Benefits of 10GBASE-T in 10GbE Data Center Migration

Large enterprises have been migrating their data center infrastructures accordingly with the bandwidth migrating from 100M Ethernet to 1/10 Gigabit Ethernet (GbE). 10GbE in the data center is very common now for 10GbE technology has been very mature. There are many interfaces options for 10GbE, such as CX4, SFP+ fiber, 10GBASE-T, and SFP+ direct attach copper (like HP J9281B SFP+ passive direct attach copper cable, or HP JG081C SFP+ passive direct attach copper cable). Among them, which one will you choose? Each one has its own advantages and disadvantages. In this post, we will talk about benefits of 10GBASE-T in 10GbE data center migration.

Shortcomings of SFP+ in 10GbE Data Center Migration

SFP+ has been adopted on Ethernet adapters and switches and supports both copper and fiber optic cables, which makes it a better solution than CX4. However, SFP+ optical transceiver (such as Cisco SFP-10G-LR-S 10GBASE-LR SFP+ transceiver) is not backward-compatible with the twisted-pair 1GbE broadly deployed throughout the data center. SFP+ connectors and their cabling were not compatible with the RJ-45 connectors used on 1GbE networks. Enterprise customers cannot just start adding SFP+ 10GbE to an existing RJ-45 1GbE infrastructure. New switches and new cables are required, which is a big chunk of change.

Why Choose 10GBASE-T in 10GbE Data Center Migration?

10GBASE-T is backward-compatible with 1000BASE-T, it can be deployed in the existing 1GbE switch infrastructures in the data centers that are cabled with CAT6, CAT6A or above cabling. As we know, 1GbE is still widely used in data center. Thus, 10GBASE-T is a great choice for gradual transition from 1GbE deployment to 10GbE. Other advantages of 10GBASE-T include:

Reach

Like all BASE-T implementations, 10GBASE-T works for lengths up to 100 meters, which gives IT managers a far-great level of flexibility in connecting devices in the data center. 10GBASE-T can accommodate either top of the rack, middle or end of the row network topologies, giving IT managers flexibility in server placement since it will work with the existing structured cabling systems.

Power

The challenge with 10GBASE-T is that even single-chip 10GBASE-T adapters consume a watt or two more than the SFP+ alternatives. More power consumption is not a good thing in the data center. However, the expected incremental costs in power over the life of a typical data center are far less than the amount of money saved from reduced cabling costs. Besides, with process improvements, chips improved from one generation to the next. The power and cost of the latest 10GBASE-T PHYs will be reduced greatly than before.

Reliability

Another challenge with 10GBASE-T is whether it could deliver the reliability and low bit-error rate of SFP+, or whether the high demands of FCoE could be met with 10GBASE-T. Cisco has announced that it had successfully qualified FCoE over 10GBASE-T and is supporting it on its newer switches that support 10GBASE-T in 2013.

Latency

10GBASE-T has a low latency range, from just over 2 microseconds to less than 4 microseconds. Latency for 10GBASE-T is more than 3 times lower than 1000BASE-T at larger packet sizes. Only the most latent sensitive applications such as HPC or high frequency trading systems would notice any latency.

Cost

When it comes to the cost, copper cables offer great savings. Typically, passive copper cables are two to five times less expensive than comparable lengths of fiber optic cables. In a 1,000-node cluster, with hundreds of required cables, that can translate into hundreds of thousands of dollars. Extending that into larger data centers, the savings can reach millions. Besides, copper cables do not consume power and because their thermal design requires less cooling, there are extensive savings on operating expenditures within the data center.

Conclusion

10GbE technology is very mature, reliable and well understood now. 10GBASE-T breaks through cable installation barriers in 10GbE deployment as well as offering investment protection via backwards compatibility with 1GbE networks. 10GBASE-T can save you money. By providing an easier path to migrate to 10GbE infrastructure, deployment of 10GBASE-T will simplify the networking transition in support of higher bandwidth needed for virtualized servers.

25GbE Cabling vs 40GbE Cabling

In recent years, 40 Gigabit Ethernet (GbE) has gained more popularity and the market of 40GbE is encouraging. But with the rapid growth of the new standard 100GbE, a new voice is announcing, namely 25GbE. As the increasing bandwidth requirements of private and public cloud data centers and communication service providers, 25GbE will to have a significant impact on server interconnect interfaces. Now you have two upgrade paths to 100G, 10G-25G-100G and 10G-40G-100G. Which one to choose? This post will make a comparison of 25GbE and 40GbE cabling, hoping it can help you make an appropriate decision.

25GbE Cabling Overview

25GbE is a standard developed by developed by IEEE 802.3 task forces P802.3by, used for Ethernet servers and switches connectivity in a datacenter environment. The single-lane design of 25 GbE gives it a low cost per bit, which enables cloud providers and large-scale data center operators to deploy fewer switches to meet the needs while still scaling their network infrastructure.

25GbE physical interface specification supports two main form factors, SFP28 (1×25 Gbps) and QSFP28 (4×25 Gbps). 25GBASE-SR SFP28 is an 850nm VCSEL 25GbE transceiver available in the market. It is designed to transmit and receive optical data over 50/125µm multi-mode optical fiber (MMF) and support up to 70m on OM3 MMF and 100m on OM4 MMF (LC duplex). In fact, using an SFP28 direct attach copper (DAC) cable for switches direct connection is a preferred option now. In addition, a more cost-effective solution is to use a QSFP28 to 4xSFP28 breakout cable to connect a 100GbE QSFP28 switch port with four SFP28 ports. DAC cable lengths are limited to three meters for 25GbE. Thus, active optic cable (AOC) solutions are also used for longer lengths of applications.

40GbE Cabling Overview

40GbE is a standard developed by the IEEE 802.3ba task force. The official development of 40GbE standards first began in January 2008, and were officially approved in June 2010. At the heart of the 40GbE network layer is a pair of transceivers connected by a fiber optic cable, OM4 or OM3 fiber cable. Fiber optic transceivers are plugged into either network servers or a variety of components, including interface cards and switches.

There are several standard form factors of 40GbE transceivers in the whole evolution. The CFP (C form-factor pluggable) transceiver uses 12 Tx and 12 Rx 10Gbps lanes to support one 100GbE port, or up to three 40GbE ports. With its large size, it can meet the needs of single-mode optics and can easily serve multi-mode optics or copper. But it is gradually falling behind since the increasing demand for high density. Another form factor is the CXP. It also provides twelve 10Gbps lanes in each direction, but is much smaller than the CFP and serves the needs of multi-mode optics and copper. At present, the most commonly used 40GbE form factor is the QSFP+ (quad small form-factor pluggable plus). It has the similar size with CXP but can provide four Tx and four Rx lanes to support 40GbE applications for single-mode, multi-mode fiber and copper.

Fiber optic cabling and copper cabling are both available for 40 GbE. The supportable channel length depends on the cable and the transceiver type. For data center 40GbE fiber optic cabling, OM3 and OM4 multi-mode cables are generally recommended because they can support a wider range of deployment configurations compared to copper solutions, and lower costs compared to single-mode solutions. MPO/MTP connectors are used at the multimode transceivers to support the multifiber parallel optics channels. For copper solutions, you can use QSFP+ direct attach copper cables, such as Cisco QSFP+ breakout cable. There are a lot of options, both active and passive, like Cisco QSFP-4SFP10G-CU5M compatible 40G QSFP+ to 4x10G SFP+ passive direct attach copper breakout cable (as shown below).

25GbE Cabling vs 40GbE Cabling

Compared to 40 GbE, 25GbE seems to be more suitable and cost-effective for cloud and web-scale data center applications. Using 25GbE with QSFP28 transceivers, users can deliver a single-lane connection, similar to the existing 10GbE technology but with 2.5X faster performance. In addition, 25GbE can provide superior switch port density by requiring just one lane (vs. 4 lanes with 40 GbE). Thus, it costs less and requires lower power consumption. Benefits of 25GbE compared to 40GbE are shown as below:

• Greater port density vs 40 GbE (one lane vs. four lanes)
• Maximum switch I/O performance and fabric capability
• Lower cost versus 40 GbE
• Reduced capital expenditures (CAPEX) and operational expenditures (OPEX)
• Fewer ToR switches and fewer cables
• Requires less power, cooling, and footprint
• Leverage of the existing IEEE 100GbE standard

Summary

25GbE seems to be a preferred option in the next step. It can provide up to 2.5 times faster performance than the existing 10GbE connections while maximizing the Ethernet controller bandwidth/pin and switch fabric capability. It can also provide greater port density with lower cost compared to 40GbE solutions. The trend will always be wider band and higher speed and port density. 25GbE or 40 GbE, let’s wait and see how things play out.