SDNRG Working Group M. Boucadair Internet-Draft C. Jacquenet Intended status: Informational France Telecom Expires: April 10, 2014 October 07, 2013 Software-Defined Networking: A Perspective From Within A Service Provider draft-sin-sdnrg-sdn-approach-04 Abstract Software-Defined Networking (SDN) has been one of the major buzz words of the networking industry for the past couple of years. And yet, no clear definition of what SDN actually covers has been broadly admitted so far. This document aims at contributing to the clarification of the SDN landscape by providing a perspective on requirements, issues and other considerations about SDN, as seen from within a service provider environment. It is not meant to endlessly discuss what SDN truly means, but rather to suggest a functional taxonomy of the techniques that can be used under a SDN umbrella and to elaborate on the various pending issues the combined activation of such techniques inevitably raises. As such, a definition of SDN is only mentioned for the sake of clarification. 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 http://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 April 10, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Boucadair & Jacquenet Expires April 10, 2014 [Page 1] Internet-Draft On SDN October 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Introducing Software-Defined Networking . . . . . . . . . . . 4 2.1. A Tautology? . . . . . . . . . . . . . . . . . . . . . . 4 2.2. On Flexibility . . . . . . . . . . . . . . . . . . . . . 4 2.3. A Tentative Definition . . . . . . . . . . . . . . . . . 5 2.4. Functional Meta-Domains . . . . . . . . . . . . . . . . . 5 3. A Few Considerations . . . . . . . . . . . . . . . . . . . . 6 3.1. Remember The Past . . . . . . . . . . . . . . . . . . . . 6 3.2. Be Pragmatic . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Measure Experience Against Expectations . . . . . . . . . 8 3.4. Design Carefully . . . . . . . . . . . . . . . . . . . . 9 3.5. There Is Life Beyond OpenFlow . . . . . . . . . . . . . . 9 3.6. Non Goals . . . . . . . . . . . . . . . . . . . . . . . . 9 4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1. Implications Of Full Automation . . . . . . . . . . . . . 10 4.2. Bootstrapping An SDN . . . . . . . . . . . . . . . . . . 11 4.3. The Intelligence Resides In The PDP . . . . . . . . . . . 12 4.4. Simplicity And Adaptability Vs. Complexity . . . . . . . 13 4.5. Performance And Scalability . . . . . . . . . . . . . . . 13 4.6. Risk Assessement . . . . . . . . . . . . . . . . . . . . 14 4.7. On Security . . . . . . . . . . . . . . . . . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 8. Informative References . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction The Internet has become the federative network that supports a wide range of service offerings. The delivery of network services such as IP VPNs assumes the combined activation of various capabilities that include (but are not necessarily limited to) forwarding and routing capabilities (e.g., customer-specific addressing scheme management, dynamic path computation to reach a set of destination prefixes, dynamic establishment of tunnels, etc.), quality of service Boucadair & Jacquenet Expires April 10, 2014 [Page 2] Internet-Draft On SDN October 2013 capabilities (e.g., traffic classification and marking, traffic conditioning and scheduling), security capabilities (e.g., filters to protect customer premises from network-originated attacks, to avoid malformed route announcements, etc.) and management capabilities (e.g., fault detection and processing). As these services not only grow in variety but also in complexity, their design, delivery and operation have become a complex alchemy that often requires various levels of expertise. This situation is further aggravated by the wide variety of (network) protocols and tools, as well as recent Any Time Any-Where Any Device (ATAWAD)-driven convergence trends that are meant to make sure an end-user can access the whole range of services he/she has subscribed to, whatever the access and device technologies, wherever the end- user is connected to the network, and whether this end-user is in motion or not. Yet, most of these services have been deployed for the past decade, primarily based upon often static service production procedures that are more and more exposed to the risk of erroneous configuration commands. In addition, most of these services do not assume any specific negotiation between the customer and the service provider or between service providers besides the typical financial terms. At best, five-year master plans are referred to as the network planning policy that will be enforced by the service provider, given the foreseen business development perspectives, manually-computed traffic forecasts and the market coverage (fixed/mobile, residential/ corporate). This so-called network planning policy may very well affect the way resources are allocated in a network, but clearly fails to be adequately responsive to highly dynamic customer requirements in an "always-on" fashion. The need for improved service delivery procedures (including the time it takes to deliver the service once possible negotiation phase is completed) is even more critical for corporate customers. In addition, various tools are used for different, sometimes service- centric, management purposes but their usage is not necessarily coordinated for the sake of event aggregation, correlation and processing. This lack of coordination may come at the cost of extra complexity and possible customer's Quality of Experience degradation. Multi-service, multi-protocol, multi-technology convergent and dynamically-adaptive networking environments of the near future have therefore become one of the major challenges faced by service providers. Boucadair & Jacquenet Expires April 10, 2014 [Page 3] Internet-Draft On SDN October 2013 This document aims at clarifying the SDN landscape by providing a perspective on the functional taxonomy of the techniques that can be used in SDN, as seen from within a service provider environment. 2. Introducing Software-Defined Networking 2.1. A Tautology? The separation of the forwarding and control planes (beyond implementation considerations) have almost become a gimmick to promote flexibility as a key feature of the SDN approach. Technically, most of current router implementations have been assuming this separation for decades. Routing processes (such as IGP and BGP route computation) have often been software-based, while forwarding capabilities are hardware-encoded. As such, the current state-of-the-art tends to confirm the said separation, which rather falls under a tautology. But a somewhat centralized, "controller-embedded", control plane for the sake of optimized route computation before FIB population is certainly another story. 2.2. On Flexibility Promoters of SDN have argued that it provides additional flexibility in how the network is operated. This is undoubtedly one of the key objectives that must be achieved by service providers. This is because the ability to dynamically adapt to a wide range of customer's requests for the sake of flexible network service delivery is an important competitive advantage. But flexibility is much, much more than separating the control and forwarding planes to facilitate forwarding decision-making processes. For example, the ability to accommodate short duration extra bandwidth requirements so that end users can stream a video file to their 4G terminal device is an example of that flexibility that several mobile operators are currently investigating. From this perspective, the ability to predict the network behavior as a function of the network services to be delivered is of paramount importance for service providers, so that they can assess the impact of introducing new services or activating additional network features or enforcing a given set of (new) policies from both a financial and technical standpoints. This argues in favor of investigating advanced network emulation engines, which can be fed with information that can be derived from [I-D.ietf-idr-ls-distribution], for example. Boucadair & Jacquenet Expires April 10, 2014 [Page 4] Internet-Draft On SDN October 2013 Given the rather broad scope that the flexibility wording suggests: o The exact characterization of what flexibility actually means is still required. o The exposure of programmable interfaces is not a goal per se, rather a means to facilitate configuration procedures for the sake of improved flexibility. 2.3. A Tentative Definition We define Software-Defined Networking as the set of techniques used to facilitate the design, the delivery and the operation of network services in a deterministic, dynamic, and scalable manner. The said determinism refers to the ability to completely master the various components of the service delivery chain, so that the service that has been delivered complies with what has been negotiated and contractually defined with the customer. As such, determinism implies the ability to control how network services are structured, designed and delivered, and where traffic should be forwarded in the network for the sake of optimized resource usage. Although not explicitly reminded in the following sections of the document, determinism lies beneath any action that may be taken by a service provider once service parameter negotiation is completed, from configuration tasks to service delivery, fulfillment and assurance (see Section 2.4 below). Such a definition assumes the introduction of a high level of automation in the overall service delivery and operation procedures. Because networking is software-driven by nature, the above definition does not emphasize the claimed "Software-Defined" properties of SDN- labeled solutions. 2.4. Functional Meta-Domains SDN techniques can be classified into the following functional meta- domains: o Techniques for the dynamic discovery of network topology, devices and capabilities, along with relevant information and data models that are meant to precisely document such topology, devices and capabilities. Boucadair & Jacquenet Expires April 10, 2014 [Page 5] Internet-Draft On SDN October 2013 o Techniques for exposing network services and their characteristics, and for dynamically negotiating the set of service parameters that will be used to measure the level of quality associated to the delivery of a given service or a combination thereof. For example, [I-D.boucadair-connectivity-provisioning-profile]) . o Techniques used by service requirements-derived dynamic resource allocation and policy enforcement schemes, so that networks can be programmed accordingly. Decisions made to dynamically allocate resources and enforce policies are typically the result of the correlation of various inputs, such as the status of available resources in the network at any given time, the number of customer service subscription requests that need to be processed over a given period of time, the traffic forecasts and the possible need to trigger additional resource provisioning cycles according to a typical multi-year master plan, etc. o Dynamic feedback mechanisms that are meant to assess how efficiently a given policy (or a set thereof) is enforced from a service fulfillment and assurance perspective. 3. A Few Considerations The networking ecosystem has become awfully complex and highly demanding in terms of robustness, performance, scalability, flexibility, agility, etc. This means in particular that service providers and network operators must deal with such complexity and operate networking infrastructures that can evolve easily, remain scalable, guarantee robustness and availability, and are resilient against denial-of-service attacks. The introduction of new SDN-based networking features should obviously take into account this context, especially from a cost impact assessment perspective. 3.1. Remember The Past SDN techniques are not the next big thing per se, but rather a kind of rebranding of proposals that have been investigated for several years, like Active or Programmable Networks. As a matter of fact, some of the claimed "new" SDN features have been already implemented (e.g., NMS (Network Management System), PCE (Path Computation Element, [RFC4655])), and supported by vendors for quite some time (references can be added if needed). Some of these features have also been standardized (e.g., DNS-based routing [RFC1383] that can be seen as an illustration of separated control and forwarding planes or ForCES ([RFC5810][RFC5812])). Boucadair & Jacquenet Expires April 10, 2014 [Page 6] Internet-Draft On SDN October 2013 Also, the Policy-Based Management framework[RFC2753] introduced in the early 2000's was designed to orchestrate available resources, by means of a typical Policy Decision Point (PDP) which masters advanced offline traffic engineering capabilities. As such, this framework has the ability to interact with in-band software modules embedded in controlled devices (or not). The Policy Decision Point (PDP) is where policy decisions are made. PDPs use a directory service for policy repository purposes. The policy repository stores the policy information that can be retrieved and updated by the PDP. The PDP delivers policy rules to the Policy Enforcement Point (PEP) in the form of policy-provisioning information that includes configuration information. The Policy Enforcement Point (PEP) is where policy decisions are applied. PEPs are embedded in (network) devices, which are dynamically configured based upon the policy-formatted information that has been processed by the PEP. PEPs request configuration from the PDP, store the configuration information in the Policy Information Base (PIB), and delegate any policy decision to the PDP. SDN techniques as a whole are an instantiation of the policy-based network management framework. Within this context, SDN techniques can be used to activate capabilities on demand, to dynamically invoke network and storage resources and to operate dynamically-adaptive networks according to events (e.g., alteration of the network topology) and triggers (e.g., dynamic notification of a link failure), etc. 3.2. Be Pragmatic SDN approaches should be holistic, i.e., global, network-wide. It is not a matter of configuring devices one by one to enforce a specific forwarding policy. SDN techniques are about configuring and operating a whole range of devices at the scale of the network for the sake of automated service delivery ([I-D.boucadair-network-automation-requirements]), from service negotiation and creation (e.g., [I-D.ietf-idr-sla-exchange]) to assurance and fulfillment. Because the complexity of activating SDN capabilities is largely hidden to the end-user and software-handled, a clear understanding of the overall ecosystem is needed to figure out how to manage this complexity and to what extent this hidden complexity does not have side effects on network operation. As an example, SDN designs that assume a central decision-making entity must avoid single points of failure. They must not affect Boucadair & Jacquenet Expires April 10, 2014 [Page 7] Internet-Draft On SDN October 2013 packet forwarding performances either (e.g., transit delays must not be impacted). SDN techniques are not necessary to develop new network services per se. The basic service remains (IP) connectivity that solicits resources located in the network. SDN techniques can thus be seen as another means to interact with network service modules and invoke both connectivity and storage resources accordingly in order to meet service-specific requirements. By definition, SDN technique activation and operation remain limited to what is supported by embedded software and hardware. One cannot expect SDN techniques to support unlimited customizable features. 3.3. Measure Experience Against Expectations Because several software modules may be controlled by external entities, there is a need for a means to make sure that what has been delivered complies with what has been negotiated. Such means belong to the set of SDN techniques. These typical policiy-based techniques should interact with both Service Structuring engines (that are meant to expose the service characteristics and to possibly negotiate those characteristics) and the network to continuously assess whether the experienced network behavior is compliant with the objectives set by the Service Structuring engine, and which may have been dynamically negotiated with the customer (e.g., as captured in a CPP [I-D.boucadair-connectivity-provisioning-profile], [I-D.boucadair-connectivity-provisioning-protocol]). This requirement applies to several regions of a network, including: 1. At the interface between two adjacent IP network providers. 2. At the access interface between a service provider and an IP network provider. 3. At the interface between a customer and the IP network provider. Ideally, a fully automated service delivery procedure from negotiation and ordering, through order processing, to delivery, assurance and fulfillment, should be supported. This approach assumes widely adopted standard data and information models, let alone interfaces. Boucadair & Jacquenet Expires April 10, 2014 [Page 8] Internet-Draft On SDN October 2013 3.4. Design Carefully Exposing open and programmable interfaces has a cost, from both a scalability and performance standpoints. Maintaining hard-coded performance optimization techniques is encouraged. So is the use of interfaces that allow the direct control of some engines (e.g., routing, forwarding) without requiring any in-between adaptation layer (generic objects to vendor-specific CLI commands for instance). SDN techniques will have to accommodate vendor-specific components anyway. Indeed, these vendor-specific features will not cease to exist mainly because of the harsh competition. The introduction of new functions or devices that may jeopardize network flexibility should be avoided, or at least carefully considered in light of possible performance and scalability impacts. SDN-enabled devices will have to coexist with legacy systems. One single SDN, network-wide deployment is therefore very unlikely. Instead, multiple instantiations of SDN techniques will be progressively deployed and adapted to various network and service segments. 3.5. There Is Life Beyond OpenFlow Empowering networking with in-band controllable modules does not necessarily mean the use of the OpenFlow protocol, which is just another protocol that helps devices populate their forwarding tables according to a set of instructions. OpenFlow is clearly not the "next big thing": there are many, many other candidate protocols that can be used for the same or even broader purposes (e.g., resource reservation purposes). The forwarding of the configuration information can indeed rely upon a variety of protocols that include (but is not necessarily limited to) PCEP [RFC5440], NETCONF [RFC6241], COPS-PR [RFC3084], Routing Policy Specification Language (RPSL, [RFC2622]), etc. There is therefore no 1:1 relationship between OpenFlow and SDN. Rather, OpenFlow is one of the candidate protocols to convey specific configuration information towards devices. As such, OpenFlow is one possible component of the global SDN toolkit. 3.6. Non Goals Boucadair & Jacquenet Expires April 10, 2014 [Page 9] Internet-Draft On SDN October 2013 There are inevitable trade-offs to be found between operating the current networking ecosystem and introducing some SDN techniques, possibly at the cost of introducing new technologies. Operators do not have to choose between the two as both environments will have to coexist. In particular, the following considerations cannot justify the deployment of SDN techniques: o Fully flexible software implementations, because the claimed flexibility will be limited by respective software and hardware limitations, anyway. o Fully modular implementations are difficult to achieve (because of the implicit complexity) and may introduce extra effort for testing, validation and troubleshooting. o Fully centralized control systems that are likely to raise some scalability issues. Distributed protocols and their ability to react to some events (e.g., link failure) in a timely manner remains a cornerstone of scalable networks. This means that SDN designs can rely upon a logical representation of centralized features (an abstraction layer that would support inter-PDP communications, for example). 4. Discussion 4.1. Implications Of Full Automation The path towards full automation is paved with numerous challenges and requirements, including: o Make sure automation is well implemented so as to facilitate testing (including validation checks) and troubleshooting. * This suggests the need for simulation tools that accurately assess the impact of introducing a high level of automation in the overall service delivery procedure, so as to avoid a typical "mad robot" syndrom whose consequences can be serious, from a control and QoS standpoints among others. * This also suggests careful management of human expertise, so that network operators can use robust, flexible means to automate repetitive or error-prone tasks, and then build on automation or stringing together multiple actions to create increasingly complex tasks that require less human interaction (guidance, input) to complete. o Simplify and foster service delivery, assurance and fulfillment, as well as network failure detection, diagnosis and root cause analysis, for the sake of cost optimization: Boucadair & Jacquenet Expires April 10, 2014 [Page 10] Internet-Draft On SDN October 2013 * Such cost optimization relates to improved service delivery times as well as optimized human expertise (see above) and global, technology-agnostic, service structuring and delivery procedures. In particular, the ability to inject new functions in existing devices should not assume a replacement of the said devices, but rather allow smart investment capitalization. * This can be achieved thanks to automation, possibly based upon a logically centralized view of the network infrastructure (or a portion thereof), yielding the need for highly automated topology, device and capabilities discovery means as well as operational procedures. * The main intelligence resides in the PDP, which suggests that an important part of the SDN-related development effort should focus on a detailed specification of the PDP function, including algorithms and behavioral state machineries, based upon a complete set of standardized data and information models. * These information models and data need to be carefully structured for the sakes of efficiency and flexibility. This probably suggests a set of simplified pseudoblocks that can be assembled as per the nature of the service to be delivered. o Need for abstraction layers: clear interfaces between business actors, between layers, let alone cross-layer considerations, etc. * For the sake of various service structuring and packaging. * Need for IP connectivity service exposure to customers, peers, applications, content/service providers, etc. (e.g., [I-D.boucadair-connectivity-provisioning-profile]). * Need for solutions that accommodate IP connectivity service requirements with network engineering objectives. * Need for dynamically-adaptive decision-making processes, which can properly operate according to a set of input data and metrics, such as current resource usage and demand, traffic forecasts and matrices, etc., all for the sake of highly responsive dynamic resource allocation and policy enforcement schemes. o Better accommodate technologically heterogeneous networking environments: * Need for vendor-independent configuration procedures, based upon the enforcement of vendor-agnostic generic policies instead of vendor-specific languages. * Need for tools to aid manageability and orchestrate resources. * Avoid proxies and privilege direct interaction with engines (e.g., routing, forwarding). 4.2. Bootstrapping An SDN Boucadair & Jacquenet Expires April 10, 2014 [Page 11] Internet-Draft On SDN October 2013 Means to dynamically discover the functional capabilities of the devices that will be steered by a PDP intelligence for the sake of automated network service delivery need to be provided. This is indeed because the acquisition of the information related to what the network is actually capable of will help structuring the PDP intelligence so that policy provisioning information can be derived accordingly. A typical example would consist in documenting a traffic engineering policy based upon the dynamic discovery of the various functions supported by the network devices, as a function of the services to be delivered, thus yielding the establlishment of different routes towards the same destination depending on the nature of the traffic, the location of the functions that need to be invoked to forward such traffic, etc. Likewise, means to dynamically acquire the descriptive information (includding the base configuration) of any network device that may participate to the delivery of a given service should be provided so as to help the PDP structure the services that can be delivered, as a function of the available resources, their location, etc. SDN-related features can be grafted into an existing network infrastructure. These features may not be enabled at once, but a gradual approach can rather be adopted. A typical deployment example would be to use an SDN decision-making process as an emulation platform that would help in making appropriate technical choices before their actual deployment in the network. 4.3. The Intelligence Resides In The PDP The proposed SDN definition in Section 2.3 assumes an intelligence that may reside in the control or the management planes (or both). This intelligence is typically represented by a Policy Decision Point (PDP), which is one of the key functional components of the Policy- Based Management framework [RFC2753]. SDN networking therefore relies upon PDP functions that are capable of processing various input data (traffic forecasts, outcomes of negotiation between customers and service providers, resource status (as depicted in appropriate information models instantiated in the PIB, etc.) to make appropriate decisions. The design and the operation of such PDP-based intelligence in a scalable manner remains of the major areas that needs to be investigated. Boucadair & Jacquenet Expires April 10, 2014 [Page 12] Internet-Draft On SDN October 2013 To avoid centralized design schemes, inter-PDP communication is likely to be required, and corresponding issues and solutions should be considered. Several PDP instances may thus be activated in a given domain. Because each of these PDP instances may be responsible for making decisions about the enforcement of a specific policy (e.g., one PDP for QoS policy enforcement purposes, another one for security policy enforcement purposes, etc.), an inter-PDP communication scheme is required for the sake of global PDP coordination and correlation. Inter-domain PDP exchanges may also be needed for specific usages. Examples of such exchanges are: (1) During the network attachment phase of a node to a visited network, the PDP operated by the visited network can contact the home PDP to retrieve the policies to be enforced for that node. (2) Various PDPs can collaborate together in order to compute inter-domain paths which satisfy a set of traffic performance guarantees. 4.4. Simplicity And Adaptability Vs. Complexity The meta functional domains introduced in Section 2.4 assume the introduction of a high level of automation, from service negotiation to delivery and operation. Automation is the key to simplicity, but must not be seen as a magic button that would be hit by a network administrator whenever a customer request has to be processed or additional resources need to be allocated. The need for simplicity and adaptability thanks to automated procedures generally assumes some complexity that lies beneath automation. 4.5. Performance And Scalability The combination of flexibility with software inevitably raises performance and scalability issues as a function of the number and the nature of the services to be delivered and their associated dynamics. For example: while the deployment of a network solely composed of OpenFlow switches within a data center environment is unlikely to raise FIB scalability issues given the current state-of-the-art, data center networking that relies upon complex, possibly IP-based, QoS- inferred, interconnect design schemes meant to dynamically manage the mobility of Virtual Machines between sites is certainly of another scale. The claimed flexibility of SDN networking in the latter context will have to be carefully investigated by operators. Boucadair & Jacquenet Expires April 10, 2014 [Page 13] Internet-Draft On SDN October 2013 4.6. Risk Assessement Various risks are to be assessed such as: o Evaluating the risk of depending on a controller technology rather than a device technology. o Evaluating the risk of operating frozen architectures because of potential interoperability issues between a controller and a controlled device. o Assessing whether SDN-labeled solutions are likely to obsolete existing technologies because of hardware limitations. o Etc. 4.7. On Security Security has to be a first-class part of any SDN design, thus giving both network and applications people the control to ensure that the other has access to the info and controls that they need (but no more), and to ensure that they are properly safeguarded against taking actions that will adversely affect the network or application as a whole [I-D.hartman-sdnsec-requirements]. Likewise, PEP-PDP interactions suggest the need to make sure that (1) A PDP is entitled to solicit PEPs so that they can apply the decisions made by the said PDP, (2) A PEP is entitled to solicit a PDP for whatever reason (request for additional configuration information, notification about the results of a set of configuration tasks, etc.), and (3) communication between PDPs within a domain or between domains is properly secured (e.g., make sure a pair of PDPs are entitled to communicate with each other, make sure the confidentiality of the information exchanged between two PDPs can be preserved, etc.). 5. IANA Considerations This document does not require any action from IANA. 6. Security Considerations This document does not define any protocol nor architecture. 7. Acknowledgements Many thanks to A. Farrel, W. George, J. Halpern, D. King, J. H. Salim, and T. Tsou for their comments. Special thanks to P. Georgatos for the fruitful discussions on SDNi (SDN Interconnection) in particular. Boucadair & Jacquenet Expires April 10, 2014 [Page 14] Internet-Draft On SDN October 2013 8. Informative References [I-D.boucadair-connectivity-provisioning-profile] Boucadair, M., Jacquenet, C., and N. Wang, "IP/MPLS Connectivity Provisioning Profile", draft-boucadair- connectivity-provisioning-profile-02 (work in progress), September 2012. [I-D.boucadair-connectivity-provisioning-protocol] Boucadair, M. and C. Jacquenet, "Connectivity Provisioning Negotiation Protocol (CPNP)", draft-boucadair- connectivity-provisioning-protocol-00 (work in progress), May 2013. [I-D.boucadair-network-automation-requirements] Boucadair, M. and C. Jacquenet, "Requirements for Automated (Configuration) Management", draft-boucadair- network-automation-requirements-01 (work in progress), June 2013. [I-D.hartman-sdnsec-requirements] Hartman, S. and D. Zhang, "Security Requirements in the Software Defined Networking Model", draft-hartman-sdnsec- requirements-01 (work in progress), April 2013. [I-D.ietf-idr-ls-distribution] Gredler, H., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and TE Information using BGP", draft-ietf-idr-ls-distribution-03 (work in progress), May 2013. [I-D.ietf-idr-sla-exchange] Shah, S., Patel, K., Bajaj, S., Tomotaki, L., and M. Boucadair, "Inter-domain SLA Exchange", draft-ietf-idr- sla-exchange-01 (work in progress), June 2013. [RFC1383] Huitema, C., "An Experiment in DNS Based IP Routing", RFC 1383, December 1992. [RFC2622] Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D., Meyer, D., Bates, T., Karrenberg, D., and M. Terpstra, "Routing Policy Specification Language (RPSL)", RFC 2622, June 1999. [RFC2753] Yavatkar, R., Pendarakis, D., and R. Guerin, "A Framework for Policy-based Admission Control", RFC 2753, January 2000. Boucadair & Jacquenet Expires April 10, 2014 [Page 15] Internet-Draft On SDN October 2013 [RFC3084] Chan, K., Seligson, J., Durham, D., Gai, S., McCloghrie, K., Herzog, S., Reichmeyer, F., Yavatkar, R., and A. Smith, "COPS Usage for Policy Provisioning (COPS-PR)", RFC 3084, March 2001. [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang, W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and Control Element Separation (ForCES) Protocol Specification", RFC 5810, March 2010. [RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control Element Separation (ForCES) Forwarding Element Model", RFC 5812, March 2010. [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011. Authors' Addresses Mohamed Boucadair France Telecom Rennes 35000 France Email: mohamed.boucadair@orange.com Christian Jacquenet France Telecom Rennes France Email: christian.jacquenet@orange.com Boucadair & Jacquenet Expires April 10, 2014 [Page 16]