Teas Working Group Young Lee Internet Draft Huawei Intended status: Informational Sergio Belotti Nokia Expires: April 16, 2018 Dhruv Dhody Huawei Daniele Ceccarelli Ericsson Bin Yeong Yoon ETRI October 16, 2017 Information Model for Abstraction and Control of TE Networks (ACTN) draft-ietf-teas-actn-info-model-04.txt Abstract This draft provides an information model for Abstraction and Control of Traffic Engineered (TE) networks (ACTN). 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 http://www.ietf.org/ietf/1id-abstracts.txt Lee & Belotti, et al. Expires April 16, 2018 [Page 1] Internet-Draft ACTN Info Model October 2017 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 16, 2018. Copyright 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...............................................4 2. ACTN Common Interfaces Information Model ......................4 3. Virtual Network primitives ....................................6 3.1. VN Instantiate............................................6 3.2. VN Modify.................................................7 3.3. VN Delete.................................................7 3.4. VN Update.................................................7 3.5. VN Compute................................................8 4. Traffic Engineering (TE) primitives ...........................8 4.1. TE Instantiate............................................9 4.2. TE Modify.................................................9 4.3. TE Delete.................................................9 4.4. TE Topology Update (for TE resources).....................9 4.5. Path Compute.............................................10 5. VN Objects ...................................................11 5.1. VN Identifier............................................11 5.2. VN Service Characteristics...............................11 5.3. VN End-Point.............................................14 5.4. VN Objective Function....................................14 5.5. VN Action Status.........................................15 5.6. VN Topology..............................................15 Lee & Belotti, et al. Expire April 16, 2018 [Page 2] Internet-Draft ACTN Info Model October 2017 5.7. VN Member................................................15 5.7.1. VN Computed Path....................................16 5.7.2. VN Service Preference...............................16 6. TE Objects ...................................................17 6.1. TE Tunnel Characteristic.................................17 7. Mapping of VN Primitives with VN Objects .....................19 8. Mapping of TE Primitives with TE Objects .....................20 9. References ...................................................21 9.1. Normative References.....................................21 9.2. Informative References...................................21 10.Contributors .................................................22 Contributors' Addresses..........................................22 Authors' Addresses...............................................22 1. Introduction This draft provides an information model for the requirements identified in the ACTN requirements [ACTN-Req] and the ACTN interfaces identified in the ACTN architecture and framework document [ACTN-Frame]. The purpose of this draft is to put all information elements of ACTN in one place before proceeding to development work necessary for protocol extensions and data models. The ACTN reference architecture [ACTN-Frame] identified a three-tier control hierarchy as depicted in Figure 1: - Customer Network Controllers (CNC) - Multi-Domain Service Coordinator (MDSC) - Provisioning Network Controllers (PNC). Lee & Belotti, et al. Expire April 16, 2018 [Page 3] Internet-Draft ACTN Info Model October 2017 +-------+ +-------+ +-------+ | CNC-A | | CNC-B | | CNC-C | +-------+ +-------+ +-------+ \ | / ---------- | CMI ------------ \ | / +-----------------------+ | MDSC | +-----------------------+ / | \ -------- | MPI ------------ / | \ +-------+ +-------+ +-------+ | PNC | | PNC | | PNC | +-------+ +-------+ +-------+ Figure 1: A Three-tier ACTN control hierarchy The two interfaces with respect to the MDSC, one north of the MDSC and the other south of the MDSC are referred to as CMI (CNC-MDSC Interface) and MPI (MDSC-PNC Interface), respectively. It is intended to model these two interfaces and derivative interfaces thereof (e.g., MDSC to MSDC in a hierarchy of MDSCs) with one common model. 1.1. Terminology Refer VN, VNS to [ACTN-Frame] and abstraction and abstract topology to [RFC7926]. 2. ACTN Common Interfaces Information Model This section provides ACTN common interface information model to describe in terms of primitives, objects, their properties (represented as attributes), their relationships, and the resources for the service applications needed in the ACTN context. Lee & Belotti, et al. Expire April 16, 2018 [Page 4] Internet-Draft ACTN Info Model October 2017 The standard interface is described between a client controller and a server controller. A client-server relationship is recursive between a CNC and a MDSC and between a MDSC and a PNC. In the CMI, the client is a CNC while the server is a MDSC. In the MPI, the client is a MDSC and the server is a PNC. There may also be MDSC- MDSC interface(s) that need to be supported. This may arise in a hierarchy of MDSCs in which workloads may need to be partitioned to multiple MDSCs. Basic primitives (messages) are required between the CNC-MDSC and MDSC-PNC controllers. These primitives can then be used to support different ACTN network control functions like network topology request/query, VN service request, path computation and connection control, VN service policy negotiation, enforcement, routing options, etc. There are two different types of primitives depending of the type of interface: - Virtual Network primitives at CMI - Traffic Engineering primitives at MPI As well described in [ACTN-Frame], at the CMI level, there is no need for detailed TE information since the basic functionality is to translate customer service information into virtual network service operation. At the MPI level, MDSC has the main scope for multi-domain coordination and creation of a single e2e abstracted network view which is strictly related to TE information. As for topology, this document employs two types of topology: - The first type is referred to as virtual network topology which is associated a VN. Virtual network topology is a customized topology for view and control by the customer. See Section 3.1 for details. - The second type is referred to as TE topology which is associated with provider network operation on which we can apply policy to obtain the required level of abstraction to represent the underlying physical network topology. Lee & Belotti, et al. Expire April 16, 2018 [Page 5] Internet-Draft ACTN Info Model October 2017 3. Virtual Network primitives This section provides a list of main VN primitives related to virtual network which are necessary to satisfy ACTN requirements specified in [ACTN-REQ] At a minimum, the following VN action primitives should be supported: - VN Instantiate (See Section 3.1.1. for the description) - VN Modify (See Section 3.1.2. for the description) - VN Delete (See Section 3.1.3. for the description) - VN Update ((See Section 3.1.4. for the description) - VN Path Compute (See Section 3.1.5. for the description) - VN Query (See Section 3.1.6. for the description) <VN Action> is an object describing the main VN primitives. VN Action can assume one of the mentioned above primitives values. <VN Action> ::= <VN Instantiate> | <VN Modify> | <VN Delete> | <VN Update> | <VN Path Compute> | <VN Query> All these actions will solely happen at CMI level between Customer Network Controller (CNC) and Multi Domain Service Coordinator (MDSC). 3.1. VN Instantiate <VN Instantiate> refers to an action from customers/applications to request the creation of VNs. Depending on the agreement between client and provider <VN instantiate> can imply different VN Lee & Belotti, et al. Expire April 16, 2018 [Page 6] Internet-Draft ACTN Info Model October 2017 operations and view, depending on the type of VN requested. You can have two types of VN instantiation: VN type 1: Where VN is viewed as a set of edge-to-edge links, referred as VN members in ACTN terminology. VN type 2: Where VN is viewed as a VN-topology which is comprised of virtual nodes and virtual links. See Section 5.6 for details. Please see [ACTN-Frame] for details regarding the types of VN. 3.2. VN Modify <VN Modify> refers to an action issued from customers/applications to modify an existing VN (i.e., an instantiated VN). 3.3. VN Delete <VN Delete> refers to an action issued from customers/applications to delete an existing VN. 3.4. VN Update <VN Update> refers to any update to the VN that needs to be updated to the customers. VN Update fulfills a push model at CMI level, to make aware customers of any specific changes in the topology details related to VN instantiated. VN Update, depending of the type of VN instantiated, can be an update of VN members (edge-to-edge links) in case of VN type 1, or a virtual topology view update in case of VN type 2. The connection-related information (e.g., LSPs) update association with VNs will be part of the "translation" function that happens in MDSC to map/translate VN request into TE semantics. This information will be provided in case customer optionally wants to have more detailed TE information associated with the instantiated VN. Lee & Belotti, et al. Expire April 16, 2018 [Page 7] Internet-Draft ACTN Info Model October 2017 3.5. VN Compute <VN Compute> consists of Request and Reply. Request refers to an action from customers/applications to request a VN computation. <VN Compute> Reply refers to the reply in response to <VN Compute> Request. <VN Compute> Request/Reply is to be differentiated from a VN Instantiate. The purpose of VN Compute is a priori exploration to compute network resources availability and getting a possible VN view in which path details can be specified matching customer/applications constraints. This a priori exploration may not guarantee the availability of the computed network resources at the time of instantiation. <VN Query> refers to inquiry pertaining to the VN that has been already instantiated. VN Query fulfills a pull model and permit to get topology view. <VN Query Reply> refers to the reply in response to <VN Query>. 4. Traffic Engineering (TE) primitives This section provides a list of main TE primitives necessary to satisfy ACTN requirements specified in [ACTN-REQ] related to typical TE operations supported at MPI level. At a minimum, the following TE action primitives should be supported: - TE Instantiate/Modify/Delete - TE Topology Update (See Section 4.4. for the description) - Path Compute <TE Action> is an object describing the main TE primitives. TE Action can assume one of the mentioned above primitives values. <TE Action> ::= <TE Instantiate> | <TE Modify> | <TE Delete> | Lee & Belotti, et al. Expire April 16, 2018 [Page 8] Internet-Draft ACTN Info Model October 2017 <TE Topology Update> | <Path Compute> | All these actions will solely happen at MPI level between Multi Domain Service Coordinator (MDSC) and Provisioning Network Controller (PNC). 4.1. TE Instantiate <TE Instantiate> refers to an action issued from MDSC to PNC to instantiate new TE tunnels. 4.2. TE Modify <TE Modify> refers to an action issued from MDSC to PNC to modify existing TE tunnels. 4.3. TE Delete <TE Delete> refers to an action issued from MDSC to PNC to delete existing TE tunnels. 4.4. TE Topology Update (for TE resources) <TE Topology Update> is a primitive specifically related to MPI to provide TE resource update between any domain controller towards MDSC regarding the entire content of any "domain controller" actual TE topology or an abstracted filtered view of TE topology depending on negotiated policy. See [TE-TOPO] for detailed YANG implementation of TE topology update. <TE Topology Update> ::= <TE-topology-list> <TE-topology-list> ::= <TE-topology> [<TE-topology-list>] Lee & Belotti, et al. Expire April 16, 2018 [Page 9] Internet-Draft ACTN Info Model October 2017 <TE-topology> ::= [<Abstraction>] <TE-Topology-identifier> <Node- list> <Link-list> <Node-list> ::= <Node>[<Node-list>] <Node> ::= <Node> <TE Termination Point-list> <TE Termination Point-list> ::= <TE Termination Point> [<TE-Termination Point-list>] <Link-list> ::= <Link>[<Link-list>] Where <Abstraction> provides information on level of abstraction (as determined a priori). <TE-topology-identifier> is an identifier that identifies a specific te-topology, e.g., te-types:te-topology-id [TE-TOPO]. <Node-list> is detailed information related to a specific node belonging to a te-topology, e.g., te-node-attributes [TE-TOPO]. <Link-list> is information related to the specific link related belonging to a te-topology, e.g., te-link-attributes [TE-TOPO]. <TE Termination Point-list> is detailed information associated with the termination points of te-link related to a specific node, e.g., interface-switching-capability [TE-TOPO]. 4.5. Path Compute <Path Compute> consists of Request and Reply. Request refers to an action from MDSC to PNC to request a path computation. <Path Compute> Reply refers to the reply in response to <Path Compute> Request. The context of <path-compute> is described in [Path-Compute]. Lee & Belotti, et al. Expire April 16, 2018 [Page 10] Internet-Draft ACTN Info Model October 2017 5. VN Objects This section provides a list of objects associated to VN action primitives. 5.1. VN Identifier <VN Identifier> is a unique identifier of the VN. 5.2. VN Service Characteristics VN Service Characteristics describes the customer/application requirements against the VNs to be instantiated. <VN Service Characteristics> ::= <VN Connectivity Type> (<VN Traffic Matrix>...) <VN Survivability> Where <VN Connectivity Type> ::= <P2P>|<P2MP>|<MP2MP>|<MP2P>|<Multi- destination> The Connectivity Type identifies the type of required VN Service. In addition to the classical type of services (e.g. P2P/P2MP etc.), ACTN defines the "multi-destination" service that is a new P2P service where the end points are not fixed. They can be chosen among a list of pre-configured end points or dynamically provided by the CNC. <VN Traffic Matrix> ::= <Bandwidth> [<VN Constraints>] The VN Traffic Matrix represents the traffic matrix parameters for the required the service connectivity. Bandwidth is a mandatory parameter and a number of optional constrains can be specified in the <VN Constrains> (e.g. diversity, cost). They can include objective functions and TE metrics bounds as specified in [RFC5441]. Further details on the VN constraints are specified below: <VN Constraints> ::= [<Layer Protocol>] [<Diversity>] Lee & Belotti, et al. Expire April 16, 2018 [Page 11] Internet-Draft ACTN Info Model October 2017 [<Shared Risk>] ( <Metric> | <VN Objective Function> ) Where: <Layer Protocol> identifies the layer topology at which the VN service is requested. It could be for example MPLS, ODU, and OCh. <Diversity> allows asking for diversity constraints for a VN Instantiate/Modify or a VN Path Compute. For example, a new VN or a path is requested in total diversity from an existing one (e.g. diversity exclusion). <Diversity> ::= (<VN-exclusion> (<VN-id>...)) | (<VN-Member-exclusion> (<VN-Member-id>...)) <Shared Risk> is used to get the SRLG associated with the different tunnels composing a VN. Based on the realization of VN required, group of physical resources can be impacted by the same risk. VN member (i.e., edge-to-edge link) can be impacted by this shared risk. <Metric> can include all the Metrics (cost, delay, delay variation, latency), bandwidth utilization parameters defined and referenced by [RFC3630] and [RFC7471]. <VN Objective Function> See Section 5.4. <VN Survivability> describes all attributes related to the VN recovery level and its survivability policy enforced by the customers/applications. <VN Survivability> ::= <VN Recovery Level> [<VN Tunnel Recovery Level>] [<VN Survivability Policy>] Where: <VN Recovery Level> is a value representing the requested level of resiliency required against the VN. The following values are defined: . Unprotected VN Lee & Belotti, et al. Expire April 16, 2018 [Page 12] Internet-Draft ACTN Info Model October 2017 . VN with per tunnel recovery: The recovery level is defined against the tunnels composing the VN and it is specified in the <VN Tunnel Recovery Level>. <VN Tunnel Recovery Level> ::= <0:1>|<1+1>|<1:1>|<1:N>|<M:N>| <On the fly restoration> The VN Tunnel Recovery Level indicates the type of protection or restoration mechanism applied to the VN. It augments the recovery types defined in [RFC4427]. <VN Survivability Policy> ::= [<Local Reroute Allowed>] [<Domain Preference>] [<Push Allowed>] [<Incremental Update>] Where: <Local Reroute Allowed> is a delegation policy to the Server to allow or not a local reroute fix upon a failure of the primary LSP. <Domain Preference> is only applied on the MPI where the MDSC (client) provides a domain preference to each PNC (server), e.g., when an inter-domain link fails, then PNC can choose the alternative peering with this info. <Push Allowed> is a policy that allows a server to trigger an updated VN topology upon failure without an explicit request from the client. Push action can be set as default unless otherwise specified. <Incremental Update> is another policy that triggers an incremental update from the server since the last period of update. Incremental update can be set as default unless otherwise specified. Lee & Belotti, et al. Expire April 16, 2018 [Page 13] Internet-Draft ACTN Info Model October 2017 5.3. VN End-Point <VN End-Point> Object describes the VN's customer end-point characteristics. <VN End-Point> ::= (<Access Point Identifier> [<Access Link Capability>] [<Source Indicator>])... Where: <Access point identifier> represents a unique identifier of the client end-point. They are used by the customer to ask for the setup of a virtual network creation. A <VN End-Point> is defined against each AP in the network and is shared between customer and provider. Both the customer and the provider will map it against his own physical resources. <Access Link Capability> identifies the capabilities of the access link related to the given access point. (e.g., max-bandwidth, bandwidth availability, etc.) <Source Indicator> indicates if an end-point is source or not. 5.4. VN Objective Function The VN Objective Function applies to each VN member (i.e., each E2E tunnel) of a VN. The VN Objective Function can reuse objective functions defined in [RFC5541] section 4. For a single path computation, the following objective functions are defined: o MCP is the Minimum Cost Path with respect to a specific metric (e.g. shortest path). o MLP is the Minimum Load Path, that means find a path composted by te-link least loaded. o MBP is the Maximum residual Bandwidth Path. Lee & Belotti, et al. Expire April 16, 2018 [Page 14] Internet-Draft ACTN Info Model October 2017 For a concurrent path computation, the following objective functions are defined: o MBC is to Minimize aggregate Bandwidth Consumption. o MLL is to Minimize the Load of the most loaded Link. o MCC is to Minimize the Cumulative Cost of a set of paths. 5.5. VN Action Status <VN Action Status> is the status indicator whether the VN has been successfully instantiated, modified, or deleted in the server network or not in response to a particular VN action. Note that this action status object can be implicitly indicated and thus not included in any of the VN primitives discussed in Section 2.3. 5.6. VN Topology When a VN is seen by the customer as a topology, it is referred to as VN topology. This is associated with VN Type 2, which is comprised of virtual nodes virtual and links. <VN Topology> ::= <VN node list> <VN link list> <VN node list> ::= <VN node> [<VN node list>] <VN link list> :: = <VN link> [<VN link list>] 5.7. VN Member <VN Member> describes details of a VN Member which is a list of a set of VN Members represented as <VN_Member_List>. <VN_Member_List> ::= <VN Member> [<VN_Member_List>] Where <VN Member> ::= <Ingress VN End-Point> [<VN Associated LSP>] <Egress VN End-Point> Lee & Belotti, et al. Expire April 16, 2018 [Page 15] Internet-Draft ACTN Info Model October 2017 <Ingress VN End-Point> is the VN End-Point information for the ingress portion of the AP. See Section 5.3 for <VN End-Point> details. <Egress VN End-Point> is the VN End-Point information for the egress portion of the AP. See Section 5.3 for <VN End-Point> details. <VN Associated LSP> describes the instantiated LSPs in the Provider's network for the VN Type 1. It describes the instantiated LSPs over the VN topology for VN Type 2. 5.7.1. VN Computed Path The VN Computed Path is the list of paths obtained after the VN path computation request from higher controller. Note that the computed path is to be distinguished from the LSP. When the computed path is signaled in the network (and thus the resource is reserved for that path), it becomes an LSP. <VN Computed Path> ::= (<Path>...) 5.7.2. VN Service Preference This section provides VN Service preference. VN Service is defined in Section 2. <VN Service Preference> ::= [<Location Service Preference >] [<Client-specific Preference >] [<End-Point Dynamic Selection Preference >] Where <Location Service Preference describes the End-Point Location's (e.g. Data Centers) support for certain Virtual Network Functions (VNFs) (e.g., security function, firewall capability, etc.) and is used to find the path that satisfies the VNF constraint. <Client-specific Preference> describes any preference related to Virtual Network Service (VNS) that application/client can enforce via CNC towards lower level controllers. For example, permission Lee & Belotti, et al. Expire April 16, 2018 [Page 16] Internet-Draft ACTN Info Model October 2017 the correct selection from the network of the destination related to the indicated VNF It is e.g. the case of VM migration among data center and CNC can enforce specific policy that can permit MDSC/PNC to calculate the correct path for the connectivity supporting the data center interconnection required by application. <End-Point Dynamic Selection Preference> describes if the End- Point (e.g. Data Center) can support load balancing, disaster recovery or VM migration and so can be part of the selection by MDSC following service Preference enforcement by CNC. 6. TE Objects 6.1. TE Tunnel Characteristic Tunnel Characteristics describes the parameters needed to configure TE tunnel. <TE Tunnel Characteristics> ::= [<Tunnel Type>] <Tunnel Id> [<Tunnel Layer>] [<Tunnel end-point>] [<Tunnel protection-restoration>] <Tunnel Constraints> [<Tunnel Optimization>] Where <Tunnel Type> ::= <P2P>|<P2MP>|<MP2MP>|<MP2P> The Tunnel Type identifies the type of required tunnel. In this draft, only P2P model is provided. <Tunnel Id> is the TE tunnel identifier <Tunnel Layer> it represents the layer technology of the LSPs supporting the tunnel Lee & Belotti, et al. Expire April 16, 2018 [Page 17] Internet-Draft ACTN Info Model October 2017 <Tunnel End Points> ::= <Source> <Destination> <Tunnel protection-restoration> ::= <prot 0:1>|<prot 1+1>|<prot 1:1>|<prot 1:N>|prot <M:N>|<restoration> <Tunnel Constraints> are the base tunnel configuration constraints parameters. Where <Tunnel Constraints> ::= [<Topology Id>] [<Bandwidth>] [<Disjointness>] [<SRLG>] [<Priority>] [<Affinities>] [<Tunnel Optimization>] [<Objective Function>] <Topology Id> references the topology used to compute the tunnel path. <Bandwidth> is the bandwidth used as parameter in path computation <Disjointness> ::= <node> | <link> | <srlg> <Disjointness> provides the type of resources from which the tunnel has to be disjointed <SRLG> is a group of physical resources impacted by the same risk from which an E2E tunnel is required to be disjointed. <Priority> ::= <Holding Priority> <Setup Priority> where <Setup Priority> indicates the level of priority to taking resources from another tunnel [RFC 3209] <Holding Priority> indicates the level of priority to hold resources avoiding preemption from another tunnel [RFC 3209] Lee & Belotti, et al. Expire April 16, 2018 [Page 18] Internet-Draft ACTN Info Model October 2017 <Affinities> it represent structure to validate link belonging to path of the tunnel (RFC 3209) <Tunnel Optimization> ::= <Metric> | <Objective Function> <Metric> can include all the Metrics (cost, delay, delay variation, latency), bandwidth utilization parameters defined and referenced by [RFC3630] and [RFC7471]. <Objective Function> ::= <objective function type> <objective function type> ::= <MCP> | <MLP> | <MBP> | <MBC> | <MLL> | <MCC> See chapter 5.4 for objective function type description. 7. Mapping of VN Primitives with VN Objects This section describes the mapping of VN Primitives with VN Objects based on Section 5. <VN Instantiate> ::= <VN Service Characteristics> <VN Member-List> [<VN Service Preference>] [<VN Topology>] <VN Modify> ::= <VN identifier> <VN Service Characteristics> <VN Member-List> [<VN Service Preference>] [<VN Topology>] <VN Delete> ::= <VN Identifier> Lee & Belotti, et al. Expire April 16, 2018 [Page 19] Internet-Draft ACTN Info Model October 2017 <VN Update> :: = <VN Identifier> [<VN Member-List>] [<VN Topology>] <VN Path Compute Request> ::= <VN Service Characteristic> <VN Member-List> [<VN Service Preference>] <VN Path Compute Reply> ::= <VN Computed Path> <VN Query> ::= <VN Identifier> <VN Query Reply> ::= <VN Identifier> <VN Associated LSP> [<TE Topology Reference>] 8. Mapping of TE Primitives with TE Objects This section describes the mapping of TE Primitives with TE Objects based on Section 6. <TE Instantiate> ::= <TE Tunnel Characteristics> <TE Modify> ::= <TE Tunnel Characteristics> Lee & Belotti, et al. Expire April 16, 2018 [Page 20] Internet-Draft ACTN Info Model October 2017 <TE Delete> ::= <Tunnel Id> <TE Update> :: = <Tunnel Id> <TE Computed Path> <Path Compute Request> ::= <TE Tunnel Characteristic> <Path Compute Reply> ::= <TE Computed Path> <TE Tunnel Characteristics> 9. References 9.1. Normative References [ACTN-Req] Y. Lee, et al., "Requirements for Abstraction and Control of Transport Networks", draft-ietf-teas-actn-requirements, work in progress. [ACTN-Frame] D. Ceccarelli, et al., "Framework for Abstraction and Control of Transport Networks", draft-ietf-teas-actn- framework, work in progress. 9.2. Informative References [TE-TOPO] Liu, X. et al., "YANG Data Model for TE Topologies", draft-ietf-teas-yang-te-topo, work in progress. Lee & Belotti, et al. Expire April 16, 2018 [Page 21] Internet-Draft ACTN Info Model October 2017 [RFC5541] JL. Le Roux, JP. Vasseur and Y. Lee, "Encoding of Objective Functions in the Path Computation Element Communication Protocol (PCEP)", RFC 5541, June 2009. [RFC7926] A. Farrel, et al., "Problem Statement and Architecture for Information Exchange between Interconnected Traffic- Engineered Networks", RFC 7926, July 2016. [Path-Compute] I. Busi, S. Belotti, et al., "Yang model for requesting Path Computation", draft-busibel-teas-yang- path-computation", work in progress. 10. Contributors Contributors' Addresses Authors' Addresses Young Lee (Editor) Huawei Technologies 5340 Legacy Drive Plano, TX 75023, USA Phone: (469)277-5838 Email: leeyoung@huawei.com Sergio Belotti (Editor) Alcatel Lucent Via Trento, 30 Vimercate, Italy Email: sergio.belotti@alcatel-lucent.com Dhruv Dhody Huawei Technologies, Divyashree Technopark, Whitefield Bangalore, India Email: dhruv.ietf@gmail.com Daniele Ceccarelli Ericsson Torshamnsgatan,48 Stockholm, Sweden Email: daniele.ceccarelli@ericsson.com Bin Yeong Yoon Lee & Belotti, et al. Expire April 16, 2018 [Page 22] Internet-Draft ACTN Info Model October 2017 ETRI Email: byyun@etri.re.kr Haomian Zheng Huawei Technologies Email: zhenghaomian@huawei.com Xian Zhang Huawei Technologies Email: zhang.xian@huawei.com Lee & Belotti, et al. Expire April 16, 2018 [Page 23]