Users Guide

Configuring 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 configuration changes.
INTERFACE mode
show config
Flow Control Using Ethernet Pause Frames
An Aggregator auto-configures 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 flow control accordingly:
• Interfaces come up with DCB disabled and link-level flow 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 flow control.
• DCB is required for PFC, ETS, DCBX, and FCoE initialization protocol (FIP) snooping to operate.
Link-level flow control uses Ethernet pause frames to signal the other end of the connection to pause data transmission for a certain
amount of time as specified 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 flow
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 defined 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 configuration applicable to half duplex ports is rx off tx off.
Note that if a port is over-subscribed, Ethernet Pause Frame flow control does not ensure no loss behavior.
The following error message appears when trying to enable flow control when half duplex is already configured:
Can’t configure flowcontrol when half duplex is configure, config ignored.
The following error message appears when trying to enable half duplex and flow control configuration is on:
Can’t configure half duplex when flowcontrol is on, config ignored.
Enabling Pause Frames
Enable Ethernet pause frames flow 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 115