Software FEX Mode Configuration

Software FEX Mode Configuration

By default, Cisco Nexus switches operate in the switch mode. However, Cisco Nexus 9300-FX3 platform switches also support the FEX mode. This FEX mode allows a switch to operate like a Cisco Nexus 2000 Series Fabric Extender. As a result, the switch will not require any independent software upgrades, configuration backups, or other maintenance tasks.

Cisco Nexus switches in software FEX mode support 25G FEX connectivity to the host for a single point of management use cases.

See Platform Support Matrix, to check for the supported switches.

TOR/Switch to FEX Conversion

This section describes how to convert the switch usage from TOR/switch mode to FEX mode.

  • Configure the switch in a way that it does not boot from Cisco NX-OS mode.

  • Run the copy running-config startup-config command before booting the FEX image.

  • Run the boot fex command. This command sets the FEX as the boot variable.

  • Reload the switch.


Note

Do not run the copy running-config startup-config command after you run the boot fex command.

A sample ToR to FEX conversion is provided below.

switch(config)# write erase 
switch(config)# no boot nxos 
switch(config)# copy running-config startup-config
switch(config)# boot fex 
switch(config)# reload

FEX to TOR/Switch Conversion

This section describes how to convert the switch usage from FEX to switch/TOR mode.

  • Run the conversion command, boot nx-os bootflash:/<nxos image> from the FEX terminal.

  • You must upload a Cisco NX-OS image when you use this conversion command.

  • This conversion command verifies the Cisco NX-OS image and sets the boot variable. Hence the FEX boots with the specified Cisco NX-OS image on the reload.


Note

FEX does not have or save any configuration. Hence you must save the running configuration as the startup configuration.

A sample FEX to ToR conversion is provided below.

fex-1(config)# boot nxos bootflash:/<nxos image>
fex-1(config)# reload

You can use the following commands to configure management IP and copy the NX-OS image to FEX.

Commands

Uses

dir

Lists all files in bootlfash.

delete file-name

Removes file in bootlfash.

interface mgmt 0

ip address ip address network mask

ip route network_gateway

Configures management IP to FEX. The management IP must be connected physically.

show interface mgmt 0 brief

Verifies the configured management IP.

copy scp:[//[username@]server][/path] bootflash:[filename]

Copies the Cisco NX-OS image file to FEX for converting it to ToR mode.