pause no-drop buffer-size

To enable Class Based Flow Control (CBFC) pause characteristics on a class referenced in a type network-qos policy map and configure the ingress buffer size for the no-drop class, use the pause no drop buffer-size command. To disable the CBFC pause characteristics on a class and reset the buffer, use the no form of this command.

pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

no pause no-drop buffer-size buffer-size pause-threshold xoff-size resume-threshold xon-size

Syntax Description

buffer-size

Buffer size for ingress traffic, in bytes. Valid values are from 10240 to 490880.

Note On a Cisco Nexus 5020 switch, you can configure a maximum buffer size of 143680 bytes.
On a Cisco Nexus 5548 switch, you can configure a maximum buffer size of 152000 bytes.

pause-threshold

Specifies the buffer limit at which the port pauses the peer.

xoff-size

Buffer limit for pausing, in bytes. Valid values are from 0 to 490880.

Note On a Cisco Nexus 5020 switch, you can configure a maximum pause threshold value of 58860 bytes.
On a Cisco Nexus 5548 switch you can configure a maximum pause threshold value of 103360 bytes.

resume-threshold

Specifies the buffer limit at which the port resumes the peer.

xon-size

Buffer limit at which to resume, in bytes. Valid values are from 0 to 490880.

Note On a Cisco Nexus 5020 switch, you can configure a maximum resume threshold value of 38400 bytes.
On a Cisco Nexus 5548 switch you can configure a maximum resume threshold value of 83520 bytes.


Command Default

By default, pause no-drop is on.

Command Modes

Policy map type network-qos class configuration

Command History

Release
Modification

5.0(2)N1(1)

This command was introduced.


Usage Guidelines

Use this command to configure the buffer size and threshold values for a no-drop class. You configure the buffer size to support lossless Ethernet over a link distance of 3000 meters (9843 feet). In Cisco NX-OS release 5.0(2)N1(1), the switch software rejects the policy if enough buffer resources are not available to support the policy.

When you configure the buffer size, ensure the following:

•The buffer size must be greater than the pause threshold value, and the pause threshold value must be greater than the resume threshold value. Otherwise, the following message appears:

ERROR: buffer-size can't be less then pause/resume-threshold

The minimum difference between the pause threshold value and the resume threshold value must be 20480 bytes on a Cisco Nexus 5020 switch and 19840 bytes on a Cisco Nexus 5548 switch. Otherwise, you see the following message on a Cisco Nexus 5020 switch:

Warning: The recommended difference between pause  and resume threshold is 20480 bytes

You see the following message on a Cisco Nexus 5548 switch:

Warning: The recommended difference between pause  and resume threshold is 19840 bytes

•The pause threshold value must be greater than the resume threshold value. Otherwise, the following message appears:

ERROR: pause-threshold can't be less then resume-threshold

Examples

This example shows how to enable pause no-drop on a class referenced in a type network-qos policy map:

switch(config)# class-map type network-qos my_class1 
switch(config-cmap-nq)# match qos-group 2 
switch(config-cmap-nq)# exit 
switch(config)# policy-map type network-qos my_policy1 
switch(config-pmap-nq)# class type network-qos my_class1 
switch(config-pmap-nq-c)# pause no-drop 
switch(config-pmap-nq-c)# 

This example shows how to set the no-drop buffer size for 3000 metres on a class referenced in a type network-qos policy map on a Cisco Nexus 5000 Series switch:

switch(config)# policy-map type network-qos pu-buffer 
switch(config-pmap-nq)# class type network-qos cu1 
switch(config-pmap-nq-c)# pause no-drop buffer-size 143680 pause-threshold 58860 resume-threshold 38400 
switch(config-pmap-nq-c)#

This example shows how to set the no-drop buffer size for 3000 metres on a class referenced in a type network-qos policy map on a Cisco Nexus 5548 switch:

switch(config-pmap-nq)# policy-map type network-qos policy-test 
switch(config-pmap-nq)# class type network-qos cu1-ta1 
switch(config-pmap-nq-c)# pause no-drop buffer-size 152000 pause-threshold 103360 resume-threshold 83520 
switch(config-pmap-nq-c)#

Related Commands

Command
Description

show class-map type network-qos

Displays type network-qos class maps.

show policy-map

Displays policy maps.