Fiber Management Solutions

Transcription

1 Fiber Management Solutions A Technology Comparison March 2013 By Fiberzone Networks Fiberzone Networks Page 1

2 Introduction The exponential growth in Big Data is fueling a similar growth in data traffic. This large demand can only be met with Fiber Optic transmission where both high-bandwidth and low latency are critical requirements. Network operators and data centers are under great market pressure to meet capacity demands with reliable and flexible networks in a costeffective fashion. Network operators can alleviate these pressures by controlling the total cost of ownership of their fiber infrastructure by: Reducing the labor required to connect, manage and reconfigure fiber networks. Maximizing network uptime by preventing outages and decreasing the time to detect, locate, and repair faults; Minimizing human error in record keeping, identification of fiber ports, and the degradation of performance due to dust from the ambient environment. The demand for Fiber Management has never been greater and is now becoming of high importance throughout the industry. I. Manual solutions legacy optical distribution frames (ODFs) and patch panels. II. Enhanced manual solutions Intelligent patch management ODFs, which provide a modest enhancement to port management, but are still manually operated. III. Automated solutions Optical crossconnects switch between links. Micro-Electro-Mechanical (MEMS), which uses mirrors to deflect light to achieve switching. Beam steering technology, which employs active collimators to direct light between ports. Optical-Electrical-Optical (OEO) switches, which provide bitmapping and switching. Latched Optical Coupling (LOC ) technology, which involves the direct, physical connection of fibers via high-tech Robotics. This document briefly describes each of these approaches to managing fiber networks and their pros and cons. Manual Management Manual solutions consist primarily of the optical distribution frames (ODFs), optical patch panels and fiber patch cords that are widely deployed today. These products fulfill the basic requirement of terminating outside plant and connecting fiber ports between active equipment, but require labor-intensive operation for provisioning, fault management and monitoring. Three main categories of fiber management solutions are available on the market: The main advantages of manual solutions are their low capital cost, scalability, connection reliability, and good optical performance. Suppliers have focused on physical space Fiberzone Networks Page 2

3 innovations, and today can manage up to two thousand fiber terminations in a single 7-foot bay. Since fibers are connected physically end-to-end, optical performance is very strong. Optical loss is low and is independent of port count, so there is minimal effect on the optical power budget regardless of the size of the distribution frame. In addition, since connections are passive, links are not affected by power failures. However, manual solutions offer no remote control or configurability, and therefore drive up operational expense and total cost of ownership while decreasing network efficiency. Anytime a fiber link needs to be provisioned, technicians must be deployed across multiple locations to physically connect patch cords. When connections are to be reconfigured, technician labor is required to identify the correct fiber, disconnect, and re-connect to the new port. Documentation is also performed manually via data entry into spreadsheets and databases. Not only does this require additional technician time, but it introduces human error. It is estimated that up to 5-10% of fibers are documented incorrectly and effectively lost. In addition, manual connect/disconnect operations often introduce dust contamination, which results in signal degradation and network outages. Management and testing operations introduce additional labor costs and are considered to be a particularly painful point for network operators. Test and measurement typically requires technicians to be deployed to each side of the link to perform monitoring operations. As with network reconfiguration, great care must be taken to ensure that the correct fiber is identified, lest a live, revenuegenerating port be disconnected by mistake. Fault management is even more expensive in terms of labor costs and network downtime. When a link failure occurs, the following steps are required to restore service: Alarms notify operator of link failure The fault is verified and a maintenance team is notified A truck roll is ordered to dispatch the team Upon reaching the site, the team takes the following steps to address the problem: Identification of correct fiber Additional time is required if there are database errors, or if the problem occurred on a weekend or a holiday. Disconnection of problem fiber taking care not to disturb adjacent fibers Routing the active port through another available fiber. Performance of required troubleshooting operation on the problem fiber, which often requires highly trained (expensive) technicians on both sides of the fiber Report of test results to the network operations center (NOC), which orders the required repair Manual documentation of all operations performed Cleaning of connectors prior to reconnection Reconnection of port to panel, again without disturbing adjacent ports Finally, the team locates the problem using an OTDR and orders the repair Therefore, while manual solutions are characterized by low initial capital cost, high scalability, connection reliability and low loss, they introduce operational costs making them not as cost-effective as initially thought. Enhanced Manual Solutions Enhanced manual solutions consist of manual ODFs and patch panels that are augmented with automated documentation and patch tracking (e.g. with visible light indicators on panels). These capabilities provide a modest enhancement to port and inventory management, but are still manually-operated. They offer similar performance advantages of manual solutions (scalability, connection reliability and low loss), but cost up to 50% more. These products include light-emitting diode Fiberzone Networks Page 3

4 (LED) indicators on each port that guide the technician in identifying which optical patch cords to connect and disconnect. The systems are connected to management software to update the inventory database automatically when a port is configured. Transparency system must handle all bitrates, transport protocols and common fiber types, including dark fiber and lit fiber. Cost-effectiveness automated solutions must meet all the above criteria at a reasonable capital cost per port. These solutions enable improved manageability of the fiber infrastructure compared to manual ODFs, by reducing the possibility for human error. However, enhanced ODFs are still basically manual solutions, suffering from most of the previously mentioned operational deficiencies. The modest enhancements in functionality have not been sufficient to capture significant market share. Automated Fiber Management (AFM) Solutions Due to the limitations of the manual fiber distribution systems described above and the tremendous growth of fiber networks, Automated Fiber Management is now becoming a strong requirement in the industry. This section discusses the requirements for such a solution and describes the available approaches. It highlights the advantages and disadvantages of each over the existing manual approach. Requirements for Automated Fiber Management An automated fiber management (AFM) solution must improve fiber management operations through remote control and automation, while retaining the key features of manual ODFs and patch panels, including: Scalability system must handle a large number of fibers Low insertion loss attenuation of less than 1 db, so as not to affect the network power budget. Low return loss better than -45 db Connection reliability all connections must be latched, i.e., maintained without power or any active components. Four technologies are attempting to address the AFM application today: Micro-Electro-Mechanical Systems (MEMS), which uses mirrors to deflect light and switch between links. Beam Steering, which employs active collimators to direct light between ports. Optical-Electrical-Optical (OEO), which convert optical signals to electrical and then back, performing protocol processing and switching through a backplane switch matrix. Latched Optical Coupling (LOC TM ), which involves the direct, physical connection of fibers via high-precision Robotics. These technologies are discussed in the following sections. MEMS Technology There are a number of available all-optical switching fabrics based on Micro-Electro- Mechanical Systems (MEMS) technology. The concept of MEMS switching is based on planes of mirrors that deflect a beam of light, coupling it between an input and output fiber. To switch between fibers, the mirrors are rotated mechanically using an electrostatic force to achieve the desired angles. There are two main categories of MEMS technologies: 2D MEMS - This is a two dimensional solution in which light is directed from input fibers to output fibers via flat mirrors that can be tipped along two orthogonal axes. The complexity of this technology and the requirement for precise transference of light signals limits the scalability of 2D MEMS. Typically, a 2D MEMS switch can comfortably handle 32 x 32 ports using 1024 mirrors on an integrated silicon chip. However, a large switching center with a thousand ports would require a 2D MEMS switch with a million mirrors on a chip, which is not feasible for a real world network Fiberzone Networks Page 4

5 deployment. The figure below provides a simplified illustration of 2D MEMS implementation. 3D Mems This technology utilizes a third dimension. In addition to the mirrors connecting input to output fibers, an array of lenses is used to control the size of the beam propagating in free space. This method provides higher scalability than 2D MEMS, but requires continuous control and calibration to ensure accuracy under challenging around a higher optical power budget. No latching capability Continuous alignment is required to maintain connections and all connections are at risk in the event of a power interruption (either internal or external to the device); battery backup can maintain connections for a period of time (typically 8-24 hours) in the event of facility power loss, but connections are dependent on the local internal power supply, the integrity of the battery, and on the embedded drivers which control the mirrors; the failure of any of these can cause the loss with over 300 x 300 ports and insertion loss increases with port count since the light must travel further through free space. Reliability Several actuators are required for each fiber, which increases the chance of an actuator malfunction. Beam-Steering Technology Beam steering, also known as piezoelectric, or environmental conditions, such as mechanical vibration, and thermal expansion. 3D MEMS also requires more complex MEMS fabrication, optical design, packaging, electrical and optical inter connection, mirror control, assembly and testing. This complexity drives up hardware cost, and poses sever limitations on manufacturability. Both MEMS technologies deliver high speed switching, but suffer from several key deficiencies for fiber management: Poor optical performance High insertion loss (2 to 4 db) and return loss (-30 to - 35 db), due to the fact that light travels through free space and is deflected off of mirrors, make MEMS unsuitable for fiber distribution and management, particularly in situations where the network would have to be redesigned solid-state actuation, involves the use of active collimators to steer light from a set of input fibers to a set of output fibers. A number of methods have been developed to steer the light, but the most effective has been the use of piezoelectric material to effect solid-state actuation. In this method, voltage is applied to the material, causing a small deformation and movement. The motion is proportional to the charge, so the position of the material, and therefore the angle of the collimated beam, can be carefully controlled. No latching capability As the name suggests, active collimators require power to maintain the beam angle; precise voltage is critical to maintaining the achievable optical performance; all connections are at risk in the event of a power interruption or software failure. No support for un-lit dark fiber When fiber is unlit ( dark ), beam-steering switches are not able to verify alignment of Fiberzone Networks Page 5

6 the input and output beams. Scalability challenges Existing products meeting the 1 db loss threshold range up to 32 x 32 ports; asymmetric products are available with over 200 ports in 1xN up to 16xN configurations, but loss rises to 2 db because the light must travel further through free space. Reliability Several actuators are required for each fiber, which increases the chance of an actuator malfunction. management applications. The principle of LOC is to physically couple two optical fibers together without mirrors, lenses, or collimators. Connectors mate together as they do with standard manual connectors. For these reasons, beam steering can be appropriate for test and measurement and certain low-port fiber management applications such as video distribution, and monitoring applications. However, they have limited applicability elsewhere in the fiber-rich network, where large numbers of fibers must be managed. OEO Layer-1 Switches Optical-Electrical-Optical (OEO) switches are OSI layer-1 switches that perform bit-mapping and switching with typically a non-blocking switch matrix. These switches perform fast switching and support both multimode and single mode fiber, but are often limited as outlined below: Lack of Transparency OEO switches are protocol and bit-rate specific, and require protocol-specific interfaces to switch traffic between fibers. They also cannot switch between fibers carrying multiple wavelengths, dark (unlit) fiber. They are limited as fiber data rates move to 16Gbps traffic and beyond. Connection reliability OEO switches are inherently active components, and cannot guarantee connection integrity in power failure. Power is required to operate the switch matrix on ongoing basis and backup battery power for many hours is not feasible. Scalability OEO switches capacity is dependent on the central matrix size and the data-carrying capacity of the matrix backplane. As fiber speeds move higher, the OEO backplane limits may require a significant upgrade or even full machine replacement. Latched Optical Coupling Latched Optical Coupling (LOC ) was developed specifically to address fiber LOC is based on a three-layer architecture with two active layers in which Robotic motors position source and destination fibers in an X & Y plane, and a passive connection layer where connections are latched in place. After completing a latched connection, LOC systems are functionally equivalent to a manual patch panel with its purity of signal and low loss characteristics. Transmission of traffic maintains full connection integrity, even if electrical power is lost. The connection operation is highly precise with, high-resolution laser encoders accurately tracking and controlling all connector positions. Because of this precision, connector life is considerably increased beyond those of manual connectors. Thus, we see several advantages: Latching with pure Physical Connectivity Highly Reliable protected against power failure and longer lifetime in-service duty cycles. High optical performance Low insertion loss (0.5 db) and return loss (-45 db) Transparency Independent of bit-rate, protocol, and fiber-type (works with both single-mode and multi-mode fiber; dark fiber and lit-fiber). Scalability Switching matrices have no degradation in optical performance. Low power consumption 55 W For traditional fiber management, fault management, provisioning, automated testing and troubleshooting operations, LOC is a compelling solution. Fiberzone Networks Page 6

7 Conclusions Manual systems represent an initial lower capital cost method of serving the most basic fiber distribution function. However, this manual nature results in a higher Total Cost of Ownership in today s environment requiring better Management, Automated Procedures, Rapid Provisioning and Troubleshooting, and product release Testing. MEMS technologies may be appropriate for lab and test environments and research networks, where the limitations in scalability, cost, optical performance and lack of latching are not critical. Beam Steering approaches perform better optically than MEMS, but suffer from their other limitations as well as from scalability challenges. They find applications in labs, video distribution networks, and for monitoring applications, where port count requirements are fairly low and high costs can be tolerated. OEO switches are suitable primarily for lab automation, testing and monitoring applications. But its lack of support for higher fiber speeds and its non-transparency of traffic are key shortcomings. Finally, LOC technology provides the advantages of manual systems in terms of optical performance, scalability, and reliability/latching. It also is idea for the higher speeds we now see in today s fiber networks. Moreover, it offers the remote management and automation capabilities designed specifically for fiber distribution to control total cost of ownership of fiber infrastructure. Fiberzone Networks Page 7

8 Sources 1. Putting Photons In Their Place, EE Magazine, 05/ Arcswitch patents and product literature 3. Calient Neworks product literature 4. Crossfiber product literature 5. Exfo product literature 6. FiberZone Networks product literature 7. JDSU product literature 8. Glimmerglass product literature 9. Polatis patent and product literature 10. Apcon product literature Fiberzone Networks Worldwide Headquarters: 7272 Wisconsin Avenue, Suite 300 Bethesda, MD Israel 2 Granit St., Kiryat-Aryeh P.O. Box 3026 Petach Tikva, Israel Fiberzone Networks Page 8