There has been a lot of discussion lately about the migration of data center Ethernet speeds from 10 Gigabit Ethernet (GbE) to 40/100GbE. While these discussions are important when designing for future needs, the fact is that most data center managers are dealing with the migration from 1G to 10GbE. The problem they experience when planning this migration using high-speed cabling is the extra cost associated with the server connections. There is a method to avoid this mistake that will help keep costs at a minimum.
It appears the predominant data center architecture today utilizes Top-of-Rack switching as the most efficient means of achieving Fiber Channel over Ethernet (FCoE). Until recently, the only way to connect a 10GbE server and support FCoE was to use a 1/10G switch or fabric extender (FEX) connected with a small form-factor pluggable (SFP) or SFP+ direct attached cable (DAC) - the Cisco 2232PP is a good example. This year Cisco introduced the 2232TM-E FEX that uses 10GBASE-T ports supported with category 6/6A copper patch cords and supports FCoE.
Why is it an important release? Consider a comparison of the two FEX options in the Cisco case. When comparing a 1/10GbE 2232PP fully loaded with SFP cables to support 1G servers and a 1/10GbE 2232TM-E fully loaded with cat6 patch cords, the cost is similar. The 10GBASE-T version is actually hundreds of dollars cheaper. This is not typically enough for a data center manager to consider the 10GBASE-T RJ-45 version.
However, the real cost comes when migrating the server connections from 1GbE to 10GbE. When migrating from 1G to 10GbE with the 2232PP DAC, you have to replace the 1GbE SFP direct attached cables. These cables do not support 10G speeds. SFP+ direct attached cables have to be installed to support 10GbE at a cost of $85 to $100 per cable. Multiply this by 32 ports - the cost has just become significant.
Contrast this with the use of the 2232TM-E version of the FEX. When migrating to 10GbE, the FEX will auto-negotiate the port speed with the server to 10GbE. The existing cat6/6A patch cord will support the higher 10GbE speed with no replacement required. There is no cost associated with the migration.
Adding the design flexibility you get when using a Category 6A cabling infrastructure in terms of extended distances of the cabling (up to 100 meters), as opposed to seven meters with the direct attached cable, and you have a very compelling reason to use the new 2232TM-E and copper patch cords.
I hope this information will be useful to some of you dealing with migration issues or planning for 10GbE in the near future. If you have any questions about this technology or the migration method, feel free to leave a comment below.