L1 Testing Scenarios

Intermittent cable connections or fiber insertion/removal can cause the optical signal to fluctuate 100s of time before becoming stable. Link flaps can cause all sorts of network failures; from routing table recalculation to the PHY not being able to re-establish the link. The ability to identify and correct switch behavior under lab conditions can save hundreds of thousands of dollars in field failures and onsite support.

ColdFusion can imitate these conditions by shutting down the output optical signal for a user-defined number of mSec and a user-defined number of times. With precise timing and order of events, multiple links failures, short time between link up/down events and other field failures are easily simulated in the lab. 

Fiber cut simulation typically assumes that both fibers (both Tx and Rx) cut, but in real life, deployments, sometimes the fiber is cut in a way where only one of the strands in the cable is damaged. When this happens, losing one fiber out may not trigger the fail over mechanism because most fail overs rely on optical power monitoring.

ColdFusion simulates this event by mapping two ports in a unidirectional fashion and can be programmed to transmit in one direction, but not in the other i.e. Device B receives signal from Device A, but Device A does not receive signal from Device B eliminating the optical power from a single strand. This can test to make sure the fail over mechanism is triggered in these situations.

ColdFusion can also simulate a microfiber cut in 100G network applications by simulating the same scenario above; eliminating optical power to one of the ports of the 4x25 Gbps lanes in QSFP28 to insure that the device under test responds or triggers the proper fail over response.

ColdFusion is capable of perform multicast (1 to n) mappings. One transmit port can multicast a signal to any number of ports within the system with a user-settable return path to the test port. This allows one port of a very expensive test set to simultaneously generate a test signal to any number of ports in the switch.

ColdFusion maximizes the use of your existing test ports, or can minimize the number of new ports required to meet your testing needs.
 

In the reverse of multicast mapping, ColdFusion can perform port mirroring which sends the same signal to any number of test devices for analysis. This 1 to n mirroring enables you to simultaneously run various tests on the same signal in a test configuration.  

Cold Fusion's port mirroring can impact the total amount of time needed to execute a test, freeing the equipment for the next test set up.

A test lab environment is filled with many different types of media. Think about the devices under test, test equipment, and any ancillary equipment used in the configuration of the test scheme and how you will establish the connectivity architecture. Some equipment only supports one type of media. some media is less expensive to implement. Comparing the cost of single mode and multi mode transceivers at higher data rates, you’ll find single mode transceivers can be two to three times more expensive than its multi mode counterpart. Copper RJ45 connections can pose these same connectivity issues.

ColdFusion supports the largest range of media types. Additionally its OEO architecture allows conversion of single mode signals to multi mode, and copper to fiber, making mappings from a single mode port to a multimode port or a copper port to a fiber port possible. Having this flexibility allows you to utilize equipment in a test configuration regardless of media type.