Cisco Systems DSC9148D8G48PK9 manual Configuring Congestion Frame Timeout Value

Chapter 2 Configuring Interfaces

Configuring Interfaces

Configuring Congestion Frame Timeout Value

The default congestion frame timeout value is 500 milliseconds. We recommend that you retain the default configuration for the ISLs and configure a value that does not exceed the default value for the edge ports. If the frame is in the switch for a longer time than the configured congestion frame timeout, it gets dropped, which empties the buffer space in the ISL and alleviates the congestion.

To configure the congestion frame timeout value, follow these steps:

	Command	Purpose
Step 1
	switch# config t	Enters configuration mode.
Step 2
	switch(config)# system default interface	Configures a new congestion frame timeout
	congestion timeout milliseconds mode {core	value in milliseconds and the port mode for the
	edge}	device.
Step 3
	switch(config)# system default interface	Configures the default congestion frame timeout
	congestion mode {core edge}	value in milliseconds and the port mode for the
		device.
		The congestion timeout range is 100-1000
		milliseconds.
Step 4
	switch# show logging onboard flow-control	(Optional) Displays the request timeout for a
	request-timeout	source-destination pair per module with the
		timestamp information.

Configuring Stuck Frame Timeout Value

The default stuck frame timeout value is 500 ms. We recommend that you retain the default configuration for ISLs and configure a value not exceeding 500 ms (100 to 200 ms) for fabric F ports.

To configure the stuck frame timeout value, follow these steps:

	Command	Purpose
Step 1
	switch# config t	Enters configuration mode.
Step 2
	switch(config)# system timeout	Specifies the stuck frame timeout value in ms
	congestion-drop seconds mode EF	and the port mode for the switch.
	switch(config)# system timeout	Specifies the default stuck frame timeout port
	congestion-drop default mode EF	mode for the switch.

Configuring No-Credit Timeout Value

When the port does not have the credits for the configured period, no-credit timeout can be enabled on that port. This will result in all frames coming to that port getting dropped in the egress. This will free the buffer space in the ISL link, which carries traffic for this port. This will help reduce fabric slow down and congestion on other unrelated flows using the same link.

The frames that will be dropped would have just entered the switch or would have stayed in the switch for the configured timeout value. These are preemptive drops and will clear the congestion completely compared to the stuck frame timeout value.

No-credit timeout feature is disabled by default. We recommend that you retain the default configuration for ISLs and configure a value not exceeding 500 ms (200 to 300 ms) for fabric F ports.

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x		2-39