Deployment Guide

Important Points to Remember
• 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 rst 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.
• 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 an SFP or SFP+ Removed event.
Example Scenarios
Consider the following scenarios:
• QSFP port 0 is connected to a QSA with SFP+ optical cables plugged in.
• QSFP port 4 is connected to a QSA with SFP optical cables plugged in.
• QSFP port 8 in fanned-out mode is plugged in with QSFP optical cables.
• QSFP port 12 in 40 G mode is plugged in with QSFP optical cables.
For these congurations, the following examples show the command output that the show interfaces tengigbitethernet
transceiver
, show interfaces tengigbitethernet, and show inventory media commands displays:
NOTE
: In the following show interfaces tengigbitethernet commands, the ports 1,2, and 3 are inactive and no physical
SFP or SFP+ connection actually exists on these ports. However, Dell Networking OS still perceives these ports as valid and the
output shows that pluggable media (optical cables) is inserted into these ports. This is a software limitation for this release.
Layer 2 Flow Control Using Ethernet Pause Frames
Ethernet pause frames allow for a temporary stop in data transmission.
A situation may arise where a sending device may transmit data faster than a destination device can accept it. The destination sends a
pause frame back to the source, stopping the sender’s transmission for a period of time.
The globally assigned 48-bit Multicast address 01-80-C2-00-00-01 is used to send and receive pause frames. To allow full duplex ow
control, stations implementing the pause operation instruct the MAC to enable reception of frames with a destination address equal to this
multicast address.
The pause frame is dened by IEEE 802.3x and uses MAC Control frames to carry the pause commands. Ethernet pause frames are
supported on full duplex only. The only conguration applicable to half duplex ports is rx off tx off.
NOTE
: If a port is over-subscribed, Ethernet Pause Frame ow control does not ensure no loss
behavior.
The following error message appears when trying to enable ow control when you already congured half duplex: Can’t configure
flowcontrol when half duplex is configure, config ignored.
The following error message appears when trying to enable half duplex and ow control conguration is on: Can’t configure half
duplex when flowcontrol is on, config ignored.
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Interfaces