40/100 Gigabit Ethernet Overview

CreateDate:2016-08-08

        The IEEE 802.3working group is concerned with the maintenance and extension of the Ethernetdata communications standard.

        The speedschosen by 802.3ba were 40 and 100 Gbit/s to support both end-point and link aggregationneeds. This was the first time two different Ethernet speeds were specified ina single standard. The decision to include both speeds came from pressure tosupport the 40 Gbit/s rate for local server applications and the 100 Gbit/srate for internet backbones. The standard was announced in July 2007 and wasratified on June 17, 2010.

        The 40/100Gigabit Ethernet standards encompass a number of different Ethernet physicallayer (PHY) specifications. A networking device may support different PHY typesby means of pluggable modules. Optical modules are not standardized by anyofficial standards body but are in multi-source agreements (MSAs). Oneagreement that supports 40 and 100 Gigabit Ethernet is the C Form-factorPluggable (CFP) MSA which was adopted for distances of 100+ meters. QSFP andCXP connector modules support shorter distances.

        The standardsupports only full-duplex operation. Other electrical objectives include:

        1. Preserve the802.3 / Ethernet frame format utilizing the 802.3 MAC

        2. Preserve minimum and maximum FrameSizeof current 802.3 standard

        3. Support a biterror rate (BER) better than or equal to 10−12 at the MAC/PLSservice interface

        4. Provideappropriate support for OTN

        5. Support MAC data rates of 40 and 100Gbit/s

        6. Providephysical layer specifications (PHY) for operation over single-mode opticalfiber (SMF), laser optimized multi-mode optical fiber (MMF) OM3 and OM4, coppercable assembly, and backplane.

        The followingnomenclature is used for the physical layers:


        The 100m laseroptimized multi-mode fiber (OM3) objective was met by parallel ribbon cablewith 850 nm wavelength 10GBASE-SR like optics (40GBASE-SR4 and 100GBASE-SR10).The backplane objective with 4 lanes of 10GBASE-KR type PHYs (40GBASE-KR4). Thecopper cable objective is met with 4 or 10 differential lanes using SFF-8642and SFF-8436 connectors. The 10 and 40 km 100 Gbit/s objectives with fourwavelengths (around 1310 nm) of 25 Gbit/s optics (100GBASE-LR4 and100GBASE-ER4) and the 10 km 40 Gbit/s objective with four wavelengths (around1310 nm) of 10 Gbit/s optics (40GBASE-LR4).

 

100G Port Types:


        All variantslisted in the table share the 64b/66b Physical Coding Sublayer, and the mediacount is given per direction (i.e. double the count is required to form alink.) RS-FEC refers to the Reed-Solomon Layer defined in Clause 91, introducedin IEEE 802.3bj. DP-QPSK refers to Dual polarization-quadrature phase shiftkeying.


40Gport types:

40GBASE-CR4

        40GBASE-CR4("copper") is a port type for twin-ax copper cable. Its 64b/66b PCSis defined in IEEE 802.3 Clause 82 and its PMD in Clause 85. It uses four lanesof twin-axial cable delivering serialized data at a rate of 10.3125 Gb/s perlane.

 

40GBASE-KR4

        40GBASE-KR4 is aport type for backplanes. Normally backplanes are board traces, such asMegtron6 or FR4 materials. Its Physical Coding Sublayer 64b/66b PCS is definedin IEEE 802.3 Clause 82 and its Physical Medium Dependent PMD in Clause 84. Ituses four lanes of backplane delivering serialized data at a rate of 10.3125Gbit/s per lane.

 

40GBASE-SR4

        40GBASE-SR4("short range") is a port type for multi-mode fiber and uses 850 nmlasers. Its Physical Coding Sublayer 64b/66b PCS is defined in IEEE 802.3Clause 82 and its Physical Medium Dependent PMD in Clause 86. It uses fourlanes of multi-mode fiber delivering serialized data at a rate of 10.3125Gbit/s per lane. 40GBASE-SR4 has a reach of 100 m on OM3 and 150m on OM4. Thereis a longer range variant 40GBASE-eSR4 with a reach of 300 m on OM3 and 400 mon OM4. This extended reach is equivalent to the reach of 10GBASE-SR.

 

40GBASE-LR4

        40GBASE-LR4("long range") is a port type for single-mode fiber and uses 1300 nmlasers. Its Physical Coding Sublayer 64b/66b PCS is defined in IEEE 802.3Clause 82 and its Physical Medium Dependent PMD in Clause 87. It uses fourwavelengths delivering serialized data at a rate of 10.3125 Gbit/s perwavelength.

 

40GBASE-ER4

        40GBASE-ER4 ("extendedrange") is a port type for single-mode fiber being defined in P802.3bm anduses 1300 nm lasers. Its Physical Coding Sublayer 64b/66b PCS is defined inIEEE 802.3 Clause 82 and its Physical Medium Dependent PMD in Clause 87. Ituses four wavelengths delivering serialized data at a rate of 10.3125 Gbit/sper wavelength.

 

40GBASE-FR

        40GBASE-FR is aport type for single-mode fiber. Its Physical Coding Sublayer 64b/66b PCS isdefined in IEEE 802.3 Clause 82 and its Physical Medium Dependent PMD in Clause89. It uses 1550 nm optics, has a reach of 2 km and is capable of receiving1550 nm and 1310 nm wavelengths of light. The capability to receive 1310 nmlight allows it to inter-operate with a longer reach 1310 nm PHY should oneever be developed. 1550 nm was chosen as the wavelength transmission to make itcompatible with existing test equipment and infrastructure.

 

40GBASE-T

        40GBASE-T is aport type for 4-pair balanced twisted-pair Cat.8 copper cabling defined in IEEE802.3bq. IEEE 802.3bq-2016 standard was approved by The IEEE-SA Standards Boardon June 30, 2016.


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