fernxu.blogg.se

In the past several decades, Ethernet has evolved to meet the growing demands of packet-switched networks. Due to its proven low cost, known reliability, and simplicity, the majority of today’s Internet traffic starts or ends on an Ethernet connection. 40 Gigabit Ethernet (40GbE) that enables the transfer of Ethernet frames at speeds of up to 40 gigabits per second (Gbps) has been developed to increase computing and network aggregation applications.

This paper offers an overview of 40GbE technology and its physical standards.

In 2007, the IEEE Higher Speed Study Group started working toward 40GbE standards with the goal of increasing available bandwidth, while maintaining maximum compatibility with existing interfaces and network management principles. Efforts drove the development of physical layer specifications for communication across copper cabling, single-mode fiber (SMF) and multi-mode fiber (MMF). And continued efforts led to the approval of IEEE Std 802.3ba-2010 40 Gb/s standard.

The IEEE Std 802.3ba-2010 amendment specifies a single architecture shown below that accommodates 40 Gigabit Ethernet all of the physical layer specifications under development. The media access controller( MAC) layer, which corresponds to Layer 2 of the OSI model, is connected to the media (optical or copper) by an Ethernet PHY device. The PHY device consists of a physical medium dependent (PMD) sublayer, a physical medium attachment (PMA) sublayer, and a physical coding sublayer (PCS).

There are several 40 Gigabit Ethernet standards, such as 40G SR4 QSFP, 40G LR4 QSFP, 40G ESR4 QSFP, etc. The following passages introduce the main two 40 Gigabit Ethernet standards: 40G SR4 QSFP, and 40G LR4 QSFP.

• 40G SR4 QSFP—It supports a link length up to 100 meters on OM3 and 150m on OM4 over 850nm MMF. For example, Fiberstore compatible Extreme 40GB-SR4-QSFP transceiver enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber connectors and can also be used in a 4x10G module for interoperability with 10GBASE-SR interfaces.

• 40G LR4 QSFP—It supports link lengths of 10km on SMF at a wavelength of 1310nm. Take Cisco QSFP-40G-LR4, this transceiver module supports 40GBase Ethernet rate. The 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device.

40GbE runs on Quad Small Form Factor Pluggable (QSFFP) cabling, a high-density fiber connector with 12 strands of fiber. According to the task force, 40GbE fulfills the following requirements and objectives:

• Preserve the 802.3 Ethernet frame format utilizing the 802.3 MAC;

• Preserve minimum and maximum FrameSize of current 802.3 standard;

• Support high-bandwidth applications such as video on demand (VoD) and high-performance computing (HPC);

• Provide appropriate support for optical transport network (OTN);

• Provide specifications for operation over single-mode optical fiber, laser optimized multimode optical fiber, copper cables, and backplanes;

40GbE QSFP optics enable high-density and low-power 40 Gigabit Ethernet connectivity for data center, high-performance computing networks, enterprise core and distribution layers, and service provider applications. Fiberstore provides various 40GbE optics options for customers. Besides QSFP-40G-LR4, 40GB-SR4-QSFP and 40G-QSFP-ESR4 transceivers mentioned above, other40GbE standard optics also available, like JNP-QSFP-40GE-IR4. You can visit Fiberstore fo rmore information about 40GbE QSFP optics.