Breakout cable assemblies are also called Fan-out, Hydra and Octopus cables depending on what market segment and application history is involved. The name Hydra is used by those in the enterprise infrastructure interconnect industry. Breakout is the term favored by many Cloud datacenter people. Fan-out has been mostly used by enterprise datacenter people and Octopus is an earlier term used by long time interconnect developers. It is good to know the best term to use depending on your audience as some folks have a sense of ownership with their technical verbiage. I have mentioned these terms in recent blogs on this website, but now here are some details on this increasingly important interconnect type.
Breakout high-speed IO cables have solved bulkhead or panel port density problems by using one higher circuit count connector on one end of the assembly with multiple cable legs coming out of it and having individual connectors on each cable leg. Let’s take a look at some popular custom and standard breakout cable assemblies.
From a cable assembly supplier viewpoint, these breakout cables represent a product that has more valued-added and more margin than a regular one-connector, single (one) leg cable to one-connector assemblies. Newer higher density port switch box and breakout cables can often represent 30-40% of cable assembly type usage by OEMs. If a supplier does well with breakout cables, they usually can enjoy a healthy portion of the more regular single leg link cables business. But be careful as it takes a lot more effort and care to do wire/shield and drain (if used), preparation and termination of four separate cable legs or exponentially more cable processing like with 12 SFP+ cable legs coming out of one CXP connector.
Telecommunications and some infrastructure interconnects have been using the 24 twisted pair MRJ21 connector with six CAT5e and CAT6a cable legs having a RJ45 plug on each end. Some newer IoT applications are taking advantage of the 50% smaller .5RJ connector on each end. Some industrial automation applications include using the MRJ21 connector and six cable legs each having a M12 Ethernet connector on each end. Currently there is no 1.5- or 2-GHz MRJ21 connector available for breakout cables to use with new CAT8 cables and connectors for supporting Ethernet 25GBAseT performance.
There can be many different configurations of breakout cable assemblies, for example, they can have different cable leg lengths as the cable bundle going from a ToR switch down to connect to every server or storage blade box. Some MoR breakout cables have the same length cable legs that can go up or down connecting to leaf server boxes.
Product developers can use a QSFP+, uQSFP, QSFP28 or OCulink connector with four cable legs each terminated with a SFP+ or uSFP or SFP28 or newer RCx1 or USB-Type C connectors or a mixture of these types. Mellanox’s cable assembly uplink product is an example of a popular new application using a QSFP28 100GbE port connected to four SFP28 25GbE single lane ports.
Potential newer breakout cable assemblies may include using an eight-leg version featuring the developing QSFP-DD 28G to eight SFP28, or uSFP, or RCx1 connectors. It is likely that we may see the need and development of having one external PCIe OcuLink 4x connector with 4 cable legs using USB-Type C plug connectors for microRack small business center applications.