EMB Guidance in IEC 60793-2-10:2019
October/November/December 2020 I 57
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
840 850 860 870 880 890 900 910 920 930 940
Wavelength (nm)
OM5
OM4
OM3
950
EMB (MHz-km)
FIGURE 14: EMB guidance for OM3/4 MMF between 850 and 953 nm according to IEC 60793-2-10:2019.
One of the major additions is effective modal bandwidth
(EMB) guidance for OM3/4 MMF at wavelengths between
840 and 953 nm (Figure 14).
This was needed to support the work of the IEEE
P802.3cm 400 Gb/s over Multimode Fiber Task Force that
specified the standard IEEE Std 802.3cmTM-2020. The standard
was approved by IEEE-SA Standards Board on January
30, 2020 and was published on March 30, 2020.
Meanwhile, TIA’s TR42 Telecommunications
Cabling Systems Committee and its TR42.12 subcommittee,
Optical Fibers and Cables, has adapted IEC’s fiber specifications;
this includes adapting IEC 60793-2 (General)
to ANSI/TIA-4920000-C and adapting IEC 60793-2-10
(MMF family) to ANSI/TIA-492AAAF. The latter standard
consolidated five TIA MMF documents (TIA-492AAAA,
AAAB, AAAC, AAAD, AAAE) into a single document.
Recent MMF Work in Fibre Channel and FCIA
The newest Fibre Channel standard is FC-PI-7,
64GFC, which specifies 100 m reach for OM4/OM5
fiber and 70 m reach for OM3. In July 2018, the T11
FC-PI-7/64GFC (serial) committee of INCITS completed
its first letter ballot vote with unanimous approval and
some comments. FC-PI-7/64GFC was published
in November 2019.
Nearing completion is T11 of FC-PI-7P, 256 GFC
parallel (4 x 64 GFC) standard, which specifies 100 m
reach for OM4/OM5 fiber and 70 m reach for OM3.
Letter ballot review has been completed and is proceeding
to public review. Publication of the standard
is expected before the end of 2020.
The latest Fibre Channel project is FC-PI-8/128GFC
(serial/single lane), which was initiated in December
2017 and became an approved project in April 2018.
The FC-PI-8 MRD has a target technical stability
date of 2021, and product availability is targeted
for 2022. The requirements include backward
compatibility to 32 GFC/64 GFC and 100 m reach
for OM5/OM4.
This project will leverage the work in the IEEE
P802.3ck 100 Gb/s, 200 Gb/s, and 400 Gb/s Electrical
Interfaces Task Force for the electrical lane specifications
and the work underway in IEEE P802.3db 100 Gb/s,
200 Gb/s, and 400 Gb/s Short Reach Fiber Task Force,
as well as potential work in OIF for 100 Gb/s optical
lanes. Key challenges remain to be solved; these include
the technical feasibility of 100 Gb/s VCSEL links meeting
100 m OM4/OM5 reach requirements, meeting backplane
loss budgets, and handling host printed circuit
board (PCB) loss.