Path Aware Networking Research Group S. Zheng Internet-Draft P. Liu Intended status: Informational Z. Chen Expires: August 26, 2021 China Mobile February 22, 2021 Required path properties for applying path aware networking in integrated space-terrestrial networks draft-zheng-panrg-path-properties-istn-00 Abstract Integrated space-terrestrial networks are heterogeneous networks with various path characteristic, and usually belong to different administrative domains. Therefore integrated space-terrestrial networks can be seen as a use case of path-aware networking. This memo introduces requirements on path properties when applying path- aware-network in integrated space-terrestrial networks. Requirements Language 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 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 26, 2021. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Zheng, et al. Expires August 26, 2021 [Page 1] Internet-Draft Network Working Group February 2021 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology and Abbreviation . . . . . . . . . . . . . . . . 3 3. Path properties . . . . . . . . . . . . . . . . . . . . . . . 3 4. Fine granular properties . . . . . . . . . . . . . . . . . . 3 4.1. node properties . . . . . . . . . . . . . . . . . . . . . 4 4.2. Link properties . . . . . . . . . . . . . . . . . . . . . 4 5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction In the integrated space-terrestrial networks, endpoint is capable to access space networks, mobile networks, and fixed networks. These heterogeneous networks have essential difference on characteristics and come from different service providers, which makes it difficult to carry out unified management and control. Furthermore, different with ground networks, the quality of links in space is fluctuating, the network topology changes dynamically, and the resources of space node is limited. It is necessary to come out a system to release the burden of networks(especially space nodes with limited resource) and leaving the complex function to endpoint. In other words, the path- aware network may help to cope with the dynamics of this kind of network. According to the definition of [RFC5136], a path is a series of links that connect a series of nodes from the source node to destination. The properties of path can be seen from the overall point of view, or decomposed into node properties and link properties. Corresponding granular path awareness can be performed in the basis of the capability of the endpoint and/or the required quality of service. This memo will describe the required path properties from different granularity in integrated space-terrestrial networks. Zheng, et al. Expires August 26, 2021 [Page 2] Internet-Draft Network Working Group February 2021 2. Terminology and Abbreviation Integrated space-terrestrial Networks(ISTN): A network system that comprehensively utilizes a variety of communication network technologies including space networks and terrestrial networks to achieve global coverage. The integrated system includes ground segment and space segment. The ground segment includes terrestrial network nodes such as ground stations, terminals, servers controllers and terrestrial links such as cable, fiber. Space segment includes space node such as satellites and space links such as laser and radio. 3. Path properties The path properties describe the overall properties of the whole path from an end-to-end perspective. Space and ground networks share some common properties, but due to the essential differences between the space network and the terrestrial network on characteristics such as mobility, link stability, resources etc., some additional properties are required to support path selection at the endpoint. Common path properties 1. Properties in path properties[I-D.irtf-panrg-path-properties],such as one way delay and one way packet loss. Additional path properties in space 1.Available time: path available time; due to the topological dynamics of the space link, the path in the world-ground integrated network is not always available. Therefore, it is necessary to set an available time for each path; 4. Fine granular properties In addition to the fluctuating latency, and bandwidth, the complex space environment will lead to unpredictable wireless link disconnection.The mobility of space nodes will lead to periodic dynamic topology change. Therefore, the performance of the path changes more frequently, and the fine granular properties can help the integrated space-terrestrial networks to quickly locate unpredictable faults and find the optimal alternative link instead of discarding the entire path. For example, path properties can be decomposed into node properties and link properties. Zheng, et al. Expires August 26, 2021 [Page 3] Internet-Draft Network Working Group February 2021 4.1. node properties Common properties of nodes 1.Node computing resources: computing resources available on ground nodes/space nodes. When the available computing resource is less, it indicates that the node is heavy-loaded, and the path that contains the node should be avoided when selecting a path. 2.Node storage resources: available storage resources of ground nodes/space nodes. Additional node properties in space 1.Node power: This is actually the most important property of space, because the energy of satellite in space comes from solar panels, which make the node energy fluctuating with time. If the power of the satellite node is not sufficient to support additional computing/ communication functions, the satellite node is not available; it can be simply set to 0/1 to indicate whether the node supports additional computing/communication functions. 2.Available interfaces of the node. The interface that can be used to establish a link, it may contain a set of information indicating the direction of interface and available next hop. This property can be use to derive the topology information. The specific link status is excluded and needs to query the link properties described below. 3.The future available interfaces of the node. The movement of satellite nodes is periodic. Periodicity can be used to predict the topology in the future to help make routing decisions. This property can be sent in different manners, depending on the mechanism the system used to deal with the network mobility. This property can be sent in each time slot if the system use snapshot. Or to reduce the interaction cost, event triggered property notification can be used, that is the notification only executes when the available interfaces changes due to unexpected event. 4.2. Link properties Common link properties 1.Propagation delay:When a data packet propagates from the source node to the destination node, the time required for the transmission from the beginning to the end of the link is the propagation delay. Data packets are propagated at the propagation rate of the link, and its rate depends on the physical medium of the link. The propagation delay is equal to the ratio of the distance between the nodes and the Zheng, et al. Expires August 26, 2021 [Page 4] Internet-Draft Network Working Group February 2021 propagation rate. As the distance between the nodes changes as space node moves, the delay changes as well. 2.Link media: the link media can be laser/cable/radio etc., and the different media can have different priority and cost, which should be used to do the path selection decision. 3.Quality of link: This property can be indicated by bit error rate or packet loss rate, depending on the network system. Additional link properties in space 1. Available time: When the nodes at both ends of a link are constantly moving relative to each other, the link may be unavailable because the nodes move out of mutual visible area. Therefore, it is necessary to know the available time of the link. 2. Link status: different from bit error rate, this property indicates the state of link, for example, when the link is temporarily unavailable due to space environment, it can be set in leave and; when the link is unavailable due to mobility, it can be set to down . The link state information may not come from space node itself but from ground measurement and control station. 5. Summary Integrated space-terrestrial Networks can take advantage of the PAN and can be seen as a typical use cases. When PAN is introduced into ISTN, it will have some different requirements on the path properties, and this memo study the first question in [I-D.irtf-panrg-questions] by list and explain some potential path properties. 6. Security Considerations It should be noticed that under the Integrated space-terrestrial Networks background, the topology information comes from different operators, they may not willing to expose their network information to other operators or other 3rd parties, so it is crucial to find a way to supply the information to end user while not expose to others. 7. IANA Considerations This document has no requests to IANA. Zheng, et al. Expires August 26, 2021 [Page 5] Internet-Draft Network Working Group February 2021 8. Normative References [I-D.irtf-panrg-path-properties] Enghardt, T. and C. Krahenbuhl, "A Vocabulary of Path Properties", draft-irtf-panrg-path-properties-01 (work in progress), September 2020. [I-D.irtf-panrg-questions] Trammell, B., "Current Open Questions in Path Aware Networking", draft-irtf-panrg-questions-08 (work in progress), December 2020. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5136] Chimento, P. and J. Ishac, "Defining Network Capacity", RFC 5136, DOI 10.17487/RFC5136, February 2008, . Authors' Addresses Shaowen Zheng China Mobile Beijing 100053 China Email: zhengshaowen@chinamobile.com Peng Liu China Mobile Beijing 100053 China Email: liupengyjy@chinamobile.com Danyang Chen China Mobile Beijing 100053 China Email: chendanyang@chinamobile.com Zheng, et al. Expires August 26, 2021 [Page 6]