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Cumulus Linux

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If you are using the current version of Cumulus Linux, the content on this page may not be up to date. The current version of the documentation is available here. If you are redirected to the main page of the user guide, then this page may have been renamed; please search for it there.

Smart System Manager

Use Smart System Manager, also known as ISSU, to upgrade and troubleshoot an active switch with minimal disruption to the network.

Smart System Manager includes the following modes:

  • Restart
  • Upgrade
  • Maintenance

Restart Mode

You can restart the switch in one of the following modes.

  • cold restarts the system and resets all the hardware devices on the switch (including the switching ASIC).

  • fast restarts the system more efficiently with minimal impact to traffic by reloading the kernel and software stack without a hard reset of the hardware. During a fast restart, the system decouples from the network to the extent possible using existing protocol extensions before recovering to the operational mode of the system. The restart process maintain the forwarding entries of the switching ASIC and the data plane is not affected. Traffic outage is much lower in this mode; there is a momentary interruption after reboot, while the system reinitializes.

  • warm restarts the system with no interruption to traffic for existing route entries. Warm mode diverts traffic from itself and restarts the system without a hardware reset of the switch ASIC. While this process does not affect the data plane, the control plane is absent during restart and is unable to process routing updates. However, if no alternate paths exist, the switch continues forwarding with the existing entries with no interruptions.

    When you restart the switch in warm mode, BGP performs a graceful restart if the BGP Graceful Restart option is on. To enable BGP Graceful Restart, refer to Optional BGP Configuration.

    A warm boot disrupts bonds, VXLAN traffic, and IP multicast traffic until reboot completes.

The following command restarts the system in cold mode:

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -c

The following command restarts the system in fast mode:

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -f

The following command restarts the system in warm mode.

Warm boot resets any manually configured FEC settings.

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -w

Upgrade Mode

Upgrade mode updates all the components and services on the switch to the latest Cumulus Linux minor release without impacting traffic. After upgrade is complete, you must restart the switch with either a cold or fast restart.

Upgrade mode includes the following options:

  • all runs apt-get upgrade to upgrade all the system components to the latest minor release without affecting traffic flow. You must restart the system after the upgrade completes with one of the restart modes.
  • dry-run provides information on the components you want to upgrade.

The following command upgrades all the system components:

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -u

The following command provides information on the components you want to upgrade:

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -d

Maintenance Mode

Maintenance mode isolates the system from the rest of the network so that you can perform intrusive troubleshooting tasks and data collection or perform system changes, such as break out ports and replace optics or cables with minimal disruption.

Depending on your configuration and network topology, complete isolation is not possible.

Enable Maintenance Mode

Run the following command to enable maintenance mode. When maintenance mode is on, Smart System Manager performs a graceful BGP shutdown, redirects traffic over the peerlink and brings down the MLAG port link. switchd maintains full capability.

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -m1

You can run additional commands to bring all the ports down, then up to restore the port admin state.

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -p0
cumulus@switch:~$ sudo csmgrctl -p1

Before you disable maintenance mode, be sure to bring the ports back up.

Disable Maintenance Mode

Run the following command to disable maintenance mode and restore normal operation. When maintenance mode is off, Smart System Manager performs a soft restart, runs a BGP graceful restart, and brings the MLAG port link back up. switchd maintains full capability.

The NVUE command is not supported. 
cumulus@switch:~$ sudo csmgrctl -m0

Show Maintenance Mode Status

To see the status of maintenance mode, run the Linux sudo csmgrctl -s command. For example:

cumulus@switch:~$ sudo csmgrctl -s
Current System Mode: Maintenance since Tue Jan  5 00:13:37 2021 (Duration: 00:00:31)
 Boot Mode: reboot_cold  
 2 registered modules
 frr     : Maintenance, down
 switchd : Maintenance, down

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