100G Lambda MSA offers preliminary specs based on PAM4 serial 100G

The 100G Lambda Multi-Source Agreement (MSA) Group has released preliminary specifications for the development of optical transceivers using 100-Gbps optical lanes and PAM4 modulation. The specifications cover both 100 Gigabit Ethernet and 400 Gigabit Ethernet applications. Final specifications are expected later this year.

The 100G Lambda Multi-Source Agreement (MSA) Group has released preliminary specifications for the development of optical transceivers using 100-Gbps optical lanes and PAM4 modulation. The specifications cover both 100 Gigabit Ethernet and 400 Gigabit Ethernet applications. Final specifications are expected later this year.

The MSA announced its formation last September (see "100G Lambda MSA targets serial 100-Gbps optical lanes for 100GbE, 400GbE"). The group has aimed to leverage the work of the IEEE P802.3bs Task Force, which has included a PMD based on 100-Gbps optical lanes and PAM4 modulation for 400 Gigabit Ethernet applications in its recently completed work (see "Ethernet Alliance salutes approval of IEEE 802.3bs 200 Gigabit Ethernet, 400 Gigabit Ethernet standard"). However, the MSA members have targeted reaches of 2 km on duplex single-mode fiber at 400G, significantly longer than the 500 m of the 400GBASE-DR4 PMD. The 100G specifications cover 2 and 10 km over single-mode fiber, which also exceeds the 500-m distance target of the 100GBASE-DR PMD the IEEE P802.3cd Task Force is contemplating (see "IEEE approves standards initiatives for 25 Gigabit Ethernet, 50, Gigabit Ethernet, 200 Gigabit Ethernet").

The preliminary specifications are available on the MSA's website. MSA promoter members include Alibaba, Applied OptoElectronics, Arista Networks, Broadcom, Ciena, Cisco, Finisar, Foxconn Interconnect Technology, Inphi, Intel, Juniper Networks, Lumentum, Luxtera, MACOM, MaxLinear, Microsoft, Molex, NeoPhotonics, Nokia, Oclaro, Semtech, Source Photonics, and Sumitomo Electric. The group is actively soliciting contributor members.

The group's approach for 400 Gigabit Ethernet contrasts sharply with that of the CWDM8 MSA, which has adapted eight lanes of 50 Gbps each using NRZ modulation for 2- and 10-km applications (see "New CWDM8 MSA specifications cover 400 Gbps over 2 km" and "CWDM8 MSA releases specifications covering 400 Gbps over 10 km"). The use of NRZ breaks with the IEEE 400 Gigabit Ethernet specs, but will result in faster time to market, the CWDM8 MSA group asserts.

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