Therefore, these cables do not need a separate fiber breakout patch cord.Ĭomparing downlink density for switches with and without breakout capability If you’re using an AOC (Active Optical Cable) such as QSFP-4X10G-AOCxM or copper cables such as QSFP-4SFP25G-CUxM, the breakout structure may be built into the cable because they are pre-terminated and plug directly into the QSFP- or SFP-type ports. Remember, fiber breakout patch cords or cartridges are for pluggable optic transceivers. The main consideration is whether the fiber type is SMF or MMF.įor the QSFP-40G-SR4, QSFP-40G-CSR4, QSFP-4x10G-LR-S, QSFP-100G-SR4-S, QSFP-100G-PSM4-S, CPAK-100G-SR4, CPAK-100G-PSM4, QDD-400G-SR4.2-BD, QDD-400G-DR4-S, QDD-4x100G-FR-S, QDD-4x100G-LR4-S, and QSFP-200G-SR4, these transceivers utilize MPO-12 (Multifiber Push On) connectors for breakout as shown in the following diagram. The patch cord doesn’t depend on the data rate. If your fiber cable vendor doesn’t have a standard breakout patch cord, and you request a custom design, you can use the diagram below as a guide. Optics-to-optics interoperability matrixįiber optic breakout diagrams and transceiver pinouts They are generally 1 to 5 m long in passive configuration and 7 to 10 m long in active configuration and include the modules that plug into the equipment ports as shown in Figure 2.Įxamples of transceivers used in breakout applications are as follows.įor a full list and mapping of which optics can connect to each other via breakout, see the Optics-to-Optics Interoperability Matrix. Some of the options include breakout DACs, breakout AOCs, and transceivers.ĭirect Attached Cables (DACs) are fixed length and made of multiple copper twinax cables. What types of breakout options are available?īreakout is physically implemented with cables or transceivers. In addition, some transceivers utilize multiple optical wavelengths on a single fiber and breakout isn’t offered because of the complexities of optical muxing/demuxing, including power level imbalances and because it hasn’t been tested.Īlso, some transceivers like the QSFP-100G-SR-BD and QSFP-40G-SR-BD don’t have breakout capability even though they have 2x50G (2x25G-PAM4) and 2x20G optical lanes that operate on duplex fiber, because they weren’t designed for breakout. For example, there could be only a single CDR (Clock Data Recovery) circuit for a single lane in a multilane transceiver, thus preventing channelized operation. For example, the new QSFP-28 100G single lambda transceivers have 1 optical lane of 100G, and the ASIC in the transceiver converts from 4 lanes of NRZ 25 GHz electrical to 1 lane of PAM4 50 GHz optical.Īlso, some multilane transceivers are incapable of breakout because of limitations of the implementation of the ASIC in the transceiver. Generally, for breakout transceivers, the optical lanes equal the electrical lanes however, some transceivers have gearboxes that enable rate conversion and thus the optical lanes are reduced.
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