Tuesday, February 26, 2013

Is 10GBase-T in fashion?


This was originally posted on March or 2008 at 10GbE.net

No. In March and April several companies began marketing 10GBase-T NICs: Chelsio, Neterion, Tehuti, and even Mellanox (the Infiniband company). Only one switch company, SMC, has dipped their toe in 10GBase-T market, why? Power. All of these products are based on first generation 10GBase-T silicon which is very thirsty for power.

In the 10GbE world all the NIC vendors separate their 10GbE chip from the physical (PHY) interface chip so they can be more responsive and flexible in creating NIC products and easily support several PHYs with a single 10GbE NIC chip. Today only three companies make 10GBase-T PHY chips: SolarFlare, Teranetics and Aquantia. Teranetics is having the most success signing Chelsio, Tehuti and Mellanox while Solarflare picked up SMC. What most avoid telling you is how much power these 10GBase-T PHY chips require, 8-12W. The vast majority of this power is used for only one purpose, separating the signal from the noise, the needle from the haystack.

What does this mean to you? Below is a simple example with 50 servers, focused only on the PHY power and the total power utilization for each of the three currently available media formats. Below is the power budget for the PHY on each end (NIC or Switch), total to support a server (both NIC and Switch PHY power) and the total for a 50 server project:

10GBase-CX4 PHY 0.5W/end, 1W/server, 50W for the project
10GBase-R XFP PHY 3W/end, 6W/server, 300W for the project
10GBase-T PHY 10W/end, 20W/server, 1000W for the project

This is the power needed to support just the 10GBase-T cabling and it is consuming enough energy to power two of the servers in your project! This is a cost you will carry for the life of the project and we all know conditioned data center power and cooling is not cheap.

When GbE first came out the initial round of PHY chips were also power hungry, of course that is no longer the case. With 10GbE the physics are significantly more challenging and it may take another year or two before 10GBase-T solutions have power consumption similar to CX4. If you are doing a project today that can benefit from 10GbE use CX4 if possible, or fiber if you need more than 15M. For fiber consider using SFP+ or XFPs as they are the most current optics, are the least expensive and consume far less power then XENPACK or X2.

Note on April 14th Solarflare announced their new PHY silicon, 10Xpress SFT9001, which consumes between 2.2 and 6W depending on cable length. This brings 10GBase-T into parity with fiber. This PHY chip will be available in sample lots to 10GbE OEMs in May. Even more recently on April 21, Aquantia announce a 10GBase-T PHY chip that is sampling in May and which claims to bring the power down to 5.5W for Cat6A cable up to 100M long. The delay from samples to OEM NIC vendors and completed NIC samples for customers is often in the neighborhood of 3-6 months. So in our opinion 10GBase-T NICs with a reasonable power envelope, 10-15W for the entire NIC, should be something that is available for consideration in the fall of 2008, just in time for those with year end budgets.

For more information and another perspective consider checking out what the Linley Group has to say on 10GBase-T.

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