ICN Research Group Prakash Suthar Internet-Draft Milan Stolic Intended status: Informational Anil Jangam Cisco Systems Expires: November 17, 2017 May 16 2017 Native Deployment of ICN in LTE, 4G Mobile Networks draft-suthar-icnrg-icn-lte-4g-01 Abstract Mobile networks using LTE, 4G technologies are complex. Managing mobility and content delivery using IP transport is challenging and not optimized for content delivery. 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 content delivery, however majority of the work is focused either on fixed networks or unlicensed WiFi-based wireless networks. The main focus of this document is on native deployment of ICN in cellular mobile networks by embedding ICN into 3GPP protocol stack at IP datagram or replacing IP for non-IP datagrams. ICN has an inherent capability for anchorless mobility, security and it is optimized for content delivery using local caching at the edge. We believe that ICN native or dual stack (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 Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress". The list of current Internet-Drafts can be accessed at Prakash, et.al. Expires November 17, 2017 [Page 1] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at 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 Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. LTE, 4G Mobile Network . . . . . . . . . . . . . . . . . . . . 3 2.1 Network Overview . . . . . . . . . . . . . . . . . . . . . 3 2.2 Virtualizing Mobile Networks . . . . . . . . . . . . . . . 5 2.3 Key characteristics of Mobile Networks . . . . . . . . . . 5 3. Content Delivery using IP . . . . . . . . . . . . . . . . . . 6 4. Content Delivery using ICN . . . . . . . . . . . . . . . . . . 6 5. ICN Deployment in 4G and LTE Networks . . . . . . . . . . . . 9 5.1 Recommendations in the Mobility Management . . . . . . . . 9 5.2 Recommendations in the User Plane . . . . . . . . . . . . . 10 5.2.1 Dual stack ICN Deployments in UE . . . . . . . . . . . 10 5.2.2 Native ICN Deployments in UE . . . . . . . . . . . . . 13 5.2.3 ICN Deployment in Base Station (eNodeB) . . . . . . . . 14 5.2.4 ICN Deployment in Packet Core (SGW/PGW) Gateways . . . 15 6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1 Normative References . . . . . . . . . . . . . . . . . . . 18 7.2 Informative References . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Prakash, et.al. Expires November 17, 2017 [Page 2] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 1 Introduction Mobile networks in 4G and LTE use IP routing and protocols such as OSPF, ISIS, BGP etc. for transport of IP packet data to end user's device. LTE technology is built as all IP network. Stickiness of IP address to a device is the key to get connected to mobile network and this same IP address is maintained through the session until the device gets detached or moves to other networks. Some of legacy and hybrid networks still use legacy protocols such as frame relay, ATM etc. but they are being replaced. Key protocol 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 content delivery although it is the most efficient routing protocol. By natively implementing Information Centric Networking (ICN) in 3GPP, we can re-architect mobile networks and optimize design for efficient content delivery. ICN also offers an opportunity to leverage inherent capabilities of anchorless mobility, authentication and optimized signaling. This draft provides insight into different options for deploying ICN in mobile networks and how they impact mobile providers and end- users. We also discuss potential issues related to IP based mobile networks content delivery and how we can leverage ICN to overcome some of the bottlenecks. 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 content is distributed using unicast mechanism. Prakash, et.al. Expires November 17, 2017 [Page 3] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 It is also important to understand the overhead of a GTP tunnel because this has impact on the carried user traffic. For average packet size of ~500 bytes GTP overhead is ~15. Additionally, if IPSec is used for security (which is often required if the Service provider is using a 3rd party backhaul provider), then it will add ~15-23 overhead based upon transport/tunneling model, and encryption and authentication header algorithms used [IPSEC]. +-------+ Diameter +-------+ | HSS |------------| SPR | +-------+ +-------+ | | +------+ +------+ S4 | +-------+ |2G/3G |---| SGSN |----------------|------+ +------| PCRF | ^ | BS | | |---------+ +---+ | | +-------+ +-+ | +------+ +------+ S3 | | S6a | |Gxc | | | | +-------+ | | |Gx +-+ | +------------------| MME |------+ | | | UE v | S1MME +-------+ S11 | | | | +----+-+ +-------+ +-------+ |4G/LTE|------------------------------| SGW |-----| PGW | | BS | 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 content delivered to mobile devices is unicast inside GTP tunnel. If we consider combined impact of GTP, IPSec and unicast traffic, the content delivery is not efficient. IETF has developed various header compression algorithms to reduce the overhead associated with IP 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 Prakash, et.al. Expires November 17, 2017 [Page 4] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 different mechanisms for header compression to achieve efficiency in content delivery [TS23.323], which can be used in ICN. 2.2 Virtualizing Mobile Networks As the adoption of LTE grew beyond traditional major Service providers and penetrated Mobile Virtual Network Operators (MVNO), public safety entities and often larger enterprises, the need for smaller-scale packet core became obvious. In addition to the requirement for a smaller scale, many operators showed tendency to do away with dedicated hardware and simplify their operations at a reduced cost by deploying the same mobility applications on the Commercially off the shelf x86 based hardware. Using common servers in a virtualized environment simplifies new deployments and provides optimized TCO. Virtual packet cores are opening way for many innovative use cases applicable to enterprise markets, however most use cases are for smaller throughput but complex policy and specialized services. Although virtualization is growing, the call flow is still the same, therefore issues related to IP are the same for traditional and virtual mobile networks. There is also work underway to separate control 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. Protocol evolution to open-flow is still under study and research at 3GPP. 2.3 Key characteristics of Mobile Networks Major benefit of the core network, with support from the underlying transport, is predictability of the traffic parameters required for the expected subscribers Quality of Service (QoS). A default bearer is always established upon subscriber's attachment to the chosen Access Point Name (APN). Additional dedicated bearer(s), real-time or non-real-time, 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 Prakash, et.al. Expires November 17, 2017 [Page 5] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 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. 3. Content Delivery using IP As described earlier, content delivery in today's mobile networks is mostly unicast 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 the 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 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 content 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 content to be delivered to the end-user. Other issues, such as out-of-order delivery due to ECMP or other reasons, contribute to this complexity and inefficiency but could be addressed at the IP transport level. However, the issue of inefficient traffic path to deliver the content has to be addressed from a different perspective, by considering a change in the approach to caching. 4. Content Delivery using ICN Content delivery using ICN is quite different compared to IP-based systems because it follows publish-subscribe paradigm using two simple types of messages, namely Interest and Data. Communication in ICN takes place between content provider (producer) and end user (consumer) as described in figure 2. Prakash, et.al. Expires November 17, 2017 [Page 6] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 +----------+ | 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 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). 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. 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 Prakash, et.al. Expires November 17, 2017 [Page 7] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 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 base station/eNodeB. Interest packet follows the TLV format [NDNTLV] 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 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. Prakash, et.al. Expires November 17, 2017 [Page 8] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 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 [NDNPUB] [CCN] [NDN], here we explained the concept and its applicability to the LTE network. 5. ICN Deployment in 4G and LTE Networks 5.1 Recommendations in the Mobility Management Mobility management includes signaling messages associated with Non- Acess Stratum (NAS). In this section we analyzed different mobility management messages and if there is any benefit to replace IP-based protocols for NAS 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. Base Station (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. Physical POA in eNodeB handle both mobility and session management for any UE attached to 4G, LTE network. Details of mobility management messages between UE, eNodeB, MME, HSS, SGW, PGW are given below in figure 4. +---------------------------+-------+-------+-------+-------+------+ | NAS Signaling Type | 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. NAS Signaling Messages in LTE Gateways In current architecture IP transport is used for all the messages associated with Control Plane for mobility and session management Prakash, et.al. Expires November 17, 2017 [Page 9] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 messages. IP is embedded very deeply into these messages as layer-3 transport and TLV carrying additional attributes. After analyzing above message structures and their inter dependencies, our recommendation is that it may not be beneficial to deploy ICN for control plane and mobility management functions. It is important to note that even though we may not 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 of authenticating ICN capable UE and authorizing create session [TS23.401]. Author [ALM] has made some important comments on mobility management in ICN. 5.2 Recommendations in the User Plane 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 Base Station (eNodeB) 4. ICN Deployment in Packet Core (SGW/PGW) Gateways 5.2.1 Dual stack ICN Deployments in UE All control and user plane communications in LTE, 4G mobile networks are specified in 3GPP documents [TS23.323] [TS23.203] [TS23.401] and many other documents. 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 quite complex because it has to support multiple radio connectivity access to base station(s). There are three points of attachments for UE. Figure 5 below provides high level protocol stacks description where IP is defined at two layers: (1) at user plane communication, (2) Transport layer. User plane communication takes place between PDCP and Application layer, whereas transport layer is at GTP protocol stack. Prakash, et.al. Expires November 17, 2017 [Page 10] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 +--------+ +--------+ | 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 Fig. 5. Dual stack ICN Deployment in UE The protocol interactions for tunneling ICN packet on top of IP or natively and how it changes the stack are described in figure 6 below. UE is a basic entity (referred to as any type of device which attaches to cellular network using 3G/UMTS or LTE technologies). 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 will leverage these techniques to deploy ICN protocol stack in UE. 1. Insert Transport Selector function between Application and network layer (consisting of ICN + IP function). Transport Selector interface with Application layer on top of it determines how traffic is routed to the lower layers. The decision can be based on preference indicated by the application, or other parameters such as congestion, cost, quality of service or any additional parameter. There can be an open Application Programmable Interface (API) to exchange additional parameters required for transport selection. The southbound interactions of Transport Selector will be either to IP or ICN at network layer. Prakash, et.al. Expires November 17, 2017 [Page 11] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 +-----------------------------------+ | 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 2. ICN forwarding protocol stack is introduced in parallel to existing IP layer. ICN forwarder contains functional capabilities to route ICN packets e.g. Interest packet to base station or response "data packet" from base station to Application. 3. For dual stack scenario when UE is not supporting ICN at transport layers, we need to overlay ICN packets on top of IP. For such scenario, we need to introduce an interface function between ICN function and IP function. ICN function will use this interface to send ICN Interest and Data packets for fetching or sending content using ICN protocol function. This interface will use ICN overlay over IP using any overlay tunneling mechanism. 4. To support ICN at network layer in UE, we need to modify existing PDCP layer. PDCP layer has to be aware of ICN Prakash, et.al. Expires November 17, 2017 [Page 12] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 capabilities and parameters. 5. 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 There is possibility to implement ICN natively in UE by modifying 3GPP protocols. Figure 7 below provides high level protocol stacks description where ICN is defined at two 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 Prakash, et.al. Expires November 17, 2017 [Page 13] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 If we implement ICN natively in UE, communication between UE and base station (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 Base Station (eNodeB) The physical point of attachment for UE is base station(s), where radio protocols are converted or interfaced with transport protocol as depicted in figure 5 and figure 7 for dual stack/overlay and native ICN attach respectively. When UE performs attach procedures and it has identity either as native IP, dual stack (IP and ICN), or native ICN, it starts sending data requests using user plane messages. UE can request using any of three different options: 1. Native IP (IPv4 or IPv6) 2. Native ICN 3. Dual stack IP (IPv4/IPv6) or ICN Protocol interactions between UE and Base Station (figure 5 and figure 7) at PDCP layer and UE provide information to Base station. As depicted in figure 8 below, Base Station contains algorithms to compare request coming from UE and also availability of transport on S1u interface. If the base station has all three types of transport e.g. Native ICN, Dual Stack (ICN, IP) and native IP, then it can forward the request as it is. If S1u interface transport is only IP, then it will overlay ICN on IP and forward the user plane traffic on it. Prakash, et.al. Expires November 17, 2017 [Page 14] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 +---------------+ | | 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 +---------+ +---------------+ | Base Station S1u (eNodeB) Fig. 8. Native ICN Deployment in Base Station (eNodeB) At the base station, transport selection on S1u interface can be based on preference indicated by application or other parameters such as congestion, cost, quality of service or any additional parameter. There can be open Application Programmable Interface (API) to exchange additional parameters required for transport selection. 5.2.4 ICN Deployment in Packet Core (SGW/PGW) Gateways Mobile gateways a.k.a. Evolved Packet Core (EPC) include SGW, PGW, GGSN, perform 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 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/PGW, it contains Protocol Configuration Option Information Element (PCO IE) containing UE capabilities. We can use PCO IE to carry ICN related capabilities information Prakash, et.al. Expires November 17, 2017 [Page 15] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 from UE to PGW/GGSN. 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 will assign attachment using both IP address and ICN identity. During initial attach procedures, UE name is registered and used 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) provides 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 EPC gateways (MME, SGW, PGW) so that they can be interpreted properly and UE can attach successfully. 6. Deployment of ICN functionalities in SGW/PGW should be matched with UE and Base station because they will exchange ICN protocols and parameters. 6. Summary We have discussed complexities of LTE network and key dependencies for deploying ICN in control and user plane. Different deployment options described cover different aspects such as inter-operability and multitechnology, which is a reality for any mobile provider. The ICN deployment options described in section 5 are derived using LTE gateway software and ICN simulator. We can definitely deploy ICN for content delivery in user plane either as an overlay, dual stack or Prakash, et.al. Expires November 17, 2017 [Page 16] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 natively (by integrating ICN with CDN, eNodeB, SGW, PGW and routers etc.); however, actual deployment scenarios will be specific to a mobile network. After analysing different control plane signaling messages, our observation is that the benefit of using ICN for control plane messages is possible only after native deployment of ICN in UE. To implement ICN in LTE mobile gateways, we are working to add capabilities such as modification of PCO-IE field to carry ICN- specific parameters for attach procedures. Further study is underway to understand capability in ICN to support deep packet inspection, lawful intercept, billing and mediation. As per Cisco Visual Networking Index (VNI) Feb 2016 report [VNIIDX] over 70% of mobile traffic is video and if this can be delivered using ICN from eNodeB/MEC, it will be significant benefit. Recent research for delivering real-time video content using ICN has also been proven to be efficient [NDNRTC]. The key aspect for ICN is its seamless integration in LTE and 5G networks with tangible benefits so that we can optimize content delivery using simple and scalable architecture. In addition, 5G architecture and possible use of ICN provides new capabilities such as network slicing and separation of control and forwarding plane allowing MEC to function as forwarding plane [CHENG] and software define radio (SDR) aspects. We will continue to explore how the ICN forwarding in MEC could be used in efficient delivery of unicast and multicast traffic. Prakash, et.al. Expires November 17, 2017 [Page 17] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 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. [IPSEC] Cisco IPSec overhead calculator tool . [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. [TS23.323] 3GPP TS25.323 Rel. 13 Packet Data Convergence Protocol (PDCP) specification, 11 Dec 2015. [TS23.203] 3GPP TS23.203 v13.7.0 (2016-03) Rel. 13, Policy and charging control and QoS architecture, 15 March 2016 [TS23.401] 3GPP TS23.401 v13.7.0 (2016-03) Rel. 13, E-UTRAN Access procedures architecture, 12 November 2015. 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. [NDNPUB] Named Data Networking . [CCN] Content Centric Networking . [NDN] Lixia Z., Lan W. et al. SIGCOMM Named Data Networking [ALM] J. Auge, 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. Prakash, et.al. Expires November 17, 2017 [Page 18] Internet-Draft Deploying ICN in 4G, LTE Mobile Networks May 16 2017 [TS24.008] 3GPP TS 24.008 Rel 13 Mobile radio interface Layer 3 specification. [VNIIDX] Cisco Visual Networking Index (VNI) dated 16 Feb 2016, . [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. 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 Prakash, et.al. Expires November 17, 2017 [Page 19]