IO interface groups are supported by AI developers, HPC, Enterprise, and other market segment leaders, driving connector/cabling solutions using higher speed rates, varying lane counts, and pin counts. Besides supporting the very high volume pluggable Hyperscale market segment, various pluggable connector systems support other new applications and network topologies that are driving the use of both standard and non-standard application-specific connectors. Let’s look at some of these pluggable connectors and their key attributes, starting with high circuit types and ending with the smaller low circuit types.
HDEM 600G is a high-density embedded Module — a 24-lane x 25G transceiver module supporting optical SR24 links up to 50 meters and some switch radix applications. It uses a 260-pin electrical interface connector and two optical pigtail cables with 24 fiber MPO photonic connectors on each OM3 cable leg.
The module is 50 mm by 36 mm by 16 mm, so it is larger than the CFP8, OSFP, and QSFP-DD modules. It also seems likely that a 24-lane x 50G version could be released later this year. Figure 1 is an HDEM module.
CDFP has been recently selected by the PCIe-6 standards group and will be specified for 16 lanes of single-lane 64GT PAM4 signaling using 4-meter external copper twin-axial cable 1024GT links. This 120-position SMT connector is also being used for new CXL-3.1 IO interface switching applications. This module’s dimensions are about 32 mm wide, 44.36 mm long, and 11.78 mm high — so larger than other 16-lane pluggable connectors because of the extra circuit sideband options.
CFP-8 is a 16-lane x 25G or 8-lane x 50G per lane module supporting optical 400 G LR links. It may be improved and used for 4×100 G and 4×200 G developing applications. It uses a 124-pin 85-ohm electrical system connector. The module has a 40 mm x 9.5 mm x 102 mm form factor, which is larger than the OSFP and QSFP-DD types. So, it is mostly used on low port count telephony switch box applications.
OSFP-XD is a current 16-lane x 112 G per lane transceiver module supporting 1.6 T link applications. Using the new OIF specification, developers have 16-lane x 224 G per lane electrical signaling running well through the same electrical connector and supporting 1-meter copper cable 3.2 T and 3.6 T link new product releases. The OSFP module is 22.58 mm wide, 107.8 mm long, and 13 mm thick, so it is bigger than the QSFP-DD module with typically better thermal margins.
The OSFP connector system supports many Fabric IO interface applications, such as InfiniBand, Ultra Ethernet, Slingshot, and NVLink. A 32-lane belly-to-belly (top and bottom of PCB) or double-stacked SMT connector solution may be possible to create a massive 7.2 T link supporting new hyperscaler systems.
QSFP-DD is an 8-lane x 224 G per lane transceiver module supporting 1.6T Link applications mostly used for Ethernet switch boxes. The module has a shape of 18.35 mm wide, 89.44 mm long, and 8.5 mm thick. It is possible to make a 16-lane belly-to-belly doubled-stack SMT connector solution to create a 3.2 T or 3.6 T link and new modules.
QSFP112 is a 4-lane connector supporting 448 G Links. Some accelerator architectures, like NVLink-3, changed from using 8 lanes to 4 lanes, which addressed a market segment application needing fewer lanes. The QSFP module is 18.4 mm wide, 70 mm long, and 14.2 mm thick, so it is smaller than QSFP-DD and OSFP. It appears that a developing QSFP224 4-lane connector, cable, and module could support future 896 G link solutions.
MicroQSFP56 connectors support four-lane x 56G and potentially 112G per lane 224 G and 448 G Links and new pluggable modules. This connector is smaller than the QSFP and larger than the SFP-DD. This smaller connector is very useful if a significant cooling system is integrated within the module.
SFF-DD 112G connectors are being used for two-lane 224 G link applications. It seems possible that potential SFF-DD 224 G connectors could be used for 448 G 2-lane Links and pluggable modules. The SFP-DD cage is 14 mm wide, 54.15 long, and 8.55 thick. This small connector has the potential to solve the needs of 3-lane and 4-lane link applications.
SFP112 is a new one-lane 112 G connector that supports copper, optical cable, and module links for smart factory applications.
DSFP56 is a new two-lane 112 G link connector supporting copper cable links for telephony and 5G applications.
MicroSFP56 connectors are used with 1-lane, two twin-axial or twisted-pair cables, or pluggable module connectors. It is 50% smaller in width and length than the standard SFP connector and can be used for smart (embedded chip optional) iX industrial ethernet applications. A developing microSFP112 connector provides a low-cost smart iX industrial Ethernet link with room for supporting SMB network DACs, active copper, and active optical cables, and various pluggable modules.
USB-4.2 Type C connector is available and supports Consumer, Prosumer, and Professional high-end user market connectivity needs. It is also being used in the SMB data center market segment as a DAC network connector port. USB Type C connectors are very useful, supporting pluggable processors, storage, and networking-capable modules. It is a two-lane time 40 Gbps; each lane is implemented using either passive or active twin-axial copper or with various fiber-optical cabling solutions, all of which support this new 80 Gbps standard link.
The USB-4.2 standard also includes an optional 3×40 = 120 Gbps link that is targeted for the implementation of application-specific DACs. It seems that this USB data bandwidth is competing in some networking applications, like versus Ethernet 25 Gbps per lane, 56 G PAM4, and 106 Gbps PAM4 per lane connectors/cables. This USB-4.2 connector system supports several leading, very high-volume AV IO interfaces, like the latest DisplayPort, HDMI, and MHL interfaces, and others. USB-5 160 G Links are in R&D mode.
Pluggable connector DCI forecasting
Looking ahead, the higher-end market segments appear to be having a significant change in major network speed rates and connectivity types. This means going up from 200 G AOC Links to using mostly newer 400 G, 800 G, and 1.6 T optical pluggable modules with passive external optical harnesses/cables. Suppliers experiencing the lessening usage of AOCs, active external optical cables, need to get their chip technologies used in active optical pluggable modules.
It appears that 200 G per lane DAC pluggable receptacle connectors and copper active electronic cable assemblies have healthy near-term volume forecasting increases, but over the next few years, most average and higher-end DACs and AOCs applications will likely be replaced with active optical modules and passive external optical fiber harnesses. So, the race is on to supply 200 G per lane media types to the varying segments and equipment types.
Pluggable interconnect consortia updates
The PCIe 7.0 committee is developing internal and external copper connector/cabling specifications. This program is called CopperLink. This is for 128 GT per lane connectors and twin-axial cables. For internal cables, they may likely use the SNIA SFF 1002, 1020, and 1034 connectors and cabling specifications. For external copper cabling, they are likely to use the current industry-standard pluggable connector system but will mostly use QSFP-DD, OSFP, and OSFP-XD versions if their thermal budgets allow.
They are also developing an optical internal and external connector and cabling specification. It will be interesting to learn how many lanes per link and at what reach lengths the committee will choose to specify. For external longer links and using maybe 16 lanes times 128 GT and 256 GT per lane for 2.048 GT and 4.096 GT, links will mostly use single-mode optical fiber, including hollow and multi-core types for switch radix and other newer topologies. Could it be 8, 16, or up to 128 lane links products?
The CXL-3 committee has specified and is supporting the development of 64G per lane connectivity with an architecture that can support 1-256-lane applications. Another CXL group is working on CXL-4 specifications for 128G and 256G per lane signaling for use in 16-lane, 32-lane, and 64-lane link product solutions.
QSFP-DD MSA and OSFP-XD MSA consortia specification groups are driving 800 G, 1.6 T, and 3.2 T connector and module link requirements and specifications, working closely with OIF and other standards groups like FibreChannel.
Conclusions
AI’s fast-growing new applications and businesses are being implemented using accelerator chips, higher-count twin-axial copper cable elements, higher fiber-count optical cables, and Pluggable modules.
Current 1-20 G per lane factory automation links can use micro-SFP, SFP, SFP-DD fanouts, and microQSFP connectors and cables for future 25 G and 56 G per lane interfaces supporting industrial 4.0 and 5.0 specifications and smart applications.
Closer collaboration is key to having sensitive, very high-performance connectors, cables, and modules that need thorough product inter-compatibility testing. Be sure to utilize the latest revision of the CMIS specification for pluggable connectors. Be sure to check out all the 224 G demos, like Samtec’s backplane, pluggable connectors, and cables.
New, different market segments and growing applications support further development investment of evolving pluggable interconnect product families.
Filed Under: Connector Tips