nmop O. G. D. Dios Internet-Draft Telefonica Intended status: Standards Track S. B. Giraldo Expires: 6 December 2024 V. Lopez Nokia 4 June 2024 A YANG Data Model for Open Shortest Path First (OSPF) Topology draft-ogondio-nmop-ospf-topology-00 Abstract This document defines a YANG data model for representing an abstracted view of a network topology that contains Open Shortest Path First (OSPF) information. This document augments the 'ietf- network' data model by adding OSPF concepts and explains how the data model can be used to represent the OSPF topology. The YANG data model defined in this document conforms to the Network Management Datastore Architecture (NMDA). 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 6 December 2024. Copyright Notice Copyright (c) 2024 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 (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 Dios, et al. Expires 6 December 2024 [Page 1] Internet-Draft OSPF Topology YANG June 2024 and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology and Notations . . . . . . . . . . . . . . . . 3 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.3. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 3 1.4. Prefix in Data Node Names . . . . . . . . . . . . . . . . 3 2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Relationship with the OSPF YANG Model . . . . . . . . . . 5 2.2. Relationship with Digital Map . . . . . . . . . . . . . . 5 3. YANG Data Model for OSPF Topology . . . . . . . . . . . . . . 6 4. RFC8345 Limitations for the OSPF Modeling . . . . . . . . . . 7 5. OSPF Topology Tree Diagram . . . . . . . . . . . . . . . . . 7 6. YANG Model for OSPF topology . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 9. Implementation Status . . . . . . . . . . . . . . . . . . . . 15 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 10.1. Normative References . . . . . . . . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . 16 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 1. Introduction Network operators perform the capacity planning for their networks and run regular what-if scenarios analysis based on representations of the real network. Those what-if analysis and capacity planning processes require, among other information, a topological view (domains, nodes, links, network interconnection) of the deployed network. This document defines a YANG data model representing an abstracted view of a network topology containing Open Shortest Path First (OSPF). It covers the topology of IP/MPLS networks running OSPF as Interior Gateway Protocol (IGP) protocol. The proposed YANG model augments the "A YANG Data Model for Network Topologies" [RFC8345] and "A YANG Data Model for Layer 3 Topologies" [RFC8346] by adding OSPF concepts. It is worth to highlight that the Yang model can also be used together with [RFC8795] and [I-D.draft-ietf-teas-yang-l3-te-topo] when Traffic engineering characteristics are required in the topological view. Dios, et al. Expires 6 December 2024 [Page 2] Internet-Draft OSPF Topology YANG June 2024 This YANG data model can be used to export the OSPF related topology directly from a network controller to Operation Support System (OSS) tools or to a higher level controller. Note that the YANG model is in this document strictly adheres to the concepts (and the YANG module) in "A YANG Data Model for Network Topologies" [RFC8345] and "A YANG Data Model for Layer 3 Topologies" [RFC8346]. While investigating the OSFP topology, some limitations have discovered in [RFC8345], regarding how the digital map can be represented. Those limitations (and potential improvements) are covered in [I-D.draft-havel-nmop-digital-map]. This document explains the scope and purpose of the OSPF topology model and how the topology and service models fit together. The YANG data model defined in this document conforms to the Network Management Datastore Architecture [RFC8342]. 1.1. Terminology and Notations This document assumes that the reader is familiar with OSPF and the contents of [RFC8345]. The document uses terms from those documents. The terminology for describing YANG data models is found in [RFC7950], [RFC8795] and [RFC8346]. The term Digital Twin, Digital Map, Digital Map Modelling, Digital Map Model, Digital Map Data, and Topology are specified in [I-D.draft-havel-nmop-digital-map]. 1.2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119], [RFC8174] when, and only when, they appear in all capitals, as shown here. 1.3. Tree Diagram Authors include a simplified graphical representation of the data model specified in Section 4 of this document. The meaning of the symbols in these diagrams is defined in [RFC8340]. 1.4. Prefix in Data Node Names In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in the following table. Dios, et al. Expires 6 December 2024 [Page 3] Internet-Draft OSPF Topology YANG June 2024 +========+=======================+===========+ | Prefix | Yang Module | Reference | +========+=======================+===========+ | ospfnt | ietf-l3-ospf-topology | RFCXXX | +--------+-----------------------+-----------+ | yang | ietf-yang-types | [RFC6991] | +--------+-----------------------+-----------+ Table 1: Prefixes and corresponding YANG modules RFC Editor Note: Please replace XXXX with the RFC number assigned to this document. Please remove this note. 2. Use Cases Use cases for this document are the same than explained in [I-D.draft-ogondio-nmop-isis-topology]. Here are included for completeness and discussion. Future versions may consider removing them. This information is required in the IP/MPLS planning process to properly assess the required network resources to meet the traffic demands in normal and failure scenarios. Network operators perform the capacity planning for their networks and run regular what-if scenarios analysis based on representations of the real network. Those what-if analysis and capacity planning processes require, among other information, a topological view (domains, nodes, links, network interconnection) of the deployed network. The standardization of an abstracted view of the OSPF topology model as NorthBound Interface (NBI) of Software Defined Networking (SDN) controllers allows the unified query of the OSFP topology in order to inject this information into third party tools covering specialized cases. The OSFP topological model should export enough OSFP information to permit these tools to simulate the IP routing. By mapping the traffic demand, ideally at the IP flow level, to the topology, we can simulate the traffic growth, evaluating this way its effect on the routing and quality of service. That is, simulating how IP-level traffic demands would be forwarded, after OSPF convergence is reached, and from there estimating, using appropriate mathematical models, related KPIs like the occupation in the links or end-to-end latencies. In summary, the network-wide view of the OSFP topology enables multiple use cases: Dios, et al. Expires 6 December 2024 [Page 4] Internet-Draft OSPF Topology YANG June 2024 * Network design: verifying that the actual deployed OSFP network conforms to the planned design. * Capacity planning. Dimensioning or redesign of the IP infrastructure to satisfy target KPI metrics under existing or forecasted traffic demands. * What-if analysis. Estimation of the network KPIs in modified network situations. For instance, failure situations, traffic anomaly situations, addition or deletion of new adjacencies, IGP weight reconfigurations, etc. * Failure analysis. Systematic and massive test of the network under multiple simulated failure situations, evaluating the network fault tolerance properties, and using mathematical models to derive statistical network availability metrics. 2.1. Relationship with the OSPF YANG Model [RFC9129] specifies a YANG data model that can be used to configure and manage the OSPF protocol on network elements. This data model covers the configuration of an OSPF routing protocol instance, as well as the retrieval of OSPF operational states. [RFC9129] is still expected to be used for individual network elements configuration and monitoring. On the other hand, the proposed YANG model in this document covers the abstracted view of the entire network topology containing OSPF. As such, this model is aimed at being available via the NBI of an SDN controller. 2.2. Relationship with Digital Map As described in [I-D.draft-havel-nmop-digital-map], the Digital Map provides the core multi-layer topology model and data for the digital twin and connects them to the other digital twin models and data. The Digital Map Modelling defines the core topological entities, their role in the network, core properties, and relationships both inside each layer and between the layers. The Digital Map Model is a basic topological model that is linked to other functional parts of the digital twin and connects them all: configuration, maintenance, assurance (KPIs, status, health, symptoms), Traffic Engineering (TE), different behaviors and actions, simulation, emulation, mathematical abstractions, AI algorithms, etc. Dios, et al. Expires 6 December 2024 [Page 5] Internet-Draft OSPF Topology YANG June 2024 As such the IGP topology of the Digital Map (in this case, OSPF) is just one of the layers of the Digital Map, for specific user (the network operator in charge of the IGP) for specific IGP use cases as described before. 3. YANG Data Model for OSPF Topology The abstract (base) network data model is defined in the "ietf- network" module of [RFC8345]. The OSPF-topology builds on the network data model defined in the "ietf-network" module [RFC8345], augmenting the nodes with OSPF information, which anchor the links and are contained in nodes. There is a set of parameters and augmentations that are included at the node level. Each parameter and description are detailed following: * Network-types: Its presence identifies the OSPF topology type. Thus, the network type MUST be ospf-topology. * OSPF timer attributes: Identifies the node timer attributes configured in the network element. They are wait timer, rapid delay, slow delay, and the timer type (linear or exponential back- off). * OSPF status: contains the neighbours' information. The following figure is based on the Figure 1 from [RFC8346], where the example-ospf-topology is replaced with ietf-l3-ospf-topology and where arrows show how the modules augment each other. Dios, et al. Expires 6 December 2024 [Page 6] Internet-Draft OSPF Topology YANG June 2024 +-----------------------------+ | +-----------------------+ | | | ietf-network | | | +----------^------------+ | | | | | +-----------------------+ | | | ietf-network-topology | | | +----------+------------+ | +-------------^---------------+ | | +------------^-------------+ | ietf-l3-unicast-topology | +------------^-------------+ | | +-----------^-----------+ | ietf-l3-ospf-topology | +-----------------------+ Figure 1: OSPF Topology module structure A second set of parameters, along with augmentations, is included at the link and termination point level. Each parameter is listed as follows: * Interface-type * Area ID * Metric * Passive mode 4. RFC8345 Limitations for the OSPF Modeling There are some limitations in the [RFC8345] that are explained in more detail in [I-D.draft-havel-nmop-digital-map]. The current version of the ietf-l3-ospf-topology module is based on the current version of [RFC8345]. 5. OSPF Topology Tree Diagram Figure 2 below shows the tree diagram of the YANG data model defined in module ietf-l3-ospf-topology.yang (Section 6). Dios, et al. Expires 6 December 2024 [Page 7] Internet-Draft OSPF Topology YANG June 2024 module: ietf-l3-ospf-topology augment /nw:networks/nw:network/nw:network-types: +--rw ospfv2-topology! augment /nw:networks/nw:network/nw:node/ l3t:l3-node-attributes: +--rw ospf-timer-attributes +--rw wait-timer? uint32 +--rw rapid-delay? uint32 +--rw slow-delay? uint32 +--rw timer-type? enumeration augment /nw:networks/nw:network/nt:link/ l3t:l3-link-attributes: +--rw ospfv2-termination-point-attributes +--rw interface-type? identityref +--rw area-id? area-id-type +--rw metric? uint64 +--rw is-passive? boolean augment /nw:networks/nw:network/nw:node/nt:termination-point/ l3t:l3-termination-point-attributes: +--rw ospfv2-termination-point-attributes +--rw interface-type? identityref +--rw area-id? area-id-type +--rw metric? uint64 +--rw is-passive? boolean Figure 2: OSPF Topology tree diagram 6. YANG Model for OSPF topology Following the YANG model is presented. file "ietf-l3-ospf-topology@2024-06-12.yang" module ietf-l3-ospf-topology { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-l3-ospf-topology"; prefix "ospfnt"; import ietf-yang-types { prefix "yang"; } import ietf-network { prefix "nw"; } import ietf-network-topology { prefix "nt"; } import ietf-l3-unicast-topology { prefix "l3t"; Dios, et al. Expires 6 December 2024 [Page 8] Internet-Draft OSPF Topology YANG June 2024 } organization "IETF NMOP (Network Management Operations) Working Group"; contact "WG Web: WG List: Editor: Oscar Gonzalez de Dios Editor: Samier Barguil Editor: Victor Lopez "; description "This module defines a model for Layer 3 OSPF topologies. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision 2022-03-07 { description "Initial version"; reference "RFC XXXX: A YANG Data Model for Open Shortest Path First (OSPF) Topology"; } typedef area-id-type { type yang:dotted-quad; description "An identifier for the OSPFv2 area."; reference "RFC 2328: OSPF Version 2"; } identity inf-type { Dios, et al. Expires 6 December 2024 [Page 9] Internet-Draft OSPF Topology YANG June 2024 description "Identity for the OSPF interface type."; reference "RFC 2328: OSPF Version 2"; } identity nbma { base inf-type; description "Identity for the NBMA interface."; reference "RFC 2328: OSPF Version 2"; } identity p2mp { base inf-type; description "Identity for the p2mp interface."; reference "RFC 2328: OSPF Version 2"; } identity p2mp-over-lan { base inf-type; description "Identity for the p2mp-over-lan interface."; reference "RFC 2328: OSPF Version 2"; } identity p2p { base inf-type; description "Identity for the p2p interface."; reference "RFC 2328: OSPF Version 2"; } grouping ospfv2-topology-type { description "Identifies the topology type to be OSPF v2."; container ospfv2-topology { presence "indicates OSPF v2 topology"; description "The presence of the container node indicates OSPF v2 topology"; } } grouping ospfv2-node-attributes { Dios, et al. Expires 6 December 2024 [Page 10] Internet-Draft OSPF Topology YANG June 2024 description "OSPF v2 node scope attributes"; container ospf-timer-attributes { description "Contains OSPFv2 node timer attributes"; leaf wait-timer { type uint32; units msec; description "The amount of time to wait without detecting SPF trigger events before going back to the rapid delay."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf rapid-delay { type uint32; units msec; description "The amount of time to wait before running SPF after the initial SPF trigger event."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf slow-delay { type uint32; units msec; description "The amount of time to wait before running an SPF."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } leaf timer-type { type enumeration { enum LINEAR_BACKOFF { description "The link state routing protocol uses linear back-off."; } enum EXPONENTIAL_BACKOFF { description "The link state routing protocol uses exponential back-off."; } } description "The timer mode that is utilised by the SPF algorithm."; reference "RFC 8541: SPF Impact on IGP Micro-loops"; } Dios, et al. Expires 6 December 2024 [Page 11] Internet-Draft OSPF Topology YANG June 2024 } } grouping ospfv2-termination-point-attributes { description "OSPF termination point scope attributes"; container ospfv2-termination-point-attributes { description "Indicates the termination point from the which the OSPF is configured. A termination point can be a physical port, an interface, etc."; leaf interface-type { type identityref { base inf-type ; } description "OSPF interface type."; reference "RFC 2328: OSPF Version 2"; } leaf area-id { type area-id-type; description "An identifier for the OSPFv2 area."; reference "RFC 2328: OSPF Version 2"; } leaf metric { type uint64; description "OSFP Protocol metric"; reference "RFC 2328: OSPF Version 2"; } leaf is-passive{ type boolean; description "Interface passive mode"; reference "RFC 2328: OSPF Version 2"; } } } augment "/nw:networks/nw:network/nw:network-types" { description "Introduces new network type for L3 Unicast topology"; uses ospfv2-topology-type; } Dios, et al. Expires 6 December 2024 [Page 12] Internet-Draft OSPF Topology YANG June 2024 augment "/nw:networks/nw:network/nw:node/" +"l3t:l3-node-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSPF topology"; } description "OSPF node-level attributes "; uses ospfv2-node-attributes; } augment "/nw:networks/nw:network/" + "nt:link/l3t:l3-link-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSFP topology"; } description "Augments topology link configuration"; uses ospfv2-termination-point-attributes; } augment "/nw:networks/nw:network/nw:node/" +"nt:termination-point/l3t:l3-termination-point-attributes" { when "/nw:networks/nw:network/nw:network-types/" +"ospfnt:ospfv2-topology" { description "Augmentation parameters apply only for networks with OSFP topology"; } description "Augments topology termination point configuration"; uses ospfv2-termination-point-attributes; } } Figure 3: OSPF Topology YANG module Dios, et al. Expires 6 December 2024 [Page 13] Internet-Draft OSPF Topology YANG June 2024 7. Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF {!RFC6241}} or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. 8. IANA Considerations This document registers the following namespace URIs in the IETF XML registry [RFC3688]: -------------------------------------------------------------------- URI: urn:ietf:params:xml:ns:yang:ietf-l3-ospf-topology Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. -------------------------------------------------------------------- This document registers the following YANG module in the YANG Module Names registry [RFC6020]: -------------------------------------------------------------------- name: ietf-l3-ospf-topology namespace: urn:ietf:params:xml:ns:yang:ietf-l3-ospf-topology maintained by IANA: N prefix: ietf-l3-ospf-topology reference: RFC XXXX -------------------------------------------------------------------- Dios, et al. Expires 6 December 2024 [Page 14] Internet-Draft OSPF Topology YANG June 2024 9. Implementation Status This section will be used to track the status of the implementations of the model. It is aimed at being removed if the document becomes RFC. 10. References 10.1. Normative References [I-D.draft-havel-nmop-digital-map] Havel, O., Claise, B., de Dios, O. G., Elhassany, A., Graf, T., and M. Boucadair, "Modeling the Digital Map based on RFC 8345: Sharing Experience and Perspectives", Work in Progress, Internet-Draft, draft-havel-nmop- digital-map-00, 3 March 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . Dios, et al. Expires 6 December 2024 [Page 15] Internet-Draft OSPF Topology YANG June 2024 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March 2018, . [RFC8346] Clemm, A., Medved, J., Varga, R., Liu, X., Ananthakrishnan, H., and N. Bahadur, "A YANG Data Model for Layer 3 Topologies", RFC 8346, DOI 10.17487/RFC8346, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and O. Gonzalez de Dios, "YANG Data Model for Traffic Engineering (TE) Topologies", RFC 8795, DOI 10.17487/RFC8795, August 2020, . [RFC9129] Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem, "YANG Data Model for the OSPF Protocol", RFC 9129, DOI 10.17487/RFC9129, October 2022, . 10.2. Informative References [I-D.draft-ietf-teas-yang-l3-te-topo] Liu, X., Bryskin, I., Beeram, V. P., Saad, T., Shah, H. C., and O. G. de Dios, "YANG Data Model for Layer 3 TE Dios, et al. Expires 6 December 2024 [Page 16] Internet-Draft OSPF Topology YANG June 2024 Topologies", Work in Progress, Internet-Draft, draft-ietf- teas-yang-l3-te-topo-16, 2 March 2024, . [I-D.draft-ogondio-nmop-isis-topology] de Dios, O. G., Barguil, S., Lopez, V., Ceccarelli, D., and B. Claise, "A YANG Data Model for Intermediate System to intermediate System (IS-IS) Topology", Work in Progress, Internet-Draft, draft-ogondio-nmop-isis- topology-00, 4 March 2024, . Acknowledgments This work is partially supported by the European Commission under Horizon 2020 ALLEGRO project. Authors' Addresses Oscar González de Dios Telefonica Email: oscar.gonzalezdedios@telefonica.com Samier Barguil Giraldo Nokia Email: samier.barguil_giraldo@nokia.com Victor Lopez Nokia Email: victor.lopez@nokia.com Dios, et al. Expires 6 December 2024 [Page 17]