IETF Ping Pan Internet Draft (Infinera) Lyndon Ong (Ciena) Shane Amante (Level 3) Expires: April 31, 2012 October 31, 2011 Software-Defined Network (SDN) Use Case for Bandwidth on Demand Applications draft-pan-sdn-bod-problem-statement-and-use-case-01.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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Abstract Bandwidth on Demand services are offered by network operators in industry and research sectors to support the needs of selected customers needing high bandwidth point-to-point connections. Without a standard interface for controlling the use of network resources, user applications and services are subject to limits of layering, security and interoperability across multiple vendors of network equipment. In this document, we argue the necessity in providing network information to the applications, thereby enabling the applications to directly provision network elements associated with the relevant applications. Pan et.al Expires April 31, 2012 [Page 2] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 Table of Contents 1. Introduction...................................................3 2. Related Work...................................................4 3. Problem Definition.............................................4 4. The Role of an SDN Layer.......................................6 5. Use Cases......................................................7 5.1. Scheduled/ Dynamic Bandwidth On-Demand Service............7 5.2. Multi-Layer BoD Support...................................8 5.3. Virtualized Network Service...............................9 5.4. BoD Actions Supported by the SDN Orchestrator.............9 6. Security Consideration........................................10 7. IANA Considerations...........................................10 8. Normative References..........................................10 9. Acknowledgments...............................................11 1. Introduction Bandwidth on Demand services are offered by network operators in industry and research sectors to support the needs of selected customers needing high bandwidth point-to-point connections. Such services take advantage of dynamic control of the underlying network to set up forwarding and resource allocation as requested by the customer. Some control is given directly to the customer via a portal so that there is no need to go through an intermediate stage of service order provisioning on the part of the network operator. Currently such services are often based on management interfaces to vendor equipment that are vendor-specific, and as a result the operator must redesign its supporting control application for each vendor domain, or limit their offering to a single vendor domain. In this document, we propose that providing a common interface to networks of different vendors and technologies would enable the network provider to offer Bandwidth on Demand and other services that are faster to deploy across a wide range of network equipment by using additional network information. Here are some of the 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]. Pan et.al Expires April 31, 2012 [Page 3] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 2. Related Work There has been much work in this area in recent years. OpenFlow has defined an architecture for offering virtualized network control through a centralized controller and proxies called FlowVisors. These allow users to configure forwarding of packets within slices of the network partitioned off for their use. The controller is designed to control each network element directly through a dedicated control interface. It is not designed to work with existing control plane protocols. More generally, TMF has developed models and interfaces for operations and administration of networks through the north-bound interface provided by the element management system. These interfaces are not intended for real-time control of the network element and need to take into account variations in the design and features of different types of equipment. PCE is a client-server protocol that operates in MPLS networks that enables the network operators to compute and potentially provision optimal point-to-point and point-to-multipoint connections. However, PCE does not interface with applications to optimize traffic from user applications. 3. Problem Definition Figure 1 illustrates the relationship between application and network today, where customer control of bandwidth on demand is provided through applications created by the network operator supporting the user interface, features and backend accounting for the service. Such applications are used in single domain deployments and have limited visibility of underlying IP/MPLS and Transport networks and, most importantly, resource availability on those networks. Pan et.al Expires April 31, 2012 [Page 4] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 +-------------+ +-------------+ | Application | | Application | | #1 | | #2 | +-------------+ +-------------+ | | | | +------------------+ +------------------+ | Network | | Network | | Domain #1 | | Domain #2 | +------------------+ +------------------+ Figure 1: Application to network relationship today This presents a number of challenges and problems. Without a standard interface to the network elements that comprise one or more network domains and their associated control software, each bandwidth on demand supporting application must be built for a specific set of vendor equipment and is not easily generalizable to different vendors or even different equipment offered by a single vendor. While signaling interfaces such as the UNI could offer standardized access to network control, such interfaces have not been adopted because they provide minimal security and functionality and are designed for more of a peer relationship between network elements, traditionally at only a single (peer) layer of the network. Similarly, bandwidth on demand applications must be designed for a single technology, which restricts the range of use and potential users. If Domain #1 uses SDH, for example, and Domain #2 uses OTN it may be necessary to design supporting Application #2 from scratch even though Application #1 has been successfully offering service. Ideally the interface should allow some level of technology independence, as well as potentially integration to permit control of multiple layers simultaneously (esp. packet and circuit). Third, the application is generally limited to simple services connecting a source to destination, because interfaces hide network topology and do not allow visualization of the topology for different customer views. For some services users may wish to exercise control over path routing aspects such as shared risk, required latency characteristics or inclusion or exclusion of areas for policy reasons. Pan et.al Expires April 31, 2012 [Page 5] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 4. The Role of an SDN Layer To solve the above problem, the proposal is to introduce a software- driven network (SDN) layer (as shown in Figure 2), that is responsible for network virtualization, programmability and monitoring, between supporting applications and the network. +-------------+ +-------------+ +-------------+ | Application | | Application | | Application | | #1 | | #2 | | #3 | +-------------+ +-------------+ +-------------+ | | | | | | +---------------------------------------------------+ | SDN Layer | | (Network virtualization, programmability | | and Monitoring) | +---------------------------------------------------+ | | | | +------------------+ +------------------+ | Physical Network | | Physical Network | | Domain #1 | | Domain #2 | +------------------+ +------------------+ Figure 2: Application to network relationship for SDN The purpose of the SDN Layer is to enable the applications supporting bandwidth on demand services to access information about and control (aggregate) traffic flows at various layers of the network through a standard, secure and customizable interface. Applications can visualize the traffic flows at the network layer, and manage the mapping or binding between its traffic flows from edge-to-edge through the associated networks. The implementation of an SDN Layer involves interfacing among different types of applications and different types of network domains, based on technology or vendor, administrative or policy control. Standardized interfaces must be defined to support this. The architecture should be agnostic as to the type of network control plan used in a supporting domain. The focus of work should Pan et.al Expires April 31, 2012 [Page 6] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 be on providing richer access to control of network resources rather than on the scheme for network control used in the domain. 5. Use Cases 5.1. Scheduled/ Dynamic Bandwidth On-Demand Service Figure 3 illustrates the flow of a scheduled or dynamic bandwidth service. In the simplest case, connectivity may already be provided between user-specified endpoints, however the bandwidth allocated between endpoints can be varied within some overall limit based on a predefined schedule or on spontaneous customer request. Note that allowing bandwidth to be partitioned so that a scheduling application has control over some pre-allocated set of resources is necessary to support the scheduled BoD service. Also, the SDN layer ideally hides the specific technology used to support the connection, offering control of the service with associated rate, latency and recovery features. In more sophisticated services, the customer may be allowed to create new connections within a specified set of endpoints and delete such connections when the connectivity is no longer required. User Req's +------------+ -------->| Controller | +------------+ | | <----- North-bound protocol to adjust connections | \|/ +---------+ +--------+ | PE1 | | PE2 | | |===== Provisioned Connection ===>| | +---------+ +--------+ Figure 3: Scheduled/Dynamic BoD Service Pan et.al Expires April 31, 2012 [Page 7] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 5.2. Multi-Layer BoD Support User Req's +------------+ -------->| Controller | +------------+ | | <----- North-bound protocol to map packets to circuits | \|/ +--------------------+ +--------------------+ Pkt | PE1 | Transport | PE2 | Pkt ====>| Classifer<->Tunnel |<=== Circuit ===>| Classifer<->Tunnel |====> +--------------------+ +--------------------+ Figure 4: Multi-Layer BoD service Figure 4 illustrates a BoD service that supports multi-layer network control. This extends allows the network operator's supporting applications to combine control of packet forwarding through guaranteed bandwidth tunnels that connect sites in a (virtual) private network as requested dynamically by the BoD customer. Different transport network technologies may be used to provide the server layer transport functions so that the application can evolve easily with new transport technologies. Pan et.al Expires April 31, 2012 [Page 8] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 5.3. Virtualized Network Service User Req's +------------+ -------->| Controller | +------------+ /|\ | Topology --->| |<----- North-bound protocol to adjust connections Gathering | | | \|/ +---------+ +--------+ | PE1 | | PE2 | | |===== Provisioned Connection ===>| | +---------+ +--------+ Figure 5: Virtualized network service Figure 5 illustrates the flow of a virtualized network service that offers some degree of topology visibility and control in addition to the features of scheduled or dynamic BoD. For some customers it may be desirable to provide visibility into the topology of the resources they control, in order for the customer so they may control the physical and/or virtual topology of the resources used within their dedicated domain. If this topology information is provided together with associated cost, latency, SRLG, etc. for the links and nodes in the topology, the customer is provided with additional flexibility to manipulate routing of their data flows so as to balance the cost, latency, energy efficiency or survivability using knowledge of client applications and their particular needs and priorities. At this time such visibility is not possible to provide, as protocols provide either no visibility into topology or full visibility into topology. For security reasons it is likely that a supporting network operator will want to limit visibility and control to some virtualized topology using functionality provided by the SDN orchestrator. 5.4. BoD Actions Supported by the SDN Orchestrator Pan et.al Expires April 31, 2012 [Page 9] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 The following summarizes actions that would be supported by the SDN orchestrator as part of a BoD service: - increase or decrease bandwidth on an existing path between two, or more, network clients; - dynamically learn if resources are available, (e.g.: bandwidth, latency, SRLG, etc.) to create a path between two, or more, network clients; - create a path and assign associated characteristics, (e.g.: bandwidth, latency, SRLG, etc.) that connect two, or more, network clients; - configure mapping of packets, Ethernet frames, OTN frames, etc. from a client interface into a specified network path (or paths) connecting the appropriate ingress and egress client interfaces; - configure some partition of network resources (e.g., links and link capacity connecting some set of nodes and client endpoints) to be controlled by a specific application; - provide real or virtual topology information (links, nodes and associated information such as costs, latency, etc.) for this partition to the associated application. 6. Security Consideration TBD 7. IANA Considerations This document has no actions for IANA. 8. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and Demon Internet Ltd., November 1997. Pan et.al Expires April 31, 2012 [Page 10] Internet-Draft Shared Mesh Protection in MPLS-TP October 2011 9. Acknowledgments This work is based on the conversation with many people, including Thomas Nadeau and Benson Schliesser. Authors' Addresses Ping Pan Email: ppan@infinera.com Lyndon Ong Email: lyong@ciena.com Shane Amante Email: shane@level3.net Pan et.al Expires April 31, 2012 [Page 11]