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Configuring switchd

switchd is the daemon at the heart of Cumulus Linux. It communicates between the switch and Cumulus Linux, and all the applications running on Cumulus Linux.

Cumulus Linux stores switchd configuration in the /etc/cumulus/switchd.conf file.

Configure switchd Parameters

You can control certain options associated with the switchd process. For example, you can set polling intervals, optimize ACL hardware resources for better utilization, configure log message levels, set the internal VLAN range, and configure default VXLAN encapsulation.

To configure switchd options, you either run NVUE commands or manually edit the /etc/cumulus/switchd.conf; however, NVUE currently supports a subset of the switchd configuration available in the /etc/cumulus/switchd.conf file.

You can run NVUE commands to set the following switchd options:

  • The statistic polling interval for physical intefaces.
  • The statistic polling interval for logical interfaces.
  • The log level you want to enable for debugging the data plane programming related code.
  • The DSCP action and value for encapsulation in VXLAN outer headers.
  • The DSCP action and value for decapsulation in VXLAN outer headers.
  • The route or neighbour preference.
  • The ACL mode (atomic or non-atomic).

To set the statistic polling interval (in seconds) for physical interfaces:

cumulus@switch:~$ nv set system counters polling-interval physical-interface 5
cumulus@switch:~$ nv config apply

To set the statistic polling interval (in seconds) for logical interfaces:

cumulus@switch:~$ nv set system counters polling-interval logical-interface 5
cumulus@switch:~$ nv config apply

To set the log level (debug, info, notice, warning, or err) you want to enable for debugging the data plane programming related code:

cumulus@switch:~$ nv set system forwarding programming log-level warning
cumulus@switch:~$ nv config apply

To set the DSCP action (copy, set, or derive) for encapsulation in VXLAN outer headers:

cumulus@switch:~$ nv set nve vxlan encapsulation dscp action copy
cumulus@switch:~$ nv config apply

To set the DSCP value for encapsulation in VXLAN outer headers for the action:

cumulus@switch:~$ nv set nve vxlan encapsulation dscp value
cumulus@switch:~$ nv config apply

To set the DSCP action (copy, preserve, or derive) for decapsulation in VXLAN outer headers:

cumulus@switch:~$ nv set nve vxlan decapsulation-dscp-action preserve
cumulus@switch:~$ nv config apply

To set the route or neighbour preference (route, neighbor, or route-and-neighbour):

cumulus@switch:~$ nv set system forwarding host-route-preference route-and-neighbour
cumulus@switch:~$ nv config apply

To set the ACL mode for ACLs (atomic or non-atomic) and enable the mode:

cumulus@switch:~$ nv set system acl mode atomic 
cumulus@switch:~$ nv set system acl mode enable on
cumulus@switch:~$ nv config apply

To configure the switchd parameters, edit the /etc/cumulus/switchd.conf file. Change the setting and uncomment the line if needed.

cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
#
# /etc/cumulus/switchd.conf - switchd configuration file
#

# Statistic poll interval (in msec)
#stats.poll_interval = 2000

# Buffer utilization poll interval (in msec), 0 means disable
#buf_util.poll_interval = 0

# Buffer utilization measurement interval (in mins)
#buf_util.measure_interval = 0

# Optimize ACL HW resources for better utilization
#acl.optimize_hw = FALSE

# Enable Flow based mirroring.
#acl.flow_based_mirroring = TRUE

# Enable non atomic acl update
acl.non_atomic_update_mode = FALSE

# Send ARPs for next hops
#arp.next_hops = TRUE

# Kernel routing table ID, range 1 - 2^31, default 254
#route.table = 254
...

When you update the /etc/cumulus/switchd.conf file, you must restart switchd with the sudo systemctl restart switchd.service command for the changes to take effect.

Restart switchd

Whenever you modify a switchd hardware configuration file (for example, you update any *.conf file that requires making a change to the switching hardware, like /etc/cumulus/datapath/traffic.conf), you must restart the switchd service for the change to take effect:

cumulus@switch:~$ sudo systemctl restart switchd.service

You do not have to restart the switchd service when you update a network interface configuration (for example, when you edit the /etc/network/interfaces file).

Restarting the switchd service causes all network ports to reset in addition to resetting the switch hardware configuration. NVIDIA recommends that you reboot the switch instead of restarting the switchd service to minimize traffic impact when redundant switches are present with MLAG.

NVUE commands restart the switchd service automatically; you do not need to run the sudo systemctl restart switchd.service command when using NVUE commands.