"Anker 633 Magnetic Battery", iPhone 13/12 can be wirelessly charged with 10,000 mAh, mobile battery that can also be a stand releasedRegarding Ethernet or 10GBASE-T, from 2017 [10GBASE-T, finally popular?], We delivered a total of 11 times and 2 extra editions.However, Ethernet for copper wiring by twisted pair is up to 10GBASE-T, and 25 / 40GBASE-T has not yet been put into practical use.As shown in the table below, which was also posted last time, the standard next to "SFP28" is "QSFP +".Originally, a standard called "QSFP (Quad SFP)" compatible with 4 Gbps was released as "SFF-8438" in November 2006.4Gbps is not in the Ethernet specification, but it is mainly used for Fiber Channel 2GFC / 4GFC and InfiniBand 4x.In short, it looks like four SFPs in one module, and when you look at the signal line, four pairs of 1Gbps signals are housed in a 38-pin connector.In order to accommodate this connector, the width of the QSFP has increased slightly as shown on the right.The size of the SFP has increased from 45 x 13.7 x 8.6 mm to 52.4 x 18.35 x 8.5 for the QSFP.By the way, in terms of the standards mentioned last time, SFP28 / SFP56 / SFP-DD have the same dimensions as SFP / SFP +, and QSFP + / QSFP28 / QSFP-DD have the same dimensions as QSFP.Returning to the story, QSFP + has increased the signal speed of this QSFP by 10 times to 10 Gbps.This was standardized as "SFF-8436".This SFF-8436, in fact, Change History started from 3.5 and the date when 1.0 was released is unknown, but when Molex released such a release on November 16, 2009, probably 1.0 was released at that time. I think it was done.In addition to 40/10 / 1GbE, it can be used with 10/8/4 / 2GFC of Fiber Channel and 4x / 2x / 1x of InfiniBand SDR / DDR / QDR, so it was widely used as it is.By the way, in SFF-8436, the module is defined as shown on the right.Next is "SFP56".In fact, this is not a standard standardized by SNIA.It is a unique specification that doubles the signal speed of QSFP28 to 50 Gbps for 50G Ethernet (eventually standardized as IEEE 802.3cd-2018) that has not been explained so far.Now about that "SFP-DD".DD stands for Double Density, which means double density.Formed in July 2017, SFP-DD MSA members include Alibaba, Broadcom, Brocade, Cisco, Dell EMC, Finisar, Hewlett Packard Enterprise, Huawei, Intel, Juniper Networks, Lumentum, Mellanox Technologies, Molex, and TE Connectivity. , There are quite a few companies in the list.As the name implies, the purpose of this SFP-DD MSA was to enable a module of the same size as the SFP to handle two lanes of signal lines.The pin layout is as follows, and it can be seen that two pairs of signals, TD / RD and TD1 / RD1, are prepared.By the way, the signal speed of SFP-DD corresponds to 14Gbps and 28Gbps.It is unclear how much the former is needed, but the idea from the beginning was to pass a 25 Gbps NRZ signal or a 56 Gbps PAM-4 signal per lane.With NRZ, 25Gbps x 2 matches exactly 50G Ethernet, and with NRZ, 100G Ethernet can be used.Since 14Gbps is half of this, we may have considered how to use 25G Ethernet for 12.5Gbps x 2 NRZ and 50G Ethernet for 14Gbps x 2 PAM-4.However, I have never seen a module that uses this method.By the way, in terms of time, the appearance of SFP-DD is long after SFP56 and QSFP28, so even though it is used for 100G Ethernet in that sense, there are not many cases where it was used for IEEE 802.3bm. ..So, I finally arrived at "QSFP28".The most used 100G Ethernet module at the moment is this QSFP28.As mentioned earlier, it is an extension of QSFP +, and as the name of QSFP28 indicates, it is a standard that passes 112 Gbps with 28 Gbps x 4 as opposed to 10 Gbps x 4 of QSFP +.However, in the case of 100G Ethernet, of course, it will be used as 25Gbps x 4.This QSFP28 was standardized as "SFF-8665" in September 2014.However, SFF-8665 is positioned as a compilation of the entire standard, and modules, connectors, cages, electrical characteristics, management mechanisms, etc. are defined in seven specifications, SFF-8636 to SFF-8683."IEEE 802.3bj" is listed alongside "IBTA EDR (InfiniBand EDR)" as the original standard. In the first place, the 25Gbps x 4 configuration is "100GBASE-KR4", "100GBASE-CR4", etc. This is because IEEE 802.3bj, which stipulates, was faster.However, since "100GBASE-SR4" will eventually have a configuration of 25Gbps x 4, it is supposed that it can be used in the same framework.The module shape of QSFP28 is exactly the same as QSFP +, only the electrical characteristics are different.In the first place, "SFF-8679" supports a large number of standards such as ITU-T G.957, Frame Relay, InfiniBand / Fiber Channel / SAS / Ethernet, etc.However, data is basically sent and received in a maximum of 4 pairs.In fact, even in the "APPLICATION REFERENCE MODEL" of SFF-8679 Figure 3-1 in the module, the transmitting side has a CTLE and the receiving side has a buffer, so it can not be very complicated, and it is assumed that it will be done. It has not been.Power Class is defined from 1 to 8, and Class 1 to 7 is from 1.5W to 5W in 0.5W increments.Only Class 8 can be used up to 10W separately, but this is only when the host side allows High Power Mode.There are three Vcc pins (Vcc1 / VccTx / VccRx) in all, and the voltage is 3.3V, so 500mA per pin is acceptable for Class 7, but it reaches 1A for Class 8.Therefore, if you are not careful, it may cause overheating, so it is natural to treat it specially.To put it the other way around, it is usually necessary to cover the processing within the range of 5W, and from this point of view, it can be said that it is difficult to incorporate complicated things such as signal conversion.Looking at Table 3-1 of SFF-8679 Figure 3, up to 200GbE is the target of QSFP28.This is 100GbE for 25Gbps NRZ x 4.This is because if 28 Gbps PAM-4 is used here, a bandwidth of 50 Gbps per lane, a total of 200 Gbps, can be realized.Free technical writer.We have a wide range of fields of expertise, from CPUs, memories and chipsets to communication-related, OS, databases, and medical-related fields.The homepage is http://www.yusuke-ohara.com/25Gbps x 4 100Gbps, optical Ethernet 2nd generation "IEEE 802.3bm-2015" standards standardizedCopyright © 2018 Impress Corporation. 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