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I am new to infiniband networks, but i need to extend an existing infiniband cluster with some nodes. During my exploratory web-research I came across some to me ambiguous descriptions of cables, connectors and switches.

According to Wikipedia QSFP is specified as 4x1Gb/s, and QSFP+ as 4x10 or 40 Gb/s. However many suppliers on the web are offering QSFP cables and switches for 40 Gb/s. This some how does not seem to match with the overviews on different infiniband cabling that i found.

Is this just sloppy naming and are these QSFP 40Gb/s actually QSFP+? Is there a difference in the physical connections between QSFP and QSFP+? Or are just the cables of a different quality (like CAT6 and CAT7 cables), but is the shape of the connectors the same?

I would be very thankful if some body could clarify this a bit.

Hjan
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2 Answers2

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QSFP+ stands for Quad (4-channel) Small Form-Factor Pluggable Plus, also known as QSFP10. Now QSFP/QSFP+/QSFP28 all use 4 channels to pass data.

QSFP - People mistake this for QSFP+ ALL the time. Make sure you read the full description. QSFP is a 4x4Gbps (16GB) transceiver/cable. These are outdated and not really used from what I have seen

QSFP+ these are 40G or 4x10Gbps as each channel has 10GB speeds. These can be a single cable, QSFP+ to QSFP+ or QSFP+ breakout to 4xSFP+

QSFP28 are 100G cables, can also be 4x25G or 2x50G breakout cables.

KrisGT
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Additionally, QSFP modules are commonly available in several different types: 4x1G QSFP, 4x10G QSFP+, 4x28G QSFP28. From this side, QSFP/QSFP+/QSFP28 all share the same small form-factor. Literally QSFP uses 4x1G lanes and was only found in some FC/IB contexts.

QSFP+ was evolved from 4x1G lanes (QSFP) to 4x10G lanes, which is designed to support 40G Ethernet, Serial Attached SCSI, QDR (40G) and FDR (56G) Infiniband, and other communications standards. So QSFP+ can break out into 4x10G or 1x40G connection.

(source: http://www.fiber-optic-equipment.com/difference-between-qsfp-qsfp-qsfp28.html)

Ableson
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