Deployment Guide

owcontrol
Controls how the system responds to and generates 802.3x pause frames on 10G and 40Gig stack units.
Syntax
flowcontrol rx {off | on} tx {off | on} pause-threshold value
Parameters
rx on Enter the keywords rx on to process the received ow control frames on this port. This
is the default value for the receive side.
rx o Enter the keywords rx off to ignore the received ow control frames on this port.
tx on Enter the keywords tx on to send control frames from this port to the connected device
when a higher rate of trac is received. This is the default value on the send side.
tx o Enter the keywords tx off so that ow control frames are not sent from this port to
the connected device when a higher rate of trac is received.
pause-threshold Enter the buer threshold limit for generating PAUSE frames.
Defaults
• rx off
• tx off
Command Modes INTERFACE
Supported Modes Programmable-Mux (PMUX)
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.4(0.0) Supported on the FN I/O Aggregator.
9.2(0.0) Introduced on the M I/O Aggregator.
8.3.16.1 Introduced on the MXL 10/40GbE Switch IO Module.
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.
The pause:
• Starts when either the packet pointer or the buer threshold is met (whichever is met rst). When the discard
threshold is met, packets are dropped.
• Ends when both the packet pointer and the buer threshold fall below 50% of the threshold settings.
The discard threshold denes when the interface starts dropping the packet on the interface. This may be
necessary when a connected device does not honor the ow control frame sent by the switch. The discard
threshold should be larger than the buer threshold so that the buer holds at least hold at least three packets.
Important Points to Remember
• Do not enable tx pause when buer carving is enabled. For information and assistance, consult Dell
Networking TAC.
• Asymmetric ow control (rx on tx off, or rx off tx on) setting for the interface port less than 100
Mb/s speed is not permitted. The following error is returned:
198 Interfaces