IEEE 802.3ba - Standards

Standards

The IEEE 802.3 working group is concerned with the maintenance and extension of the Ethernet data communications standard. Additions to the 802.3 standard are performed by task forces which are designated by one or two letters. For example the 802.3z task force drafted the original gigabit Ethernet standard.

802.3ba is the designation given to the higher speed Ethernet task force which is working on modifications to support speeds higher than 10 Gbit/s.

The chosen speeds are 40 and 100 Gbit/s to support both end-point and link aggregation needs. This is the first time two different Ethernet speeds have been specified in a single standard. The decision to include both speeds comes from pressure to support the 40 Gbit/s rate for local server applications and the 100 Gbit/s rate for internet backbones. The standard was announced in July 2007 and was ratified on June 17, 2010.

The 40/100 Gigabit Ethernet standards encompass a number of different Ethernet physical layer (PHY) specifications. A networking device may support different PHY types by means of pluggable modules. Optical modules are not standardized by any official standards body but are in multi-source agreements (MSAs). One agreement that supports 40 and 100 Gigabit Ethernet is the C Form-factor Pluggable (CFP) MSA which was adopted for distances of 100+ meters. QSFP and CXP connector modules support shorter distances.

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

• Preserve the 802.3 / Ethernet frame format utilizing the 802.3 MAC
• Preserve minimum and maximum FrameSize of current 802.3 standard
• Support a bit error ratio (BER) better than or equal to 10−12 at the MAC/PLS service interface
• Provide appropriate support for OTN
• Support MAC data rates of 40 and 100 Gbit/s
• Provide Physical Layer specifications (PHY) for operation over single-mode optical fiber (SMF), laser optimized multi-mode optical fiber (MMF) OM3 and OM4, copper cable assembly, and backplane.

The following nomenclature was used for the physical layers:

The 100 m laser optimized multi-mode fiber (OM3) objective was met by parallel ribbon cable with 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). The copper cable objective is met with 4 or 10 differential lanes using SFF-8642 and SFF-8436 connectors. The 10 and 40 km 100G objectives with four wavelengths (around 1310 nm) of 25G optics (100GBASE-LR4 and 100GBASE-ER4) and the 10 km 40G objective with four wavelengths (around 1310 nm) of 10G optics (40GBASE-LR4).

In January 2010 another IEEE project authorization started a task force to define a 40 gigabit per second serial single-mode optical fiber standard (40GBASE-FR). This was approved as standard 802.3bg in March 2011. It used 1550 nm optics, had a reach of 2 km and was capable of receiving 1550 nm and 1310 nm wavelengths of light. The capability to receive 1310 nm light allows it to inter-operate with a longer reach 1310 nm PHY should one ever be developed. 1550 nm was chosen as the wavelength for 802.3bg transmission to make it compatible with existing test equipment and infrastructure.

In December 2010, a 10x10 Multi Source Agreement (10x10 MSA) began to define an optical Physical Medium Dependent (PMD) sublayer and establish compatible sources of low-cost, low-power, pluggable optical transceivers based on 10 optical lanes at 10 gigabits/second each. The 10x10 MSA was intended as a lower cost alternative to 100GBASE-LR4 for applications which do not require a link length longer than 2 km. It was intended for use with standard single mode G.652.C/D type low water peak cable with ten wavelengths ranging from 1523 to 1595 nm. The founding members were Google, Brocade Communications, JDSU and Santur. Other member companies of the 10x10 MSA included MRV, Enablence, Cyoptics, AFOP, OPLINK, Hitachi Cable America, AMS-IX, EXFO, Huawei, Kotura, Facebook and Effdon when the 2 km specification was announced in March 2011. The 10X10 MSA modules were intended to be the same size as the C Form-factor Pluggable specifications.

There are currently two projects in 802.3 underway to specify additional PHYs. The 802.3bj task force is working to produce 100 Gbps 4x25G PHYs for backplane and twin-ax cable (100GBASE-KR4, 100GBASE-KP4 and 100GBASE-CR4). The 802.3bm task force is working to produce lower cost optical PHYs. The detailed objectives for these projects can be found on the 802.3 website.