Optical Software Defined Networks

Transcription

1 Optical Software Defined Networks BRINGING OPTICAL NETWORKS INTO THE MODERN AGE MATHEMATICAL EVOLUTIONS FOR RISK MANAGEMENT: THETARAY ANOMALY DETECTION ALGORITHMS ARE A GAME CHANGER Whitepaper

2 NEED FOR A PROGRAMMABLE OPTICAL LAYER Optical networks support world communications for a good reason. They carry information in a virtually frictionless fashion on photons over fiber optic tubes. This enables moving business applications to the cloud, movies over the Internet, massively parallel multiplayer games, or communicating with anyone, anywhere, anytime practically for free. In the past, optical networks were highly fixed in nature. Wavelengths were nailed up from point to point, with little capability for change. Recently, this has been changing, with agility and configurability being added at various locations and sublayers within the optical network. However, these are not being fully exploited. Provisioning, restoration, and ongoing optimization still require long cycles of labor-intensive planning. Programmability can change this. Carriers can modernize optical transport networks to obtain multiple service and operational benefits, by adopting software defined networking. SDN harnesses dynamic capabilities embedded in state-of-the-art optical transport and switching fabrics, allowing: Fast service provisioning Real-time multilayer path computation and software control rapidly create cost-effective connections for transport of Ethernet, fibre channel, video, TDM, and other types of services traffic. This increases customer responsiveness, and enables Network-as-a-Service (NaaS) and bandwidth-on-demand services. Dynamic service restoration Creates restoration paths, based on available capacity at multiple layers. This improves overall network reliability and reduces reliance on expensive, dedicated protection, which is disjoint at each network layer. Multilayer Network Optimization (MLO) Optimizes across multiple layers simultaneously to serve the aggregated traffic demand, delaying the need to add new resources, thus providing Capex savings. Network automation Automates network reconfiguration, based on alarms, events, or pre-scheduling, thus eliminating human error and saving on operations costs. This serves as a basis for creating advanced programmatic IoT and M2M services. 2

3 OPTICAL NETWORK PROGRAMMABILITY ENABLERS So what is this agility within the optical network that enables programmability? In fact, multiple capabilities exist, operating across the sublayers of the optical network. At Layer 0, the wavelength (photonics) layer: Optical switching using colorless, directionless, contentionless (CDC) ROADMs, route wavelengths under software control. This enables centralized end-to-end provisioning of all-optical links, and dynamic service restoration at the wavelength level. Tunable optics program transceiver modules to transmit or receive at any wavelength, without any manual intervention, vastly simplifying provisioning. Flexible spectrum allocates the minimum spectral capacity needed for an optical signal, maximizing fiber capacity. Integrated performance monitoring provides continuous awareness of optical network health, to anticipate problems and manage SLAs. At Layer 1, the OTN (electrical) layer: OTN switching flexibly packs multiple clients onto network interfaces, maximizing wavelength fill through grooming, and enabling dynamic service restoration at the client interface level. Adaptive rate transmission allows a single network interface to support multiple line rates (e.g. 100Gbps, 200Gbps), to maximize the speed of an optical link, based on distance and link conditions. ODUflex and Flexible Ethernet employ complementary techniques to optimize bandwidth matching between Ethernet clients (the dominant service using the optical network) and optical line rates. In addition, modern optical networks now integrate Layer 2 packet services like Carrier Ethernet, ensuring the most efficient optical transport of these services. 3

4 USING SDN TO MAXIMIZE THE FULL VALUE OF AGILE OPTICAL NETWORKS The main tool for harnessing embedded optical agility is software defined networking. SDN provides intelligent, centralized, real-time control over networks with application-level awareness of the services they support. SDN originated in data centers, where it was used to dissociate packet routing decisions (the control plane) from the actual forwarding mechanisms (the data plane). Centralized controllers communicated with the delivery infrastructure using interfaces like OpenFlow. In turn, programmatic interfaces to the centralized controllers were used to create powerful networking applications abstracted from the underlying infrastructure. SDN is now progressing into the WAN to provide similar programmatic benefits to service providers. As part of this process, SDN s architecture for the WAN is evolving to deal with many more technologies and networking layers encountered there. Rather than a flat control architecture, SDN for the WAN has evolved into a hierarchical approach. Domain controllers gather information and extend real-time control over different layers or geographic clusters of networking equipment. Each domain controller can support applications, and report into higher levels of service orchestration that have successively greater scopes of network control. This hierarchical model has been adopted by Tier 1 carriers, standards bodies, and open community projects alike. In the WAN, there is also less emphasis on standardizing southbound interfaces between a controller and its underlying technology. The focus is on the controller northbound interfaces with standardization initiatives taking place in the ONF, IETF, and MEF industry organizations. Applying this to an optical network, an Optical Domain Controller (ODC) resides between the Layer optical resources, and an application layer or higher level orchestrator. The ODC presents a clear programmatic and abstracted view of the underlying elastic optical network via northbound interfaces, and accepts intent-driven commands to manipulate the network. Together with higher level SDN orchestration, services can be uniformly and abstractly controlled across multiple optical domains by different vendors. In the next sections, we explore how an optical SDN can be applied to various use cases. 4

5 FAST SERVICE PROVISIONING The Cloud is changing users expectations from services. They expect a portal interface, through which they can order services and have them turned-up, turned-down, or modified, in real-time. The existing method of setting up lightpaths (optical connections) using network management systems does not support this direction. In a very slow process, each lightpath must be planned and provisioned manually, including taking protection paths into account. Optical SDN brings lightpath provisioning across optical networks into the modern cloud-oriented world. In particular, it enables packet-optical convergence, with IP services being the largest consumer of the optical infrastructure. Using abstract intent-driven interfaces, optical SDN enables applications to automatically and rapidly create cost-effective lightpaths for new IP, Ethernet, fibre-channel, video, TDM, and other service connections. Besides speeding-up service responsiveness, by moving to automated processes, optical SDN saves on operations expenses. It changes the way service providers think about exploiting their optical networks fundamentally. Optical SDN also enables new services and revenue streams. This is based typically on variations of bandwidth-on-demand. One example is a dynamic data center interconnect (DCI) service. While data centers already have fixed links among themselves, they often require an immediate short-term high bandwidth connection for applications like cloud bursting, unplanned backups, or data and VM migration. Data centers subscribing to a Dynamic DCI service have a basic connection to a service provider network. Using Dynamic DCI these data centers can obtain any-to-any short-term high-bandwidth connections among themselves, and pay just for the bandwidth that they use, and when they use it. This supplements their fixed connections and provides redundancy in the event of failures. Dynamic Data Center Interconnect Service Besides on-demand services, fast service provisioning can also be used for pre-scheduled applications. For example, it can support automated traffic load balancing, whereby bandwidth is shifted to different portions of the network at different times of day, to maximize responsiveness for business or residential traffic. 5

6 DYNAMIC RESTORATION End-users expect telecommunications services and their underlying networks to have very high availability. To support this, optical networks have relied primarily on automatic protection switching to shift traffic to dedicated backup facilities in the event of a failure. A drawback of this approach is the high cost associated with infrastructure that is sitting idle most of the time. Recently, this has been supplemented by WSON and ASON architectures. These use distributed control to support dynamic restoration, based on existing available capacity at the wavelength (L0) and OTN (L1) layers, respectively. This reduces the reliance on dedicated protection schemes and improves overall network availability without increasing costs. Optical SDN takes dynamic restoration to a whole new level, using centralized control and multilayer restoration. Rather than working at individual layers independently (and incidentally networks today will support either WSON or ASON, but not both, due to race conditions), optical SDN can coordinate between Layers 0 and 1 for a much greater range of restoration schemes. Using centralized control, optical SDN has a big-picture view, which can recognize restoration approaches that would not be visible under distributed control. The bottom line is even higher service availability, using existing resources. This approach can also be used in a broader context with Layer 3 routers, as shown. Intelligent Optical Network Dynamic Service Restoration Example Intelligent dynamic restoration using statistically-available but non-dedicated bandwidth also opens the door to new service offerings, based on tiered levels of service availability guarantees. For example, imagine an Enterprise that has a 1G point-to-point connection. For a very high fee, this link can be fully protected in the event of a failure, using dedicated facilities. However, for a more moderate fee, an offer can be created, whereby 50% of the bandwidth is fully protected, and the other 50% is restored more slowly, using dynamic resource reallocation. This concept, which starts to align traditional bandwidth services with on-demand cloud computing concepts, is only possible under the umbrella of optical SDN, which combines a holistic view of network resources with real-time control. 6

7 OPTICAL MULTILAYER OPTIMIZATION Networks start out well-planned and organized, but over time churn can leave resources used in sub-optimal ways, especially in multilayer networks where resources at one layer may be stranded, due to churn in other layers. Optical multilayer optimization continuously reorganizes Layer network elements to handle both existing and incremental connectivity requirements in the most efficient manner. This delays the need to add new resources for new connectivity requests, saving Capex. This can be thought of as optical network defragmentation. For example, consider the various service-carrying lightpaths that the optical network has built up, over time, between any two nodes. These will likely be a mix of sub-10g services (e.g. 1GbE, 10GbE, FC-8/10/16, STM64/OC192), employing a mix of 10G and 100G links with different fill rates, depending on the use of transponders, muxponders, and OTN switching. By analyzing these lightpaths holistically, defragmentation can consolidate the transport traffic into just a few 100G and new 200G links, simplifying the network and freeing up capacity. By multiplying this approach across all lightpaths in the network, and in many cases finding new routes that may eliminate unnecessary transits, it is easy to see how network-wide resources can be optimized. Intelligent Optical Network Optimization Example When performing this exercise, it is important that the SDN ODC has some contextual knowledge of the services it is transporting. For example, if a lightpath is a backup path for a primary service, then these should not share a common fiber. Or, it may be mandatory that a particular service be transported through an OTN switch to facilitate dynamic restoration. These rules can be provided by a higher-level SDN controller, or associated with information tagged to each lightpath. Another role of optical MLO is policy alignment. Optical networks are governed by high-level policies such as fiber fill, maximum number of transit nodes, and minimum OSNR. In the current situation, it is difficult to track when these drift out of spec, and even once this is discovered, fixes tend to be isolated patches. By using SDN to continuously scan the overall network situation, it is much easier to catch problems early on and implement improvements, to keep the optical network humming like a fine-tuned machine. 7

8 LOOKING FURTHER OPTICAL SDN WITHIN A COMPLETE SDN ECOSYSTEM LOOKING FURTHER OPTICAL SDN WITHIN A COMPLETE SDN ECOSYSTEM Until now, the discussion has been on the value of optical SDN, which is derived by applying SDN concepts to an agile optical network. Looking further, if we combine an SDN Optical Domain Controller with an IP (Layer 3) Packet Domain Controller, we can extend all the SDN benefits described above to a holistic Layer 0 to Layer 3 network. As this encompasses complete knowledge of the packet services being transported, the optical network essentially becomes an integrated resource for these services. It can extend the benefits, as follows: Fast Service Provisioning This allows automated provisioning of packet services, and the creation of new services like SD-WANs featuring dynamic bandwidth MPLS VPNs. Moreover, when you add Network Function Virtualization to a Layer 0-3 SDN, this provides a firm footing for a NaaS ecosystem. This is the complete cloud vision and holy grail of extending an ability to dynamically dial up all manner of network services to end users, and have them available within minutes. Dynamic Restoration This allows moving packet service restoration from routers to the less expensive optical network. This can reduce, for example, the minimum number of ports on a core router from three ports (e.g. one primary, two backup) to only two ports. By homing these router ports onto an OTN switch or a ROADM, in the event of a link failure, an SDN controller can immediately direct packet traffic through an alternate optical network path, instead of relying on a pure router layer solution. Multilayer Optimization By continuous reorganization across Layers network elements to handle existing and incremental new service requirements in the most efficient manner, this provides an even greater ability to delay adding new resources. A typical scenario is termed router bypass, which trades off expensive router ports for less expensive optical ones. Contact us to discover how ECI is taking SDN to a new level ABOUT ECI ECI is a global provider of ELASTIC network solutions to CSPs, utilities as well as data center operators. Along with its long-standing, industry-proven packet-optical transport, ECI offers a variety of SDN/NFV applications, end-to-end network management, a comprehensive cyber security solution, and a range of professional services. ECI's ELASTIC solutions ensure open, future-proof, and secure communications. With ECI, customers have the luxury of choosing a network that can be tailor-made to their needs today while being flexible enough to evolve with the changing needs of tomorrow. For more information, visit us at