Capturing the Cost Savings of 10G to 25G Migration
In June of 2016 the 25GbE Ethernet Consortium released its final recommendation for 25GbE Ethernet. The new standard was defined to allow users 2.5 times the performance of 10GbE by utilizing existing server hardware. 25GbE makes sense in part because it can cost-effectively leverage the single-lane 25 gigabit per second signaling technologies. Industry giants such as Mellanox® and Intel® have introduced economical server NIC cards. We will reference Intel in this article because East Coast Datacom, Inc has extensive experience with Intel server NIC cards within our embedded network latency emulator designs. The Intel 25GbE model XXV710 delivers wide interoperability with SFP , SFP28 and QSFP28 switches in the market, enabling a smooth adoption and upgrade to 25GbE within customers existing network infrastructure. The XXV710 supports 1/10/25GbE data rates. The NIC card SFP28 insert model E25GSFP28SR for Fiber connections is very economically priced and supports both 10G and 25G rates. Users will benefit with greater port density utilizing 25GbE as compared to the hardware and 4-lane cabling upgrade costs associated with 40GbE.
It should be noted that the new 25GbE standard has required two important features for optimum performance. These features are called auto-negotiation (AN) and link training (LT) as both are required by the 25GbE IEEE 802.3by standard and was not specified prior for 10GbE. AN and LT are utilized to support two things, link speed and which type, if any, Forward Error Correction or FEC will be utilized. Both AN and LT contribute to the speed and quality of the 25GbE link. So, before upgrading to 25GbE confirm your vendor supplied switches support both auto-negotiation (AN) and link training (LT) as some vendors pre-released equipment before the standard was adopted may not support these important features.
Obviously, this has thrown the 40GbE migration in many cases to a standstill because of the cost vs performance justification. It is easy to understand that 25GbE presents a more economical growth for 10G to 25G migration.
It’s all about cost savings while gaining the benefit of 2.5 times the performance compared to 10GbE. Servers utilizing Intel 10GbE NIC Cards can accept the PCIe 3.0 25GbE NIC Cards utilizing the existing x8 buss width. Simple adjustments for peak performance are easily obtained by follow Intel’s Tuning Throughput Performance for Intel Ethernet Adapters guide found on their support pages for the XXV710 NIC card. For line rate packet performance it is recommended to utilize Intel’s Data Plane Development Kit also known as DPDK. The DPDK technology allows up to 10x the performance for 64byte packet throughput and is heavily used in cloud computing environments and is being adopted by some carriers.
It should also be well noted that the effect of 1G to 10G, 10G to 25G migration can affect system latency. In all cases it is a recommended practice to test your applications to insure a smooth migration. East Coast Datacom, Inc manufactures an economical network latency emulator for network migration testing.
In conclusion, 25GbE delivers the same bandwidth at a lower capital expense when compared with 10GbE. For example, two 25GbE ports versus five 10GbE ports to deliver 50Gb of bandwidth. With 25Gb backward compatibility to 10Gb, it provides a natural upgrade migration path for customers who require more bandwidth.