Concept Guide

Conguring wavelength for 10–Gigabit SFP+ optics
You can set the wavelength for tunable 10–Gigabit SFP+ optics using the wavelength command. To set the wavelength, follow these
steps:
• Enter the interface mode and set the wavelength.
INTERFACE mode
wavelength 1529.0
The wavelength range is from 1528.3 nm to 1568.77nm.
• Verify conguration changes.
INTERFACE mode
show config
Flow Control Using Ethernet Pause Frames
An Aggregator auto-congures to operate in auto-DCB-enable mode (Refer to Data Center Bridging: Auto-DCB-Enable Mode). In this
mode, Aggregator ports detect whether peer devices support converged enhanced Ethernet (CEE) or not, and enable DCBX and PFC or
link-level ow control accordingly:
• Interfaces come up with DCB disabled and link-level ow control enabled to control data transmission between the Aggregator and
other network devices.
• When DCB is disabled on an interface, PFC, ETS, and DCBX are also disabled.
• When DCBX protocol packets are received, interfaces automatically enable DCB and disable link level ow control.
• DCB is required for PFC, ETS, DCBX, and FCoE initialization protocol (FIP) snooping to operate.
Link-level ow control uses Ethernet pause frames to signal the other end of the connection to pause data transmission for a certain
amount of time as specied in the frame. 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 o tx o.
Note that 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 half duplex is already congured:
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.
Enabling Pause Frames
Enable Ethernet pause frames ow control on all ports on a chassis. If not, the system may exhibit unpredictable behavior.
NOTE
: If you disable rx flow control, Dell Networking recommends rebooting the system.
Interfaces 117