Two module standards "OSFP" and "CDFP" that realize up to 400Gbps

"OSFP" is targeted by 400g/200g Ethernet with 8 PAM-4 or 25Gbps NRZ for 50Gbps

　Following the previous "CFP8" and "QSFP-DD", I would like to explain "OSFP" and "CDFP" this time.

　The OSFP MSA was launched in November 2016.There are 49 companies, including Nel America, NOKIA, OCLARO, PHY-SI, SAE, Senko, Source Photonics, Sumitomo Electric, TE Connectivity, and Yamaichi Electric.

　In the case of MSA, it is usually a little more narrowed down, and the standardization is completed, but if there are so many member companies so far, it seems to be somewhat confused.In fact, SPECIFICATION Revision 1.0 was released in May 2017, six months later, and it took a little time for this kind.By the way, OSFP is an abbreviation for Octal Small Factor Pluggable.

　By the way, both OSFP modules and Optical/Copper are compatible, but is the feature that is short on the module but the heat sink is integrated?The outer shape (width x depth x height) 22.58 x 100.40 x 13.00mm (maximum) is a little larger than CFP4.

OSFPモジュール。出典はOSFP MSAのトップページヒートシンクのフィンは貫通式で、フロントパネル側からシャーシ内部に冷却風を流すような形状。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 3-1

　However, there are not many cases in which a heat sink is attached to the module side (usually the heat is escaped to the cage in the form of contacting the cage side and the heat sink is attached to it).By the way, in the upper right figure, the upper lid is on the heat sink, but the standard does not have to be this, as shown in the lower left.

　However, there is a limit to the ability to dissipate heat with this level (up to 3.80 mm), and it is assumed that a heat dissipation fin is attached to the cage side.

あくまでも外形寸法が規格内（つまり高さ13.00mm以内）なら、放熱用フィンがそのまま見えていても問題ないとのこと。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 3-14このケージ側のフィンの寸法の規定を探したが見つからなかった。採用側がシャーシ内のレイアウトなどと考慮しながら決める話なので、ここで上限を定めても意味がないのかもしれない。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 9-2むしろなぜRevision 3.0まで定義されなかったのか、ちょっと不思議である。ちなみにこれは2x1タイプだが、Specificationには2x4/2x6タイプのものも定義されている。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 5-1

　By the way, the original Specification had no stack -type one in the cage, and only one row was prepared.This is defined as the right figure in Revision 3.0.

　By the way, this OSFP, as shown in the lower left, the main target is "400GBASE-DR4", "400GBASE-SR8", "400GBASE-SR4.2", "400GBASE-FT4", "400GBASE-FT4", "400GBASE-FR8", and 400GBASE-LR8.I am.However, in addition to the 400g Ethernet, it also covers 200GBASE-FR4 × 2 and CWDM4 × 2 (this is later) as shown in the lower right.

400GBASE-SR8の場合のブロック図。ホスト側とは「400GAUI-8」で接続する。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 10-2CWDM4はCWDM4 MSAの策定する100G Ethernet規格。こちらはもう少し後に取り上げる予定だ。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 10-7Vccは全部でわずか4本。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のFigure 11-1

　The connector itself is 60 pins as shown on the right, and a pair of transmission and receiving signals are passed here.

　As for its signal, it is a 25Gbps NRZ or 50Gbps PAM-4 in mind, but in addition to 400G, it is possible to use it for 200GBase-SR4 × 2 as shown below.。

一番下の構成だと、1つのOSFPモジュールから25GBASE-SR×8（NRZ）ないし50GBASE-SR×8（PAM-4）を出すことも技術的には可能。ただ、そうしたモジュールは見たことも聞いたこともない。出典は"OSFP OCTAL SMALL FORM FACTOR PLUGGABLE MODULE Rev 3.0"のTable 11-3

　Another point that OSFP is different from other modules is the power supply.As I wrote earlier, 4 VCC pins are 4 and the power supply voltage is 3.3V, but in order to allow 1.6A per pin, the maximum configuration is 3.3V x 6.4a ≒ 21.1W, so the module introduced so far.It has a composition that can withstand higher power consumption.

OSFPの方がQSFPよりもサイズが大きいので、アダプターを介してOSFPのケージにQSFPモジュールを搭載できる。もっとも、スイッチ側が対応した信号を出していなければ意味はないが。出典は"OSFP to QSFP adapter for backward compatibility"

　Power Classは1～8まで、それぞれ1.5/3.5W/7W/8W/10W/12W/14W/>14Wが定義されている。Class 3から妙に細かく刻んでいる気がしなくはないが、放熱のことも考えると、むやみに消費電力枠を引き上げても自らの首が締まるだけなので、できれば14Wまでで抑えたいのだと思われる。

　By the way, the interesting thing about OSFP is that there is an adapter for QSFP as shown on the right.As a result, the QSFP module can be used in the OSFP -compatible cage (or switch).However, I have never actually seen this adapter is used.