Users Guide

Version Description
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 ow 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 trac at a higher rate than it can process, the frames are stored in the port buer. As
a result, buer usage increases. When the buer usage reaches the value specied in the “pause-threshold”
argument, the port sends PAUSE frame to the connected link partner to stop sending the trac. Eventually
this reduces the buer usage. When the buer usage drops by the value specied in the “resume-
threshold”, the port again sends a PAUSE frame with 0 as wait-time. This results in resume of the paused
trac ow.
Important Points to Remember
• Do not enable tx pause when buer carving is enabled. For information and assistance, consult Dell
Networking TAC.
• The only conguration 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 congured when the ow control conguration 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 ow control must be o (rx off tx off) before conguring the half duplex.
• Speeds less than 1 Gig cannot be congured when the asymmetric ow control conguration 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.
Example
Dell(conf-if-Te-1/1)#show config
!
interface TenGigabitEthernet 1/1
no ip address
switchport
no negotiation auto
flowcontrol rx off tx on
no shutdown
...
Interfaces
725