Supported Cabling Types for 10GBASE-T

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:

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.

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.

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

The main challenge of  IT managers faced 

In particular to 10 gigabit Ethernet (10GbE), IT managers are now faced with the challenge of selecting the appropriate 10-gigabit physical media, as 10GbE is offered in two broad categories: optical and copper.

The main challenge IT managers face when selecting a new cable solution is the ability to support current and future data center deployments and trends::

• Many-core Servers – servers include more and more CPU cores to cope with data growth and application requirements.
• Virtualization – consolidating application workloads onto more highly utilized servers using virtualization technologies such as VMware, Hyper-V, XEN and KVM.
• Storage Area Networks (SAN) – networked storage delivers services to multiple compute elements, both at block storage or file system.
• I/O Consolidation – usage of a single interconnect infrastructure for all communications needs: compute, storage and management.
• Data Center Network Aggregation – as the deployment of 10GbE increases, there is a need for higher speed switch uplinks for network aggregation in the data center (40GbE and above).

10GBASE-T Cabling vs. SFP+ DAC Cable: What Are Their Differences?

Now let us compare 10GBASE-T Cabling vs. SFP+ DAC Cable. The below table shows the detailed 10GBASE-T cabling and SFP+ DAC cable difference.

#1 – Cost Comparison

The SFP+ DAC is a lower-cost alternative to fiber, but it can only reach 10 meters. It requires purchasing an adapter card and a new top-of-rack (ToR) switch topology. DAC Cables are much more expensive than structured copper channels and cannot be field terminated. This makes the DAC more expensive than 10GBASE-T.

Many networks now have Cat 6, or Cat 6a cabling installed, so they are ready for 10GBase-T. Any existing fiber can be reused for 10GbE. The new Cat 6 or Cat 6a cable can be added at a lower cost than direct-attached dual-axis copper or fiber multi-mode connections.

Finally, training and knowledge transfer costs can be reduced because IT personnel are already familiar with Ethernet technology and RJ-45 connectors. Because SFP+ DAC does not have the flexibility and longer distance of 10GBASE-T, it only applies to 10GbE short-distance cabling.

#2 – Latency Comparison

The 10GBase-T PHY standard uses block coding to enable data to pass through the cable without error. The block encoding requires reading the data block into the transmitter PHY, running a mathematical function on the data, and sending the encoded data over the link. The opposite happens at the receiving end. The standard specifies 2.6 microseconds for the transmit-receive pair, and the data block size indicates that the wait time cannot be improved by approximately 2.0 microseconds per link.

The SFP+ DAC cable uses simpler electronics without the need for code blocks. Typical latency is about 300 nanoseconds per link. By comparison, SFP+ DAC provides lower latency, but 10GBASE-T and SFP+ fiber cabling provide higher latency.

#3 – Distance Comparison

Use the latest Cat 6A or Cat 7 cable, 10GBase-T up to 100 meters. The standard has been designed to allow patch panels and jumper cables. The SFP+ DAC provides a maximum distance of 10 meters (about 33 feet) based on passive copper cable. There are no patch panels used with DACs.

#4 – Flexibility Comparison

SFP+ DAC is not backward-compatible with existing GbE switches and only used for 10GbE switches. Where rose, 10GBASE-T SFP+is backward compatible with existing 1 GbE networks. Therefore, 10GBASE-T cabling offers the most flexibility and the lowest cost media.

What is the difference between 10GBASE-T and 10gb SFP+?10GBASE-T and 10G SFP+ are two different kinds of technology which transmit data via copper and fiber respectively. 10GBASE-T technology provides the most flexible and economical solution while 10G SFP+ offers the compatible and user-friendly solution for 10G Ethernet connectivity option.
 

What is the difference between 10gb SFP and SFP+?

SFP and SFP+ transceivers are virtually identical in size and appearance. The primary difference is that SFP+ is an updated version that supports higher speeds up to 10Gbps. The difference in data rate also accounts for a difference in transmission distance—SFP typically has a longer transmission distance.

What is the difference between 10baset and SFP?

Compared to fiber-based SFP+ transceivers, 10GBASE-T transceivers require a higher power consumption. The max power consumption of a 10GBASE SR SFP+ optical transceiver is only 0.8W, while the 10G copper transceiver is 2.5W.

When planning a new cluster cabling, IT managers are faced with the challenge of future proofing their investment, as well as the predicting  future application requirements.

Considerations for Cable Infrastructure

When planning a future cable infrastructure, it is important to make sure that the physical infrastructure will support future application needs, and future technology roadmaps. IT or the data center managers prefer to avoid installing multiple cable infrastructures for separate application traffic requirements – such as High Speed CPU-to-CPU communication using 40Gbps Infiniband and Storage and Internet connectivity using 10Gbps Ethernet.

IO consolidation, which is critical to reducing data center capital and operational costs, mandates that the cable infrastructure support new dynamics and challenges.