Monday, November 20, 2017

Service Assured: No Broadbandits Here!

Providing Ethernet services is usually never easy, and configuring them can be a wild west shootout. Sometimes services don't always burn-in as intended. On other occasions, factory configurations become field modifications. Even if everything goes perfectly at installation, problems can occur when services are upgraded. Pushing the gas pedal on a 10G link to 40G and beyond may bring to light fiber characterization issues you weren't prepared to deal with. Back reflectance values in the network that were once tolerable, are now stealing your valuable packets.

Well, I have good news for you. New devices and applications make it easier to not only verify the speeds of an Ethernet link and check for packet stability, you can maintain SLAs with greater efficiency and visibility.

Let's take a look at three products that further simplify service assurance and verification testing.

The EX1 from EXFO is an elegantly simple device that should become to the telecom service technician what the Non-Contact Voltage Tester is to the electrician. Use the EX1 paired with an Android device to qualify broadband connections delivered to both resident and business Ethernet customers. This platform will soon be available for iOS as well, and it allows service providers to quickly validate delivery of full line rate Gigabit Ethernet speeds to their subscribers.

The on-board power of the EX1 is a field-programmable gate array (FPGA) circuit that provides an open-platform. This is a critical feature that will help the EX1 keep pace and provide reliable results for years to come. This tester also features a partnership with the industry-leading Speedtest by Ookla, which provides a simple, easy-to-read interface you can share with your customers.

The EX1 is capable of hosting EXFO's Active Verifier Virtual Network Functions (VNF) to deliver a complete level 3 to level 7 service assurance solution. When activated, the Verifier VNF can offer a suite of more than 140 performance tests for the EX1 including Y.1564, IP connectivity, VoIP qualification, internet experience and more.

Furthermore, the EX1 can be left on site for temporary troubleshooting, or permanently deployed as a fixed performance endpoint that continuously reports on network and service performance. The cost of leaving the device behind might certainly be less than rolling a truck with a service technician qualified to troubleshoot Ethernet links.

The next product fits a wider range of applications. Are you transitioning your network from legacy technologies over to Ethernet? We know a device that can replace up to 8 sleepy, older test sets with a new one capable of verifying up to 10G Ethernet. Utilities, municipalities, E911, data centers and service providers alike can benefit from the power packed into Greenlee's DataScout® 10G.

The 10G can test multiple services simultaneously including Ethernet, DS0 (TIMS), DS1, DS3, T1, DDS and more. There is a separate unit capable of DDS, but all other services can reign on one device with easily navigated menus on a 7 inch color touchscreen. The 10G is fast, and it powers up 3 times faster than competitive devices.

It is a tablet-based design that comes loaded with standard applications including a web browser, email, document viewer and more. You can control the DataScout® 10G remotely via bluetooth, or a standard web browser. This instrument is also proudly designed, manufactured and supported in the United States.

Finally, I would like to discuss a powerful application that can pay dividends for those who take advantage.

Technicians who maintain Service Level Agreements (SLAs) undergo significant amounts of training to understand ITU-U Y.1564 and RFC 6349. Not only for commissioning services, but monitoring key performance indicators (KPIs) is a significant challenge in our industry. In a highly volatile world of mergers and acquisitions, lit service providers must juggle deployment standards when new networks come online. If the goal of a merger is continued sales growth, how can you ensure that your new technicians are fully trained in periods of explosive growth? Meet iSAM.

As a leader in test and verification equipment, EXFO is no stranger to designing simple GUIs and platforms that put time back into a technician's day. EXFO's iOLM interface revolutionized how OTDR traces are performed, and many competitors today offer link mapping integration. iSAM is another innovation for Ethernet Service Activation, and is available for multiple EXFO platforms.

Designed for end-to-end validation of layer-2/-3 and TCP layer-4 services, iSAM handles everything from GigE to 100 GigE in a simple 3-step process. That simplified process translates to a reduced test time of up to 10x, thus increasing the number of tests that can be done in a day's work. With service turn-ups and assurance testing that takes less time, service providers can take advantage of the greater revenues resulting from better service.

So don't forget, old singlemode fiber is out there. 100 GbE is going to find your macrobends and your high back reflectance that may not effect 10 Gig. Or are there issues with the networking equipment causing jitter? These problems are out there today to rob your network of valuable packets and performance. Find those hidden Broadbandits before they cause damage to your valuable services.

Wednesday, November 1, 2017

The #2 Pencil of Fiber Testing

Don't Take Fiber Launch Boxes For Granted

How often were we reminded to use only a #2 pencil when taking a standardized test? How ridiculous did it seem that instructors thought we would use anything but a #2 pencil? Not only would we bring our #2 pencils, but we would make sure we had at least one fully sharpened backup. Inevitably, the first circle would spell doom for a weak tip no matter how well you thought it was sharpened.

Many of us can still recite the litany of requirements for test taking. We've heard them so often, they're etched into our minds and our culture.

When I relate this to fiber testing, one question lingers in my mind. Where is our instructor to remind us the importance of fiber launch boxes? I am shocked by the stories I hear from the field where OTDR tests are performed with faulty or even without launch boxes. Two incidents I recently heard dealing with separate service providers encouraged me to write this blog.

The first situation caused quite a lot of havoc with a supplier who provided passive splitter cabinets for a large FTTP deployment. Tests were showing significant loss through splitter ports, but the results were inconsistent. Some ports tested fine while others were failing. Those results would not automatically cause you to question the launch cable you're testing with, but the end result proved that the launch cable used was faulty. Before the launch cable was called into question, additional replacement cabinets were shipped, many hours of resources utilized, and construction was delayed.

Another similar situation occurred with fiber access terminals on a FTTP project. Some hardened ports on the terminals were failing, but not every port or every terminal. It is reasonable to assume the product may be at fault due to the inconsistency of the tests. How could a launch cable be the issue when it is passing through the other ports? The connectors may still pass, but they may pass with higher insertion loss levels or back reflectance than they actually have. In this particular case, the launch cable used did not have the appropriate connector to mate with the hardened ports, therefore additional loss occurred due to air gaps.

These scenarios deal with inspecting and cleaning connectors as well as using the proper connections to ensure the best results. Let's take a look at the role of launch cables as well as highlight suppliers that make the extra effort to provide a superior launch box.

The launch cable (aka pulse suppressor) covers what is known as the dead zone of an Optical Time Domain Reflectometer (OTDR). Due to the high power pulse coming from the OTDR, the initial pulse plus a few meters is the length of cable where events are not seen--hence the dead zone. Using a launch cable and a receive cable allows you to see the first and last connections of the fiber under test. The image below shows an OTDR trace with launch and receive cables attached.

How long does a launch cable need to be? That is determined by the maximum pulse width of the OTDR, and the cable should be longer than the pulse dead zone used for the tests. For instance, a 1 μs pulse is approximately 100 m long. Therefore selecting a 150 m - 300 m pulse suppressor box or launch test cable would be appropriate.

Several OTDR manufacturers claim to have pulsewidths today as small as 3 nanoseconds, which is great for added visibility in shorter access network links. First of all, buyer beware if you source an OTDR in search of the short pulsewidth. Tests have shown that several equipment manufacturers are closer to 5ns when the gear is on the lowest setting. Second, it becomes even more critical to use a long launch cable to ensure you can accurately test the leading connector in the short run.

Nothing more than a jumper in a rugged enclosure, fiber test cords are made by a multitude of suppliers with a wide array of optical fiber types inside. Simply saying you would like a "Singlemode launch cable with an SC-APC connector" does not mean that you'll get a G.652.D singlemode OS2 fiber in the box. The popular mini launch coils might feature a bend-insensitive G.657.A1 singlemode fiber, while your fiber under test is G.652.x.

The case of mixed singlemode types is very common, but it is important to be aware of the TIA-526-14B standard (IEC 61280-4-1). This standard dictates that if you cannot validate the fiber characteristics between the test cords and fiber under test are the same, you must do a bi-directional fiber test. Optical Loss Test Sets accomplish this task, but it is less common for OTDR testing.

In order to test to this standard properly with an OTDR, the test cords may not move. It requires 3 test cables: a launch fiber, loopback fiber and a receive fiber. Bi-directional tests average the absolute values in each direction over a single strand or fiber pair.  This approach simplifies the test because the OTDR operator stays at one end of the fiber under test, and only moves the OTDR from the launch cable to the receive fiber.

Based on these requirements, it is only logical to require a high quality test cord that is rugged and reliable. It's important to make sure the test cords are supplied with the highest quality factory polished and terminated connectors. Those connections will be used more than any jumper in the network, so let's make sure they have low insertion loss, return loss and are prepared for the abuse.

Over the years, Fiber Plus International became a name that our customers associated with high quality launch cables. Service providers offering the highest speed and bandwidth service recognized the consistently low reflectance and insertion loss values. Fiber Plus' Dead Zone Eliminators are available in traditional pelican cases as well as small launch coils. Fiber Plus also manufactures bare fiber adapters that make testing fiber reels and non-terminated fiber a snap.

Another supplier of distinction for test cords is Megladon. Their patented Hardened Lens Contact (HLC) process changes the physical properties of the glass at the connector endface. HLC creates a higher performance connector endface as well as a scratch resistant surface that significantly increases the number of insertions per connector. Every assembly that Megladon manufactures features the HLC technology, so you can insist on the highest quality jumpers and test cords.

No matter how durable the endface of your test cords and jumpers may be, you still need to inspect and clean them. Comstar Supply carries a wide array of hybrid and dry cleaning solutions to keep your test cables performing consistently and reliably.

So the next time you break out the OTDR or loss test set, don't forget you're #2 pencil! Make sure they are sharpened (clean), and make sure you have enough of them to complete your test without having to leave your desk.