What is it that operators miss on 100G optics/transponders ?
Is it reach, cost or availability ?
In fact none of them.Telecom Lighthouse
We have Coherent optics that can span thousands of kilometers, and we have prices getting competitive reasonably, so what is it that operators would still want on 100g optics. Read further.
What operators want, is an efficient solution for metro applications; more specifically, pluggable type of “Coherent transceiver” for the network( line) side of DWDM . The bulky and power-hungry coherent transceiver today is suitable for long haul applications but not for metro applications. Deploying them for metro applications ( lets say 100 KM or even more) is an overkill for price, space and power.
Let me show you where is the gap today:
Link distances > 2000 KM:
We have,today, coherent line side transceiver that can span 2000 KM or more. OIF ( Optical Interworking Forum) did a good job of standardizing the modulation scheme as PM-QPSK in addition to size ( 5 x 7 inches) and power requirements ( 80 watts). This considerable power requirement comes because of the ASIC inside transceiver that uses DSP for demodulation and link equalization of received signal. In addition, it performs Analog to Digital conversion ( ADC), Digital to Analog converter ( DAC) and also SD-FEC processing. All these functions, naturally, call for considerable power requirements for processing purpose.
Link distances <40 KM:
Here we talk about the client side transceiver usually CFP which is a pluggable type. IEEE has standardized 100base-LR4 that cover distance up to 10 KM and 100base-ER4 that can go up to 40 KM. These CFP have much better power requirements i.e. in the range of 32 watts. It means that it would not be possible to deploy it for any reach beyond 40 KM. ( At the time of this writing, one vendor is claiming to have developed CFP for distance up to 80 KM).
So where are we left when we have a requirement to have a DWDM reach for 100 KM for metro applications or lets say a few hundred Kilometers , the only solution would be to go with the coherent based fixed optics since CFP does not offer that reach. All this at a price of power, size and cost.
Lets take each of them one by one:
The Size needs to be smaller so that multiple 100Gs can be accommodated on single line card. The issue with the metro application is always one of space. The transponder needs to be space efficient and should be able to accommodate multiple 100gs.
The power needs to be equal to that of a typical CFP applications eg. 32 watt since the fixed optics today consume power as high as 80 watts. Installing huge number of coherent transponders in metro would call for huge power requirements.
The price needs to be attractive for mass deployment because metro market is cost sensitive. This is a direct benefit of using CFP/pluggable on DWDM side which will result in lowering prices.
What is status today in the market ?
Earlier Ocalaro Inc was the first one to announce Coherent CFP2 in March this year (2013), followed by Sumitomo who also announced the launch of coherent based CFP2. However mass development of the new CFP2 will still not be before mid of 2014.
The other vendors need to catch up and push their roadmaps. Equipment vendors would need aggressive roadmaps for integrating new coherent CFPs into their transponders thus pushing the efficiency of 100G to next level.
What is a message for operators today in the absence of the metro Coherent optics.
For the moment, operators have to live with the current coherent based optics for their metro applications. There are some vendors that provide a cost optimized coherent transponder for metro applications. It is worth looking at those options. If cost is a big driver then there are some solutions in market for non coherent 100G solutions that are cost effective but I would rather recommend to wait for the next wave of Coherent CFPs. I am of the view of having a larger eco system around Coherent based optics rather than keeping two different technologies for 100G. I have touched on this issue in the following post.
Do let me know, what are your views on this issue and how would you go ahead with your metro 100G applications.