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Versions: 00 01 02 03 04 draft-irtf-icnrg-icn-lte-4g

ICN Research Group                                        Prakash Suthar
Internet-Draft                                              Milan Stolic
Intended status: Informational                               Anil Jangam
                                                           Cisco Systems
Expires: January 3, 2018                                    July 02 2017


          Native Deployment of ICN in LTE, 4G Mobile Networks
                    draft-suthar-icnrg-icn-lte-4g-02

Abstract

   LTE, 4G mobile networks use IP transport which is not optimized for
   data transport. IP unicast routing from server to clients is used for
   delivery of multimedia content to User Equipment (UE), where each
   user gets separate stream. From 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
   majority of the work is focused on fixed networks. The main focus of
   this draft is on native deployment of ICN in cellular mobile networks
   by using ICN into 3GPP protocol stack. ICN has an inherent capability
   for multicast, anchorless mobility, security and it is optimized for
   data delivery using local caching at the edge. The native ICN or dual
   stack (along with IP) deployment will bring all inherent benefits and
   help in optimizing mobile networks.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts.

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   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

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   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2017 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  LTE, 4G Mobile Network . . . . . . . . . . . . . . . . . . . .  3
     2.1  Network Overview  . . . . . . . . . . . . . . . . . . . . .  3
     2.2  QoS Challenges  . . . . . . . . . . . . . . . . . . . . . .  5
     2.3  Data Transport Using IP . . . . . . . . . . . . . . . . . .  5
     2.4  Virtualizing Mobile Networks  . . . . . . . . . . . . . . .  6
   4.  Data Transport Using ICN . . . . . . . . . . . . . . . . . . .  7
   5.  ICN Deployment in 4G and LTE Networks  . . . . . . . . . . . .  9
     5.1  Recommendations in LTE Signaling  . . . . . . . . . . . . .  9
     5.2  Recommendations in the User Plane . . . . . . . . . . . . . 10
       5.2.1  Dual stack ICN Deployments in UE  . . . . . . . . . . . 11
       5.2.2  Native ICN Deployments in UE  . . . . . . . . . . . . . 14
       5.2.3  ICN Deployment in eNodeB  . . . . . . . . . . . . . . . 15
       5.2.4  ICN Deployment in Packet Core (SGW, PGW) Gateways . . . 16
   6. Security Considerations . . . . . . . . . . . . . . . . . . . . 18
   7. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
   7  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     7.1  Normative References  . . . . . . . . . . . . . . . . . . . 21
     7.2  Informative References  . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23








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1  Introduction

   LTE mobile technology is built as all IP network. It uses IP routing
   protocols such as OSPF, ISIS, BGP etc. to establish network routes to
   route the data traffic to end user's device. Stickiness of IP address
   to a device is the key to get connected to a mobile network and 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
   mobile network and optimize its design for efficient data transport
   by leveraging the caching feature of ICN. ICN also offers an
   opportunity to leverage inherent capabilities of multicast,
   anchorless mobility management, authentication. This draft provides
   insight into different options for deploying ICN in mobile networks
   and how they impact mobile providers and end-users.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  LTE, 4G Mobile Network

2.1  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 like 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). This tunnel is
   used to carry user traffic between gateways and mobile devices so the
   data can only be distributed 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



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   provider is using a shared backhaul), it adds additional overhead
   based upon IPSec tunneling model (tunnel or transport), and
   encryption and authentication header algorithm used. If we factor
   Advanced Encryption Standard (AES) encryption with packet size the
   overhead can vary significantly [IPSEC2].

                                          +-------+  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

   When any UE is powered-up, it attaches to a mobile network based on
   its configuration and subscription. After successful attach
   procedure, UE registers with the mobile core network and 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).

   The data delivered to mobile devices is unicast inside GTP tunnel. If
   we consider combined impact of GTP, IPSec and unicast traffic, the
   data delivery is not efficient. IETF has developed various header
   compression algorithms to reduce the overhead associated with IP



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   packets. Some of 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 achieve efficiency in
   data delivery [TS25.323], and can also be used in ICN as well.

2.2  QoS Challenges

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

   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 depending on the 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 etc.) can be very different.

   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 CoS to DSCP
   takes place at layer-2/3 switching and routing elements. 3GPP has
   specified QoS Class Identifier (QCI) which represents different types
   of content and equivalent mapping to DSCP at transport layer
   [TS23.203] [TS23.401]; however, this again requires manual
   configuration at different elements and if there is misconfiguration
   at any place in the path it will not work properly.

   In summary QoS configuration for mobile network for user plane (for
   user traffic) and transport in IP based mobile network is complex and
   it require synchronization of parameters among different platforms.
   Any misconfiguration in IP QoS can result in poor subscriber
   experience. By deploying ICN, we intend to enhance the subscriber
   experience using its inherent capabilities.

2.3  Data Transport Using IP

   The data delivered to mobile devices is unicast inside GTP tunnel
   from a eNodeB to a PDN gateway (PGW), as described in 3GPP
   specifications [TS23.401]. While the technology exists to address the



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   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 have addressed
   the multicast delivery long time 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
   mobility of the clients, handovers, and the fact that the potential
   gain to the Service Providers may not justify the investment. With
   that said, the data delivery in the mobility remains greatly unicast.

   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, a 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 the 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 has to 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 but could be addressed at the IP transport level.

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

2.4  Virtualizing Mobile Networks

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

   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 underway to separate control plane and user plane so that
   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. Some of early architecture work for 5G mobile



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   technologies provide mechanism for control and user plane separation
   and simplifies mobility call flow by introduction of open-flow based
   signaling is described in [TS23.501] and [TS23.214].

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.

   MEC transforms radio into an intelligent service edge that is capable
   of delivering highly personalized 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 content provider (producer) and end user (consumer) as
   described in figure 2.

     +----------+
     | 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



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                    Fig. 2. ICN Architecture

   Every node in a physical path between a client and a content provider
   is called ICN forwarder or router, and it has the ability to route
   the request intelligently and also cache the content so that 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).

   In order to understand 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 |
                   +------------------------------------+

              Fig. 3. ICN Interest, Data Packet and Forwarder

   For 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 [CCNxTLV] and contains
   mandatory fields such as name of the content and nonce. Name and
   nonce together uniquely identify an Interest packet. Nonce is also
   used to detect looping Interest messages. Interest packet also
   contains optional fields such as selector and guider fields.
   Selectors provides a specific filtering action during matching and



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   selection of the name prefixes. Guiders provides specific set of
   rules on how the Interest packet can be processed at the forwarder.

   First ICN router will receive Interest packet and perform lookup if
   request for such content has come earlier from any other client. If
   yes, it is served from the local cache, otherwise request is
   forwarded to the next-hop ICN router. Each ICN router maintains three
   data structures, namely Pending Interest Table (PIT), Forwarding
   Information Base (FIB), and Content Store (CS). The Interest packet
   travels hop-by-hop towards content provider. Once the Interest
   reaches the content provider it will return a Data packet containing
   information such as content name, signature, signed key and data.

   Data packet travels in reverse direction following the same path
   taken by the interest packet so routing symmetry is maintained.
   Details about algorithms used in PIT, FIB, CS and security trust
   models are described in various resources [CCN], here we explained
   the concept and its applicability to the LTE network.

5.  ICN Deployment in 4G and LTE Networks

5.1  Recommendations in LTE Signaling

   In this section we analyze signaling messages which are required for
   different procedures, such as attach, handover, tracking area update
   etc. The goal of analysis is to see if there is any benefit to
   replace 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 at least three
   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 current architecture IP transport is used for all the messages
   associated with Control Plane for mobility and session management. IP
   is embedded very deeply into these messages and TLV carrying
   additional attributes 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 given
   below in figure 4.




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   Normally two types of UE devices attach to LTE network: SIM based
   (need 3GPP mobility protocol for authentications) or non-SIM based
   (which connect to WiFi network), and authentication is required for
   both of these device types. For non-SIM based devices, AAA is used
   for authentication. We do not propose to change UE authentication
   procedures for user data transport using ICN, or any other mobility
   management messaging. A separate study would be required to analyze
   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.

   +---------------------------+-------+-------+-------+-------+------+
   | 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   |  1   |
   | 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   |  0    |  0    |   0   |  0   |
   | Total                     |  34   |  2    | 14    |   6   |  3   |
   +---------------------------+-------+-------+-------+-------+------+

                Fig. 4. Signaling Messages in LTE Gateways

   It is important to note that even if we don't implement ICN in MME
   and HSS, they still need to support either dual stack or native ICN
   UE capabilities. When UE initiates attach request using the identity
   as ICN, MME must be able to parse that message and create a session.
   MME forwards UE authentication to HSS so HSS must be able to
   authenticate ICN capable UE and authorize create session [TS23.401].

   Anchorless mobility [ALM] has made some important comments on how
   mobility management is done in ICN. Author comments about handling
   mobility without having a dependency on the core network function
   e.g. MME. However, location update to the core network would still be
   required to support some of the legal compliance requirements such as
   lawful intercept and emergency services.

   The main advantage of ICN is in caching and reusing the content,
   which does not apply to the transactional signaling exchange. After
   analyzing LTE signaling call-flows [TS23.401] and messages inter-
   dependencies [Fig 4], our recommendation is that it is not beneficial
   to deploy ICN for control plane and mobility management functions.

5.2  Recommendations in the User Plane



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   We will consider figure 1 to discuss different mechanisms to deploy
   ICN in mobile networks. We consider the following options:

      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)

5.2.1  Dual stack ICN Deployments in UE

   The control and user plane communications in LTE, 4G mobile networks
   are specified in 3GPP documents [TS23.323] [TS23.203] [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 as it has to
   support multiple radio connectivity access to eNodeB(s).

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

   +--------+                                               +--------+
   |   App  |                                               |  CDN   |
   +--------+                                  +--------+   +--------+
   |Transp. | |              |               | |Transp. | | |Transp. |
   |Selector|.|..............|...............|.|Selector|.|.|Selector|
   +--------+ |              |               | +--------+ | +--------+
   |        |.|..............|...............|.|        |.|.|        |
   | 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




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                 Fig. 5. Dual stack ICN Deployment in UE

   The protocol interactions and impact of supporting tunneling of ICN
   packet into IP or to support ICN natively are described in figure 6
   and figure 7 respectively.

   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 describe 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).

                 +-----------------------------------+
                 |     Applications (existing)       |
                 +-----------------------------------+
                                   |
                 +-----------------------------------+
                 |     Transport Selector (new)      |
                 +-----------------------------------+
                        |                     |
                 +-------------+       +-------------+
                 |ICN function +-------+ IP function |
                 |   (New)     |       | (Existing)  |
                 +-------------+       +-------------+
                        | (native)         | (overlay)
                 +-----------------------------------+
                 | PDCP (updated to support ICN)     |
                 +-----------------------------------+
                                   |
                 +-----------------------------------+
                 |          RLC (Existing)           |
                 +-----------------------------------+
                                   |
                 +-----------------------------------+
                 |        MAC Layer (Existing)       |
                 +-----------------------------------+
                                   |
                 +-----------------------------------+
                 |       Physical L1 (Existing)      |
                 +-----------------------------------+

             Fig. 6. Dual stack ICN protocol interactions

      1. Application layer has the option of selecting either ICN or IP
         transport layer as well as the radio interface to send and
         receive data traffic. Our proposal is to provide a common
         Application Programming Interface (API) to the application



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         developers such that there is no impact on the application
         development when they choose either ICN or IP transport for
         exchanging the traffic with the network. We introduce a
         transport selector function to handle the interaction of
         application with the multiple transport options.

      2. The transport selector helps determine what type of transport
         (e.g. ICN or IP) as well as type of radio interface (e.g. LTE
         or WiFi or both) is used to send and receive the traffic.
         Application layer can make the decision to select a specific
         transport based on preference e.g. content location, content
         type, content publisher, congestion, cost, quality of service
         etc. There can be an Application Programming Interface (API) to
         exchange parameters required for transport selection. The
         southbound interactions of Transport Selector will be either to
         IP or ICN at network layer.

      3. ICN function (forwarder) is introduced in parallel to the
         existing IP layer. ICN forwarder contains functional
         capabilities to forward ICN packets, e.g. Interest packet to
         eNodeB or response "data packet" from eNodeB to the
         application.

      4. For dual stack scenario, when UE is not supporting ICN at
         transport layer, 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 layer) and Radio Link Control Layer (RLC). PDCP
         performs following functions [TS36.323]:

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

         b) Header compression and decompression using ROHC (Robust
            Header Compression)

         c) Security protections such as ciphering, deciphering and
            integrity protection

         d) Radio layer messages associated with sequencing, packet drop
            detection and re-transmission etc.




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      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.

5.2.2  Native ICN Deployments in UE

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

      1. at user plane communication

      2. at transport layer

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

   +--------+                                                +--------+
   |  App   |                                                |   CDN  |
   +--------+                                                +--------+
   |Transp. | |              |              |              | |Transp. |
   |Selector|.|..............|..............|..............|.|Selector|
   +--------+ |              |              |              | +--------+
   |        |.|..............|..............|..............|.|        |
   | 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

                         Fig. 7. Native ICN Deployment in UE

   If we implement ICN natively in UE, communication between UE and



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   eNodeB will change and also we will not need to tunnel user plane
   traffic from eNodeB to mobile packet core (SGW, PGW) using GTP
   tunnel.

   For native ICN deployment, Application is configured to use ICN
   forwarder so there is no need for Transport Selector. Also to support
   ICN at network layer in UE, we need to modify existing PDCP layer.
   PDCP layer has to 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 interactions with
   mobile gateways, etc.

5.2.3  ICN Deployment in eNodeB

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

      1. Native IP (IPv4 or IPv6)

      2. Native ICN

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

   UE encapsulates user data transport request into PDCP layer as
   described in section 5.2.1 and send the information on air interface
   to eNodeB. eNodeB receives the information and using PDCP [TS
   36.323], de-encapsulate air-interface messages and convert them to
   forward to core mobile gateways (SGW, PGW). In order to support ICN
   natively in eNodeB, it is proposed to provide transport selector
   capabilities in eNodeB (similar as provided in UE), which provides
   following functions:

      1. It decides the forwarding strategy for user data request coming
         from UE. The strategy can make decision based on preference
         indicated by the application such as, congestion, cost, quality
         of service, etc.

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

      3. eNodeB shall be upgraded to support three different types of



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         transport IP, ICN, and dual stack IP+ICN towards mobile
         gateways, as depicted in figure 8. It is also recommended to
         deploy IP and/or ICN forwarding capabilities into eNodeB for
         efficient transfer of data between eNodeB and mobile gateways.
         There can be four choices for forwarding data request towards
         mobile gateways:

         a) Assuming eNodeB is IP enabled and UE requests for IP
            transfer, eNodeB forwards data over IP.

         b) Assuming eNodeB is ICN enabled and UE request for ICN
            transfer, eNodeB forwards data over ICN.

         c) Assuming eNodeB is IP enabled and UE request ICN, eNodeB
            overlays ICN on IP and forwards the user plane traffic over
            IP.

         d) Assuming eNodeB is ICN enabled and UE request IP, eNodeB
            overlays IP on ICN and forwards the user plane traffic over
            ICN [IPoICN].

                        +---------------+  |
                        | 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

                   Fig. 8. Native ICN Deployment in eNodeB

5.2.4  ICN Deployment in Packet Core (SGW, PGW) Gateways

   Mobile gateways a.k.a. Evolved Packet Core (EPC) include SGW, PGW,
   which performs session management for UE from the initial attach to
   disconnection. When UE is powered on, it performs NAS signaling and
   after successful authentication it attaches to PGW. PGW is an



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   anchoring point for UE and responsible for service creations,
   authorization, maintenance etc. Entire functionality is managed using
   IP address(es) for UE.

   In order to implement ICN in EPC, the following functions are needed.

      1. Insert ICN function at 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
         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 contains 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
         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, or 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 IP address and
         ICN identity. UE selects the either of the identities during
         initial attach procedures and registers with network for
         session management. For ICN capable UE it will provide only ICN
         attachment. For native IP capable UE there is no change.

      4. In order 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 etc. 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. Protocol configuration options information elements 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.

         - Octet 3 (configuration protocols defines PDN types) which
           contains details about IPv4, IPv6, both or ICN.

         - 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



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           mobile gateways (SGW, PGW) so that they can be interpreted
           properly and 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.

6. Security Considerations

   To ensure only authenticated UEs are connected to the network, LTE
   mobile network implements various security mechanisms. From
   perspective of ICN deployment in user plane, it need to take care of
   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
   security UE authentication, key exchange, ciphering and integrity
   protections message are given in 3GPP call flow [TS23.401].

   LTE is an all IP network and uses IP transport in its mobile backhaul
   (e.g. 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 shared or a leased network. The native IP
   transport continue 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 which are deployed in mobile backhaul.



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   When ICN forwarding is enabled on mobile transport routers, we need
   to deploy security practices based on RFC7476 and RFC7927.

   Some of the key functions supported by LTE mobile gateway (SGW, PGW)
   are content based billing, deep packet inspection (DPI), lawful
   intercept (LI). For ICN based user plane traffic, it is required to
   integrate ICN security for session between UE and gateway; however,
   in ICN network, since only consumers are in possession of decryption
   keys can access the content, some of the services provided mobile
   gateway mentioned above may not work. Further research in this area
   is needed.

7. Summary

   Authors have discussed complexities of LTE network and key
   dependencies for deploying ICN in user plane data transport.
   Different deployment options described covers aspects such as inter-
   operability and multi-technology, which is a reality for any service
   provider. The ICN deployment options described in section 5, we
   currently evaluating using LTE gateway software and ICN simulator.
   One can deploy ICN for data transport in user plane either as an
   overlay, dual stack (IP + ICN) or natively (by integrating ICN with
   CDN, eNodeB, SGW, PGW and transport network etc.). It is important to
   understand that for the actual deployment scenarios, additional
   research study is required to identify dependencies specific to a
   mobile network.

   As far as control plane signaling is concerned, our observation is
   that further research is required to understand the benefits of using
   ICN to complement or replace traditional control plane signaling. As
   a starting step towards ICN deployment, it is recommended that the
   focus should be on enhancement of user data plane.

   Mobile Edge Computing (MEC) [CHENG] provides capabilities to deploy
   functionalities such as content data Network (CDN) caching and mobile
   user plane functions (UPF) [TS23.501]. Recent research for delivering
   real-time video content using ICN has also been proven to be
   efficient [NDNRTC] and we 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 that we can optimize content
   delivery using simple and scalable architecture. Authors will
   continue to explore how the ICN forwarding in MEC could be used in
   efficient delivery of unicast and multicast traffic.







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7  References

7.1  Normative References

   [GRAYSON]  Grayson M, Shatzkamer K, Wainner S.; Cisco Press book "IP
              Design for Mobile Networks" by. page 108-112.

   [IPSEC1]   Cisco IPSec overhead calculator tool
              <https://cway.cisco.com/tools/ipsec-overhead-calc/ipsec-
              overhead-calc.html>.

   [IPSEC2]   IPSec Bandwidth Overhead Using AES
              <http://packetpushers.net/ipsec-bandwidth-overhead-using-
              aes/>.

   [BROWER]   Brower, E.; Jeffress, L.; Pezeshki, J.; Jasani, R.;
              Ertekin, E. "Integrating Header Compression with IPsec",
              Military Communications Conference, 2006. MILCOM 2006.
              IEEE, On page(s): 1 - 6.

   [TS25.323] 3GPP TS25.323 Rel. 14 (2017-03) Packet Data Convergence
              Protocol (PDCP) specification.

   [TS23.501] 3GPP TS23.501 Rel. 15 (2017-06) System Architecture for
              the 5G System.

   [TS23.203] 3GPP TS23.203 Rel. 14 (2017-03) Policy and charging
              control and QoS architecture

   [TS23.401] 3GPP TS23.401 Rel. 14 (2017-03) E-UTRAN Access procedures
              architecture

   [TS33.310] 3GPP TS33.310 Rel. 14 (2016-12) LTE Network Domain
              Security (NDS); Authentication Framework (AF)

   [TS33.320] 3GPP TS33.320 Rel. 14 (2016-12) Security of Home Node B
              (HNB) / Home evolved Node B (HeNB)

   [TS24.008] 3GPP TS24.008 Rel. 14 (2017-06) Mobile radio interface
              Layer 3 specification.

   [TS23.501] 3GPP TS23.501 Rel. 14 (2017-06) System Architecture for
              the 5G System

   [TS23.214] 3GPP TS23.214 Rel. 14 (2017-06) Architecture enhancements
              for control and user plane separation of EPC nodes

   [TS36.323] 3GPP TS36.323 Rel. 14 (2017-06) Evolved Universal



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              Terrestrial Radio Access (E-UTRA); Packet Data Convergence
              Protocol (PDCP) specification

   [RFC7476]  Information-Centric Networking: Baseline Scenarios

   [RFC7927]  Information-Centric Networking (ICN) Research Challenges


7.2  Informative References


   [MECSPEC]  European Telecommunication Standards Institute (ETSI) MEC
              specification ETSI-GS-MEC-IEG-001 V1.1.1 (2015-11).

   [NDNTLV]   NDN Interest Packet Format Specification 0.2-2.
              https://named-data. net/doc/ndn-tlv/interest.html.

   [CCNxTLV]   CCNx Messages in TLV Format
              https://datatracker.ietf.org/doc/draft-irtf-icnrg-
              ccnxmessages/

   [NDNPUB]   Named Data Networking <http://named-
              data.net/publications/>.

   [CCN]      Content Centric Networking <http://www.ccnx.org and
              http://blogs.parc.com/ccnx/documentation-guide/>.

   [NDN]      Lixia Z., Lan W. et al. SIGCOMM Named Data Networking

   [ALM]      J. Aug'e, G. Carofiglio et al. "Anchor-less producer
              mobility in icn," in Proceedings of the 2Nd ACM Conference
              on Information-Centric Networking, ACM-ICN '15, pp. 189-
              190, ACM, 2015.

   [VNIIDX]   Cisco Visual Networking Index (VNI) dated 16 Feb 2016,
              <http://www.cisco.com/c/en/us/solutions/service-
              provider/visual-networking-index-vni/index.html>.

   [NDNRTC]   Peter Gusev,Zhehao Wang, Jeff Burke, Lixia Zhang et. All,
              IEICE Trans Communication, RealtimeStreaming Data Delivery
              over Named Data Networking, Vol E99-B, No.5 May 2016.

   [CHENG]    Chengchao L., F. Richard Yu, Information-centric network
              fucntion virtualization over 5G mobile wireless networks,
              IEEE network (Volume:29, Issue:3), page 68-74, 01 June
              2015.

   [NGMN]     Backhaul Provisioning for LTE-Advanced & Small Cells



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              <https://www.ngmn.org/uploads/media/150929_NGMN_P-
              SmallCells_Backhaul_for_LTE-Advanced_and_Small_Cells.pdf>

   [IPoICN]   IP Over ICN - The Better IP?
              <http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7194109>



Authors' Addresses


   Prakash Suthar
   9501 Technology Blvd.
   Rosemont, Illinois 50618

   EMail: psuthar@cisco.com


   Milan Stolic
   9501 Technology Blvd.
   Rosemont, Illinois 50618

   EMail: mistolic@cisco.com


   Anil Jangam
   3625 Cisco Way
   San Jose, CA  95134
   USA

   Email: anjangam@cisco.com




















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