We evaluated a scenario with an eight-slot chassis fully populated with 36-port QSFP line cards. The line cards were populated with 40G parallel optic transceivers operating in breakout mode for a total chassis port count of 1,152x10G ports. Achieving the equivalent 10G port capacity using 10G SFP+ line cards requires a total of three eight-slot chassis with 48-port line cards. The cost comparison includes the cost of the switch chassis, the line cards and the associated transceivers, using standard list pricing for all components. The chassis cost in Figure 6 includes the required power supplies, fan trays, supervisors, system controller and fabric modules. As the number of chassis needed to support the 10G port density increases when using SFP+ transceivers, these additional required components increase as well. As a result, the study shows that on a per-port basis, deploying discrete 10G ports costs almost 85 percent more compared with deploying 40G ports in breakout mode for multimode applications. Figures 6 and 7 show the results in graphical and tabular form, respectively.
Now let’s evaluate the opex benefits. To begin, most vendors’ 40G and 10G switch chassis and line cards have similar power requirements. An approximately 67-percent reduction in required power and cooling comes from reducing the number of chassis and line cards by two-thirds, in addition to the space savings discussed above. And as an added benefit, we can save the additional power required to operate the transceivers. The data in Figure 8 shows a greater than 60-percent transceiver-power savings when deploying multimode breakout configurations,
In addition to the benefits in space savings and cost, you can gain an additional benefit on Day 2 when you increase your network speeds from a high-density 10G (or 25G) architecture to a native 40G (or 100G) network. As the network moves from breakout 10G (or 25G) to native 40G (or 100G), the existing 40/100G optics and line cards operating in breakout mode can continue to handle the native 40/100G links. This approach allows for two speed generations out of the switches, line cards and associated parallel optic transceivers.
Because parallel optic transceivers operate over eight fibers, it’s important to consider how to design the data center structured cabling to support breakout mode. Recommended designs include solutions that employ Base-8 MTP connectivity for the optical infrastructure to optimize fiber utilization and port mapping. As Figures 9a, 9b and 9c show, deploying connectivity with an eight-fiber MTP connector interface allows a simple and optimized solution to breakout to four LC duplex ports for patching to 10G equipment ports.