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…(Read More)

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…(Read More)

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…(Read More)

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…(Read More)

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…(Read More)

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…(Read More)

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…(Read More)

Polarisation multiplexing is commonly used in 100Gb/s line side transmission as a method to increase the bit rate over the line without increasing the transmitted symbol rate. Using polarisation controllers it is possible to generate two perpendicular polarised optical signals on the same wavelength for transmission through a single fibre. As two separate signals…(Read More)

There are a number of challenges to achieving 100Gb/s optical transmission rates using the technologies that have been deployed at 10Gb/s and even 40Gb/s. Using traditional transmission technologies such as NRZ modulation on the line will result in very poor spectral efficiency and a 100G signal using NRZ would not fit into…(Read More)

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…(Read More)

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