10GBASE-T or SFP Plus

If I want to migrate our Data Center to 10G and I face the first problem: 10GBASE-T or SFP+. I understand this decision will affect to switches, servers and SAN (iscsi) and their interoperability, right? My first step is to allow 10 G in the switch, so does it must support SFP+ or 10GBASE-T?

What are the advantages and disadvantages of using 10GBase-T vs. SFP+ Direct Attach to interconnect devices where distance is not a determining factor?

I want to create a new home network as fast, reliable and future proof as possible and I cannot decide which of the two interfaces should I use: SFP+ Optic or 10GBASE-T? The max length will be 20m. I don’t have any issues with the cost (as long as the cost differences between them are reasonable). Which one should I choose?  Are there any switches (preferably managed) that support them both (at least two ports of each of them)?

These questions were asked by network switch users. Maybe you have the same question. What’s the main difference when you choose the 10GBASE-T or SFP+?

10GBase-T works at 100 meters for Cat6A cable and up to 50 meters for Cat6 cable. Also it is compatible with 1G and 100m speeds, so you can deploy your switch ports and start using it to connect to existing 1G server ports and migrate the server ports as you can.

Supported Cabling Types for 10GBASE-T

Cabling Type Maximum Distance According to IEEE 802.3an-2006 Standard Specification and Comments
Class F, Category 7: shielded 100m (328 ft) ●  ISO/IEC 11801●  These cabling systems exceed the minimum requirements for IEEE 10GBASE-T performance
Class Ea, Augmented Category 6 (Category 6A): both shielded and unshielded 100m (328 ft) ●  ISO/IEC 11801 Ed 2.1/TIA -568-C.2●  These cabling systems exceed the minimum requirements for IEEE 10GBASE-T performance
Class E, Category 6: screened (shielded) 100m (328 ft) ●  ISO/IEC TR-24750 TSB-155● Category 6 is specified only to 250 MHz. The cabling system must be certified to 500 MHz according to TSB-155 to help ensure 10GBASE-T compliance
Class E, Category 6: unscreened (unshielded) 55m (180 ft) ●  ISO/IEC TR-24750 TSB-155● Category 6 is specified only to 250 MHz. The cabling system must be certified to 500 MHz according to TSB-155 to help ensure 10GBASE-T compliance

Many IT managers are now evaluating the newly refreshed 10GBase-T technology, as the perception is that 10GBase-T is cheaper and easier to deploy than the alternative SFP+ technologies. The following table compares these two technologies:

10GBASE-T or SFP Plus01

Some comparisons of 10GBASE-T and SFP+ were list here by some experts and marketing managers, you can refer to the following comparison provided by Industry Perspectives.

Application Latency

As the adoption of private cloud applications increases, the need for low latency, large scale data centers is growing fast. Low latency is critical to ensuring fast response time and reducing CPU idle cycles; therefore, increasing data center efficiency and ROI.

When it comes to 10GBase-T, the PHY standard uses block encoding to transport data across the cable without errors. The block encoding requires a block of data to be read into the transmitter PHY, a mathematical function run on the data before the encoded data are sent over the link. The reverse happens on the receiver side. The standard specifies 2.6 microseconds for the transmit-receive pair, and the size of the block requires that latency to be less that 2 microseconds. SFP+ uses simplified electronics without encoding, and typical latency is around 300 nanoseconds (ns) per link.

Two microseconds may not seem high at first; however, if we imagine a TOR infrastructure where traffic is passing 4 hops to reach the destination, as much as 10.4usec delay is introduced when using 10GBase-T. This is a significant performance penalty compared to using 1.2usec introduced by the SFP+ DAC technology.   For each technology, the latency of physical media must be added. In fiber or wire, the speed is roughly 5ns per meter.

10GBASE-T or SFP Plus02

The 10GBase-T delay becomes the same order of magnitude as Solid State Disk latency, and therefore dramatically delays data delivery by nearly 50 percent.  High latencies in the data center infrastructure results in delays in CPU and application works, therefore limiting data center efficiency and increasing operational costs.

Power Consumption

As power grid companies cap power supplies to data centers, IT managers have become sensitive to server power consumption. Data center managers aspire for the lowest possible power consumption technologies. It is important to note that for every watt of power consumed; typically two additional watts are needed for cooling.  

10GBase-T components require anywhere from 2 to 5 watts per port at each end of the cable–depending on the distance of the cable–while SFP+ requires approximately 0.7 watt, regardless of distance.

10GBASE-T or SFP Plus03

When deploying thousands of cables in a data center, huge power saving can be achieved by choosing SFP+ DAC and fiber technology.

When planning for new data center cable infrastructures, new dynamics must to be considered:

  • Server, storage and interconnect virtualization
  • Application mobility across server and storage data center
  • Future proofing the data center cabling structure and applications

SFP+ Technology Ensures Optimal Performance and Lowest Latency

New dynamics within data centers mandate that the cable infrastructure handles latency sensitive applications anywhere.  When comparing 10GBase-T technology with the alternative SFP+ technology, it is evident that SFP+ is the right technology to ensure optimal performance with lowest latency in the data center.

SFP+ technology lowers the power budget

SFP+ technology delivers far lower power usage than the 10GBase-T technology. The cost saving becomes obvious when deploying from 1000 to 10,000 cables in the data center.

Some terms may help you know the difference well:

  1. 10GBase-T–IEEE standard 802.3an-2006 for operation at 10 gigabits per second over Cat 5/6/7 twisted pair cable at distances up to 100 meters
  2. 10GBase-SR–IEEE standard 802.3ae-2002 for operation at 10 gigabits per second over fiber optic cable at distances up to 300 meters
  3. DAC–Direct Attach Cable (also known as twinax). Some vendors incorrectly call these 10GBase-CU or 10GBase-CR cables, but there is no IEEE standard at this time.
  4. SFP–Small form-factor pluggable (also known as mini GBIC), for Fibre Channel and 1 gigabit Ethernet
  5. SFP+–Small form-factor pluggable, for 10 Gigabit Ethernet
  6. XFP–10 Gigabit, small form-factor, pluggable–larger than SFP+
  7. X2 and XenPak–10 Gigabit pluggable, older and larger than XFP or SFP+
  8. MSA–Multi-Source Agreement
  9. NIC–Network Interface Card
  10. PHY–physical layer standard, or the circuitry which drives it
  11. RJ45–connector widely used for Ethernet
  12. Cat 5/Cat 5E/Cat 6/Cat 6A/Cat7–different grades of twisted pair Ethernet cable

 

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