Administrator Guide

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
EMC Networking TAC.
● Speeds less than one 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 EMC Networking OS only supports rx on tx on and rx off tx off for speeds less than
one Gig (Symmetric).
NOTE: If you use the disable rx flow control command, Dell EMC Networking recommends
rebooting the system.
NOTE: Dell EMC Networking OS does not support mirroring of tx pause frames.
Example
DellEMC(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
...
Example (Values)
This Example shows how Dell EMC Networking OS negotiates the flow control values between two Dell
EMC Networking chassis connected back-to-back using 1G copper ports.
Configured
LocRxConf LocTxConf RemoteRxConf RemoteTxConf
off off off off
off on
on off
on on
off on off off
off on
on off
on on
on off off off
off on
on off
on on
on on off off
off on
on off
on on
LocNegRx LocNegTx RemNegRx RemNegTx
off off off off
off off off off
off off off off
off off off off
off off off off
off off off off
Interfaces
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