Reference 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.
You must enable the fan-out mode in order for this mechanism to work.
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: Trident2 chip sets do not work at 1G speeds with auto-negotiation enabled. As a result, when you peer any device
using SFP, the link does not come up if auto-negotiation is enabled. Therefore, you must disable auto-negotiation on
platforms that currently use Trident2 chip sets (S6000 and Z9000). 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.
Important Points to Remember
● Before using the QSA to convert a 40 Gigabit Ethernet port to a 10 Gigabit SFP or SFP+ port, you must 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 in a QSA setup.
● When you remove the QSA module alone from a 40 Gigabit port, without connecting any SFP or SFP+ cables; Dell
Networking OS does not generate any event. However, when you remove a QSA module that has SFP or SFP+ optical
cables plugged in, Dell Networking OS generates a SFP or SFP+ Removed event.
● The QSA module does not have a designated EEPROM. To recognize a QSA, Dell Networking OS reads the EEPROM
corresponding to a SFP+ or SFP module that is plugged into QSA. The access location of this EEPROM is different from the
EEPROM location of the QSFP+ module.
● The diagnostics application is capable of detecting insertion or removal of both the QSA as well as the SFP+ or SFP optical
cables plugged into the QSA. In addition, the diagnostic application is also capable of reading the DDS and Vendor
information from the EEPROM corresponding to SFP+ or SFP optical cables. As a result, no separate detection of QSA is
required.
Support for LM4 Optics
The newly supported LM4 optics are similar in behavior to the LR4 optics that are already supported. However, in the output of
show inventory media command, an LM4 optical module is denoted as 40G-LM4. Barring this exception, the functionality
and behavior of LM4 optics is similar to LR4 optics.
Example Scenarios
Consider the following scenarios:
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Interfaces