Delay Tolerant Networking Taixin Li Internet Draft Huachun Zhou Intended status: Informational Qi Xu Expires: December 2016 Guanwen Li Guanglei Li Beijing Jiaotong University June 11, 2016 software defined dtn-based satellite networks draft-li-dtn-sd-dtn-sat-net-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 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 http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on December 11, 2016. Li Expires December 11, 2016 [Page 1] Internet-Draft sd-dtn-based satellite networks June 2016 Copyright Notice Copyright (c) 2016 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. Abstract Delay/Disruption Tolerant Networking (DTN) is designed for a severe environment where communication quality is not guaranteed. It works as an overlay network associated with Bundle Protocol (BP) and some convergence layer protocols like Licklider Transmission Protocol (LTP). DTN is suitable for satellite networks. Because communication delay is long and peer-to-peer communication is not guaranteed in satellite networks. We implement SDN to solve the problems of controllable, manageable, and flexible in satellite networks. In this document, we propose a framework of Software Defined DTN-based satellite networks, using Bundle tunnel and protocol translation gateway. Table of Contents 1. Introduction ................................................ 3 2. Conventions used in this .................................... 3 3. Key points of the design .................................... 3 3.1. Separated control plane and forwarding plane ........... 4 3.2. Bundle tunnel .......................................... 5 3.3. Satellite gateway ...................................... 6 3.4. Use case ............................................... 7 4. Security Considerations ..................................... 8 5. IANA Considerations ......................................... 8 6. Conclusions ................................................. 8 7. References .................................................. 8 7.1. Normative References ................................... 8 7.2. Informative References ................................. 9 Li Expires December 11, 2016 [Page 2] Internet-Draft sd-dtn-based satellite networks June 2016 8. Acknowledgments ............................................. 9 1. Introduction Delay/Disruption Tolerant Networking (DTN) [RFC4838] is designed for a severe environment where connectivity of network is intermittent and communication quality is not guaranteed. It works as an overlay network associated with Bundle Protocol (BP) [RFC5050] and convergence layer protocols like Licklider Transmission Protocol (LTP) [RFC5325] [RFC5326]. We implement DTN in the satellite networks to meet the need of high transmission delay with the help of Interplanetary Overlay Network (ION) [BURLEIGH07]. ION is an implementation of DTN architecture and is designed to enable inexpensive insertion of DTN functionality into embedded systems. SDN [NUNES14] is a state-of-the-art network concept, introducing new possibilities for network management and configuration methods by decoupling the control decisions from forwarding hardware. A controller communicates with the switches by southbound interface, such as OpenFlow [LARA14], which is the core technology of SDN. We apply the idea of SDN to satellite network by separating control plane and forwarding plane in satellite network control structure and taking advantage of the global view of a controller. In this document, we propose a framework of Software Defined DTN- based satellite networks, using Bundle tunnel to deploy OpenFlow over DTN and protocol translation gateway to achieve protocol translation between Bundle packets and IP packets. 2. Conventions used in this document 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]. 3. Key points of the design The idea of SDN is applied in the proposed framework. The control link between the control plane and the forwarding plane is Bundle tunnel. Because we use DTN protocol stack in space network and the protocol stack of ground network is TCP/IP. There should be a Li Expires December 11, 2016 [Page 3] Internet-Draft sd-dtn-based satellite networks June 2016 protocol translation gateway to achieve protocol translation between Bundle packets and IP packets. 3.1. Separated control plane and forwarding plane We apply the idea of SDN to satellite network by separating control plane and forwarding plane in satellite network control structure and taking advantage of the global view of a controller. The whole space network is divided into two parts, control plane and forwarding plane. The control plane contains Geosynchronous Earth Orbit (GEO) satellites, on which SDN controllers are deployed. The forwarding plane contains Medium Earth Orbit (MEO) satellites and Low Earth Orbit (LEO) satellites, and OpenFlow enabled switches are deployed on them. We implement DTN with the help of ION in space network. The topology configuration mode of ION is reading the configuration scripts (.rc file), which contains the information of connections and nodes. To achieve the goal of separating the control plane and forwarding plane in the space network, we adopt two set of unrelated ION configuration scripts when creating the topology. One is the script of Bundle tunnel (or we can say the control link). The other one is the script of data link. Two ION processes run in the MEO/LEO satellite nodes without affecting each other. Li Expires December 11, 2016 [Page 4] Internet-Draft sd-dtn-based satellite networks June 2016 3.2. Bundle tunnel XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X X X Bundle tunnel header X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X X X Bundle tunnel payload X X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X +---------------------+--------------------+ X X | Ethernet header | IP header | X X +---------------------+--------------------+ X X | UDP header | LTP header | X X +---------------------+--------------------+ X X |Primary Bundle header| Payload header | X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X | OpenFlow signaling data | X X +------------------------------------------+ X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Figure 1: Encapsulation Format of the Bundle Tunnel We deploy OpenFlow over DTN by a method of tunnel. That is, signaling packets are transmitted in bundle tunnel when controller (GEO satellite) sets up connection to switches (MEO satellites) and when controllers send instructions to switches. The encapsulation format of the bundle tunnel is shown in Figure 1. Because DTN is implemented in ION in an overlay way, the first half of the Bundle tunnel header is the same as normal IP packets. The difference is that there are a 4-byte LTP header, a 14-byte Primary Bundle header, and a 5-byte Payload header before the payload data field due to the protocol stack of DTN. The link layer field is removed from the OpenFlow signaling packets between controller and switches and then the remaining fields are encapsulated in payload data. The design of the Bundle tunnel adopts a dual process approach. One process is responsible for receiving OpenFlow signaling packets from the local controller or switches. Then signaling data are separated out and encapsulated in the Bundle packets. Finally, the Bundle packets are sent to the control link. The other process is responsible for receiving Bundle packets from the control link and decapsulating the Bundle packets and get the OpenFlow signaling data. Li Expires December 11, 2016 [Page 5] Internet-Draft sd-dtn-based satellite networks June 2016 Then the signaling data are sent to the local controller or switches. In this way, the SDN controller in GEO satellite can communicate with the OpenFlow enabled switches in MEO/LEO satellites. 3.3. Satellite gateway +------------+ +------------+ |Application <-----------------------------------> Application| | data | | data | +------------+ +----------+----------+ +------------+ | |ground| | Bundle |space | Bundle | | | link | +----------+link +------------+ | TCP/UDP <------> TCP/UDP | LTP <------> LTP | | | | +----------+ +------------+ | | | | UDP | | UDP | +------------+ +---------------------+ +------------+ | IPv4/6 | | IPv4/6 | IPv4 | | IPv4 | +------------+ +----------+----------+ +------------+ ground node satellite gateway satellite node Figure 2: Protocol Stacks We use DTN protocol stack in space network and TCP/IP stack in the terrestrial network, so there should be protocol translation for data transmission and service delivery in the Software Defined DTN- based satellite networks framework. We develop DTN to TCP/IP bidirectional protocol translation and deploy this function on the satellite gateways. The protocol stacks of the ground node, satellite gateway node, and satellite node are shown in Figure 2. The physical layer and the data link layer are omitted because they are not involved in the proposed framework. The bidirectional translation between IP packets that belongs to TCP/IP stack and the Bundle packets that belongs to DTN stack is achieved at the satellite gateway by adopting hierarchical, modular, and multi-process protocol translation function. Li Expires December 11, 2016 [Page 6] Internet-Draft sd-dtn-based satellite networks June 2016 3.4. Use case GEO satellite +---+XX+---+ +---+XX+---+ X X X X XX X X XX XX X X X Bundle tunnels XX X X X Bundle tunnels XXX X X X XXX X X XX XX X +---+XX+---+ XX +---+XX+---+ X +---+XX+---+ XX +---+XX+---+ X MEO/LEO XX MEO/LEO X satellite3 XX satellite1 X ^ + XX X | | X X | | +---+XX+---+ X | +---------> +---+XX+---+ +---+XX+---+ | Space links MEO/LEO +---+XX+---+----+ satellite4 MEO/LEO + satellite2 | ^ | | | +---------+ +----------+ | | + v +-----------+ X X +--------+ |Data Center+------------->XXX XXX+------> User | +-----------+ Ground XXXXX XXXXX +--------+ links Satellite Satellite gateway 1 gateway 2 Figure 3: Use Case of the Proposed Framework The use case of proposed framework is shown in Figure 3. The GEO satellite set up control link to the four MEO/LEO satellites. The data center data are transmitted among the four MEO/LEO satellites. The ION configuration script of the control plane is about the connections of one GEO satellite to four MEO/LEO satellites. The ION configuration script of the forwarding plane is about the connections among the four MEO/LEO satellites. That is to say, two sets of unrelated ION processes are running in the four MEO/LEO satellites. Li Expires December 11, 2016 [Page 7] Internet-Draft sd-dtn-based satellite networks June 2016 A user applies for data from the data center via satellite networks. The traffic is sent to satellite gateway 1 and converted from IP packets to Bundle packets. The controller in GEO satellite send instructions to the MEO/LEO satellites and configure the flow tables of the switches in MEO/LEO satellites. Then the traffic is forwarded via the path: satellite2-->satellite3-->satellite4 under control of GEO satellite. Then, the traffic is sent to satellite gateway 2 and converted from Bundle packets to IP packets. Finally, the data are sent to the user. 4. Security Considerations Introducing SDN in DTN-based space network can bring in some problems that any SDN-based frameworks have. The proposed framework adopts a centralized control architecture. So if GEO satellite is attacked (by viruses or physical attack), security problem should be considered. The possible solution may be reserving spare GEO satellite. When the GEO satellite in use breaks down, the spare one will take on the responsibility. 5. IANA Considerations This document does not update or create any IANA registries. 6. Conclusions This document describes the key points of the design of the proposed Software Defined DTN-based satellite networks framework: Separated control plane and forwarding plane in space network, Bundle tunnel, and satellite protocol translation gateway. And we describe the use case of the proposed framework in this document. 7. References 7.1. Normative References [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, R., Scott, K., Fall, K., and Weiss, H., "Delay-Tolerant Networking Architecture", RFC 4838, April 2007. Li Expires December 11, 2016 [Page 8] Internet-Draft sd-dtn-based satellite networks June 2016 [RFC5050] Scott, K., and Burleigh, S., "Bundle Protocol Specification", RFC 5050, RFC5050, November 2007. [RFC5325] Burleigh, S., Ramadas, M., and Farrell, S., "Licklider Transmission Protocol - Motivation", RFC 5325, September 2008. [RFC5326] Ramadas, M., Burleigh, S., and Farrell, S., "Licklider Transmission Protocol - Specification", RFC 5326, September 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [BURLEIGH07] Burleigh S. ''Interplanetary Overlay Network: An Implementation of the DTN Bundle Protocol'' Consumer Communications and NETWORKING Conference (CCNC), 2007, vol. 45(2). pp. 147-153, 2007. [NUNES14] B. Nunes, M. Mendonca, X. Nguyen, K. Obraczka, & T, Turletti, ''A survey of software-defined networking: Past, present, and future of programmable networks,'' Communications Surveys & Tutorials, IEEE, vol. 16 (3), pp. 1617-1634, Feb. 2014. [LARA14] A. Lara, A. Kolasani, & B. Ramamurthy, ''Network Innovation using Openflow: A Survey,'' Communications Surveys & Tutorials, IEEE, vol. 16(1), pp. 493-512, Feb. 2014. 8. Acknowledgments This work in this document was supported by National High Technology of China (''863 program'') under Grant No.2015AA015702. Li Expires December 11, 2016 [Page 9] Internet-Draft sd-dtn-based satellite networks June 2016 Authors' Addresses Taixin Li Beijing Jiaotong University Beijing, 100044, P.R. China Email: 14111040@bjtu.edu.cn Huachun Zhou Beijing Jiaotong University Beijing 100044, P.R. China Email: hchzhou@bjtu.edu.cn Qi Xu Beijing Jiaotong University Beijing, 100044, P.R. China Email: 15111046@bjtu.edu.cn Guanwen Li Beijing Jiaotong University Beijing, 100044, P.R. China Email: 14120079@bjtu.edu.cn Guanglei Li Beijing Jiaotong University Beijing, 100044, P.R. China Email: 15111035@bjtu.edu.cn Li Expires December 11, 2016 [Page 10]