Configure IEEE 802.3X Pause Frame Transmit
About this task
Configure IEEE 802.3X Pause frame transmit to eliminate or minimize packet loss.
By default, flow control mode is disabled. When disabled, the system does not generate nor configure the transmission of flow control messages. The system always honors received flow control messages regardless of the flow control mode status. You must enable this mode before you configure an interface to send pause frames.
By default, an interface does not send pause frames.
Note
If you enable MACsec on an interface and you send small packet size traffic near line rate, the In FlowCtrl frame might increment in the output of the show interfaces gigabitEthernet statistics command because of the processing overhead caused by adding the MACsec header of 32 bytes. This is part of the expected over-subscription footprint.
Procedure
Example
Enable flow control on the system and configure slot 1, port 10 to send pause frames. Verify the configuration.
Switch:1>enable Switch:1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch:1(config)#boot config flags flow-control-mode Warning: Please save the configuration and reboot the switch for this configuration to take effect. Switch:1<config>#save config CP-1: Save config to file /intflash/config.cfg successful. CP-1: Save license to file /intflash/license.xml successful. Switch:1<config>#disable Switch:1#boot Are you sure you want to re-boot the switch (y/n) ?y
Note
Flag support can vary across hardware models.
Switch:1#show boot config flags flags advanced-feature-bandwidth-reservation low flags block-snmp false flags debug-config false flags debugmode false flags dvr-leaf-mode false flags enhancedsecure-mode false flags factorydefaults false flags flow-control-mode true flags ftpd true flags hsecure false flags ipv6-egress-filter true flags ipv6-mode false flags logging true flags macsec false flags nni-mstp false flags reboot true flags spanning-tree-mode mstp flags spbm-config-mode true flags spbm-node-scaling true flags sshd true flags syslog-rfc5424-format true flags telnetd true flags tftpd true flags trace-logging false flags urpf-mode true flags verify-config true flags vrf-scaling true flags vxlan-gw-full-interworking-mode false
Switch:1(config-if)#show interfaces gigabitEthernet l1-config 1/10 ================================================================================================== Port Config L1 ================================================================================================== PORT AUTO OPERATE CUSTOM AUTO NEGOTIATION CANA ADMIN OPERATE ADMIN OPERATE NUM NEG. AUTO-NEG ADVERTISEMENTS ORIGIN DPLX SPD DPLX SPD TX-FLW-CTRL TX-FLW-CTRL -------------------------------------------------------------------------------------------------- 1/10 true true Not Configured RADIUS full 10000 0 enable enable
View the pause-frame packet count for slot 1, port 10.
Switch:1(config-if)#show interfaces gigabitEthernet statistics 1/10 ========================================================================================== Port Stats Interface ========================================================================================== PORT IN OUT IN OUT NUM OCTETS OCTETS PACKET PACKET ------------------------------------------------------------------------------------------ 1/1 29964704384 22788614528 234106526 178034166 PORT IN OUT IN OUT OUTLOSS NUM FLOWCTRL FLOWCTRL PFC PFC PACKETS ------------------------------------------------------------------------------------------ 1/1 0 11014 0 0 0
Variable Definitions
The following table defines parameters for the tx-flow-control command.
Variable |
Value |
---|---|
enable |
Configures the interface to send pause frames. By default, flow control is disabled. |
port {slot/port[/sub-port][-slot/port[/sub-port]][,...][slot/all][all]} |
Identifies the
slot and port in one of the following formats:
|
Use the data in the following table to use the show interfaces gigabitEthernet l1-config and show interfaces gigabitEthernet statistics commands.
Variable |
Value |
---|---|
{slot/port[/sub-port][-slot/port[/sub-port]][,...][slot/all][all]} |
Identifies the
slot and port in one of the following formats:
|