ICN Research Group                                        Prakash Suthar
Internet-Draft                                              Milan Stolic
Intended status: Informational                          Anil Jangam, Ed.
Expires: November 26, 2020                            Cisco Systems Inc.
                                                            Dirk Trossen
                                                     Huawei Technologies
                                                   Ravishankar Ravindran
                                                   Sterlite Technologies
                                                            May 25, 2020

          Native Deployment of ICN in LTE, 4G Mobile Networks


   LTE, 4G mobile networks use IP-based transport for control plane to
   establish the data session and user plane for actual data delivery.
   In existing architecture, IP transport used in the user plane is not
   optimized for data transport, which leads to an inefficient data
   delivery.  IP unicast routing from server to clients is used for
   delivery of multimedia content to User Equipment (UE), where each
   user gets a separate stream.  From a bandwidth and routing
   perspective, this approach is inefficient.  Multicast and broadcast
   technologies have emerged recently for mobile networks, but their
   deployments are very limited or at an experimental stage due to
   complex architecture and radio spectrum issues.  ICN is a rapidly
   emerging technology with built-in features for efficient multimedia
   data delivery.  However much of the work is focused on fixed
   networks.  The focus of this draft is on native deployment of ICN in
   cellular mobile networks by using ICN in a 3GPP protocol stack.  ICN
   has an inherent capability for multicast, anchorless mobility and
   security, and it is optimized for data delivery using local caching
   at the edge.  The proposed approaches in this draft allow ICN to be
   enabled natively over the current LTE stack comprising PDCP/RLC/MAC/
   PHY, or in a dual stack mode (along with IP).  These approaches can
   help optimize the mobile networks by leveraging the inherent benefits
   of ICN.  This document is a product of the Information-Centric
   Networking Research Group (ICNRG).

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute

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   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   This Internet-Draft will expire on November 26, 2020.

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  3GPP Terminology and Concepts . . . . . . . . . . . . . . . .   3
   3.  LTE, 4G Mobile Network  . . . . . . . . . . . . . . . . . . .   7
     3.1.  Network Overview  . . . . . . . . . . . . . . . . . . . .   7
     3.2.  QoS Challenges  . . . . . . . . . . . . . . . . . . . . .   9
     3.3.  Data Transport Using IP . . . . . . . . . . . . . . . . .  10
     3.4.  Virtualizing Mobile Networks  . . . . . . . . . . . . . .  10
   4.  Data Transport Using ICN  . . . . . . . . . . . . . . . . . .  11
   5.  ICN Deployment in 4G and LTE Networks . . . . . . . . . . . .  14
     5.1.  General ICN Deployment Considerations . . . . . . . . . .  14
     5.2.  ICN Deployment Scenarios  . . . . . . . . . . . . . . . .  14
     5.3.  ICN Deployment in LTE Control Plane . . . . . . . . . . .  18
     5.4.  ICN Deployment in LTE User Plane  . . . . . . . . . . . .  19
       5.4.1.  Dual stack ICN deployments in UE  . . . . . . . . . .  20
       5.4.2.  Native ICN Deployments in UE  . . . . . . . . . . . .  24
     5.5.  ICN Deployment in eNodeB  . . . . . . . . . . . . . . . .  25
     5.6.  ICN Deployment in Packet Core (SGW, PGW) Gateways . . . .  27
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  29
   7.  Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  31
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  31

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     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  31
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  32
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  36

1.  Introduction

   LTE mobile technology is built as an all-IP network.  It uses IP
   routing protocols (OSPF, ISIS, BGP, etc.) to establish network routes
   to route data traffic to the end user's device.  Stickiness of an IP
   address to a device is the key to get connected to a mobile network.
   The same IP address is maintained through the session until the
   device gets detached or moves to another network.

   One of the key protocols used in 4G and LTE networks is GPRS
   Tunneling protocol (GTP).  GTP, DIAMETER and other protocols are
   built on top of IP.  One of the biggest challenges with IP-based
   routing is that it is not optimized for data transport, although it
   is the most efficient communication protocol.  By native
   implementation of Information Centric Networking (ICN) in 3GPP, we
   can re-architect a mobile network and optimize its design for
   efficient data transport by leveraging ICN's caching feature.  ICN
   also offers an opportunity to leverage inherent capabilities of
   multicast, anchorless mobility management, and authentication.  This
   draft proposes options for deploying ICN in mobile networks, and how
   they affect mobile providers and end users.

   This document represents the consensus of the Information-Centric
   Networking Research Group (ICNRG).  It has been reviewed extensively
   by the Research Group (RG) members active in the specific areas of
   work covered by the document.

2.  3GPP Terminology and Concepts

   1.   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.  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 GGSN, PGW.

   2.   Control Plane

        The control plane carries signaling traffic and is responsible
        for routing between eNodeB and MME, MME and HSS, MME and SGW,
        SGW and PGW, etc.  Control plane signaling is required to
        authenticate and authorize UE and establish a mobility session

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        with mobile gateways (SGW/PGW).  Control plane functions also
        include system configuration and management.

   3.   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.

   4.   eNodeB

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

   5.   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 sub components
        of the EPS core such as Mobility Management Entity (MME),
        Serving Gateway (SGW), Packet Data Network Gateway (PDN-GW), and
        Home Subscriber Server (HSS).

   6.   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
        the Evolved Universal Terrestrial Radio Access (E-UTRA) and the
        Evolved Universal Terrestrial Radio Access Network (E-UTRAN).

   7.   Evolved UTRAN

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

   8.   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 and is like Proxy Mobile IPv6
        (PMIPv6).  However, GTP also provides functionality beyond
        mobility, such as in-band signaling related to QoS and charging,
        among others.

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   9.   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 assigned to it by an operator.  The GGSN also serves
        as the topological anchor for addresses/prefixes assigned to the
        User Equipment.

   10.  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.

   11.  Home Subscriber Server

        The Home Subscriber Server (HSS) 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.

   12.  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.

   13.  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.

   14.  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.

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   15.  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 either by
        GGSNs or PDN Gateways (PGWs).

   16.  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 UE 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.

   17.  Packet Data Network Gateway

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

   18.  Packet Data Protocol Context

        A Packet Data Protocol (PDP) context is the equivalent of a
        virtual connection between the User Equipment (UE) and a PDN
        using a specific gateway.

   19.  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).

   20.  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-UE point-to-point (p2p) tunnel between the GGSN
        and SGSN transports the packets between the UE and the gateway.

   21.  Terminal Equipment

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        The Terminal Equipment (TE) is any device/host connected to the
        Mobile Terminal (MT) offering services to the user.  A TE may
        communicate to an MT, for example, over the Point-to-Point
        Protocol (PPP).

   22.  UE, MS, MN, and Mobile

        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 a Mobile Terminal
        (MT).  The terms UE, MS, MN, and mobile are used interchangeably
        within this document.

   23.  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.  LTE, 4G Mobile Network

3.1.  Network Overview

   With the introduction of LTE, mobile networks moved to all-IP
   transport for all elements such as eNodeB, MME, SGW/PGW, HSS, PCRF,
   routing and switching, etc.  Although LTE network is data-centric, it
   has support for legacy Circuit Switch features such as voice and SMS
   through transitional CS fallback and flexible IMS deployment
   [GRAYSON].  For each mobile device attached to the radio (eNodeB),
   there is a separate overlay tunnel (GPRS Tunneling Protocol, GTP)
   between eNodeB and Mobile gateways (i.e., SGW, PGW).

   The GTP tunnel is used to carry user traffic between gateways and
   mobile devices.  This forces data to be distributed only by using
   unicast mechanism.  It is also important to understand the overhead
   of a GTP and IPSec protocols because it has impact on the carried
   user data traffic.  All mobile backhaul traffic is encapsulated using
   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),
   and the encryption and authentication header algorithm used.  If we
   factor Advanced Encryption Standard (AES) encryption with the packet
   size, the overhead can be significant [OLTEANU], particularly for the
   smaller payloads.

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   When any UE is powered up, it attaches to a mobile network based on
   its configuration and subscription.  After a successful attach
   procedure, UE registers with the mobile core network, and an IPv4
   and/or IPv6 address is assigned.  A default bearer is created for
   each UE and it is assigned to default Access Point Name (APN).

                                          +-------+  Diameter  +-------+
                                          |  HSS  |------------|  SPR  |
                                          +-------+            +-------+
                                              |                    |
           +------+   +------+      S4        |                +-------+
           |  3G  |---| SGSN |----------------|------+  +------| PCRF  |
        ^  |NodeB |   |      |---------+  +---+      |  |      +-------+
   +-+  |  +------+   +------+   S3    |  |  S6a     |  |Gxc       |
   | |  |                          +-------+         |  |          |Gx
   +-+  |       +------------------|  MME  |------+  |  |          |
   UE   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 |       +-----+
                                +---------+   +---------+
                                     |             |
                                    +-+           +-+
                                    | |           | |
                                    +-+           +-+
                                    UE            UE

                 Figure 1: LTE, 4G Mobile Network Overview

   The data delivered to mobile devices is unicast inside the GTP
   tunnel.  If we consider the combined impact of GTP, IPSec and unicast
   traffic, the data delivery is not efficient.  IETF has developed
   various header compression algorithms to reduce overhead associated
   with IP packets.  Some techniques are robust header compression
   (ROHC) and enhanced compression of the real-time transport protocol
   (ECRTP) so that 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

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   achieve efficiency in data delivery [TS25.323], and can be adapted to
   ICN, as well [ICNLOWPAN] [TLVCOMP].

3.2.  QoS Challenges

   During the attach procedure, a default bearer is created for each UE
   and it is assigned to the default Access Point Name (APN).  The QoS
   values that uplink and downlink bandwidth assigned during the initial
   attach are minimal.  Additional dedicated bearer(s) with enhanced QoS
   parameters are established depending on specific application needs.

   While all traffic within a certain bearer gets 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: at
   content prioritization/marking and transport marking, and congestion
   management.  From the transport perspective, QoS is defined at layer
   2 as class of service (CoS) and at layer 3 either as DiffServ code
   point (DSCP) or type of service (ToS).  The mapping of 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 mapping to DSCP at transport layer
   [TS23.401].  However, this requires manual configuration at different
   elements and, if there are misconfigurations at any place in the
   path, it will not work properly.

   In summary, QoS configuration for mobile networks for user plane (for
   user traffic) and transport in an IP-based mobile network is complex
   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., 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 needed to understand how QoS in
   ICN can be implemented to meet the IP QoS requirements [RFC4594].

   Research papers published so far explore the possibility of
   classifications based on name prefixes (thus addressing the problem
   of IP QoS not being information aware), or on popularity or placement
   (looking at a distance of a content from a requester).  However,

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   focus of these research efforts is on faster routing of Interest
   requests towards the content rather than content delivery.

3.3.  Data Transport Using IP

   The data delivered to mobile devices is unicast inside 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 implementation on the RAN side of the
   network.  Transport networks in the backhaul and core addressed the
   multicast delivery long ago and have implemented it in most cases in
   their multi-purpose integrated transport.  But the RAN part of the
   network 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.  With that said, the data
   delivery in the mobility remains greatly unicast.  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 content (or video) on
   demand model.

   To ease the burden on the bandwidth of the SGi interface, caching is
   introduced in a similar manner as with many Enterprises.  In the
   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 interface).  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.

   Data delivered to mobile devices is unicast inside a GTP tunnel.  If
   we consider the combined impact of GTP, IPSec, and unicast traffic,
   the end-to-end data delivery is not efficient.  By deploying ICN, we
   intend to either terminate the GTP tunnel at the mobility anchoring
   point by leveraging control and user-plane separation, or replace it
   with native ICN protocols.

3.4.  Virtualizing Mobile Networks

   The Mobile packet core deployed in a major Service Provider network
   is either based on dedicated hardware or, in some cases, large
   capacity x86 platforms.  With adoption of Mobile Virtual Network
   Operators (MVNO), public safety network, and enterprise mobility
   network, we need elastic mobile core architecture.  By deploying

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   mobile packet core on a commercially off-the-shelf (COTS) platform
   using virtualized infrastructure (NFVI) framework and end-to-end
   orchestration, we can simplify new deployments and provide optimized

   While virtualization is growing, and many mobile providers use hybrid
   architecture consisting of dedicated and virtualized infrastructures,
   the control and data delivery planes are still the same.  There is
   also work under way to separate the control plane and user plane so
   the network can scale better.  Virtualized mobile networks and
   network slicing with control and user plane separation provide
   mechanism to evolve GTP-based architecture to open-flow SDN-based
   signaling for LTE and proposed 5G core.  Some early architecture work
   for 5G mobile technologies provides a mechanism for control and user
   plane separation and simplifies mobility call flow by introduction of
   open-flow-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 to the network is between
   radio and a router or mobile edge computing (MEC) [MECSPEC] element.
   MEC 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.

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

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

                        Figure 2: ICN Architecture

   MEC transforms radio 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.  MEC can be an
   ideal candidate for ICN forwarder in addition to its usual function
   of managing mobile termination.  In addition to MEC, other transport
   elements, such as routers, can work as ICN forwarders.

   Data transport using ICN is different compared to IP-based transport.
   It evolves the Internet infrastructure by introducing uniquely named
   data as a core Internet 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 to cache the content so it can be delivered locally
   for subsequent request from any other client.  For mobile network,
   transport between a client and a content provider consists of radio
   network + mobile backhaul and IP core transport + Mobile Gateways +
   Internet + content data network (CDN).

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   To understand the suitability of ICN for mobile networks, we will
   discuss the ICN framework describing protocols architecture and
   different types of messages, and then consider how we can use this in
   a mobile network for delivering 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
    UE         <--------+      Intf v       Nack v     |
            Data  |                                    |

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

             Figure 3: ICN Interest, Data Packet and Forwarder

   In an LTE network, when a mobile device wants to get certain content,
   it will send an Interest message to the closest eNodeB.  Interest
   packet follows the TLV format [RFC8609] and contains mandatory fields
   such as name of the content and content matching restrictions
   (KeyIdRestr and ContentObjectHashRestr) forming the 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 perform lookup if a
   request for such content has come earlier from another client.  If
   yes, it is 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
   reaches the content provider, it will return a Data packet containing
   information such as content name, signature, and data.

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   Data packet travels in reverse direction following the same path
   taken by the Interest packet, which maintains 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 LTE network.

5.  ICN Deployment in 4G and LTE Networks

5.1.  General ICN Deployment Considerations

   In LTE/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 existing mobile packet core using
   Control and User Plane Separation (CUPS) [TS23.714] enables flexible
   network deployment and operation, by distributed deployment and the
   independent scaling between control plane and user plane functions -
   while not affecting the functionality of existing nodes subject to
   this split.

   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, 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 optimization allows for the
   introduction of ICN and amplifies its advantages.  This section
   analyzes the potential impact of ICN on control and user plane
   traffic for centralized and disaggregate CUPS-based mobile network

5.2.  ICN Deployment Scenarios

   Deployment of ICN provides an opportunity to further optimize the
   existing data transport in LTE/4G mobile networks.  The various
   deployment options that ICN and IP provide are somewhat analogous to
   the deployment scenarios when IPv6 was introduced to interoperate
   with IPv4 except, with ICN, the whole IP stack is being 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
   deployed by natively replacing IP transport (IPv4 and IPv6) or as an
   overlay protocol.  Figure 4 describes a modified protocol stack to
   support ICN deployment scenarios.

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                   +----------------+ +-----------------+
                   | 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 and Deployment Scenarios

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

   Combined with the existing IP function, the ICN function provides
   support for either native ICN and/or the dual stack (ICN/IP)
   transport 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 even a user-facing setting realized through a user
   interface, like those used today that select cellular over WiFi being
   used for selected applications.  In another option, it might use a
   software API, which an adapted IP application could use to specify
   (such as an ICN transport) for obtaining its benefits.

   Another potential application of TCL is in implementation of network
   slicing, where it can have a slice management capability locally or
   it can interface to an external slice manager through an API [GALIS].

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   This solution can enable network slicing for IP and ICN transport
   selection from the UE itself.  The TCL could apply slice settings to
   direct certain traffic (or applications) over one slice and others
   over another slice, determined by some form of 'slicing policy'.
   Slicing policy can be obtained externally from the slice manager or
   configured locally on UE.

   From the perspective of applications either on UE or a content
   provider, the following options are possible for ICN deployment
   natively and/or with IP.

   1.  IP over IP

       In this scenario, UE uses applications tightly integrated with
       the existing IP transport infrastructure.  In this option, the
       TCL has no additional function because packets are forwarded
       directly using an IP protocol stack, which sends packets over the
       IP transport.

   2.  ICN over ICN

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

   3.  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 user equipment (UE) and content provider).  IP routing is
       used from Radio Access Network (eNodeB) to mobile backhaul, IP
       core, and Mobile Gateway (SGW/PGW).  UE attaches to Mobile
       Gateway (SGW/PGW) using IP address.  Also, the data transport
       between Mobile Gateway (SGW/PGW) and content publisher uses IP.
       Content provider can serve content either using IP or ICN, based
       on the UE request.

       An approach to implement ICN in mobile backhaul networks is
       described in [MBICN].  It implements a GTP-U extension header
       option to encapsulate ICN payload in 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 GTP-U tunnel can be terminated by hairpinning the packet
       before it reaches 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
       repos, caches) in the tunnel path; it can reply right away

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       without going all the way through the mobile core.  While GTP-U
       extension header is used to carry UE specific ICN payload, they
       are not visible to the transport, including SGW.  On the other
       hand, the PGW can use the UE-specific ICN header extension and
       ICN payload to set up an uplink transport towards 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.

   4.  IP over ICN (IPoICN)

       H2020 project [H2020] provides an architectural framework for
       deployment of IP as an overlay over ICN protocol [IPoICN].
       Implementing IP services over ICN provides an opportunity
       leveraging benefit of ICN in the transport infrastructure and
       there is no impact on end devices (UE and access network) as they
       continue to use IP.  IPoICN however, will require an inter-
       working function (IWF/Border Gateway) to translate various
       transport primitives.  The IWF function will provide a mechanism
       for protocol translation between IPoICN and native IP deployment
       for mobile network.  After reviewing [IPoICN], we understand and
       interpret that ICN is implemented in the transport natively;
       however, IP is implemented in UE, eNodeB, and Mobile gateway
       (SGW/PGW), which is also called as 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.

   5.  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,

       At 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

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       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 UE, in the eNodeB, in the mobile
       backhaul, or in the mobile core.  Finally, as hICN itself uses
       IPv6, it cannot be considered as an alternative transport layer.

5.3.  ICN Deployment in LTE 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 LTE signaling
   in the current architecture.  It is important to understand the
   concept of point of attachment (POA).  When UE 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

   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 and TLV,
   carrying additional attributes such as a layer 3 transport.  Physical
   POA in eNodeB handles both mobility and session management for any UE
   attached to 4G, LTE network.  The number of mobility management
   messages between different nodes in an LTE network per signaling
   procedure are shown in Table 1.

   Normally, two types of UE devices attach to the LTE network: SIM
   based (need 3GPP mobility protocol for authentication) or non-SIM
   based (which connect to WiFi network).  Both device types require
   authentication .  For non-SIM based devices, AAA is used for
   authentication.  We do not propose to change UE 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 UE capable of dual stack or
   native ICN.  When UE initiates an attach request using the identity
   as ICN, MME must be able to parse that message and create a session.

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   MME forwards UE authentication to HSS, so HSS must be able to
   authenticate an ICN-capable UE and authorize create session

       | LTE 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 LTE Gateways

   Anchorless mobility [ALM] provides a fully decentralized, control-
   plane agnostic solution to handle producer mobility in ICN.  Mobility
   management at layer-3 level makes it 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

   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 LTE signaling call flows [TS23.401] and
   messages inter-dependencies (see Table 1), our recommendation is that
   it is not beneficial to deploy 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.  ICN Deployment in LTE User Plane

   We will consider Figure 1 to discuss different mechanisms to deploy
   ICN in mobile networks.  In Section 5.2, we discussed generic
   deployment scenarios of ICN.  In this section, we discuss the
   specific use cases of native ICN deployment in LTE user plane.  We
   consider the following options:

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   1.  Dual stack ICN deployment in UE

   2.  Native ICN deployments in UE

   3.  ICN deployment in eNodeB

   4.  ICN deployment in mobile gateways (SGW/PGW)

5.4.1.  Dual stack ICN deployments in UE

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

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

   The protocol interactions and impact of supporting tunneling of ICN
   packet into IP or to support ICN natively are described in Figure 5
   and Figure 6, respectively.

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    +--------+                                               +--------+
    |   App  |                                               |  CDN   |
    +--------+                                               +--------+
    |Transp. | |              |               |              |Transp. |
    +--------+ |              |               | +--------+ | +--------+
    |        |.|..............|...............|.|        |.|.|        |
    | 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   |
    +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+
        UE     |  BS(eNodeB)  |      SGW      |     PGW    |
              Uu             S1U            S5/S8         SGi

                 Figure 5: Dual Stack ICN Deployment in UE

   The protocols and software stack used inside LTE capable UE support
   both 3G and LTE software interworking and handover.  Latest 3GPP
   Rel.13 onward specification describes the use of IP and non-IP
   protocols to establish logical/session connectivity.  We intend to
   leverage the non-IP protocol-based mechanism to deploy ICN protocol
   stack in UE, as well as in eNodeB and mobile gateways (SGW, PGW).

   1.  Existing application layer can be modified to provide options for
       a new ICN-based application and existing IP-based applications.
       UE can continue to support existing IP-based applications or host
       new applications developed to support native ICN as transport,
       ICNoIP, or IPoICN-based transport.  Application layer has the
       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 transport convergence layer (TCL)
       function handles the interaction of applications with multiple
       transport options.

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   2.  The transport convergence layer helps determine the type of
       transport (such as ICN, hICN, or IP) and type of radio interface
       (LTE or WiFi, or both) used to send and receive traffic.
       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 Application Programming Interface (API) to exchange
       parameters required for transport selection.  Southbound
       interactions of Transport Convergence Layer (TCL) will be either
       to IP or 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 maintains a pending request mapping table to
       map returning responses to the originating HTTP request.  The
       common API will provide a common '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 UE to the receiving UE 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.

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                  +----------------+ +-----------------+
                  | 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.  ICN function (forwarder) is introduced in parallel to the
       existing IP layer.  ICN forwarder contains functional
       capabilities to forward ICN packets, such as Interest packet to
       eNodeB or response "data packet" from eNodeB to the application.

   4.  For the dual-stack scenario, when UE is not supporting ICN as
       transport, we use IP underlay to transport ICN packets.  ICN
       function will use IP interface to send Interest and Data packets
       for fetching or sending data using ICN protocol function.  This
       interface will use ICN overlay over IP using any overlay
       tunneling mechanism.

   5.  To support ICN at network layer in UE, PDCP layer has to be aware
       of ICN capabilities and parameters.  PDCP is located in the Radio
       Protocol Stack in the LTE Air interface, between IP (Network

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       layer) and Radio Link Control Layer (RLC).  PDCP performs the
       following functions [TS36.323]:

       1.  Data transport by listening to upper layer, formatting and
           pushing down to Radio Link Layer (RLC)

       2.  Header compression and decompression using Robust Header
           Compression (ROHC)

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

       4.  Radio layer messages associated with sequencing, packet drop
           detection and re-transmission, and so on.

   6.  No changes are required for lower layer such as RLC, MAC, and
       Physical (L1) because 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.  Native ICN Deployments in UE

   We propose to implement ICN natively in UE by modifying the PDCP
   layer in 3GPP protocols.  Figure 7 provides a high-level protocol
   stack description where ICN is used at the following different

   1.  User plane communication

   2.  Transport layer

   User plane communication takes place between PDCP and application
   layer, whereas ICN transport is a substitute of GTP protocol.
   Removal of GTP protocol stack is a significant change in mobile
   architecture because GTP is used not just for routing but for
   mobility management functions, such as billing, mediation, and policy

   If we implement ICN natively in UE, communication between UE and
   eNodeB will change.  Also, this will avoid tunneling the user plane
   traffic from eNodeB to the mobile packet core (SGW, PGW) using GTP

   For native ICN deployment, an application will be configured to use
   ICN forwarder so there is no need for Transport Convergence.  Also,
   to support ICN at the network layer in UE, we need to modify the

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   existing PDCP layer.  PDCP layer must be aware of ICN capabilities
   and parameters.

   Native implementation will also provide opportunities to develop new
   use cases leveraging ICN capabilities, such as seamless mobility, UE
   to UE content delivery using radio network without traversing the
   mobile gateways, and more.

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

                   Figure 7: Native ICN Deployment in UE

5.5.  ICN Deployment in eNodeB

   eNodeB is a physical point of attachment for UE, where radio
   protocols are converted into IP transport protocol for dual stack/
   overlay and native ICN, respectively (see Figure 6 and Figure 7).
   When UE performs attach procedures, it is assigned an identity either
   as IP or dual stack (IP and ICN), or ICN.  UE can initiate data
   traffic using any of the following options:

   1.  Native IP (IPv4 or IPv6)

   2.  Native ICN

   3.  Dual stack IP (IPv4/IPv6) or ICN

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

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

   2.  eNodeB to provide open Application Programming Interface (API) to
       external management systems, to provide capability to eNodeB to
       program the forwarding strategies.

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

                 Figure 8: Native ICN Deployment in eNodeB

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

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       1.  Assuming eNodeB is IP enabled and UE requests IP transfer,
           eNodeB forwards data over IP.

       2.  Assuming eNodeB is ICN enabled and UE requests ICN transfer,
           eNodeB forwards data over ICN.

       3.  Assuming eNodeB is IP enabled and UE requests ICN, eNodeB
           overlays ICN on IP and forwards user plane traffic over IP.

       4.  Assuming eNodeB is ICN enabled and UE requests IP, eNodeB
           overlays IP on ICN and forwards user plane traffic over ICN

5.6.  ICN Deployment in Packet Core (SGW, PGW) Gateways

   Mobile gateways---also known as Evolved Packet Core (EPC)--include
   SGW, PGW, which perform session management for UE from the initial
   attach to disconnection.  When UE is powered on, it performs NAS
   signaling and attaches to PGW after successful authentication.  PGW
   is an anchoring point for UE and responsible for service creations,
   authorization, maintenance, and so on.  The Entire functionality is
   managed using IP address(es) for UE.

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

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

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

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

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   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 content store (CS), Pending Interest Table (PIT), Forwarding
       Information Base (FIB) capabilities, and so on.  If UE requests
       ICN in PCO IE, then PGW registers UE with ICN names.  For ICN
       forwarding, PGW caches content locally using CS functionality.

   5.  PCO IE described in [TS24.008] (see Figure 10.5.136 on page 598)
       and [TS24.008] (see Table 10.5.154 on page 599) provide details
       for different fields.

       1.  Octet 3 (configuration protocols define PDN types), which
           contains details about IPv4, IPv6, both 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 UE and
           mobile gateways (SGW, PGW) so they can be interpreted
           properly and the UE can attach successfully.

   6.  Deployment of ICN functionalities in SGW and PGW should be
       matched with UE and 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 UE 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 a UE
       attached with an ICN identity, if PGW has to 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.

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6.  Security Considerations

   To ensure only authenticated UEs are connected to the network, LTE
   mobile network implements various security mechanisms.  From the
   perspective of ICN deployment in the user plane, it needs to take
   care of the following security aspects:

   1.  UE authentication and authorization

   2.  Radio or air interface security

   3.  Denial of service attacks on mobile gateway, services

   4.  Content positioning either in 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
   technique.  When UE is powered up, it performs key exchange between
   UE's USIM and HSS/Authentication Center using NAS messages, including
   ciphering and integrity protections between UE and MME.  Details of
   secure UE authentication, key exchange, ciphering, and integrity
   protections messages are given in the 3GPP call flow [TS23.401].

   LTE is an all-IP network and uses IP transport in its mobile backhaul
   (between eNodeB and core network).  In case of provider-owned
   backhaul, it may not implement security mechanisms; however, they are
   necessary in case it uses a shared or leased network.  The native IP
   transport continues to leverage security mechanism such as Internet
   key exchange (IKE) and the IP security protocol (IPsec).  More
   details of mobile backhaul security are provided in 3GPP network
   security [TS33.310] and [TS33.320].  When mobile backhaul is upgraded
   to support dual stack (IP+ICN) or native ICN, it is required to
   implement security techniques that are deployed in mobile backhaul.
   When ICN forwarding is enabled on mobile transport routers, we need
   to deploy security practices based on [RFC7476] and [RFC7927].

   Some key functions supported by LTE mobile gateway (SGW, PGW) are
   content based billing, deep packet inspection (DPI), and lawful
   intercept (LI).  For ICN-based user plane traffic, it is required to
   integrate ICN security for sessions between UE and gateway.  However,
   in the ICN network, some of the services provided by mobile gateways
   mentioned above may not work because only consumers who have

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   decryption keys can access the content.  Further research in this
   area is needed.

7.  Summary

   In this draft, we have discussed complexities of LTE network and key
   dependencies for deploying ICN in user plane data transport.
   Different deployment options described cover aspects such as inter
   operability and multi-technology, which is a reality for any Service
   Provider.  One can use LTE gateway software and ICN simulator and
   deploy ICN data transport in user plane as an overlay, dual stack (IP
   + ICN), hICN, or natively (by integrating ICN with CDN, eNodeB, SGW,
   PGW and transport network).  Notice that, for deployment scenarios
   discussed above, additional study is required for lawful
   interception, billing/mediation, network slicing, and provisioning

   Mobile Edge Computing (MEC) [CHENG] provides capabilities to deploy
   functionalities such as Content Delivery Network (CDN) caching and
   mobile user plane functions (UPF) [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 ICN deployment in eNodeB, MEC, mobile gateways (SGW, PGW)
   and CDN.  The key aspect for ICN is in its seamless integration in
   LTE and 5G networks with tangible benefits so we can optimize content
   delivery using simple and scalable architecture.  Authors will
   continue to explore how ICN forwarding in MEC could be used in
   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 mentioned in
   [TS23.501], 5G network architecture proposes simplification of
   control plane messages and can be a candidate for use of ICN.

   As a starting step towards ICN user plane deployment, it is proposed
   to incorporate protocol changes in UE, eNodeB, 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.  Authors welcome contributions and
   suggestions, including those related to further validations of the
   principles by implementing prototype and/or proof of concept in the
   lab and in the production environment.

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8.  Acknowledgements

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

   The IRSG review was provided by Colin Perkins.

9.  References

9.1.  Normative References

              3GPP, "Mobile radio interface Layer 3 specification; Core
              network protocols; Stage 3", 3GPP TS 24.008 3.20.0,
              December 2005,

              3GPP, "Packet Data Convergence Protocol (PDCP)
              specification", 3GPP TS 25.323 3.10.0, September 2002,

              3GPP, "3GPP Evolved Packet System (EPS); Evolved General
              Packet Radio Service (GPRS) Tunneling Protocol for Control
              plane (GTPv2-C); Stage 3", 3GPP TS 29.274 10.11.0, June
              2013, <http://www.3gpp.org/ftp/Specs/html-info/29274.htm>.

              3GPP, "General Packet Radio System (GPRS) Tunneling
              Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0,
              September 2011,

              3GPP, "Evolved Universal Terrestrial Radio Access
              (E-UTRA); Packet Data Convergence Protocol (PDCP)
              specification", 3GPP TS 36.323 10.2.0, January 2013,

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9.2.  Informative References

   [ALM]      Auge, J., Carofiglio, G., Grassi, G., Muscariello, L.,
              Pau, G., and X. Zeng, "Anchor-Less Producer Mobility in
              ICN", Proceedings of the 2Nd ACM Conference on
              Information-Centric Networking, ACM-ICN'15, ACM DL,
              pp.189-190, September 2013,

   [BROWER]   Brower, E., Jeffress, L., Pezeshki, J., Jasani, R., and E.
              Ertekin, "Integrating Header Compression with IPsec",
              MILCOM 2006 - 2006 IEEE Military Communications
              conference IEEE Xplore DL, pp.1-6, October 2006,

   [CCN]      "Content Centric Networking", <http://www.ccnx.org>.

   [CHENG]    Liang, C., Yu, R., and X. Zhang, "Information-centric
              network function virtualization over 5g mobile wireless
              networks", IEEE Network Journal vol. 29, number 3, pp.
              68-74, June 2015,

   [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,

   [GALIS]    Galis, A., Makhijani, K., Yu, D., and B. Liu, "Autonomic
              Slice Networking", draft-galis-anima-autonomic-slice-
              networking-05 (work in progress), September 2018.

   [GRAYSON]  Grayson, M., Shatzkamer, M., and S. Wainner, "Cisco Press
              book "IP Design for Mobile Networks"", Cisco
              Press Networking Technology series, June 2009,

   [H2020]    H2020, "The POINT Project", <https://www.point-h2020.eu/>.

   [HICN]     Muscariello, L., Carofiglio, G., Auge, J., and M.
              Papalini, "Hybrid Information-Centric Networking", draft-
              muscariello-intarea-hicn-01 (work in progress), December

   [ICN5G]    Ravindran, R., suthar, P., Trossen, D., and G. White,
              "Enabling ICN in 3GPP's 5G NextGen Core Architecture",
              draft-ravi-icnrg-5gc-icn-02 (work in progress), July 2018.

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              Gundogan, C., Schmidt, T., Waehlisch, M., Scherb, C.,
              Marxer, C., and C. Tschudin, "ICN Adaptation to LowPAN
              Networks (ICN LoWPAN)", draft-irtf-icnrg-icnlowpan-02
              (work in progress), March 2019.

   [ICNQoS]   Al-Naday, M., Bontozoglou, A., Vassilakis, G., and M.
              Reed, "Quality of Service in an Information-Centric
              Network", 2014 IEEE Global Communications Conference IEEE
              Xplore DL, pp. 1861-1866, December 2014,

   [IPoICN]   Trossen, D., Read, M., Riihijarvi, J., Georgiades, M.,
              Fotiou, N., and G. Xylomenos, "IP over ICN - The better
              IP?", 2015 European Conference on Networks and
              Communications (EuCNC) IEEE Xplore DL, pp. 413-417, 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, April
              2015, <https://ieeexplore.ieee.org/document/7114719>.

   [MECSPEC]  "Mobile Edge Computing (MEC); Framework and Reference
              Architecture", ETSI European Telecommunication Standards
              Institute (ETSI) MEC specification, March 2016,

   [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, June 2015,

   [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
              on Communications vol. E99.B, pp. 974-991, May 2016,

   [NGMN]     Robson, J., "Data Offloading Techniques in Cellular
              Networks: A Survey", Next Generation Mobile Networks, LTE-
              Advanced Transport Provisioning, V0.0.14, October 2015,

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   [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
              Surveys and Tutorials, IEEE Xplore DL, vol:17, issue:2,
              pp.580-603, November 2014,

   [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, ACM DL, pp.575-579, June 2009,

   [RFC4594]  Babiarz, J., Chan, K., and F. Baker, "Configuration
              Guidelines for DiffServ Service Classes", RFC 4594,
              DOI 10.17487/RFC4594, August 2006,

   [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,

   [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,

   [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,

   [RFC8569]  Mosko, M., Solis, I., and C. Wood, "Content-Centric
              Networking (CCNx) Semantics", RFC 8569,
              DOI 10.17487/RFC8569, July 2019,

   [RFC8609]  Mosko, M., Solis, I., and C. Wood, "Content-Centric
              Networking (CCNx) Messages in TLV Format", RFC 8609,
              DOI 10.17487/RFC8609, July 2019,

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   [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) IEEE Xplore DL, pp. 1-7, May 2016,

   [TLVCOMP]  Mosko, M., "Header Compression for TLV-based Packets",
              ICNRG Buenos Aires IETF 95, April 2016,

              3GPP, "Policy and charging control architecture", 3GPP
              TS 23.203 10.9.0, September 2013,

              3GPP, "General Packet Radio Service (GPRS) enhancements
              for Evolved Universal Terrestrial Radio Access Network
              (E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013,

              3GPP, "System Architecture for the 5G System", 3GPP
              TS 23.501 15.2.0, June 2018,

              3GPP, "Technical Specification Group Services and System
              Aspects: Study on control and user plane separation of EPC
              nodes", 3GPP TS 23.714 0.2.2, June 2016,

              3GPP, "General Packet Radio Service (GPRS); GPRS Tunneling
              Protocol (GTP) across the Gn and Gp interface", 3GPP
              TS 29.060 3.19.0, March 2004,

              3GPP, "Network Domain Security (NDS); Authentication
              Framework (AF)", 3GPP TS 33.310 10.7.0, December 2012,

              3GPP, "Security of Home Node B (HNB) / Home evolved Node B
              (HeNB)", 3GPP TS 33.320 10.5.0, June 2012,

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Authors' Addresses

   Prakash Suthar
   Cisco Systems Inc.
   Rosemont, Illinois  60018

   Email: psuthar@cisco.com

   Milan Stolic
   Cisco Systems Inc.
   Rosemont, Illinois  60018

   Email: mistolic@cisco.com

   Anil Jangam (editor)
   Cisco Systems Inc.
   San Jose, California  95134

   Email: anjangam@cisco.com

   Dirk Trossen
   Huawei Technologies
   Riesstrasse 25
   Munich  80992

   Email: dirk.trossen@huawei.com

   Ravishankar Ravindran
   Sterlite Technologies
   5201 Greatamerica Pkwy
   Santa Clara, California  95054

   Email: ravishankar.ravindran@sterlite.com

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