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Test and Measurement

  • 24 June 2020

    In the optical time domain, the reflector provides an analysis report in fiber optic cables by verifying the loss of fiber insertion, measuring its length and detecting the cable breakage, if any, by characterizing the fiber optic cable.

  • 12 June 2020

    Multifiber push-on (MPO) connectors are becoming more and more popular because of their many advantages for high-speed network operators, owners and installation companies. They are used to connect the fastest links that deliver the most sensitive services and data to customers, enable high-speed interconnects and create redundancy. More and more, telcos are reconfiguring their central offices into data centers (CORDs) and deploying MPO cables with 12 or, increasingly, 24 fibers. In fact, MPOs are quickly emerging as the connectors of choice. However, since the main source of loss in links is connector related, the failure to properly test and maintain MPO connectors puts the entire network at risk. In fact, without proper validation, CORD operators may end up having to pull the plug on critical lines for troubleshooting. So, how can you ensure peak MPO performance? It all starts with testing. Let’s take a closer look at the three essential tests to ensure the quality of your link: polarity-type validation, continuity confirmation and connector inspection. Testing polarity Polarity simply refers to the way the fibers are arranged inside the cable. During installation, MPO connectors must be properly aligned and mated, which is not as simple as it sounds. Ensuring accurate polarity for MPO fiber array cables is a big deal and can be complicated, due to multiple polarity schemes available for these connectors and polarity flipping during connecting and installation. Three different polarity types, corresponding to different cable structures, are used with MPO cables. Validating these helps you confirm their type, ensures that signals are traveling in the correct path and connections between the transmitting and receiving end are intact.   In testing polarity, your main goal is to make sure the right transmitter (TX) is sending signals to the right receiver (RX). To accurately send and receive data, MPO connectors must be properly aligned and mated. Bad coupling will impede signal transmission, as the signal could be sent in the wrong direction. Undiagnosed polarity issues increase CAPEX and work for technicians (i.e., OPEX). Technicians may unnecessarily rip and replace expensive MPO patch cords, believing they are faulty, when in fact they simply did not have the expected polarity type. If polarity issues are not corrected before turn-up, then trying to pinpoint which cable connections have polarity problems after they have been installed becomes a frustrating and tedious guessing game. Testing continuity Confirming the continuity of a link ensures that there is no break and that light travels properly all the way to the end of the link. It’s a quick validation test that, when done during installation, can save a lot of potential troubleshooting later. Testing connector cleanliness Considering that 80% of network problems are due to dirty connectors, and the No. 1 cause of network failure is contaminated connectors1, it goes without saying that inspection and cleaning are critical. With multifiber push-on connectors, inspecting and cleaning is particularly important because each port represents a potential point of failure. Additional fibers create more surfaces, which means there is a higher risk of contamination and failure. Bad connectors are a significant cause of loss, and the impact is ever greater for MPO links, where a single dirty or damaged connector can affect as many as 12 or 24 fibers. How to clean MPOs Inspect, clean, reinspect. 1. Inspect Always inspect the connectors first. You don’t need to clean a connector if it’s already clean, as cleaning it might make it dirty. This is especially true for MPO connectors, which are highly sensitive. For example, for an MPO-24, dirt from the first row could potentially migrate to the second row while cleaning. Make sure to inspect both mating connectors, as residue from a dirty connector will transfer to a perfectly clean connector once they mate.   2. Clean If the connector is dirty, first try the dry method. If the dry method fails to remove the dirt, try the hybrid cleaning method, which involves using a solvent. 3. Reinspect Always dry your connector after using wet cleaning tools and always reinspect the connector. Choosing high-performance tools for easy inspection Given the popularity of MPOs, it’s important to know how to take full advantage of these powerful cables. Choosing the right testing tools and making sure your cables have passed the three essential MPO tests—polarity, continuity and inspection—are critical to turning up and maintaining efficient links. What’s more, to guarantee that your network is future proof and can meet the ever-increasing demand for bandwidth, it is crucial to ensure connectors are in good condition. The tools and solutions on the market today are better than ever, allowing you to: Inspect single and multifiber cables using the same tool by simply switching the adapter Take advantage of a slim design to easily access recessed connectors and dense panel settings Get an automated analysis of all fibers for multifiber cables and obtain a clear pass or fail result according to your test configuration One solution, three essential MPO tests EXFO’s ConnectorMax MPO Link Test Solution is an automated, all-in-one solution to validate polarity, continuity and connector cleanliness of MPO fiber optic links of any type, including MPO 12 and MPO 24 singlemode or multimode cables as well as APC or UPC and male or female connectors. The ConnectorMax MPO Link Test Solution pairs a light source at one end of the cable with a fiber inspection probe for analysis at the other end—a first in the industry. The solution brings together the ConnectorMax Multifiber Source with the ConnectorMax Fiber Inspection Probe to deliver a quick and easy-to-use solution that helps operators test and turn up networks right the first time—making deployments faster, more efficient and cost effective. Results are loaded in ConnectorMax Analysis Software, an app for mobile devices that provides clear pass/fail status and reporting functions, making it easy for technicians to perform and view the results of all three of these tests on the spot.

  • 08 June 2020

    Well in our case, “TAP” is an acronym for “Traffic Access Point” or “Test Access Point” and is a hardware device inserted at a specific point in a network where data can be accessed for testing or troubleshooting purposes. Network TAP's are mainly used to monitor the network traffic between two points in a network infrastructure   Figure 1. Network TAP   A network TAP typically consists of four ports: a network port A and B and two monitoring ports A and B. The network ports collect traffic from the network. Network port A receives the Eastbound traffic and port B receives the Westbound traffic. The monitoring ports provide a copy of this traffic to an attached monitoring device. Monitor port A will copy the Eastbound traffic and monitor port B will copy the Westbound traffic.   Figure 2. Copper and Fiber Network Link   Typically, a network TAP is placed between two points in the network. The network cable between points A and B is replaced with a pair of cables, which are then connected to the TAP. Traffic is passively routed through the TAP, without the network’s knowledge. This allows the TAP to make a copy of the traffic, which is sent out of the monitoring port to be used by another tool without changing the network traffic flow.     Figure 3. TAP inserted in a Network Link Figure 4. Network TAP Traffic Flow   Why do we need a Network TAP? There are different methods for gaining access to your network. Some of the traditional methods used for gaining access to network traffic include using a SPAN/VACL port on your switch or connecting a monitoring device in-line on the network. There are challenges with both scenarios and are easily resolved with a TAP without introducing a point of failure.  The Network TAP (also known as a Breakout TAP) is the only TAP that will guarantee copying all of the network traffic, including errors,  to the monitoring ports A and B.  Monitor port A gets the Eastbound traffic and monitor port B gets the Westbound traffic.   Figure 5. Network TAP Traffic Flow   What are other types of TAPs used on a network? Although the Network TAP is the TAP that lets you see all the traffic running through your network, there are other types of TAPs that can be used on a network. Two for when it is not important to see all of the traffic and one to be used with monitoring in-line devices like an Intrusion Prevention System (IPS).  Aggregating TAPs allow you to take the eastbound and westbound network traffic and aggregate it out to a single monitoring port. This will allow you to use just one monitoring port to see your eastbound and westbound traffic aggregated together on one monitor port.   What are other types of TAPs used on a network? Although the Network TAP is the TAP that lets you see all the traffic running through your network, there are other types of TAPs that can be used on a network. Two for when it is not important to see all of the traffic and one to be used with monitoring in-line devices like an Intrusion Prevention System (IPS).  Aggregating TAPs allow you to take the eastbound and westbound network traffic and aggregate it out to a single monitoring port. This will allow you to use just one monitoring port to see your eastbound and westbound traffic aggregated together on one monitor port.   Figure 6. Aggregate TAP Flow   SPAN/Regeneration TAPs will permit you to take unidirectional traffic from one network segment and send it to multiple monitoring tools. This allows you to send a single traffic stream to a range of different monitoring tools, each serving a different purpose.   Figure 7. SPAN/Regenerating TAP Flow   Bypass TAPs (also known as In-Line TAPs) allow you to place an active network tool "Inline" on your critical links. These TAPs are used where monitoring devices need to be placed inline on the network to be effective but putting these devices inline will compromise the integrity of a critical network.  By placing a Bypass TAP in place of the monitoring appliance  and connecting the monitoring tool to the Bypass TAP, you can guarantee that the network link will continue to flow, and the in-line device will not become a ‘point of failure’.   "As long as the monitor appliance is on-line, it will keep returning the heartbeat packets received from the TAP back to the TAP keeping the in-line appliance from becoming a point of failure. If the monitor appliance should go off-line for any reason, the heartbeats will no longer be returned to the TAP causing the TAP to switch to the by-pass mode."   Figure 8. Bypass TAP Flow Normal Operation   There are different problems when a tool is installed in-line. Especially when dealing with a critical network, it is essential that the network is available all the time because down time can be very costly. When a device is installed in-line, the network must be brought down every time updates are required, or the tool needs to be re-booted. Similarly, if the monitoring tool fails, the network will go down as well. These problems can be resolved by using a Bypass TAP. When using an In-Line TAP, you will be guaranteed that every packet being sent from the network will get to the monitoring tool. Because these devices can never be over-subscribed, they always pass every packet including layer 1 and layer 2 errors. The Bypass TAP when it is in its normal operating mode will keep critical traffic running through the in-line appliance and at the same time will send ‘heartbeat’ packets to the in-line appliance and as long as the in-line appliance passes the heartbeat packets back to the in-line TAP the TAP will remain in the in-line mode.  If the in-line appliance should go off-line for any reason, the In-Line TAP will stop getting the heartbeat packets.  The In-Line TAP will switch to the by-pass mode until the TAP starts to receive heartbeat packets again which will indicate that the in-line appliance is back on-line.   "When the monitor appliance goes off-line for any reason, the heartbeat packets are no longer returned to the TAP causing the TAP to bypass the monitor appliance and keep the critical link running."   Figure 9. Bypass TAP Flow in "Bypass" Mode

  • 07 March 2019

    Fiber Optic / Copper Test Equipment, Wireless Network Test Equipment, Transport and Datacom Test Equipment, Virtual Network Test Solutions, Fusion Splicers, Device Rental Services

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