Optical network diagnostics capabilities for meeting high level Services S ervice Line Agreements (SLA) are one of the key operating necessities for telecom service providers. Using different levels of SLA's, service providers can deliver their service level reliability and cost bundle to meet customer needs. SLA is in effect a tool that enables service providers to offer reliable and fast service to its customers, whether those are small enterprise or large enterprise customers. Therefore, SLA's must have integrated features that provide fast and accurate information (alarms, events, performance monitoring, etc) to the network manager even before the customer notices the problem. Additionally, a set of built-in diagnostic tools must be present in order to provide accurate fault isolation to the specific link/network element and optical module so that an engineer can be dispatched to the correct site as fast as possible, thus staying within the SLA committed response time and service quality criteria. This white paper explores some of the diagnostic tools integrated into all PacketLight's fiber optic, CWDM/DWDM and OTN products that aid network managers in reducing network downtime and maximizing SLA commitments. The following diagnostic capabilities will be reviewed: 1) EMS/NMS Management system 2) PRBS (Pseudo Random Binary Sequence) generators and testers 3) Loop back 4) Fiber attenuation monitoring 5) Dying gasp EMS/NMS Management System One of the most important tools for optical network management is network monitoring and fault/events notifications and control of the entire optical network elements in a centralized location or as known Network Operation Center (NOC). A centralized element/network management system such as PacketLight's Lightwatch EMS/NMS collects fault and alarm notifications and PM from the entire network into a central database thus allowing a network manager a quick and easy overview of the optical network performance. After detecting a problem and sending required notifications, EMS/NMS allows service manager to isolate the problem utilizing the built-in diagnostic tools accessed and activated via the EMS/NMS over any element in the network. A course of action can be quickly outlined and a solution can be achieved as fast as possible, thus maintaining the SLA commitments with the customers. EMS/NMS provides additional tools for network managers important for SLA fulfillment. These are: a report of performance monitoring (PM) data for each individual service with 15 minute intervals; provide network inventory; task scheduling for network
maintenance; and many other features. These tools further assist the service providers to provide proper reporting to the customer, and document the service levels provided. Figure 1: LightWatch EMS/NMS PRBS Generator and Tester PRBS (Pseudo Random Binary Sequence) generators and testers can be viewed as array of BER (Bit Error Rate) testers which can be activated remotely by the system manager in order to check the health of each service across the network between any two points. All PacketLight s product support such BER testers for all the services thus providing the network manager full visibility to diagnose any link remotely without the use of expansive external test equipment and the need to send technical person to the site. The PRBS tests can assist in isolating a problem to the level of a specific link and optical module in an exact network element. The PRBS will not affect operation of other services. PRBS is also a very useful tool to isolate any errors occurring in the WDM layer. This way, the service provider can provide the customer with a report of the BER test for each of the links during the signoff and network commissioning. The PRBS test will generate a report including the test duration, number of BITS passed, number of errors encountered and the BER calculation of the link. Thus, the committed BER SLA of the service can be verified in case of any issues raised by the client regarding the service provided.
Figure 2: PacketLight's PRBS tester screenshot Loopback Loopback capabilities enable the network manager to segment the network into smaller parts for isolating the faulty segment of the network and verifying the demarcation interface between the customer appliance and the WDM equipment. PacketLight s product suite provides both terminal and network loop back capabilities per optical interface in the system thus enabling segmentation of the network easily for quick fault isolation. Figure 3: Loopback capabilities block diagram
Fiber Attenuation Monitoring One of the most valuable tools for maintaining high level of SLA, is knowledge of possible upcoming problems in performance, such as degradation of fiber attenuation. Alerts about the degradation of performance in optical link quality allow the service provider to take necessary measures to improve optical link performance before it starts influencing the customer service. PacketLight s solutions enable network managers to automatically detect degradation of the fiber optic attenuation performance between the sites. PacketLight's products provide built-in optical power monitor testers over each and every link constantly measuring the link performance and alerting as of any degradation. The network manager can set a threshold for alarms regarding the change of fiber attenuation of the fiber optic link and get the relevant event and alarm information to the management station upon such case. Thus, the service provider has full visibility to the dark fiber quality and can perform pre-planned maintenance activity on the infrastructure during the next service window insuring the committed SLA levels. Dying Gasp Dying gasp is another powerful diagnostic tool that helps the network manager identify the real problem behind the loss of a site: due to a fiber cut or due to a power failure at the remote site. In case of power failure, the system manger will get an SNMP trap indicating the loss of power to the network element. According to the "dying gasp" trap, the system manager can then take the right course of action which will be either to send technical people to fix the generator or send a team to find and fix fiber cut. This information will save the time needed for fixing the problem and meeting the SLA. Figure 4: Remote power failure notification
Summary Providing better SLA and faster response time in case of crises can be one of the differentiators for service providers and one that leads to greater customer satisfaction. PacketLight s solutions are designed for providing this high level of SLA with its multiple diagnostic tools and embedded monitoring features. Utilizing the management system and activating the tools enables the system manager high level of control over the network performance and fault isolation while allowing him to take proactive measures to ensure the network operation, test the network performance and provide reports of the link performance to the customer. About PacketLight Networks, Ltd. PacketLight Networks offers a suite of Leading 1U Metro CWDM and DWDM solutions, for transport of data, storage, voice and video applications, over dark fiber and WDM networks, featuring high quality, reliability and performance at affordable prices. Our products are distinguished with low power consumption ideal for CLE (Customer Located Equipment) allowing maximum flexibility as well as ease of maintenance and operation and providing real Pay-as-you-grow architecture. PacketLight customers are carriers, service providers, data centers, IT integrators and enterprises who are active in meeting the demands for metro Ethernet, business continuity, Triple Play solutions and enterprise data sharing applications. For product and reseller information, Please contact info@packetlight.com