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40G Needed for Data Center Networks
Driven by growing bandwidth and network performance demand, data center network infrastructure is witnessing a transformation. As technology evolves, standards are completed to define data rates such as 40 Gigabit Ethernet (GbE) to meet such demands of high networking speed and performance. 40GbE addresses physical layer specifications for
communication across backplanes, copper cabling, single-mode fiber(SMF), and multi-mode fiber (MMF).
1G and 10G data rates are not adequate to meet the future needs of high-bandwidth applications. The requirement for higher data rates is being driven by many factors. Switching and routing, virtualization, convergence and high-performance computing environments are examples of where these higher network speeds will be required within the data center environment. Additionally, Internet exchanges and service provider peering points and high-bandwidth applications, such as video-on-demand driving the need for a migration from 10G to 40G interfaces.40G Physical Layer Alternatives
40GbE standards already exist for SMF, MPO based MMF, as well as copper cables. Listed below are three physical layer solutions for 40GbE.
- Single-mode Fiber
Due to its long reach and superior transmission performance, SMF is specified for carrying 40Gbps data up to a distance as long as 10km (40GBASE-LR4). The physical layer electronics and optics consist of four channels, each carrying 10Gbps data with different wavelengths. When there is no need to consider budget or the link distances are long, SMF is the preferred option for 40GbE in data center networks.
- Multi-mode Fiber
MMF with parallel optics MPO interface is the most popular medium for 40GbE today (40GBASE-SR4). Take F5-UPG-QSFP+ for example, Fiberstore compatible F5 Networks F5-UPG-QSFP+ (figure shown below) is a 40GBASE-SR4 QSFP+ transceiver with MPO connectors. It supports link lengths of 100m and 150m, respectively, on OM3 and OM4 MMFs at a wavelength of 850nm in a data center network. (OM3 and OM4 fibers were selected as the only MMFs for 40G consideration.)
- Copper Twinax
For short reach channels up to a length of 7m, 40GBASE-CR4 standard specifies use of twinax copper cable assembly. One typical application of this kind of copper cable is in 40G QSFP+ direct attach cable (DAC). For instance, Fiberstore compatible Brocade 40G-QSFP-C-0101 is the QSFP+ to QSFP+ passive copper cable assembly for very short distances.
40G transceivers were developed along several standard form factors. The C Form-Factor Pluggable (CFP) transceiver features 12 transmit and 12 receive 10-Gbps lanes to support one 100 Gigabit Ethernet port, or up to three 40 Gigabit Ethernet ports. Its larger size is suitable for the needs of single-mode optics and can easily serve multi-mode optics or copper as well. The CXP transceiver form factor also provides 12 lanes in each direction, but is much smaller than the CFP and serves the needs of multi-mode optics and copper. The Quad Small-Form-Factor Pluggable (QSFP) is similar in size to the CXP and provides four transmit and four receive lanes to support 40 Gigabit Ethernet applications
for multi-mode fiber and copper today.
40GbE supports high-speed switching, routing, and application functions in data centers. It provides optimized performance in meeting data center requirements. As a professional fiber optic products supplier and manufacturer, Fiberstore offers various 40GbE products, like 40G transceivers, and 40G cabling available both in fiber and copper. You can visit Fiberstore for more information about 40GbE solutions.
Originally published at www.fiber-optic-components.com/40g-needed-for-data-center-networks.html