Version Description
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
8.1.1.0 Introduced on the E-Series ExaScale.
6.5.1.9 and 7.4.1.0 Introduced on the E-Series.
7.8.1.0 Introduced on the C-Series and S-Series with the
thresholds option.
Usage
Information 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 the reception of frames with a
destination address equal to this multicast address.
When a port receives traffic at a higher rate than it can process, the frames are
stored in the port buffer. As a result, buffer usage increases. When the buffer usage
reaches the value specified in the “pause-threshold” argument, the port sends
PAUSE frame to the connected link partner to stop sending the traffic. Eventually
this reduces the buffer usage. When the buffer usage drops by the value specified
in the “resume-threshold”, the port again sends a PAUSE frame with 0 as wait-time.
This results in resume of the paused traffic flow.
Important Points to Remember
• Do not enable tx pause when buffer carving is enabled. For information and
assistance, consult Dell Networking TAC.
• The only configuration applicable to half duplex ports is rx off tx off. The
following error is returned:
Can’t configure flowcontrol when half duplex is configure,
config ignored
• Half duplex cannot be configured when the flow control configuration is on
(default is rx on tx on). The following error is returned:
Can’t configure half duplex when flowcontrol is on, config
ignored
NOTE: The flow control must be off (rx off tx off) before configuring the
half duplex.
• Speeds less than 1 Gig cannot be configured when the asymmetric flow control
configuration is on. The following error is returned:
Can’t configure speed <1G when Asymmetric flowcontrol is on,
config ignored
• Dell Networking OS only supports rx on tx on and rx off tx off for
speeds less than 1 Gig (Symmetric).
NOTE: If you use the disable rx flow control command, Dell
Networking recommends rebooting the system.
672 Interfaces