Users Guide

Converting a QSFP or QSFP+ Port to an SFP or SFP+
Port
You can convert a QSFP or QSFP+ port to an SFP or SFP+ port using the Quad to Small Form Factor Pluggable Adapter (QSA).
QSA provides smooth connectivity between devices that use Quad Lane Ports (such as the 40 Gigabit Ethernet adapters) and 10 Gigabit
hardware that uses SFP+ based cabling. Using this adapter, you can effectively use a QSFP or QSFP+ module to connect to a lower-end
switch or server that uses an SFP or SFP+ based module.
When connected to a QSFP or QSFP+ port on a 40 Gigabit adapter, QSA acts as an interface for the SFP or SFP+ cables. This interface
enables you to directly plug in an SFP or SFP+ cable originating at a 10 Gigabit Ethernet port on a switch or server.
You can use QSFP optical cables (without a QSA) to split a 40 Gigabit port on a switch or a server into four 10 Gigabit ports. To split the
ports, enable the fan-out mode.
Similarly, you can enable the fan-out mode to configure the QSFP port on a device to act as an SFP or SFP+ port. As the QSA enables a
QSFP or QSFP+ port to be used as an SFP or SFP+ port, Dell Networking OS does not immediately detect the QSA after you insert it into
a QSFP port cage.
After you insert an SFP or SFP+ cable into a QSA connected to a 40 Gigabit port, Dell Networking OS assumes that all the four fanned-
out 10 Gigabit ports have plugged-in SFP or SFP+ optical cables. However, the link UP event happens only for the first 10 Gigabit port and
you can use only that port for data transfer. As a result, only the first fanned-out port is identified as the active 10 Gigabit port with a
speed of 10G or 1G depending on whether you insert an SFP+ or SFP cable respectively.
NOTE
: Although it is possible to configure the remaining three 10 Gigabit ports, the Link UP event does not occur for these
ports leaving the lanes unusable. Dell Networking OS perceives these ports to be in a Link Down state. You must not try to use
these remaining three 10 Gigabit ports for actual data transfer or for any other related configurations.
NOTE: You can use the QSA adaptor to establish connectivity between a high-density 100 Gigabit platform and a relatively
lower-end 1 Gigabit switch or a server. The QSA acts as an interface between the QSFP28 ports (that support 100 Gigabit
speeds) and SPF optics with a maximum speed of 1 Gigabit per second. Depending on the type of optics you plug into the QSA
connected to a 100 Gigabit port, the system automatically detects the supported speed of the optics and sets the interface
speed accordingly. For example, if you plug in optics that support 40 Gigabit speeds, the speed of the interface is set to 40G.
Similarly, if you plug in optics that support 1G speed, the speed of the interface is set to 1G.
NOTE: You cannot enable 1G speed on any port with auto-negotiation enabled. As a result, when you connect to a device using
SFP, the link does not come up if auto-negotiation is enabled. To use a port in 1G speed, disable auto-negotiation. This limitation
applies only when you convert QSFP to SFP using the QSA. This constraint does not apply for QSFP to SFP+ conversions using
the QSA.
NOTE: You can use a copper SFP module on QSFP ports using a QSA adapter.
Important Points to Remember
• Starting from Dell OS 9.7(0.0), as part of dynamic fan-out support, only 96 ports can be split into 10G mode. Remaining eight ports
stay in 40G. For more information, see Fanning out 40G Ports Dynamically.
• Before using the QSA to convert a 40 Gigabit Ethernet port to a 10 Gigabit SFP or SFP+ port, enable 40 G to 4*10 fan-out mode on
the device.
• When you insert a QSA into a 40 Gigabit port, you can use only the first 10 Gigabit port in the fan-out mode to plug-in SFP or SFP+
cables. The remaining three 10 Gigabit ports are perceived to be in Link Down state and are unusable.
• You cannot use QSFP Optical cables on the same port where QSA is used.
Interfaces
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