Users Guide

Version Description
9.10(0.0) Introduced on the S6100–ON.
9.8(1.0) Introduced on the Z9100–ON.
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S6000-ON.
9.2(1.0) Introduced on the Z9500.
9.0.2.0 Introduced on the S6000.
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.
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.
• 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-Gi-1/1)# show config
!
interface GigabitEthernet 1/1
no ip address
switchport
no negotiation auto
flowcontrol rx off tx on
no shutdown
...
Interfaces 609