100G Power Measurement Challenges

On , in Client Side, Ethernet, General, OTN, by Tony Goodchild

Deploying networks using CFP transceivers presents a set of challenges that did not exist with previous generations of Ethernet. Any CFP based 100G Ethernet deployment will commonly use a WDM interface – the only exception to this is in the case of using SR10 CFPs – and this in itself is enough to require a […]

 

Troubleshooting 100G Links Using PCS Lanes

On , in Client Side, Errors & Alarms, Ethernet, General, by Tony Goodchild

Understanding the condition of the PCS lanes is crucial to troubleshooting 100G links during network deployments. At the most basic level understanding that there are errors at the PCS indicates that the root cause of the fault lies with the physical signalling and not at the MAC layer or any of the high network layers […]

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Understanding 100G OTN Error & Alarm Conditions – LOL

On , in All Posts, Client Side, Errors & Alarms, General, OTN, by Tony Goodchild

Loss Of Lane Alignment (LOL) is declared on 100G interfaces when it has not been possible to successfully recover the Logical Lane Marker (LLM) from the logical lanes and then re-assemble the OTU4 frame. During the lane recovery process the LLM will be present in a lane every 16320 bytes, when the same LLM value […]

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Understanding 100G Ethernet Error & Alarm Conditions – High BER

On , in All Posts, Client Side, Errors & Alarms, Ethernet, General, by Tony Goodchild

100G Ethernet includes a process that continually monitors the performance of  received PCS data and triggers an alarm condition in the event that an excessive error ratio is detected. When receiving data at the PCS each lane is checked for errors in the 2 bit sync header in each 66b block. A counter is maintained […]

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Understanding 100G OTN Error & Alarm Conditions – LOFLANE

On , in All Posts, Client Side, Errors & Alarms, OTN, by Tony Goodchild

At 100G speeds OTN uses a multilane implementation to achieve the OTU4 client interface. Using these multilane interfaces can present a number of challenges and new defect conditions have been defined to support these. LOFLANE is a loss of frame defect on a logical lane. In some ways it is similar to Loss Of Block Lock […]

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How does Skew impact latency measurement?

On , in All Posts, Client Side, Ethernet, General, by Tony Goodchild

Now more than ever latency is a key network quality metric, with financial institutions and other Enterprise customers demanding absolutely minimal latency from their service provider. With Skew being an inherent part of a 100G Ethernet link, field engineers starting to roll out these services commonly ask how will Skew levels affect the latency measurements […]

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Understanding 100G OTN

On , in All Posts, Client Side, General, OTN, by Tony Goodchild

OTN uses a similar multi-lane mechanism to 100G Ethernet to achieve 100G rates. The parallel interfaces are defined in an appendix of the G.709 recommendation.  The recommendation includes definitions of parallel interfaces for both 40G and 100G rates and within this a new signal was defined for parallel interfaces – the Optical Channel Transport Lane (OTL). […]

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Staged CFP Testing

On , in All Posts, Client Side, by Tony Goodchild

Unlike previous pluggable transceiver modules there is a real requirement to test the CFP in a staging area prior to deployment. Previous devices such as the SFP or XFP currently are available with commodity pricing from almost $50 to a a few thousand dollars depending on the required interface support. In comparison the CFP can […]

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Alignment Markers And Associated Alarm & Error Conditions

On , in All Posts, Client Side, Errors & Alarms, Ethernet, by Tony Goodchild

The alignment marker is used for the identification of the PCS lanes. They allow the receiving network equipment to identify the lanes as they are received so that that they can be re-ordered. So what is an alignment marker? An alignment marker is a single 66 bit block that is inserted into the stream of […]

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Understanding 100G Ethernet Error & Alarm Conditions – Loss Of Block Lock

On , in All Posts, Client Side, Errors & Alarms, Ethernet, by Tony Goodchild

On the 100G Ethernet interface the Loss Of Block Lock (LOBL) alarm is raised when it is not possible to lock onto the sync. header within the 64b/66b line coded blocks. As the serial stream of blocks are distributed over the 20 PCS lanes during transmission the LOBL alarm should be reported within a specific […]

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Testing The Physical Interface

On , in All Posts, Client Side, Ethernet, General, OTN, by Tony Goodchild

100G testing plans must include specific attention to the physical interface. The CFP interface is no longer a single transmitter and receiver pair that can simply be checked with simple tests such as a basic optical power measurement or receiver sensitivity measurement. Utilising multiple optical lanes simultaneously makes testing the interface more complex and also testing […]

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A New Sublayer

On , in All Posts, Client Side, Ethernet, General, by Tony Goodchild

The multi-lane architecture within 100G Ethernet that comprises the PCS Lanes, CAUI and Gearbox (depending on CFP) represent a whole new sublayer of the network that must be specifically tested. This new sublayer exists only between two directly adjacent network elements that are connected via the CFP interfaces. To support this there are a number […]

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Understanding The 100G Ethernet Client

On , in All Posts, Client Side, Ethernet, by Tony Goodchild

The client interface for 100Gb/s Ethernet is standardised in IEEE802.3ba as an amendment to the full 802.3 specification. The client interface for Ethernet at 40Gb/s and 100Gb/s is fundamentally different from the earlier 10Gb/s and lower rates. At these lower rates the interface is specified as a serial stream of data that is line coded […]

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