40 Gigabit Ethernet (40GbE) is a group of computer networking technologies for transmitting Ethernet frames at rates of 40 gigabits per second. The technology was first defined by the IEEE 802.3ba-2010 standard. Users of this technology continue to increase as network operators need high data rates over a single connection. One critical step to migrate to 40G in a cost-effective way is to know more about it and choose appropriate cables and transceivers. This article gives a brief overview of the current 40G port types to aid in planning for future high-performance Ethernet needs.

40GBASE-SR4 ("short range") is a port type for multi-mode fiber and uses 850nm lasers. It uses four lanes of multi-mode fiber delivering serialized data at a rate of 10.3125 Gbit/s per lane. Its PCS (physical coding sublayer) 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD (physical medium dependent) in Clause 86. 40GBASE-SR4 has a reach of 100m on OM3 parallel fibers and 150m on OM4 parallel fibers. There is a longer range variant 40GBASE-eSR4 with a reach of 300m on OM3 and 400m on OM4. This extended reach is equivalent to the reach of 10GBASE-SR. QSFP+ transceiver is the primary module type used to deliver 40GbE. There are many QSFP+ transceivers for 40GBASE-SR4 applications, and they are branded by famous companies like Cisco, HP, Brocade and Finisar. For example, the following picture shows a FinisarFTL410QD2C40GBASE-SR4/4x10GBASE-SR QSFP+ transceiver.

40GBASE-LR4 ("long range") is a port type for single-mode fiber (SMF) and uses 1310nm lasers. Its PCS 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD in Clause 87. 40GBASE-LR4 is based on coarse wave division multiplexing (CWDM) technology and supports transmission over 10km on single-mode fiber. The grid is based on the ITU G.694.2 specification using wavelengths of 1270, 1290, 1310, and 1330nm. It uses four wavelengths delivering serialized data at a rate of 10.3125Gbit/s per wavelength. This will help provide maximum reuse of existing 10G PMD technology. In this way, the 40GBASE-LR4 PMD supports transmission of 40 Gigabit Ethernet over 4 wavelengths on each SMF in each direction. The following picture shows a Brocade40G-QSFP-LM440GBASE-LR4 QSFP+ transceiver.

40GBASE-CR4 ("copper") is a port type for twinax copper cable. Its PCS 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD in Clause 85. 40GBASE-CR4 uses four lanes of twin-axial cable delivering serialized data at a rate of 10.3125Gbit/s per lane. CR4 involves two clauses: CL73 for auto-negotiation, and CL72 for link training. CL73 allows communication between the two PHYs to exchange technical capability pages, and both PHYs come to a common speed and media type. Once CL73 has been completed, CL72 starts. CL72 allows each of the four lanes' transmitters to adjust pre-emphasis via feedback from the link partner.

40GBASE-ER4 ("extended range") is a port type for single-mode fiber and uses 1300nm lasers. Its PCS 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD in Clause 87. It uses four wavelengths delivering serialized data at a rate of 10.3125Gbit/s per wavelength.

40GBASE-FR is a port type for single-mode fiber and uses 1550nm optics. Its PCS 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD in Clause 89. 40GBASE-FR has a reach of 2 km and is capable of receiving 1550nm and 1310nm wavelengths of light. The capability to receive 1310nm light allows it to inter-operate with a longer reach 1310nm physical layer. 1550nm was chosen as the transmission wavelength to make it compatible with existing test equipment and infrastructure.

40GBASE-KR4 is a port type for backplanes. Its PCS 64B/66B is defined in IEEE 802.3 Clause 82 and its PMD in Clause 84. It uses four lanes of backplane delivering serialized data at a rate of 10.3125Gbit/s per lane.

40 Gigabit Ethernet has been demonstrated to be a viable solution for increased bandwidth requirements for growing networks. There are many 40GBASE transceivers in the market for your applications. Fiberstore is a professional manufacturer and supplier, which offers a large amount of cables and transceivers for your 40GbE applications. You can get what you need from us.

Posted by: jowang at 06:29 AM | No Comments | Add Comment
Post contains 687 words, total size 7 kb.