exchange ICN protocols and
       parameters.

   7.  Mobile Gateways (SGW/PGW) will also need ICN forwarding and
       caching capability.  This is especially important if CUPS is
       implemented.  User Plane Function (UPF), comprising the SGW and
       PGW user plane, will be located at the edge of the network and
       close to the end user.  ICN-enabled gateway means that this UPF
       would serve as a forwarder and should be capable of caching, as
       is the case with any other ICN-enabled node.

   8.  The transport between PGW and CDN provider can be either IP or
       ICN.  When MT is attached to PGW with ICN identity and
       communicates with an ICN-enabled CDN provider, it will use ICN
       primitives to fetch the data.  On the other hand, for an MT
       attached with an ICN identity, if PGW must communicate with an
       IP-enabled CDN provider, it will have to use an ICN-IP
       interworking gateway to perform conversion between ICN and IP
       primitives for data retrieval.  In the case of CUPS
       implementation with an offload close to the edge, this
       interworking gateway can be collocated with the UPF at the
       offload site to maximize the path optimization.  Further study is
       required to understand how this ICN-to-IP (and vice versa)
       interworking gateway would function.

5.5.  An Experimental Test Setup

   This section proposes an experimental lab setup and discusses the
   open issues and questions that use of the ICN protocol is intended to
   address.  To further test the modifications proposed in different
   scenarios, a simple lab can be set up, as shown in Figure 9.

     +------------------------------------------+
     | +-----+   +------+   (```).     +------+ |   (````).    +-----+
     | | SUB |-->| EMU  |--(x-haul'.-->| EPC  |--->(  PDN ).-->| CDN |
     | +-----+   +------+   `__..''    +------+ |   `__...'    +-----+
     +------------------------------------------+
                   4G Mobile Network Functions

                 Figure 9: Native ICN Deployment Lab Setup

   The following test scenarios can be set up with deployment based on
   Virtual Machine (VM):

   1.  SUB: An ICN-simulated client (using ndnSIM) - a client
       application on a workstation requesting content.

   2.  EMU: Test unit emulating an eNodeB.  This is a test node allowing
       for UE attachment and routing traffic subsequently from the
       Subscriber to the Publisher.

   3.  EPC: Evolved Packet Core in a single instance (such as Open5GCore
       [Open5GCore]).

   4.  CDN: Content delivery by a Publisher server.

   For the purpose of this testing, ICN-emulating code can be inserted
   in the test code in EMU to emulate an ICN-capable eNodeB.  An example
   of the code to be used is NS3 in its LTE model.  The effect of such
   traffic on EPC and CDN can be observed and documented.  In a
   subsequent phase, EPC code supporting ICN can be tested when
   available.

   Another option is to simulate the UE/eNodeB and EPC functions using
   NS3's LTE [NS3LTE] and EPC [NS3EPC] models, respectively.  The LTE
   model includes the LTE Radio Protocol stack, which resides entirely
   within the UE and the eNodeB nodes.  This capability provides the
   simulation of UE and eNodeB deployment use cases.  Similarly, the EPC
   model includes core network interfaces, protocols, and entities,
   which reside within the Mobile Gateways (SGW/PGW), and MME nodes and
   partially within the eNodeB nodes.

   Even with its current limitations (such as IPv4 only, lack of
   integration with ndnSIM, and no support for UE idle state), LTE
   simulation may be a very useful tool.  In any case, both control and
   user-plane traffic should be tested independently according to the
   deployment model discussed in Section 5.4.

6.  Expected Outcomes from Experimentation

   The experimentation explained in Section 5 can be categorized in
   three broader scopes as follows.  Note that further research and
   study is required to fully understand and document the impact.

   Architecture scope:  to study the aspect of use of ICN at the user
      plane to reduce the complexities in current transport protocols
      while also evaluating its use in the control plane.

   Performance scope:  to evaluate the gains through multicast, caching,
      and other ICN features.

   Deployment scope:  to check the viability of ICN inclusion in the
      3GPP protocol stack and in real-world deployments.

6.1.  Feeding into ICN Research

   Specifically, we have identified the following open questions, from
   the architectural and performance perspective, that the proposed
   experiments with ICN implementation scenarios in 4G mobile networks
   could address in further research:

   1.  Efficiency gains in terms of the amount of traffic in multicast
       scenarios (i.e., quantify the possible gains along different use
       cases) and latency for cached content, mainly in the CDN use
       case.

   2.  How the new transport would coexist or replace the legacy
       transport protocols (e.g., IPv4, IPv6, MPLS, RSVP, etc.) and
       related services (e.g., bandwidth management, QoS handling,
       etc.).

   3.  To what extent the simplification in the IP-based transport
       protocols will be achieved.  The multiple overlays (e.g., the
       MPLS, VPN, Virtual Private LAN Service (VPLS), Ethernet VPN,
       etc.) of services in the current IP-based transport adds to the
       complexity on top of basic IP transport.  This makes the
       troubleshooting extremely challenging.

   4.  How the new transport can become service aware such that it
       brings in more simplicity in the system.

   5.  Confirm how (in)adequate ICN implementation would be in the
       control plane (which this document discourages).  Given that the
       5G system, as specified in [TS23.501] (Appendix G.4), encourages
       the use of name-based routing in the (5G) control plane for
       realizing the 5G-specific service-based architecture for control
       plane services (so-called network function service), it would be
       worthwhile to investigate whether the 4G control plane would
       benefit similarly from such use or whether specific 4G
       architectural constraints would prevent ICN from providing any
       notable benefit.

6.2.  Use of Results Beyond Research

   With the experiments and their outcomes outlined in this document, we
   believe that this technology is ready for a wider use and adoption,
   providing additional insights.  Specifically, we expect to study the
   following:

   1.  Viability of ICN inclusion in the 3GPP protocol stack, i.e.,
       investigating how realistic it would be to modify the stack,
       considering the scenarios explained in Section 5.4, and
       completing the user session without feature degradation.

   2.  Viability of utilizing solutions in greenfield deployments, i.e.,
       deploying the ICN-based extensions and solutions proposed in this
       document in greenfield 4G deployments in order to assess real-
       world benefits when doing so.

7.  IANA Considerations

   This document has no IANA actions.

8.  Security and Privacy Considerations

   This section will cover some security and privacy considerations in
   mobile and 4G networks because of the introduction of ICN.

8.1.  Security Considerations

   To ensure only authenticated mobile terminals are connected to the
   network, 4G mobile networks implement various security mechanisms.
   From the perspective of using ICN in the user plane, the following
   security aspects need to be taken care of:

   1.  MT authentication and authorization

   2.  Radio or air interface security

   3.  Denial-of-service attacks on the Mobile Gateway; services are
       either by the MT or by external entities in the Internet

   4.  Content poisoning in either transport or servers

   5.  Content cache pollution attacks

   6.  Secure naming, routing, and forwarding

   7.  Application security

   Security over the LTE air interface is provided through cryptographic
   techniques.  When MT is powered up, it performs a key exchange
   between the MT's Universal Mobile Telecommunications System
   Subscriber Identity Module (USIM) and HSS/Authentication Center using
   NAS messages, including ciphering and integrity protections between
   MT and MME.  Details for secure MT authentication, key exchange,
   ciphering, and integrity protection messages are given in the 3GPP
   call flow [TS23.401].  With ICN, we are modifying the protocol stack
   for the user plane and not the control plane.  The NAS signaling is
   exchanged between MT and Mobile Gateways, e.g., MME, using the
   control plane; therefore, there is no adverse impact of ICN on MT.

   4G uses IP transport in its mobile backhaul (between an eNodeB and
   the core network).  In case of provider-owned backhaul, the Service
   Provider may require implementing a security mechanism in the
   backhaul network.  The native IP transport continues to leverage
   security mechanisms such as Internet Key Exchange (IKE) and the IP
   Security (IPsec) protocol.  More details of mobile backhaul security
   are provided in 3GPP network security specifications [TS33.310] and
   [TS33.320].  When a mobile backhaul is upgraded to support dual
   transport (IP+ICN) or native ICN, it is required to implement
   security techniques that are deployed in the mobile backhaul.  When
   ICN forwarding is enabled on mobile transport routers, we need to
   deploy security practices based on [RFC7476] and [RFC7927].

   4G Mobile Gateways (SGW/PGW) perform some key functions such as
   content-based online/offline billing and accounting, deep packet
   inspection (DPI), and lawful interception (LI).  When ICN is deployed
   in the user plane, we need to integrate ICN security for sessions
   between MT and the gateway.  If we encrypt user-plane payload
   metadata, then it might be difficult to perform routing based on
   contents and it may not work because we need decryption keys at every
   forwarder to route the content.  The content itself can be encrypted
   between publisher and consumer to ensure privacy.  Only the user with
   the right decryption key shall be able to access the content.  We
   need further research for ICN impact on LI, online/offline charging,
   and accounting.

8.2.  Privacy Considerations

   In 4G networks, there are two main privacy issues [MUTHANA]:

   1.  User Identity Privacy Issues.  The main privacy issue within 4G
       is the exposure of the International Mobile Subscriber Identity
       (IMSI).  The IMSI can be intercepted by adversaries.  Such
       attacks are commonly referred to as "IMSI catching".

   2.  Location Privacy Issues.  IMSI catching is closely related to the
       issue of location privacy.  Knowing the IMSI of a user allows the
       attacker to track the user's movements and create a profile about
       the user and thus breach the user's location privacy.

   In any network, caching implies a trade-off between network
   efficiency and privacy.  The activity of users is exposed to the
   scrutiny of cache owners with whom they may not have any
   relationship.  By monitoring the cache transactions, an attacker
   could obtain significant information related to the objects accessed,
   topology, and timing of the requests [RFC7945].  Privacy concerns are
   amplified by the introduction of new network functions such as
   information lookup and network storage, and different forms of
   communication [FOTIOU].  Privacy risks in ICN can be broadly divided
   in the following categories [TOURANI]:

   1.  Timing attack

   2.  Communication monitoring attack

   3.  Censorship and anonymity attack

   4.  Protocol attack

   5.  Naming-signature privacy

   The introduction of TCL effectively enables ICN at the application
   and/or transport layer depending on the scenario described in
   Section 5.  Enabling ICN in 4G networks is expected to increase
   efficiency by taking advantage of ICN's inherent characteristics.
   This approach would potentially leave some of the above-mentioned
   privacy concerns open as a consequence of using ICN transport and ICN
   inherent privacy vulnerabilities.

   1.  IPoIP (Section 5.2) would not be affected as TCL has no role in
       it, and ICN does not apply.

   2.  The ICNoICN scenario (Section 5.2) has increased risk of a
       privacy attack, and that risk is applicable to the ICN protocol
       in general rather than specifically to the 4G implementation.
       Since this scenario describes communication over ICN transport,
       every forwarder in the path could be a potential risk for a
       privacy attack.

   3.  The ICNoIP scenario (Section 5.2) uses IP for transport, so the
       only additional ICN-related potential privacy risk areas are the
       endpoints (consumer and publisher) where, at the application
       layer, content is being served.

   4.  The IPoICN scenario (Section 5.2) could have potentially
       increased risk due to possible vulnerability of the forwarders in
       the path of ICN transport.

   Privacy issues already identified in 4G remain a concern if ICN is
   introduced in any of the scenarios described earlier and compounds to
   the new ICN-related privacy issues.  Many research papers have been
   published that propose solutions to the privacy issues listed above.
   For LTE-specific privacy issues, some of the proposed solutions
   [MUTHANA] are IMSI encryption by an MT; mutual authentication;
   concealing the real IMSI within a random bit stream of certain size
   where only the subscriber and HSS could extract the respective IMSI;
   IMSI replacement with a changing pseudonym that only the HSS server
   can map to the UE's IMSI; and others.  Similarly, some of the
   proposed ICN-specific privacy concerns mitigation methods, applicable
   where ICN transport is introduced as specified earlier in this
   section, include the following [FOTIOU]:

   *  Delay for the first, or first k, interests on edge routers (timing
      attack)

   *  Creating a secure tunnel or clients flagging the requests as non-
      cacheable for privacy (communication monitoring attack)

   *  Encoding interest by mixing the content and cover file or using a
      hierarchical DNS-based brokering model (censorship and anonymity
      attack)

   *  Use of rate-limiting requests for a specific namespace (protocol
      attack)

   *  Cryptographic content hash-based naming or digital identity in an
      overlay network (naming-signature privacy)

   Further research in this area is needed.  Detailed discussion of
   privacy is beyond the scope of this document.

9.  Summary

   In this document, we have discussed 4G networks and the experimental
   setups to study the advantages of the potential use of ICN for
   efficient delivery of contents to mobile terminals.  We have
   discussed different options to try and test ICN and dependencies such
   as ICN functionalities and changes required in different 4G network
   elements.  In order to further explore potential use of ICN, one can
   devise an experimental setup consisting of 4G network elements and
   deploy ICN data transport in the user plane.  Different options can
   be overlay, dual transport (IP + ICN), hICN, or natively (by
   integrating ICN with CDN, eNodeB, SGW, PGW, and a transport network).
   Note that, for the scenarios discussed above, additional study is
   required for lawful interception, billing/mediation, network slicing,
   and provisioning APIs.

   Edge Computing [CHENG] provides capabilities to deploy
   functionalities such as CDN caching and mobile user plane functions
   (UPFs) [TS23.501].  Recent research for delivering real-time video
   content [MPVCICN] using ICN has also been proven to be efficient
   [NDNRTC] and can be used towards realizing the benefits of using ICN
   in an eNodeB, edge computing, Mobile Gateways (SGW/PGW), and CDN.
   The key aspect for ICN is in its seamless integration in 4G and 5G
   networks with tangible benefits so we can optimize content delivery
   using a simple and scalable architecture.  The authors will continue
   to explore how ICN forwarding in edge computing could be used for
   efficient data delivery from the mobile edge.

   Based on our study of control plane signaling, it is not beneficial
   to deploy ICN with existing protocols unless further changes are
   introduced in the control protocol stack itself.

   As a starting step towards use of ICN in the user plane, it is
   proposed to incorporate protocol changes in MT, an eNodeB, and SGW/
   PGW for data transport.  ICN has inherent capabilities for mobility
   and content caching, which can improve the efficiency of data
   transport for unicast and multicast delivery.  The authors welcome
   contributions and suggestions, including those related to further
   validations of the principles by implementing prototypes and/or proof
   of concepts in the lab and in the production environment.

10.  References

10.1.  Normative References

   [TS24.008] 3GPP, "Mobile radio interface Layer 3 specification; Core
              network protocols; Stage 3", 3GPP TS 24.008 17.7.0, June
              2022,
              <https://www.3gpp.org/ftp/Specs/html-info/24008.htm>.

   [TS25.323] 3GPP, "Packet Data Convergence Protocol (PDCP)
              specification", 3GPP TS 25.323 17.0.0, April 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/25323.htm>.

   [TS29.274] 3GPP, "3GPP Evolved Packet System (EPS); Evolved General
              Packet Radio Service (GPRS) Tunnelling Protocol for
              Control plane (GTPv2-C); Stage 3", 3GPP TS 29.274 17.6.0,
              June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/29274.htm>.

   [TS29.281] 3GPP, "General Packet Radio System (GPRS) Tunnelling
              Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 17.3.0,
              June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/29281.htm>.

   [TS36.323] 3GPP, "Evolved Universal Terrestrial Radio Access
              (E-UTRA); Packet Data Convergence Protocol (PDCP)
              specification", 3GPP TS 36.323 17.1.0, July 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/36323.htm>.

10.2.  Informative References

   [ALM]      Augé, J., Carofiglio, G., Grassi, G., Muscariello, L.,
              Pau, G., and X. Zeng, "Anchor-Less Producer Mobility in
              ICN", ACM-ICN '15: Proceedings of the 2nd ACM Conference
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   [BROWER]   Brower, E., Jeffress, L., Pezeshki, J., Jasani, R., and E.
              Ertekin, "Integrating Header Compression with IPsec",
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   [CCN]      FD.io, "Cicn", January 2020,
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   [CHENG]    Liang, C., Yu, R., and X. Zhang, "Information-centric
              network function virtualization over 5g mobile wireless
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              2015, <https://ieeexplore.ieee.org/document/7113228>.

   [EMBMS]    Zahoor, K., Bilal, K., Erbad, A., and A. Mohamed,
              "Service-Less Video Multicast in 5G: Enablers and
              Challenges", IEEE Network, Vol. 34, Issue 3, pp. 270-276,
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   [EPCCUPS]  Schmitt, P., Landais, B., and F. Yong Yang, "Control and
              User Plane Separation of EPC nodes (CUPS)", 3GPP, The
              Mobile Broadband Standard, July 2017,
              <https://www.3gpp.org/news-events/3gpp-news/1882-cups>.

   [FOTIOU]   Fotiou, N. and G. Polyzos, "ICN privacy and name based
              security", ACM-ICN '14: Proceedings of the 1st ACM
              Conference on Information-Centric Networking, pp. 5-6,
              DOI 10.1145/2660129.2666711, September 2014,
              <https://dl.acm.org/doi/10.1145/2660129.2666711>.

   [GALIS]    Galis, A., Ed., Makhijani, K., Yu, D., and B. Liu,
              "Autonomic Slice Networking", Work in Progress, Internet-
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              September 2018, <https://datatracker.ietf.org/doc/html/
              draft-galis-anima-autonomic-slice-networking-05>.

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              for Mobile Networks", Cisco Press, Networking Technology
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              <https://www.ciscopress.com/store/ip-design-for-mobile-
              networks-9781587058264>.

   [HICN]     Muscariello, L., Carofiglio, G., Auge, J., and M.
              Papalini, "Hybrid Information-Centric Networking", Work in
              Progress, Internet-Draft, draft-muscariello-intarea-hicn-
              04, 20 May 2020, <https://datatracker.ietf.org/doc/html/
              draft-muscariello-intarea-hicn-04>.

   [ICN5G]    Ravindran, R., Suthar, P., Trossen, D., Wang, C., and G.
              White, "Enabling ICN in 3GPP's 5G NextGen Core
              Architecture", Work in Progress, Internet-Draft, draft-
              irtf-icnrg-5gc-icn-04, 10 January 2021,
              <https://datatracker.ietf.org/doc/html/draft-irtf-icnrg-
              5gc-icn-04>.

   [ICNQoS]   Al-Naday, M.F., Bontozoglou, A., Vassilakis, G., and M. J.
              Reed, "Quality of service in an information-centric
              network", 2014 IEEE Global Communications Conference, pp.
              1861-1866, DOI 10.1109/GLOCOM.2014.7037079, December 2014,
              <https://ieeexplore.ieee.org/document/7037079>.

   [IPoICN]   Trossen, D., Read, M. J., Riihijarvi, J., Georgiades, M.,
              Fotiou, N., and G. Xylomenos, "IP over ICN - The better
              IP?", 2015 European Conference on Networks and
              Communications (EuCNC), pp. 413-417,
              DOI 10.1109/EuCNC.2015.7194109, June 2015,
              <https://ieeexplore.ieee.org/document/7194109>.

   [MBICN]    Carofiglio, G., Gallo, M., Muscariello, L., and D. Perino,
              "Scalable mobile backhauling via information-centric
              networking", The 21st IEEE International Workshop on Local
              and Metropolitan Area Networks, Beijing, pp. 1-6,
              DOI 10.1109/LANMAN.2015.7114719, April 2015,
              <https://ieeexplore.ieee.org/document/7114719>.

   [MECSPEC]  ETSI, "Mobile Edge Computing (MEC); Framework and
              Reference Architecture", ETSI GS MEC 003, Version 1.1.1,
              March 2016, <https://www.etsi.org/deliver/etsi_gs/
              MEC/001_099/003/01.01.01_60/gs_MEC003v010101p.pdf>.

   [MPVCICN]  Jangam, A., Ravindran, R., Chakraborti, A., Wan, X., and
              G. Wang, "Realtime multi-party video conferencing service
              over information centric network", IEEE International
              Conference on Multimedia and Expo Workshops (ICMEW),
              Turin, Italy, pp. 1-6, DOI 10.1109/ICMEW.2015.7169810,
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   [MUTHANA]  Muthana, A. and M. Saeed, "Analysis of User Identity
              Privacy in LTE and Proposed Solution", International
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              DOI 10.5815/ijcnis.2017.01.07, January 2017,
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              v9n1-7.html>.

   [NDNRTC]   Gusev, P., Wang, Z., Burke, J., Zhang, L., Yoneda, T.,
              Ohnishi, R., and E. Muramoto, "Real-Time Streaming Data
              Delivery over Named Data Networking", IEICE Transactions
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   [NGMN]     Robson, J., "Backhaul Provisioning for LTE-Advanced &
              Small Cells", Next Generation Mobile Networks, LTE-
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              2015, <https://www.ngmn.org/wp-content/uploads/
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   [NS3EPC]   ns-3, "The EPC Model", July 2022,
              <https://www.nsnam.org/docs/models/html/lte-
              design.html#epc-model>.

   [NS3LTE]   ns-3, "The LTE Model", July 2022,
              <https://www.nsnam.org/docs/models/html/lte-
              design.html#lte-model>.

   [OFFLOAD]  Rebecchi, F., Dias de Amorim, M., Conan, V., Passarella,
              A., Bruno, R., and M. Conti, "Data Offloading Techniques
              in Cellular Networks: A Survey", IEEE Communications
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              <https://ieeexplore.ieee.org/document/6953022>.

   [OLTEANU]  Olteanu, A. and P. Xiao, "Fragmentation and AES encryption
              overhead in very high-speed wireless LANs", Proceedings of
              the 2009 IEEE International Conference on Communications
              ICC'09, pp. 575-579, June 2009,
              <https://dl.acm.org/doi/10.5555/1817271.1817379>.

   [Open5GCore]
              Open5GCore, "Open5GCore - 5G Core Network for Research,
              Testbeds and Trials", <https://www.open5gcore.org>.

   [QoS-ICN]  Jangam, A., Ed., Suthar, P., and M. Stolic, "QoS
              Treatments in ICN using Disaggregated Name Components",
              Work in Progress, Internet-Draft, draft-anilj-icnrg-dnc-
              qos-icn-02, 9 March 2020,
              <https://datatracker.ietf.org/doc/html/draft-anilj-icnrg-
              dnc-qos-icn-02>.

   [RFC4594]  Babiarz, J., Chan, K., and F. Baker, "Configuration
              Guidelines for DiffServ Service Classes", RFC 4594,
              DOI 10.17487/RFC4594, August 2006,
              <https://www.rfc-editor.org/info/rfc4594>.

   [RFC6459]  Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
              T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, DOI 10.17487/RFC6459, January 2012,
              <https://www.rfc-editor.org/info/rfc6459>.

   [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,
              <https://www.rfc-editor.org/info/rfc7476>.

   [RFC7927]  Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I.,
              Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch,
              "Information-Centric Networking (ICN) Research
              Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016,
              <https://www.rfc-editor.org/info/rfc7927>.

   [RFC7945]  Pentikousis, K., Ed., Ohlman, B., Davies, E., Spirou, S.,
              and G. Boggia, "Information-Centric Networking: Evaluation
              and Security Considerations", RFC 7945,
              DOI 10.17487/RFC7945, September 2016,
              <https://www.rfc-editor.org/info/rfc7945>.

   [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>.

   [RFC9064]  Oran, D., "Considerations in the Development of a QoS
              Architecture for CCNx-Like Information-Centric Networking
              Protocols", RFC 9064, DOI 10.17487/RFC9064, June 2021,
              <https://www.rfc-editor.org/info/rfc9064>.

   [RFC9139]  Gündoğan, C., Schmidt, T., Wählisch, M., Scherb, C.,
              Marxer, C., and C. Tschudin, "Information-Centric
              Networking (ICN) Adaptation to Low-Power Wireless Personal
              Area Networks (LoWPANs)", RFC 9139, DOI 10.17487/RFC9139,
              November 2021, <https://www.rfc-editor.org/info/rfc9139>.

   [SDN5G]    Page, J. and J. Dricot, "Software-defined networking for
              low-latency 5G core network", 2016 International
              Conference on Military Communications and Information
              Systems (ICMCIS), pp. 1-7,
              DOI 10.1109/ICMCIS.2016.7496561, May 2016,
              <https://ieeexplore.ieee.org/document/7496561>.

   [TLVCOMP]  Mosko, M., "Header Compression for TLV-based Packets",
              ICNRG, Buenos Aires, IETF 95, April 2016,
              <https://datatracker.ietf.org/meeting/interim-2016-icnrg-
              02/materials/slides-interim-2016-icnrg-2-7>.

   [TOURANI]  Tourani, R., Misra, S., Mick, T., and G. Panwar,
              "Security, Privacy, and Access Control in Information-
              Centric Networking: A Survey", IEEE Communications Surveys
              and Tutorials, Vol. 20, Issue 1, pp. 566-600,
              DOI 10.1109/COMST.2017.2749508, September 2017,
              <https://ieeexplore.ieee.org/document/8027034>.

   [TS23.203] 3GPP, "Policy and charging control architecture", 3GPP
              TS 23.203 17.2.0, December 2021,
              <https://www.3gpp.org/ftp/Specs/html-info/23203.htm>.

   [TS23.401] 3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", 3GPP TS 23.401 17.5.0, June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/23401.htm>.

   [TS23.501] 3GPP, "System architecture for the 5G System (5GS)", 3GPP
              TS 23.501 17.5.0, June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/23501.htm>.

   [TS23.714] 3GPP, "Study on Control Plane (CP) and User Plane (UP)
              separation of Evolved Packet Core (EPC) nodes", 3GPP
              TS 23.714 14.0.0, June 2016,
              <https://www.3gpp.org/ftp/Specs/html-info/23714.htm>.

   [TS29.060] 3GPP, "General Packet Radio Service (GPRS); GPRS Tunneling
              Protocol (GTP) across the Gn and Gp interface", 3GPP
              TS 29.060 17.3.0, June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/29060.htm>.

   [TS29.336] 3GPP, "Home Subscriber Server (HSS) diameter interfaces
              for interworking with packet data networks and
              applications", 3GPP TS 29.336 17.13.1, March 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/29336.htm>.

   [TS33.310] 3GPP, "Network Domain Security (NDS); Authentication
              Framework (AF)", 3GPP TS 33.310 17.3.0, June 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/33310.htm>.

   [TS33.320] 3GPP, "Security of Home Node B (HNB) / Home evolved Node B
              (HeNB)", 3GPP TS 33.320 17.0.0, March 2022,
              <https://www.3gpp.org/ftp/Specs/html-info/33320.htm>.

Acknowledgements

   We thank all contributors, reviewers, and the chairs for their
   valuable time in providing comments and feedback that helped improve
   this document.  We especially want to mention the following members
   of the IRTF Information-Centric Networking Research Group (ICNRG),
   listed in alphabetical order: Kashif Islam, Thomas Jagodits, Luca
   Muscariello, David R. Oran, Akbar Rahman, Martin J. Reed, Thomas
   C. Schmidt, and Randy Zhang.

   The IRSG review was provided by Colin Perkins.

Authors' Addresses

   Prakash Suthar
   Google Inc.
   Mountain View, California 94043
   United States of America
   Email: psuthar@google.com


   Milan Stolic
   Cisco Systems Inc.
   Naperville, Illinois 60540
   United States of America
   Email: mistolic@cisco.com


   Anil Jangam (editor)
   Cisco Systems Inc.
   San Jose, California 95134
   United States of America
   Email: anjangam@cisco.com


   Dirk Trossen
   Huawei Technologies
   Riesstrasse 25
   80992 Munich
   Germany
   Email: dirk.trossen@huawei.com


   Ravi Ravindran
   F5 Networks
   3545 North First Street
   San Jose, California 95134
   United States of America
   Email: r.ravindran@f5.com