--- 1/draft-ietf-pce-applicability-actn-09.txt 2019-03-07 18:13:39.538410574 -0800 +++ 2/draft-ietf-pce-applicability-actn-10.txt 2019-03-07 18:13:39.590411845 -0800 @@ -1,21 +1,21 @@ PCE Working Group D. Dhody Internet-Draft Y. Lee Intended status: Informational Huawei Technologies -Expires: September 8, 2019 D. Ceccarelli +Expires: September 9, 2019 D. Ceccarelli Ericsson - March 7, 2019 + March 08, 2019 Applicability of the Path Computation Element (PCE) to the Abstraction and Control of TE Networks (ACTN) - draft-ietf-pce-applicability-actn-09 + draft-ietf-pce-applicability-actn-10 Abstract Abstraction and Control of TE Networks (ACTN) refers to the set of virtual network (VN) operations needed to orchestrate, control and manage large-scale multi-domain TE networks so as to facilitate network programmability, automation, efficient resource sharing, and end-to-end virtual service aware connectivity and network function virtualization services. @@ -37,65 +37,91 @@ 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 September 8, 2019. + This Internet-Draft will expire on September 9, 2019. Copyright Notice Copyright (c) 2019 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 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. Background Information . . . . . . . . . . . . . . . . . . . 2 - 1.1. Path Computation Element (PCE) . . . . . . . . . . . . . 2 - 1.1.1. Role of PCE in SDN . . . . . . . . . . . . . . . . . 3 - 1.1.2. PCE in Multi-domain and Multi-layer Deployments . . . 4 - 1.1.3. Relationship to PCE Based Central Control . . . . . . 4 - 1.2. Abstraction and Control of TE Networks (ACTN) . . . . . . 5 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 7 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. Background Information . . . . . . . . . . . . . . . . . . . 3 + 2.1. Path Computation Element (PCE) . . . . . . . . . . . . . 3 + 2.1.1. Role of PCE in SDN . . . . . . . . . . . . . . . . . 4 + 2.1.2. PCE in Multi-domain and Multi-layer Deployments . . . 4 + 2.1.3. Relationship to PCE Based Central Control . . . . . . 5 + 2.2. Abstraction and Control of TE Networks (ACTN) . . . . . . 5 3. Architectural Considerations . . . . . . . . . . . . . . . . 7 - 3.1. Multi-Domain Coordination via Hierarchy . . . . . . . . . 8 + 3.1. Multi-Domain Coordination via Hierarchy . . . . . . . . . 7 3.2. Abstraction . . . . . . . . . . . . . . . . . . . . . . . 8 3.3. Customer Mapping . . . . . . . . . . . . . . . . . . . . 9 3.4. Virtual Service Coordination . . . . . . . . . . . . . . 10 - 4. Interface Considerations . . . . . . . . . . . . . . . . . . 11 + 4. Interface Considerations . . . . . . . . . . . . . . . . . . 10 5. Realizing ACTN with PCE (and PCEP) . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.1. Normative References . . . . . . . . . . . . . . . . . . 16 9.2. Informative References . . . . . . . . . . . . . . . . . 16 Appendix A. Additional Information . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 -1. Background Information +1. Introduction -1.1. Path Computation Element (PCE) + Abstraction and Control of TE Networks (ACTN) [RFC8453] refers to the + set of virtual network (VN) operations needed to orchestrate, control + and manage large-scale multi-domain TE networks so as to facilitate + network programmability, automation, efficient resource sharing, and + end-to-end virtual service aware connectivity and network function + virtualization services. + + The Path Computation Element (PCE) [RFC4655] is a component, + application, or network node that is capable of computing a network + path or route based on a network graph and applying computational + constraints. The PCE serves requests from Path Computation Clients + (PCCs) that communicate with it over a local API or using the Path + Computation Element Communication Protocol (PCEP). + + This document examines the PCE and ACTN architecture and describes + how PCE architecture is applicable to ACTN. It also lists the PCEP + extensions that are needed to use PCEP as an ACTN interface. This + document also identifies any gaps in PCEP, that exist at the time of + publication of this document. + + Further, ACTN, stateful H-PCE [I-D.ietf-pce-stateful-hpce], and PCE + as a central controller (PCECC) [RFC8283] are based on the same basic + hierarchy framework and thus compatible with each other. + +2. Background Information + +2.1. Path Computation Element (PCE) The Path Computation Element Communication Protocol (PCEP) [RFC5440] provides mechanisms for Path Computation Clients (PCCs) to request a Path Computation Element (PCE) [RFC4655] to perform path computations. The ability to compute shortest constrained TE LSPs in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across multiple domains has been identified as a key motivation for PCE development. @@ -118,39 +144,39 @@ computations. The additional state allows the PCE to compute constrained paths while considering individual LSPs and their interactions. [RFC8281] describes the setup, maintenance and teardown of PCE-initiated LSPs under the stateful PCE model. [RFC8231] also describes the active stateful PCE. The active PCE functionality allows a PCE to reroute an existing LSP or make changes to the attributes of an existing LSP, or a PCC to delegate control of specific LSPs to a new PCE. -1.1.1. Role of PCE in SDN +2.1.1. Role of PCE in SDN Software-Defined Networking (SDN) [RFC7149] refers to a separation between the control elements and the forwarding components so that software running in a centralized system called a controller, can act to program the devices in the network to behave in specific ways. A required element in an SDN architecture is a component that plans how the network resources will be used and how the devices will be programmed. It is possible to view this component as performing specific computations to place flows within the network given knowledge of the availability of network resources, how other forwarding devices are programmed, and the way that other flows are routed. It is concluded in [RFC7399], that this is the same function that a PCE might offer in a network operated using a dynamic control plane. This is the function and purpose of a PCE, and the way that a PCE integrates into a wider network control system including SDN is presented in Application-Based Network Operation (ABNO) [RFC7491]. -1.1.2. PCE in Multi-domain and Multi-layer Deployments +2.1.2. PCE in Multi-domain and Multi-layer Deployments Computing paths across large multi-domain environments requires special computational components and cooperation between entities in different domains capable of complex path computation. The PCE provides an architecture and a set of functional components to address this problem space. A PCE may be used to compute end-to-end paths across multi-domain environments using a per-domain path computation technique [RFC5152]. The Backward Recursive PCE based path computation (BRPC) mechanism [RFC5441] defines a PCE-based path computation procedure to compute inter-domain constrained MPLS and @@ -178,30 +204,30 @@ (including PCE- initiated LSP setup and active PCE usage) in the context of networks using the H-PCE architecture. [RFC5623] describes a framework for applying the PCE-based architecture to inter-layer to (G)MPLS TE. It provides suggestions for the deployment of PCE in support of multi-layer networks. It also describes the relationship between PCE and a functional component in charge of the control and management of the Virtual Network Topology (VNT) [RFC5212], called the VNT Manager (VNTM). -1.1.3. Relationship to PCE Based Central Control +2.1.3. Relationship to PCE Based Central Control [RFC8283] introduces the architecture for PCE as a central controller (PCECC), it further examines the motivations and applicability for PCEP as a southbound interface, and introduces the implications for the protocol. Section 2.1.3 of [RFC8283] describe a hierarchy of PCE-based controller as per the Hierarchy of PCE framework defined in [RFC6805]. -1.2. Abstraction and Control of TE Networks (ACTN) +2.2. Abstraction and Control of TE Networks (ACTN) [RFC8453] describes the high-level ACTN requirements and the architecture model for ACTN including the entities Customer Network Controller (CNC), Multi-domain Service Coordinator (MDSC), and Provisioning Network Controller (PNC) and their interfaces. The ACTN reference architecture is shown in Figure 1 which is reproduced here from [RFC8453] for convenience. [RFC8453] remains the definitive reference for the ACTN architecture. As depicted in Figure 1, the ACTN architecture identifies a three-tier hierarchy. @@ -242,45 +268,20 @@ Figure 1: ACTN Hierarchy There are two interfaces with respect to the MDSC: one north of the MDSC (the CNC-MDSC Interface : CMI), and one south (the MDSC-PNC Interface : MPI). A hierarchy of MDSCs is possible with a recursive MPI interface. [RFC8454] provides an information model for ACTN interfaces. -2. Introduction - - Abstraction and Control of TE Networks (ACTN) refers to the set of - virtual network (VN) operations needed to orchestrate, control and - manage large-scale multi-domain TE networks so as to facilitate - network programmability, automation, efficient resource sharing, and - end-to-end virtual service aware connectivity and network function - virtualization services. - - The Path Computation Element (PCE) is a component, application, or - network node that is capable of computing a network path or route - based on a network graph and applying computational constraints. The - PCE serves requests from Path Computation Clients (PCCs) that - communicate with it over a local API or using the Path Computation - Element Communication Protocol (PCEP). - - This document examines the PCE and ACTN architecture and describes - how PCE architecture is applicable to ACTN. It also lists the PCEP - extensions that are needed to use PCEP as an ACTN interface. This - document also identifies any gaps in PCEP, that exist at the time of - publication of this document. - - Further, ACTN, stateful H-PCE, and PCECC are based on the same basic - hierarchy framework and thus compatible with each other. - 3. Architectural Considerations The ACTN architecture [RFC8453] is based on hierarchy and recursiveness of controllers. It defines three types of controllers (depending on the functionalities they implement). The main functionalities are - o Multi-domain coordination o Abstraction