IETF Ping Pan Internet Draft (Infinera) Lyndon Ong (Ciena) Expires: January 9, 2012 October 17, 2011 Software-Defined Network (SDN) Use Case for Bandwidth on Demand Applications draft-pan-sdn-bod-problem-statement-and-use-case-00.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 This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft.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. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. 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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 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on January 3, 2012. Copyright Notice Copyright (c) 2011 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. Abstract Service providers and enterprises are increasingly offering services and applications from data centers. Subsequently, data centers originate significant amount of network traffic. Without proper network provisioning, user applications and services are subject to congestion and delay. In this document, we argue the necessity in providing network information to the applications, and thereby enabling the applications to directly provision network edge devices and relevant applications. Table of Contents 1. Introduction...................................................3 Pan et.al Expires January 3, 2012 [Page 2] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 2. Related Work...................................................3 3. Problem Definition.............................................4 4. The Role of SDN Layer..........................................6 5. Use Cases......................................................7 5.1. Scheduled/Dynamic bandwidth service.......................7 5.2. Multi-Layer BoD Support...................................9 5.3. Virtualized Network service..............................11 6. Security Consideration........................................11 7. IANA Considerations...........................................11 8. Normative References..........................................11 9. Acknowledgments...............................................12 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 point-to-point bandwidth 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 services that are more widely deployable, less complex to develop and capable of offering more sophisticated features, 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]. 3. Related Work There has been much work in this area in recent years. Pan et.al Expires January 3, 2012 [Page 3] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 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. 4. 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 networks and resource availability. +-------------+ +-------------+ | Application | | Application | | #1 | | #2 | +-------------+ +-------------+ | | | | +------------------+ +------------------+ | Network | | Network | | Domain #1 | | Domain #2 | +------------------+ +------------------+ Figure 1: Application to network relationship today Pan et.al Expires January 3, 2012 [Page 5] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 This presents a number of challenges and problems. Without a standard interface to the network domain and its control plane, 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. 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 of control of multiple layers (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, or inclusion or exclusion of areas for policy reasons. Pan et.al Expires January 3, 2012 [Page 6] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 5. 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 traffic flows at the network layer through a standard, secure and customizable interface. Applications can visualize the traffic flows at the network layer, and manage the mapping or binding between user traffic flows to the network connections from the edge of the 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. Pan et.al Expires January 3, 2012 [Page 7] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 For the architecture to be useful for existing technologies as well as new, it should be capable of interworking with existing forms of network control plane as well as potential new control structures for networks, such as OpenFlow. The focus should be on providing richer access to network resources as opposed to redesigning network control itself. 5. Use Cases 5.1. Scheduled/ Dynamic Bandwidth On-Demand Service Figure 3 illustrates flow in 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 predefined schedule or on spontaneous customer request. 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 January 3, 2012 [Page 8] Internet-Draft SDN BoD Problem and Use Cases October 3, 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 control mapping of end user packet flows onto an underlying circuit-based transport network to support high speed bandwidth on demand service. 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. 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 flow in 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 tailored visibility into the topology of the resources they control, in order for the customer to put into effect their own routing of traffic within their dedicated domain. Pan et.al Expires January 3, 2012 [Page 9] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 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. Pan et.al Expires January 3, 2012 [Page 10] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 6. Security Considerations 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 January 3, 2012 [Page 11] Internet-Draft SDN BoD Problem and Use Cases October 3, 2011 10. Acknowledgments This work is based on the conversation with many people, including Thomas Nadeau, Shane Amante and Benson Schliesser. Authors Addresses Ping Pan Email: ppan@infinera.com Lyndon Ong Email: lyong@ciena.com Pan et.al Expires January 3, 2012 [Page 12]