Technical progress is only half the story: a shift is underway in how issues are defined so that even consumer markets appear within fibre's grasp, according to Karen Liu, Vice President of Components at Ovum RHK.
"The interplay between ITU and IEEE worlds continues, but the commercial motivations have subtly shifted. When 10Gbps first came out, telecom was there first, focused on its own core capacity. Only later did the coincidence of data rates suggest that telecom vendors could leverage technology to cross over to the potentially larger datacomms market."
Active optical cables emerged suddenly as a product category in mid-2007. At last count, there were six vendors offering products in this area. These were not the result of a coordinated multi-source agreement (MSA) development nor were they all driven by the same large customers. They don't even aim at the same application. While four vendors' products (Zarlink, Intel, Xloom, Tyco) use the CX4 connector for 10GbE and Infiniband, Finisar's product is serial 10Gbps and Luxtera's uses the QSFP connector for 40Gbps.
Technical progress is only half the story, as a shift is under way in how issues are defined, as shown in the table below:
Table 1 Generational issues shift
Old School New School Optics vs copper in datacomms Active optical cable 40Gbps vs 100Gbps in telecom 40 and 100Gbps in telecom & datacomms Cost of tenability Size of tunability Telecom cross-over to datacomms volumes Datacomms cross-over to consumer volumes
Source: Ovum RHK
Old school - Optics vs. copper: Optics is clearly superior in bandwidth-distance products and therefore will win as soon as the next speed jump comes. In the meantime, it is a high-end product with a justified premium.
New school - Active optical cable: The equipment maker and the end customer would rather not get dragged into the struggle between copper and optical. Universal ports and cable operations will help the total market and reduce barriers for optics. I want business and volume so I need to be price competitive with copper.
In the last year, the debate about 40Gbps and 100Gbps has been resolved into an agreement to go forward with both data rates with technology coordination between the two to minimise investment burden. Actually, there were two separate versions of the debate, one for telecom distances and one for datacomms. While telecom has moved from the expected 40Gbps to add 100Gbps to its plans, datacomms has added 40Gbps to its 100Gbps plans. Proposals for both 40 and 100GbE use multiple lanes of 10Gbps to extend the relevance of 10Gbps technologies. In fact, the IEEE's Higher Speed Study Group believes 100Gbps switches will enable more 10GbE in the data centre.
The interplay between ITU and IEEE worlds continues, but the commercial motivations have subtly shifted.
Despite interest in aligning with ITU, the datacomms community is more concerned about accommodating the disparate elements of the data centre: servers, switches, chips and backplanes are in the midst of their own roadmap shifts on a number of levels. While a portion of the dense wave division multiplexing market continues to use fixed transmitters for cost minimisation, equipment vendors face a tough decision regarding the trade-off between the ability to tune the network and density. Until now, designs with XFP density had to sacrifice full band tunability. Now that XFP that can be tuned is becoming available (JDSU has announced the critical high-density TOSA), some system vendors already want (fixed) SFP+ density on their platforms.
As for the potential to reach high-volume applications, telecom and datacomms are mounting separate attacks on the consumer or end-user market. In telecom, FTTH deployments are driving product and practices toward fibre optics being easier to use and testable by non-specialists. Datacomms vendors see the connected home moving to similar data rates as enterprise and conjecture that optics will be attractive for extending reach. For example, high-definition multimedia interface requires 5Gbps in the home. Admittedly, this is a special case, but there are other examples, such as Optical Display Port and USB 3.0. That makes three separate formats for the home in the range of 5 to 10Gbps and (with optics) tens of metres.
Karen Liu, Vice President of Components at Ovum RHK